The impact of vorticity waves on the shock dynamics in core-collapse supernovae

NASA Astrophysics Data System (ADS)

Huete, César; Abdikamalov, Ernazar; Radice, David

2018-04-01

Convective perturbations arising from nuclear shell burning can play an important role in propelling neutrino-driven core-collapse supernova explosions. In this work, we analyse the impact of vorticity waves on the shock dynamics, and subsequently on the post-shock flow, using the solution of the linear hydrodynamics equations. As a result of the interaction with the shock wave, vorticity waves increase their kinetic energy, and a new set of entropic and acoustic waves is deposited in the post-shock region. These perturbations interact with the neutrino-driven turbulent convection that develops in that region. Although both vorticity and acoustic waves inject non-radial motion into the gain region, the contribution of the acoustic waves is found to be negligibly small in comparison to that of the vorticity waves. On the other hand, entropy waves become buoyant and trigger more convection. Using the concept of critical neutrino luminosity, we assess the impact of these modes on the explosion conditions. While the direct injection of non-radial motion reduces the critical neutrino luminosity by ˜ 12 per cent for typical problem parameters, the buoyancy-driven convection triggered by entropy waves reduces the critical luminosity by ˜ 17-24 per cent, which approximately agrees with the results of three-dimensional neutrino-hydrodynamics simulations. Finally, we discuss the limits of validity of the assumptions employed.

The soft X-ray background as a supernova blast wave viewed from inside - Solar abundance models

NASA Technical Reports Server (NTRS)

Edgar, R. J.

1986-01-01

A model of the soft X-ray background is presented in which the sun is assumed to be inside an active supernova blast wave. The blast wave evolves in a preexisting cavity. The broad band surface brightnesses is explained by such a blast wave with an explosion energy of E sub approximately 5 x 10 to the 50th power ergs and radius 80 to 100 pc, using solar abundances. An approach to treating the problem of large anisotropies in the ambient medium is also explored, accommodating the observed anticorrelation between the soft X-ray surface brightness and the 21 cm column density. It is found that only for post shock temperatures below 10 to the 6 power K a shock propagating into a density enhancement will be dimmer than a similar shock in a lower density region.

A kinematic study of 0509-67.5, the second youngest supernova remnant in the Large Magellanic Cloud, and its astrophysical implications

NASA Astrophysics Data System (ADS)

Hovey, Luke

2016-05-01

Supernova remnants are the lasting interactions of shock waves that develop in the wake of supernovae. These remnants, especially those in our galaxy and our companion galaxies, allow us to study supernovae for thousands of years after the initial stellar explosions. Remnants that are formed from Ia supernovae, which are the explosions and complete annihilation of white dwarf stars, are of particular interest due to the explosions' value as standard candles in cosmological studies. The shock waves in these young supernova remnants offer an unparalleled look into the physical processes that take place there, especially since these shocks are often simpler to study than shocks with strong radiative components that are present in remnants that are formed from the core-collapse supernovae of massive stars. I will detail the work of my kinematic study of the second youngest remnant in the Large Magellanic Cloud, 0509--67.5, which has been confirmed to be the result of a Ia supernova. Chapter 2 details the proper motion measurements made on the forward shock of this remnant, which has led to many key results. I was able to use the results of ii the global shock speed in the remnant to measure the density of neutral hydrogen in the ambient medium into which these shocks expand. In addition, I use the measurements of the shock speed for select portions of the forward shock to search for signatures of efficient cosmic-ray acceleration. Hydrodynamic simulations are then employed to constrain the age and ambient medium density of 0509--67.5, as well as to place limits on the compression factor at the immediate location of the blast wave. Chapter 3 uses the proper motion results from chapter 2 to determine possible asymmetries in the expansion of the remnant for the eastern and western limbs. These measurements are then used as constraints in hydrodynamic simulations to assess the possible dynamical offset of the explosion site compared to the geometric center of 0509?67.5 that we observe today. I find a continuum of possible offsets, which are sensitive to assumptions that are made about the evolutionary history of the remnant, and use the uncertainties in these calculations to determine the area in which to search for a leftover progenitor companion star in the event that the explosion resulted from a single-degenerate system. The stars within this search area are explored with a multi-band photometric study, wherein we determine the mass ranges for these candidates. Chapter four concludes this thesis, recapping the main results from chapters 2 and 3, and highlights the future projects I will carry out that are motivated by my findings in this comprehensive study of the supernova remnant 0509--67.5.

NASA's Great Observatories May Unravel 400-Year Old Supernova Mystery

NASA Astrophysics Data System (ADS)

2004-10-01

Four hundred years ago, sky watchers, including the famous astronomer Johannes Kepler, best known as the discoverer of the laws of planetary motion, were startled by the sudden appearance of a "new star" in the western sky, rivaling the brilliance of the nearby planets. Kepler's Supernova Remnant Multiple Images of Kepler's Supernova Remnant Modern astronomers, using NASA's three orbiting Great Observatories, are unraveling the mysteries of the expanding remains of Kepler's supernova, the last such object seen to explode in our Milky Way galaxy. When a new star appeared Oct. 9, 1604, observers could use only their eyes to study it. The telescope would not be invented for another four years. A team of modern astronomers has the combined abilities of NASA's Great Observatories, the Spitzer Space Telescope (SST), Hubble Space Telescope (HST), and Chandra X-ray Observatory, to analyze the remains in infrared radiation, visible light, and X-rays. Ravi Sankrit and William Blair of the Johns Hopkins University in Baltimore lead the team. The combined image unveils a bubble-shaped shroud of gas and dust, 14 light-years wide and expanding at 4 million mph. Observations from each telescope highlight distinct features of the supernova, a fast-moving shell of iron-rich material, surrounded by an expanding shock wave sweeping up interstellar gas and dust. Interview with Dr. Ravi Sankrit Interview with Dr. Ravi Sankrit "Multi-wavelength studies are absolutely essential for putting together a complete picture of how supernova remnants evolve," Sankrit said. Sankrit is an associate research scientist, Center for Astrophysical Sciences at Hopkins and lead for HST astronomer observations. "For instance, the infrared data are dominated by heated interstellar dust, while optical and X-ray observations sample different temperatures of gas," Blair added. Blair is a research professor, Physics and Astronomy Department at Hopkins and lead astronomer for SST observations. "A range of observations is needed to help us understand the complex relationship that exists among the various components," Blair said. The explosion of a star is a catastrophic event. The blast rips the star apart and unleashes a roughly spherical shock wave that expands outward at more than 22 million mph like an interstellar tsunami. The shock wave spreads out into surrounding space, sweeping up any tenuous interstellar gas and dust into an expanding shell. The stellar ejecta from the explosion initially trail behind the shock wave. It eventually catches up with the inner edge of the shell and is heated to X-ray temperatures. Kepler's Supernova Remnant Hubble Optical Image of Kepler's Supernova Remnant Visible-light images from Hubble's Advanced Camera for Surveys reveal where the supernova shock wave is slamming into the densest regions of surrounding gas. The bright glowing knots are dense clumps that form behind the shock wave. Sankrit and Blair compared their HST observations with those taken with ground-based telescopes to obtain a more accurate distance to the supernova remnant of about 13,000 light-years. Kepler's Supernova Remnant Spitzer Infrared Image of Kepler's Supernova Remnant The astronomers used the SST to probe for material that radiates in infrared light, which shows heated microscopic dust particles that have been swept up by the supernova shock wave. SST is sensitive enough to detect both the densest regions seen by HST and the entire expanding shock wave, a spherical cloud of material. Instruments on SST also reveal information about the chemical composition and physical environment of the expanding clouds of gas and dust ejected into space. This dust is similar to dust which was part of the cloud of dust and gas that formed the sun and planets in our solar system. Interview with Dr. William Blair Interview with Dr. William Blair The Chandra X-ray data show regions of very hot gas. The hottest gas, higher-energy X-rays, is located primarily in the regions directly behind the shock front. These regions also show up in the HST observations and also align with the faint rim of material seen in the SST data. Cooler X-ray gas, lower-energy X-rays, resides in a thick interior shell and marks the location of the material expelled from the exploded star. There have been six known supernovas in our Milky Way over the past 1,000 years. Kepler's is the only one, which astronomers do not know what type of star exploded. By combining information from all three Great Observatories, astronomers may find the clues they need. "It's really a situation where the total is greater than the sum of the parts," Blair said. "When the analysis is complete, we will be able to answer several questions about this enigmatic object." Information and images from this research is available on the Web at: http://www.nasa.gov http://hubblesite.org/newscenter/newsdesk/archive/releases/2004/29/ http://chandra.harvard.edu and http://www.spitzer.caltech.edu/

Shocked Clouds in the Vela Supernova Remnant

NASA Technical Reports Server (NTRS)

Nichols, Joy S.; Slavin, Jonathan D.

2004-01-01

Unusually strong high-excitation C I has been detected in eleven lines of sight through the Vela supernova remnant by means of UV absorption-line studies of IUE data. Most of these lines of sight lie near the western edge of the X-ray bright region of the supernova remnant in a spatially distinct band approximately 1deg by 4deg oriented approximately north/south. The high-excitation C I (denoted C I*) is interpreted as evidence of a complex of shocked dense clouds inside the supernova remnant, due to the high pressures indicated in this region. To further analyze the properties of this region of C I*, we present new HIRES-processed IRAS data of the entire Vela SNR. A temperature map calculated from the HIRES IRAS data, based on a two-component dust model, reveals the signature of hot dust at several locations in the SNR. The hot dust is anti-correlated spatially with X-ray emission as revealed by ROSAT, as would be expected for a dusty medium interacting with a shock wave. The regions of hot dust are strongly correlated with optical filaments, supporting a scenario of dense clouds interior to the SNR that have been shocked and are now cooling behind the supernova blast wave. With few exceptions, the lines of sight to the strong C I* pass through regions of hot dust and optical filaments. Possible mechanisms for the production of the anomalously large columns of C I and C I* are discussed. Dense clouds on the back western hemisphere of the remnant may explain the relatively low X-ray emission in the western portion of the Vela supernova remnant due to the slower forward shock velocity in regions where the shock has encountered the dense clouds. An alternate explanation for the presence of neutral, excited state, and ionized species along the same line of sight may be a magnetic precusor that heats and compresses the gas ahead of the shock.

DESTRUCTION OF INTERSTELLAR DUST IN EVOLVING SUPERNOVA REMNANT SHOCK WAVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P., E-mail: jslavin@cfa.harvard.edu

2015-04-10

Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however, that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al., we adopt the same dust properties as in that paper. We find that the efficiencies of grainmore » destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities ≳200 km s{sup −1} for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of ∼2 compared to those of Jones et al., who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of ∼3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of ∼2–3 Gyr. These increases, while not able to resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step toward understanding the origin and evolution of dust in the ISM.« less

Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves

NASA Technical Reports Server (NTRS)

Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.

2015-01-01

Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities 200 km s(exp -1) for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of approximately 2 compared to those of Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of approximately 3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of approximately 2-3 Gyr. These increases, while not able resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step towards understanding the origin, and evolution of dust in the ISM.

Combining collective, MSW, and turbulence effects in supernova neutrino flavor evolution

DOE PAGES

Lund, Tina; Kneller, James P.

2013-07-16

In order to decode the neutrino burst signal from a Galactic core-collapse supernova and reveal the complicated inner workings of the explosion we need a thorough understanding of the neutrino flavor evolution from the proto-neutron star outwards. The flavor content of the signal evolves due to both neutrino collective effects and matter effects which can lead to a highly interesting interplay and distinctive spectral features. In this paper we investigate the supernova neutrino flavor evolution in three different progenitors and include collective flavor effects, the evolution of the Mikheyev, Smirnov & Wolfenstein conversion due to the shock wave passage throughmore » the star, and the impact of turbulence. In the Oxygen-Neon-Magnesium supernova we find that the impact of turbulence is both brief and slight during a window of 1-2 seconds post bounce. Thus the spectral features of collective and shock effects in the neutrino signals from ONeMg supernovae may be almost turbulence free making them the easiest to interpret. For the more massive progenitors we again find that small amplitude turbulence, up to 10%, leads to a minimal modification of the signal, and the emerging neutrino spectra retain both collective and MSW features. However, when larger amounts of turbulence is added, 30% and 50%, the features of collective and shock wave effects in the high density resonance channel are almost completely obscured at late times. Yet at the same time we find the other mixing channels - the low density resonance channel and the non-resonant channels - begin to develop turbulence signatures. Large amplitude turbulent motions in the outer layers of more massive, iron core-collapse supernovae may obscure the most obvious fingerprints of collective and shock wave effects in the neutrino signal but cannot remove them completely, and additionally bring about new features in the signal.« less

Modeling Type IIn Supernovae: Understanding How Shock Development Effects Light Curves Properties

NASA Astrophysics Data System (ADS)

De La Rosa, Janie

2016-06-01

Type IIn supernovae are produced when massive stars experience dramatic mass loss phases caused by opacity edges or violent explosions. Violent mass ejections occur quite often just prior to the collapse of the star. If the final episode happens just before collapse, the outward ejecta is sufficiently dense to alter the supernova light-curve, both by absorbing the initial supernova light and producing emission when the supernova shock hits the ejecta. Initially, the ejecta is driven by shock progating through the interior of the star, and eventually expands through the circumstellar medium, forming a cold dense shell. As the shock wave approaches the shell, there is an increase in UV and optical radiation at the location of the shock breakout. We have developed a suite of simple semi-analytical models in order to understand the relationship between our observations and the properties of the expanding SN ejecta. When we compare Type IIn observations to a set of modeled SNe, we begin to see the influence of initial explosion conditions on early UV light curve properties such as peak luminosities and decay rate.The fast rise and decay corresponds to the models representing a photosphere moving through the envelope, while the modeled light curves with a slower rise and decay rate are powered by 56Ni decay. However, in both of these cases, models that matched the luminosity were unable to match the low radii from the blackbody models. The effect of shock heating as the supernova material blasts through the circumstellar material can drastically alter the temperature and position of the photosphere. The new set of models redefine the initial modeling conditions to incorporate an outer shell-like structure, and include late-time shock heating from shocks produced as the supernova ejecta travels through the inhomogeneous circumstellar medium.

Color Composite Image of the Supernova Remnant

NASA Technical Reports Server (NTRS)

2000-01-01

This image is a color composite of the supernova remnant E0102-72: x-ray (blue), optical (green), and radio (red). E0102-72 is the remnant of a star that exploded in a nearby galaxy known as the Small Magellanic Cloud. The star exploded outward at speeds in excess of 20 million kilometers per hour (12 million mph) and collided with surrounding gas. This collision produced two shock waves, or cosmic sonic booms, one traveling outward, and the other rebounding back into the material ejected by the explosion. The radio image, shown in red, was made using the Australia Telescope Compact Array. The radio waves are due to extremely high-energy electrons spiraling around magnetic field lines in the gas and trace the outward moving shock wave. The Chandra X-ray Observatory image, shown in blue, shows gas that has been heated to millions of degrees by the rebounding, or reverse shock wave. The x-ray data show that this gas is rich in oxygen and neon. These elements were created by nuclear reactions inside the star and hurled into space by the supernova. The Hubble Space Telescope optical image, shown in green, shows dense clumps of oxygen gas that have 'cooled' to about 30,000 degrees. Photo Credit: X-ray (NASA/CXC/SAO); optical (NASA/HST): radio: (ACTA)

Dust in Supernovae and Supernova Remnants II: Processing and Survival

NASA Astrophysics Data System (ADS)

Micelotta, E. R.; Matsuura, M.; Sarangi, A.

2018-03-01

Observations have recently shown that supernovae are efficient dust factories, as predicted for a long time by theoretical models. The rapid evolution of their stellar progenitors combined with their efficiency in precipitating refractory elements from the gas phase into dust grains make supernovae the major potential suppliers of dust in the early Universe, where more conventional sources like Asymptotic Giant Branch (AGB) stars did not have time to evolve. However, dust yields inferred from observations of young supernovae or derived from models do not reflect the net amount of supernova-condensed dust able to be expelled from the remnants and reach the interstellar medium. The cavity where the dust is formed and initially resides is crossed by the high velocity reverse shock which is generated by the pressure of the circumstellar material shocked by the expanding supernova blast wave. Depending on grain composition and initial size, processing by the reverse shock may lead to substantial dust erosion and even complete destruction. The goal of this review is to present the state of the art about processing and survival of dust inside supernova remnants, in terms of theoretical modelling and comparison to observations.

A model for the origin of high-energy cosmic rays

NASA Technical Reports Server (NTRS)

Jokipii, J. R.; Morfill, G. E.

1985-01-01

It is suggested that cosmic rays, up to the highest energies observed, originate in the Galaxy and are accelerated in astrophysical shock waves. If there is a galactic wind, in analogy with the solar wind, a hierarchy of shocks ranging from supernova shocks to the galactic wind termination shock is expected. This leads to a consistent model in which most cosmic rays, up to perhaps 10 to the 14th eV energy, are accelerated by supernova shocks, but that particles with energies of 10 to the 15th eV and higher are accelerated at the termination shock of the galactic wind. Intermediate energies may be accelerated by intermediate-scale shocks, and there may be larger scale shocks associated with the Local Group of galaxies.

Impact! Chandra Images a Young Supernova Blast Wave

NASA Astrophysics Data System (ADS)

2000-05-01

Two images made by NASA's Chandra X-ray Observatory, one in October 1999, the other in January 2000, show for the first time the full impact of the actual blast wave from Supernova 1987A (SN1987A). The observations are the first time that X-rays from a shock wave have been imaged at such an early stage of a supernova explosion. Recent observations of SN 1987A with the Hubble Space Telescope revealed gradually brightening hot spots from a ring of matter ejected by the star thousands of years before it exploded. Chandra's X-ray images show the cause for this brightening ring. A shock wave is smashing into portions of the ring at a speed of 10 million miles per hour (4,500 kilometers per second). The gas behind the shock wave has a temperature of about ten million degrees Celsius, and is visible only with an X-ray telescope. "With Hubble we heard the whistle from the oncoming train," said David Burrows of Pennsylvania State University, University Park, the leader of the team of scientists involved in analyzing the Chandra data on SN 1987A. "Now, with Chandra, we can see the train." The X-ray observations appear to confirm the general outlines of a model developed by team member Richard McCray of the University of Colorado, Boulder, and others, which holds that a shock wave has been moving out ahead of the debris expelled by the explosion. As this shock wave collides with material outside the ring, it heats it to millions of degrees. "We are witnessing the birth of a supernova remnant for the first time," McCray said. The Chandra images clearly show the previously unseen, shock-heated matter just inside the optical ring. Comparison with observations made with Chandra in October and January, and with Hubble in February 2000, show that the X-ray emission peaks close to the newly discovered optical hot spots, and indicate that the wave is beginning to hit the ring. In the next few years, the shock wave will light up still more material in the ring, and an inward moving, or reverse, shock wave will heat the material ejected in the explosion itself. "The supernova is digging up its own past," said McCray. The observations were made on October 6, 1999, using the Advanced CCD Imaging Spectrometer (ACIS) and the High Energy Transmission Grating, and again on January 17, 2000, using ACIS. Other members of the team were Eli Michael of the University of Colorado; Dr. Una Hwang, Dr. Steven Holt and Dr. Rob Petre of NASA's Goddard Space Flight Center in Greenbelt, MD; Professor Roger Chevalier of the University of Virginia, Charlottesville; and Professors Gordon Garmire and John Nousek of Pennsylvania State University. The results will be published in an upcoming issue of the Astrophysical Journal. The ACIS instrument was built for NASA by the Massachusetts Institute of Technology, Cambridge, and Pennsylvania State University. The High Energy Transmission Grating was built by the Massachusetts Institute of Technology. NASA's Marshall Space Flight Center in Huntsville, AL, manages the Chandra program. TRW, Inc., Redondo Beach, CA, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, MA. More About SN 1987A Images to illustrate this release and more information on Chandra's progress can be found on the Internet at: http://chandra.harvard.edu/photo/2000/sn1987a/index.html AND http://chandra.nasa.gov More About SN 1987A

The effect of cosmic-ray acceleration on supernova blast wave dynamics

NASA Astrophysics Data System (ADS)

Pais, M.; Pfrommer, C.; Ehlert, K.; Pakmor, R.

2018-05-01

Non-relativistic shocks accelerate ions to highly relativistic energies provided that the orientation of the magnetic field is closely aligned with the shock normal (quasi-parallel shock configuration). In contrast, quasi-perpendicular shocks do not efficiently accelerate ions. We model this obliquity-dependent acceleration process in a spherically expanding blast wave setup with the moving-mesh code AREPO for different magnetic field morphologies, ranging from homogeneous to turbulent configurations. A Sedov-Taylor explosion in a homogeneous magnetic field generates an oblate ellipsoidal shock surface due to the slower propagating blast wave in the direction of the magnetic field. This is because of the efficient cosmic ray (CR) production in the quasi-parallel polar cap regions, which softens the equation of state and increases the compressibility of the post-shock gas. We find that the solution remains self-similar because the ellipticity of the propagating blast wave stays constant in time. This enables us to derive an effective ratio of specific heats for a composite of thermal gas and CRs as a function of the maximum acceleration efficiency. We finally discuss the behavior of supernova remnants expanding into a turbulent magnetic field with varying coherence lengths. For a maximum CR acceleration efficiency of about 15 per cent at quasi-parallel shocks (as suggested by kinetic plasma simulations), we find an average efficiency of about 5 per cent, independent of the assumed magnetic coherence length.

SNR-shock impact on star formation

NASA Astrophysics Data System (ADS)

Sasaki, M.; Dincel, B.

2016-06-01

While stars form out of cores of molecular clouds due to gravitational collapse of the clouds, external pressure caused by shock waves of stellar winds or supernovae are believed to be responsible for triggering star formation. However, since massive stars evolve fast and their supernova remnants (SNRs) can only be observed up to an age of around 10^5 years, SNRs found near star-forming regions have most likely resulted from the same generation of stars as the young stellar objects (YSOs). Shock waves of these SNRs might show interaction with the existing YSOs and change their nature. We study YSO candidates in Galactic SNRs CTB 109, IC 443 and HB21, which are known to show interaction with molecular clouds and have associated infrared emission. By photometric and spectroscopic studies of YSOs in the optical and the near-infrared, we aim to find clear observational evidences for an interaction of SNR-shocks with YSOs.

Shock Waves in Supernova Ejecta

NASA Astrophysics Data System (ADS)

Raymond, J. C.

2018-02-01

Astrophysical shock waves are a major mechanism for dissipating energy, and by heating and ionizing the gas they produce emission spectra that provide valuable diagnostics for the shock parameters, for the physics of collisionless shocks, and for the composition of the shocked material. Shocks in SN ejecta in which H and He have been burned to heavier elements behave differently than shocks in ordinary astrophysical gas because of their very large radiative cooling rates. In particular, extreme departures from thermal equilibrium among ions and electrons and from ionization equilibrium may arise. This paper discusses the consequences of the enhanced metal abundances for the structure and emission spectra of those shocks.

Dance into the fire: dust survival inside supernova remnants

NASA Astrophysics Data System (ADS)

Micelotta, Elisabetta R.; Dwek, Eli; Slavin, Jonathan D.

2016-06-01

Core collapse supernovae (CCSNe) are important sources of interstellar dust, potentially capable of producing 1 M_{⊙}) of dust in their explosively expelled ejecta. However, unlike other dust sources, the dust has to survive the passage of the reverse shock, generated by the interaction of the supernova blast wave with its surrounding medium. Knowledge of the net amount of dust produced by CCSNe is crucial for understanding the origin and evolution of dust in the local and high-redshift universe. Our goal is to identify the dust destruction mechanisms in the ejecta, and derive the net amount of dust that survives the passage of the reverse shock. To do so, we have developed analytical models for the evolution of a supernova blast wave and of the reverse shock, and the simultaneous processing of the dust inside the cavity of the supernova remnant. We have applied our models to the special case of the clumpy ejecta of the remnant of Cassiopeia A (Cas A), assuming that the dust (silicates and carbon grains) resides in cool oxygen-rich ejecta clumps which are uniformly distributed within the remnant and surrounded by a hot X-ray emitting plasma (smooth ejecta). The passage of the reverse shock through the clumps gives rise to a relative gas-grain motion and also destroys the clumps. While residing in the ejecta clouds, dust is processed via kinetic sputtering, which is terminated either when the grains escape the clumps, or when the clumps are destroyed by the reverse shock. In either case, grain destruction proceeds thereafter by thermal sputtering in the hot shocked smooth ejecta. We find that 12 and 16 percent of silicate and carbon dust, respectively, survive the passage of the reverse shock by the time the shock has reached the center of the remnant. These fractions depend on the morphology of the ejecta and the medium into which the remnant is expanding, as well as the composition and size distribution of the grains that formed in the ejecta. Results will therefore differ for different types of supernovae. I will discuss our models and results and briefly illustrate the impact of the capabilities of the Athena+ X-ray mission on the variety of astrophysical problems involving the processing of dust particles in extreme environments characterized by the presence of shocked X-ray emitting gas.

A Parametric Study of the Acoustic Mechanism for Core-collapse Supernovae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harada, A.; Nagakura, H.; Iwakami, W.

We investigate the criterion for the acoustic mechanism to work successfully in core-collapse supernovae. The acoustic mechanism is an alternative to the neutrino-heating mechanism. It was proposed by Burrows et al., who claimed that acoustic waves emitted by g -mode oscillations in proto-neutron stars (PNS) energize a stalled shock wave and eventually induce an explosion. Previous works mainly studied to which extent the g -modes are excited in the PNS. In this paper, on the other hand, we investigate how strong the acoustic wave needs to be if it were to revive a stalled shock wave. By adding the acousticmore » power as a new axis, we draw a critical surface, which is an extension of the critical curve commonly employed in the context of neutrino heating. We perform both 1D and 2D parametrized simulations, in which we inject acoustic waves from the inner boundary. In order to quantify the power of acoustic waves, we use the extended Myers theory to take neutrino reactions into proper account. We find for the 1D simulations that rather large acoustic powers are required to relaunch the shock wave, since the additional heating provided by the secondary shocks developed from acoustic waves is partially canceled by the neutrino cooling that is also enhanced. In 2D, the required acoustic powers are consistent with those of Burrows et al. Our results seem to imply, however, that it is the sum of neutrino heating and acoustic powers that matters for shock revival.« less

Shock-turbulence interaction in core-collapse supernovae

NASA Astrophysics Data System (ADS)

Abdikamalov, Ernazar; Zhaksylykov, Azamat; Radice, David; Berdibek, Shapagat

2016-10-01

Nuclear shell burning in the final stages of the lives of massive stars is accompanied by strong turbulent convection. The resulting fluctuations aid supernova explosion by amplifying the non-radial flow in the post-shock region. In this work, we investigate the physical mechanism behind this amplification using a linear perturbation theory. We model the shock wave as a one-dimensional planar discontinuity and consider its interaction with vorticity and entropy perturbations in the upstream flow. We find that, as the perturbations cross the shock, their total turbulent kinetic energy is amplified by a factor of ˜2, while the average linear size of turbulent eddies decreases by about the same factor. These values are not sensitive to the parameters of the upstream turbulence and the nuclear dissociation efficiency at the shock. Finally, we discuss the implication of our results for the supernova explosion mechanism. We show that the upstream perturbations can decrease the critical neutrino luminosity for producing explosion by several per cent.

Combining collective, MSW, and turbulence effects in supernova neutrino flavor evolution

NASA Astrophysics Data System (ADS)

Lund, Tina; Kneller, James P.

2013-07-01

In order to decode the neutrino burst signal from a Galactic core-collapse supernova (ccSN) and reveal the complicated inner workings of the explosion we need a thorough understanding of the neutrino flavor evolution from the proto-neutron star outwards. The flavor content of the signal evolves due to both neutrino collective effects and matter effects which can lead to a highly interesting interplay and distinctive spectral features. In this paper we investigate the supernova neutrino flavor evolution in three different progenitors and include collective flavor effects, the evolution of the Mikheyev, Smirnov & Wolfenstein (MSW) conversion due to the shock wave passage through the star, and the impact of turbulence. We consider both normal and inverted neutrino mass hierarchies and a value of θ13 close to the current experimental measurements. In the Oxygen-Neon-Magnesium (ONeMg) supernova we find that the impact of turbulence is both brief and slight during a window of 1-2 seconds post bounce. This is because the shock races through the star extremely quickly and the turbulence amplitude is expected to be small, less than 10%, since these stars do not require multidimensional physics to explode. Thus the spectral features of collective and shock effects in the neutrino signals from Oxygen-Neon-Magnesium supernovae may be almost turbulence free making them the easiest to interpret. For the more massive progenitors we again find that small amplitude turbulence, up to 10%, leads to a minimal modification of the signal, and the emerging neutrino spectra retain both collective and MSW features. However, when larger amounts of turbulence is added, 30% and 50%, which is justified by the requirement of multidimensional physics in order to make these stars explode, the features of collective and shock wave effects in the high (H) density resonance channel are almost completely obscured at late times. Yet at the same time we find the other mixing channels—the low (L) density resonance channel and the nonresonant channels—begin to develop turbulence signatures. Large amplitude turbulent motions in the outer layers of more massive, iron core-collapse supernovae may obscure the most obvious fingerprints of collective and shock wave effects in the neutrino signal but cannot remove them completely, and additionally bring about new features in the signal.

Supernova shock breakout through a wind

NASA Astrophysics Data System (ADS)

Balberg, Shmuel; Loeb, Abraham

2011-06-01

The breakout of a supernova shock wave through the progenitor star's outer envelope is expected to appear as an X-ray flash. However, if the supernova explodes inside an optically thick wind, the breakout flash is delayed. We present a simple model for estimating the conditions at shock breakout in a wind based on the general observable quantities in the X-ray flash light curve; the total energy EX, and the diffusion time after the peak, tdiff. We base the derivation on the self-similar solution for the forward-reverse shock structure expected for an ejecta plowing through a pre-existing wind at large distances from the progenitor's surface. We find simple quantitative relations for the shock radius and velocity at breakout. By relating the ejecta density profile to the pre-explosion structure of the progenitor, the model can also be extended to constrain the combination of explosion energy and ejecta mass. For the observed case of XRO08109/SN2008D, our model provides reasonable constraints on the breakout radius, explosion energy and ejecta mass, and predicts a high shock velocity which naturally accounts for the observed non-thermal spectrum.

New Hubble Observations of Supernova 1987A Trace Shock Wave

NASA Image and Video Library

2017-12-08

Image release September 2, 2010 ABOUT THIS IMAGE: This image shows the entire region around supernova 1987A. The most prominent feature in the image is a ring with dozens of bright spots. A shock wave of material unleashed by the stellar blast is slamming into regions along the ring's inner regions, heating them up, and causing them to glow. The ring, about a light-year across, was probably shed by the star about 20,000 years before it exploded. An international team of astronomers using the Hubble Space Telescope reports a significant brightening of the emissions from Supernova 1987A. The results, which appear in this week's Science magazine, are consistent with theoretical predictions about how supernovae interact with their immediate galactic environment. The team observed the supernova remnant in optical, ultraviolet, and near-infrared light. They studied the interaction between the ejecta from the stellar explosion and a glowing 6-trillion-mile-diameter ring of gas encircling the supernova remnant. The gas ring was probably shed some 20,000 years before the supernova exploded. Shock waves resulting from the impact of the ejecta onto the ring have brightened 30 to 40 pearl-like "hot spots" in the ring. These blobs likely will grow and merge together in the coming years to form a continuous, glowing circle. "We are seeing the effect a supernova can have in the surrounding galaxy, including how the energy deposited by these stellar explosions changes the dynamics and chemistry of the environment," said University of Colorado at Boulder Research Associate Kevin France of the Center for Astrophysics and Space Astronomy. "We can use these new data to understand how supernova processes regulate the evolution of galaxies." Discovered in 1987, Supernova 1987A is the closest exploding star to Earth to be detected since 1604 and it resides in the nearby Large Magellanic Cloud, a dwarf galaxy adjacent to our own Milky Way Galaxy. Credit: NASA, ESA, K. France (University of Colorado, Boulder), and P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics) NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

LAD Early Career Prize Talk:Laboratory astrophysics experiments investigating the effects of high energy fluxes on Rayleigh-Taylor instability growth relevant to young supernova remnants

NASA Astrophysics Data System (ADS)

Kuranz, Carolyn C.; Drake, R. Paul; Park, Hye Sook; Huntington, Channing; Miles, Aaron R.; Remington, Bruce A.; Plewa, Tomek; Trantham, Matt; Shvarts, Dov; Raman, Kumar; MacLaren, Steven; Wan, Wesley; Doss, Forrest; Kline, John; Flippos, Kirk; Malamud, Guy; Handy, Timothy; Prisbey, Shon; Grosskopf, Michael; Krauland, Christine; Klein, Sallee; Harding, Eric; Wallace, Russell; Marion, Donna; Kalantar, Dan

2017-06-01

Energy-transport effects can alter the structure that develops as a supernova evolves into a supernova remnant. The Rayleigh Taylor (RT) instability is thought to produce structure at the interface between the stellar ejecta and the circumstellar matter (CSM), based on simple models and hydrodynamic simulations. When a blast wave emerges from an exploding star, it drives a forward shock into the CSM and a reverse shock forms in the expanding stellar ejecta, creating a young supernova remnant (SNR). As mass accumulates in the shocked layers, the interface between these two shocks decelerates, becoming unstable to the RT instability. Simulations predict that RT produces structures at this interface, having a range of spatial scales. When the CSM is dense enough, as in the case of SN 1993J, the hot shocked matter can produce significant radiative fluxes that affect the emission from the SNR. Here we report experimental results from the National Ignition Facility (NIF) to explore how large energy fluxes, which are present in supernovae such as SN 1993J, might affect this structure. The experiment used NIF to create a RT unstable interface subject to a high energy flux by the emergence of a blast wave into lower-density matter, in analogy to the SNR. We also preformed and with a low energy flux to compare the affect of the energy flux on the instability growth. We found that the RT growth was reduced in the experiments with a high energy flux. In analyzing the comparison with SN 1993J, we discovered that the energy fluxes produced by heat conduction appear to be larger than the radiative energy fluxes, and large enough to have dramatic consequences. No reported astrophysical simulations have included radiation and heat conduction self-consistently in modeling SNRs.

Survival of carbon grains in shocks

NASA Technical Reports Server (NTRS)

Seab, C. Gregory

1990-01-01

Supernova shocks play a significant part in the life of an interstellar grain. In a typical 10 to the 9th power year lifetime, a grain will be hit by an average of 10 shocks of 100 km s(sup -1) or greater velocity, and even more shocks of lower velocity. Evaluation of the results of this frequent shock processing is complicated by a number of uncertainties, but seems to give about 10 percent destruction of silicate grains and about half that for graphite grains. Because of the frequency of shocking, the mineralogy and sizes of the grain population is predominately determined by shock processing effects, and not by the initial grain nucleation and growth environment. One consequence of the significant role played by interstellar shocks is that a certain fraction (up to 5 percent) of the carbon should be transformed into the diamond phase. Diamond transformation is observed in the laboratory at threshold shock pressures easily obtainable in grain-grain collisions in supernova shocks. Yields for transforming graphite, amorphous carbon, glassy carbon, and other nearly pure carbon solids into diamond are quite high. Impurities up to at least the 10 percent level (for oxygen) are tolerated in the process. The typical size diamond expected from shock transformation agrees well with the observed sizes in the Lewis et al. findings in meteoritic material. Isotropic anomalies already contained in the grain are likely to be retained through the conversion process, while others may be implanted by the shock if the grain is close to the supernova. The meteoritic diamonds are likely to be the results of transformation of carbon grains in grain-grain collisions in supernova shock waves.

REVIEWS OF TOPICAL PROBLEMS: Acceleration of cosmic rays by shock waves

NASA Astrophysics Data System (ADS)

Berezhko, E. G.; Krymskiĭ, G. F.

1988-01-01

Theoretical work on various processes by which shock waves accelerate cosmic rays is reviewed. The most efficient of these processes, Fermi acceleration, is singled out for special attention. A linear theory for this process is presented. The results found on the basis of nonlinear models of Fermi acceleration, which incorporate the modification of the structure caused by the accelerated particles, are reported. There is a discussion of various possibilities for explaining the generation of high-energy particles observed in interplanetary and interstellar space on the basis of a Fermi acceleration mechanism. The acceleration by shock waves from supernova explosions is discussed as a possible source of galactic cosmic rays. The most important unresolved questions in the theory of acceleration of charged particles by shock waves are pointed out.

Dark matter balls help supernovae to explode

NASA Astrophysics Data System (ADS)

Froggatt, C. D.; Nielsen, H. B.

2015-10-01

As a solution to the well-known problem that the shock wave potentially responsible for the explosion of a supernova actually tends to stall, we propose a new energy source arising from our model for dark matter. Our earlier model proposed that dark matter should consist of cm-large white dwarf-like objects kept together by a skin separating two different sorts of vacua. These dark matter balls or pearls will collect in the middle of any star throughout its lifetime. At some stage during the development of a supernova, the balls will begin to take in neutrons and then other surrounding material. By passing into a ball nucleons fall through a potential of order 10 MeV, causing a severe production of heat — of order 10 foe for a solar mass of material eaten by the balls. The temperature in the iron core will thereby be raised, splitting up the iron into smaller nuclei. This provides a mechanism for reviving the shock wave when it arrives and making the supernova explosion really occur. The onset of the heating due to the dark matter balls would at first stop the collapse of the supernova progenitor. This opens up the possibility of there being two collapses giving two neutrino outbursts, as apparently seen in the supernova SN1987A — one in Mont Blanc and one 4 h 43 min later in both IMB and Kamiokande.

Kepler Supernova Remnant: A View from Spitzer Space Telescope

NASA Image and Video Library

2004-10-06

This Spitzer false-color image is a composite of data from the 24 micron channel of Spitzer's multiband imaging photometer (red), and three channels of its infrared array camera: 8 micron (yellow), 5.6 micron (blue), and 4.8 micron (green). Stars are most prominent in the two shorter wavelengths, causing them to show up as turquoise. The supernova remnant is most prominent at 24 microns, arising from dust that has been heated by the supernova shock wave, and re-radiated in the infrared. The 8 micron data shows infrared emission from regions closely associated with the optically emitting regions. These are the densest regions being encountered by the shock wave, and probably arose from condensations in the surrounding material that was lost by the supernova star before it exploded. The composite above (PIA06908, PIA06909, and PIA06910) represent views of Kepler's supernova remnant taken in X-rays, visible light, and infrared radiation. Each top panel in the composite above shows the entire remnant. Each color in the composite represents a different region of the electromagnetic spectrum, from X-rays to infrared light. The X-ray and infrared data cannot be seen with the human eye. Astronomers have color-coded those data so they can be seen in these images. http://photojournal.jpl.nasa.gov/catalog/PIA06910

Supernova dynamics in the laboratory: Radiative shocks produced by ultra-high pressure implosion experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Pak, Arthur

2012-10-01

Thermonuclear fuel experiments on the National Ignition Facility implode 2-mm diameter capsules with a cryogenic deuterium-tritium ice layer to 1000x liquid density and pressures exceeding 100 Gbar (10^11 atm). About 200 ps after peak compression, a spherical supernova-like radiative shock wave is observed that expands with shock velocities of uS = 300 km/s, temperatures of order 1 keV at densities of 1 g/cc resulting in a radiation strength parameter of Q ˜uS^5 = 10^4. Radiation-hydrodynamic simulations indicate that the shock launched at stagnation first goes down a strong density gradient while propagating outward from the highly compressed DT fuel (˜ 1000g/cc) to the ablation front (˜ 1 g/cc). Similar to what happens inside a star, the shock pressure drops as it accelerates and heats. The radiative shock emission is first observed when it breaks out of the dense compressed fuel shell into the low-density inflowing plasma at the ablation front mimicking the supernova situation where the shock breaks out through the star surface into surrounding in-falling matter [1,2]; the shock is subsequently approaching the supercritical state with a strong pre-cursor followed by rapid cooling. These observations are consistent with the rapid vanishing of the radiation ring 400 ps after peak compression due to strong radiation losses and spherical expansion. The evolution and brightness of the radiative shock provides insight into the performance of these implosions that have the goal to produce burning fusion plasmas in the laboratory. By modifying the capsule ablator composition and thickness, the stagnation pressure, density gradients, shock velocity and radiative properties could be tailored to study various regimes related to supernovae radiative remnants.[4pt] [1] W. David Arnett, Supernovae as phenomena of high-energy astrophysics, Ann NY Aca. Science 302, 90 (1977).[0pt] [2] L. Ensman and A. Burrows, Shock breakout in SN1987A, ApJ 393, 742.

New developments in the mechanism for core-collapse supernovae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guidry, M.

1994-12-31

Recent results indicate that the standard type-2 supernova scenario in which the shock wave stagnates but is reenergized by neutrino heating fails to consistently produce supernova explosions having the required characteristics. The authors review the theory of convection and survey some recent calculations indicating the importance of convection operating on millisecond timescales in the protoneutron star. These calculations suggest that such convection is probably generic to the type-2 scenario, that this produces a violet overturn of material below the stalled shock, and that this overturn could lead to significant alterations in the neutrino luminosity and energy. This provides a mechanismmore » that could be effective in reenergizing the stalled shock and producing supernovae explosions having the quantitative characteristics demands by observations. This mechanism implies, in turn, that the convection cannot be adequately described by the 1-dimensional hydrodynamics employed in most simulations. Thus, a full understanding of the supernova mechanism and the resulting heavy element production is likely to require 3-dimensional relativistic hydrodynamics and a comprehensive description of neutrino transport. The prospects for implementing such calculations using a new generation of massively parallel supercomputers and modern scalable algorithms are discussed.« less

Hot interstellar tunnels. 1: Simulation of interacting supernova remnants

NASA Technical Reports Server (NTRS)

Smith, B. W.

1976-01-01

The theory required to build a numerical simulation of interacting supernova remnants is developed. The hot cavities within a population of remnants will become connected, with varying ease and speed, for a variety of assumed conditions in the outer shells of old remnants. Apparently neither radiative cooling nor thermal conduction in a large-scale galactic magnetic field can destroy hot cavity regions, if they grow, faster than they are reheated by supernova shock waves, but interstellar mass motions disrupt the contiguity of extensive cavities necessary for the dispersal of these shocks over a wide volume. Monte Carlo simulations show that a quasi-equilibrium is reached in the test space within 10 million yrs of the first supernova and is characterized by an average cavity filling fraction of the interstellar volume. Aspects of this equilibrium are discussed for a range of supernova rates. Two predictions are not confirmed within this range: critical growth of hot regions to encompass the entire medium, and the efficient quenching of a remnant's expansion by interaction with other cavities.

Chandra Reveals Rich Oxygen Supply

NASA Technical Reports Server (NTRS)

2003-01-01

This striking Chandra X-Ray Observatory image of supernova remnant SNR0103-72.6 reveals a nearly perfect ring about 150 light years in diameter surrounding a cloud of gas enriched in oxygen and shock-heated to millions of degrees Celsius. The ring marks the outer limits of a shock wave produced as material ejected in the supernova explosion collides with the interstellar gas. The size of the ring indicates that we see the supernova remnant as it was about 10,000 years after its progenitor star exploded. Located in the Small Magenellanic Cloud (SMC), SNR 0103-72.6 is about 190,000 light years from Earth. The x-rays take about 190,000 years to reach us from the SMC, so the supernova explosion occurred about 200,000 years ago, as measured on Earth. Scientists have know for years that oxygen and many other elements necessary for life are created in massive stars and dispersed in supernova explosions, but few remnants rich in these elements have been observed. This supernova remnant will hence become an important laboratory for studying how stars forge the elements necessary for life.

The Origin and Evolution of the Infrared Light Curve of SN2010jl

NASA Astrophysics Data System (ADS)

Dwek, Eli; Sarangi, Arkaprabha; Arendt, Richard; Fox, Ori; Kallman, Timothy; Kazanas, Demosthenes

2018-01-01

SN2010jl is a luminous core-collapse supernova (CCSN) of Type IIn that is surrounded by a dense circumstellar medium (CSM). The supernova (SN) luminosity vastly exceeds the available power from radiactive elements in the ejecta, and is powered by the interaction of the SN shock wave with the ambient medium. Upper limits on the UV and near-IR (NIR) emission from pre-explosion images of the region suggest that any progenitor star was hidden by pre-existing CSM dust. After day ~80, the SN spectrum shows the development of an IR excess above the extrapolated UVO emission arising from the shocked CSM. This IR component is attributed to thermal emission from dust.After day ~300, the light curve exhibits a rise in the NIR luminosity, concurrent with a steep decline at UVO wavelengths. Ruling out any possible contribution of SN-condensed dust to the IR light curve, we show that the early IR emission arises from the pre-existing CSM dust that survived the flash of radiation from the shock breakout. The late IR emission arises from newly-formed CSM dust that condensed in the cooling dust-free postshock gas of the advancing SN shock wave. Our analysis presents the first detailed modeling of dust formation in a cooling postshock environment, and provides important insights into the interaction of the SN shock wave with the CSM.

Plasma physics. Stochastic electron acceleration during spontaneous turbulent reconnection in a strong shock wave.

PubMed

Matsumoto, Y; Amano, T; Kato, T N; Hoshino, M

2015-02-27

Explosive phenomena such as supernova remnant shocks and solar flares have demonstrated evidence for the production of relativistic particles. Interest has therefore been renewed in collisionless shock waves and magnetic reconnection as a means to achieve such energies. Although ions can be energized during such phenomena, the relativistic energy of the electrons remains a puzzle for theory. We present supercomputer simulations showing that efficient electron energization can occur during turbulent magnetic reconnection arising from a strong collisionless shock. Upstream electrons undergo first-order Fermi acceleration by colliding with reconnection jets and magnetic islands, giving rise to a nonthermal relativistic population downstream. These results shed new light on magnetic reconnection as an agent of energy dissipation and particle acceleration in strong shock waves. Copyright © 2015, American Association for the Advancement of Science.

Interaction of Interstellar Shocks with Dense Obstacles: Formation of ``Bullets''

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

The so-called cumulative effect take place in converging conical shock waves arising behind dense obstacles overtaken by incident interstellar shock. A significant part of energy of converging flow of matter swept-up by a radiative conical shock can be transferred to a dense jet-like ejection (``bullet'') directed along the cone axis. Possible applications of this effect for star-forming regions (e.g., OMC-1) and supernova remnants (e.g., Vela SNR) are discussed.

Spitzer Observations of Dust Destruction in the Puppis A Supernova Remnant

NASA Technical Reports Server (NTRS)

Arendt, Richard G.; Dweek, Eli; Blair, William P.; Ghavamian, Parviz; Hwang, Una; Long, Knox X.; Petre, Robert; Rho, Jeonghee; Winkler, P. Frank

2010-01-01

The interaction of the Puppis A supernova remnant (SNR) with a neighboring molecular cloud provides a unique opportunity to measure the amount of grain destruction in an SNR shock. Spitzer Space Telescope MIPS imaging of the entire SNR at 24, 70, and 160 micrometers shows an extremely good correlation with X-ray emission, indicating that the SNR's IR radiation is dominated by the thermal emission of swept-up interstellar dust, collisionally heated by the hot shocked gas. Spitzer IRS spectral observations targeted both the Bright Eastern Knot (BEK) of the SNR where a small cloud has been engulfed by the supernova blast wave and outlying portions of the associated molecular cloud that are yet to be hit by the shock front. Modeling the spectra from both regions reveals the composition and the grain size distribution of the interstellar dust, both in front of and behind the SNR shock front. The comparison shows that the ubiquitous polycyclic aromatic hydrocarbons of the interstellar medium are destroyed within the BEK, along with nearly 25% of the mass of graphite and silicate dust grains.

Temperature relaxation in supernova remnants, revisited

NASA Technical Reports Server (NTRS)

Itoh, H.

1984-01-01

Some supernova remnants are expanding into a partially neutral medium. The neutral atoms which are engulfed by the fast blast shock are collisionally ionized to eject low-energy secondary electrons. Calculations are conducted of the temperature relaxation through Coulomb collisions among the secondary electrons, the shocked electrons, and the ions, assuming that the three species have Maxwellian velocity distributions. The results are applied to a self-similar blast wave. If the efficiency of collisionless electron heating at the shock front is high in young remnants such as Tycho, the secondary electrons may be much cooler than both the shocked electrons and the ions. In this case, the emergent X-ray continuum spectrum will have a two-temperature, or a power-law, appearance. This effect may have been observed in the bright rim of the remnant of SN 1006.

Delayed Shock-induced Dust Formation in the Dense Circumstellar Shell Surrounding the Type IIn Supernova SN 2010jl

NASA Astrophysics Data System (ADS)

Sarangi, Arkaprabha; Dwek, Eli; Arendt, Richard G.

2018-05-01

The light curves of Type IIn supernovae are dominated by the radiative energy released through the interaction of the supernova shock waves with their dense circumstellar medium (CSM). The ultraluminous Type IIn supernova SN 2010jl exhibits an infrared emission component that is in excess of the extrapolated UV–optical spectrum as early as few weeks postexplosion. This emission has been considered by some as evidence for the rapid formation of dust in the cooling postshock CSM. We investigate the physical processes that may inhibit or facilitate the formation of dust in the CSM. When only radiative cooling is considered, the temperature of the dense shocked gas rapidly drops below the dust condensation temperature. However, by accounting for the heating of the postshock gas by the downstream radiation from the shock, we show that dust formation is inhibited until the radiation from the shock weakens as it propagates into the less dense outer regions of the CSM. In SN 2010jl, dust formation can therefore only commence after day ∼380. Only the IR emission since that epoch can be attributed to the newly formed CSM dust. Observations on day 460 and later show that the IR luminosity exceeds the UV–optical luminosity. The postshock dust cannot extinct the radiation emitted by the expanding SN shock. Therefore, its IR emission must be powered by an interior source, which we identify as the reverse shock propagating through the SN ejecta. IR emission before day 380 must therefore be an IR echo from preexisting CSM dust.

Nonuniform Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3

NASA Technical Reports Server (NTRS)

Borkowski, Kazimierz J.; Reynolds, Stephen P.; Green, David A.; Hwang, Una; Petre, Robert; Krishnamurthy, Kalyani; Willett, Rebecca

2014-01-01

We report measurements of the X-ray expansion of the youngest Galactic supernova remnant, G1.9+0.3, using Chandra observations in 2007, 2009, and 2011. The measured rates strongly deviate from uniform expansion, decreasing radially by about 60 along the X-ray bright SE-NW axis from 0.84 plus or minus 0.06% yr(exp -1) to 0.52% plus or minus 0.03 yr(exp -1). This corresponds to undecelerated ages of 120-190 yr, confirming the young age of G1.9+0.3 and implying a significant deceleration of the blast wave. The synchrotron-dominated X-ray emission brightens at a rate of 1.9% plus or minus 0.4% yr(exp -1). We identify bright outer and inner rims with the blast wave and reverse shock, respectively. Sharp density gradients in either the ejecta or ambient medium are required to produce the sudden deceleration of the reverse shock or the blast wave implied by the large spread in expansion ages. The blast wave could have been decelerated recently by an encounter with a modest density discontinuity in the ambient medium, such as may be found at a wind termination shock, requiring strong mass loss in the progenitor.

History of Chandra X-Ray Observatory

NASA Image and Video Library

2000-11-01

This image is a color composite of the supernova remnant E0102-72: x-ray (blue), optical (green), and radio (red). E0102-72 is the remnant of a star that exploded in a nearby galaxy known as the Small Magellanic Cloud. The star exploded outward at speeds in excess of 20 million kilometers per hour (12 million mph) and collided with surrounding gas. This collision produced two shock waves, or cosmic sonic booms, one traveling outward, and the other rebounding back into the material ejected by the explosion. The radio image, shown in red, was made using the Australia Telescope Compact Array. The radio waves are due to extremely high-energy electrons spiraling around magnetic field lines in the gas and trace the outward moving shock wave. The Chandra X-ray Observatory image, shown in blue, shows gas that has been heated to millions of degrees by the rebounding, or reverse shock wave. The x-ray data show that this gas is rich in oxygen and neon. These elements were created by nuclear reactions inside the star and hurled into space by the supernova. The Hubble Space Telescope optical image, shown in green, shows dense clumps of oxygen gas that have "cooled" to about 30,000 degrees. Photo Credit: X-ray (NASA/CXC/SAO); optical (NASA/HST): radio: (ACTA)

Resonant spin-flavor conversion of supernova neutrinos: Dependence on presupernova models and future prospects

NASA Astrophysics Data System (ADS)

Ando, Shin'ichiro; Sato, Katsuhiko

2003-07-01

We study the resonant spin-flavor (RSF) conversion of supernova neutrinos, which is induced by the interaction between the nonzero neutrino magnetic moment and the supernova magnetic fields, and its dependence on presupernova models. As the presupernova models, we adopt the latest ones by Woosley, Heger, and Weaver, and, further, models with both solar and zero metallicity are investigated. Since the (1-2Ye) profile of the new presupernova models, which is responsible for the RSF conversion, suddenly drops at the resonance region, the completely adiabatic RSF conversion is not realized, even if μνB0=(10-12μB)(1010 G), where B0 is the strength of the magnetic field at the surface of the iron core. In particular for the model with zero metallicity, the conversion is highly nonadiabatic in the high energy region, reflecting the (1-2Ye) profile of the model. In calculating the flavor conversion, we find that the shock wave propagation, which changes density profiles drastically, is a much more severe problem than it is for the pure Mikheyev-Smirnov-Wolfenstein (MSW) conversion case. This is because the RSF effect occurs at a far deeper region than the MSW effect. To avoid the uncertainty concerning the shock propagation, we restrict our discussion to 0.5 s after the core bounce (and for more conservative discussion, 0.25 s), during which the shock wave is not expected to affect the RSF region. We also evaluate the energy spectrum at the Super-Kamiokande detector for various models using the calculated conversion probabilities, and find that it is very difficult to obtain useful information on the supernova metallicities and magnetic fields or on the neutrino magnetic moment from the supernova neutrino observation. Future prospects are also discussed.

Impacto ambiental de los remanentes de supernova

NASA Astrophysics Data System (ADS)

Dubner, G. M.

2015-08-01

The explosion of a supernovae (SN) represents the sudden injection of about ergs of thermal and mechanical energy in a small region of space, causing the formation of powerful shock waves that propagate through the interstellar medium at speeds of several thousands of km/s. These waves sweep, compress and heat the interstellar material that they encounter, forming the supernova remnants. Their evolution over thousands of years change forever, irreversibly, not only the physical but also the chemical properties of a vast region of space that can span hundreds of parsecs. This contribution briefly analyzes the impact of these explosions, discussing the relevance of some phenomena usually associated with SNe and their remnants in the light of recent theoretical and observational results.

Infrared Emission from Supernova Remnants: Formation and Destruction of Dust

NASA Astrophysics Data System (ADS)

Williams, Brian J.; Temim, Tea

2016-09-01

We review the observations of dust emission in supernova remnants (SNRs) and supernovae (SNe). Theoretical calculations suggest that SNe, particularly core-collapse, should make significant quantities of dust, perhaps as much as a solar mass. Observations of extragalactic SNe have yet to find anywhere near this amount, but this may be the result of observational limitations. SN 1987A, in the process of transitioning from a SN to an SNR, does show signs of a significant amount of dust forming in its ejecta, but whether this dust will survive the passage of the reverse shock to be injected into the ISM is unknown. IR observations of SNRs have not turned up significant quantities of dust, and the dust that is observed is generally swept up by the forward shock, rather than created in the ejecta. Because the shock waves also destroy dust in the ISM, we explore the question of whether SNe might be net destroyers, rather than net creators of dust in the universe.

Infrared Emission from Supernova Remnants: Formation and Destruction of Dust

NASA Astrophysics Data System (ADS)

Williams, Brian J.; Temim, Tea

We review the observations of dust emission in supernova remnants (SNRs) and supernovae (SNe). Theoretical calculations suggest that SNe, particularly core-collapse, should make significant quantities of dust, perhaps as much as a solar mass. Observations of extragalactic SNe have yet to find anywhere near this amount, but this may be the result of observational limitations. SN 1987A, in the process of transitioning from a SN to an SNR, does show signs of a significant amount of dust forming in its ejecta, but whether this dust will survive the passage of the reverse shock to be injected into the ISM is unknown. IR observations of SNRs have not turned up significant quantities of dust, and the dust that is observed is generally swept up by the forward shock, rather than created in the ejecta. Because the shock waves also destroy dust in the ISM, we explore the question of whether SNe might be net destroyers, rather than net creators of dust in the universe.

Long term variability of the cosmic ray intensity

NASA Technical Reports Server (NTRS)

Bhat, C. L.; Houston, B. P.; Mayer, C. J.; Wolfendale, A. W.

1985-01-01

In a previous paper Bhat, et al., assess the evidence for the continuing acceleration of cosmic rays in the Loop I supernova remnant. The enhanced gamma-ray emission is found consistent with the Blandford and Cowie model for particle acceleration at the remnant shock wave. The contributions of other supernovae remnants to the galactic cosmic ray energy density are now considered, paying anisotropy of cosmic rays accelerated by local supernovae ( 100 pc). The results are compared with geophysical data on the fluctuations in the cosmic ray intensity over the previous one billion years.

On the cosmic ray diffusion in a violent interstellar medium

NASA Technical Reports Server (NTRS)

Bykov, A. M.; Toptygin, I. N.

1985-01-01

A variety of the available observational data on the cosmic ray (CR) spectrum, anisotropy and composition are in good agreement with a suggestion on the diffusion propagation of CR with energy below 10(15) eV in the interstellar medium. The magnitude of the CR diffusion coefficient and its energy dependence are determined by interstellar medium (ISM) magnetic field spectra. Direct observational data on magnetic field spectra are still absent. A theoretical model to the turbulence generation in the multiphase ISM is resented. The model is based on the multiple generation of secondary shocks and concomitant large-scale rarefactions due to supernova shock interactions with interstellar clouds. The distribution function for ISM shocks are derived to include supernova statistics, diffuse cloud distribution, and various shock wave propagation regimes. This permits calculation of the ISM magnetic field fluctuation spectrum and CR diffusion coefficient for the hot phase of ISM.

An extremely luminous X-ray outburst at the birth of a supernova

NASA Astrophysics Data System (ADS)

Soderberg, A. M.; Berger, E.; Page, K. L.; Schady, P.; Parrent, J.; Pooley, D.; Wang, X.-Y.; Ofek, E. O.; Cucchiara, A.; Rau, A.; Waxman, E.; Simon, J. D.; Bock, D. C.-J.; Milne, P. A.; Page, M. J.; Barentine, J. C.; Barthelmy, S. D.; Beardmore, A. P.; Bietenholz, M. F.; Brown, P.; Burrows, A.; Burrows, D. N.; Byrngelson, G.; Cenko, S. B.; Chandra, P.; Cummings, J. R.; Fox, D. B.; Gal-Yam, A.; Gehrels, N.; Immler, S.; Kasliwal, M.; Kong, A. K. H.; Krimm, H. A.; Kulkarni, S. R.; Maccarone, T. J.; Mészáros, P.; Nakar, E.; O'Brien, P. T.; Overzier, R. A.; de Pasquale, M.; Racusin, J.; Rea, N.; York, D. G.

2008-05-01

Massive stars end their short lives in spectacular explosions-supernovae-that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their `delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of the explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the `break-out' of the supernova shock wave from the progenitor star, and show that the inferred rate of such events agrees with that of all core-collapse supernovae. We predict that future wide-field X-ray surveys will catch each year hundreds of supernovae in the act of exploding.

An extremely luminous X-ray outburst at the birth of a supernova.

PubMed

Soderberg, A M; Berger, E; Page, K L; Schady, P; Parrent, J; Pooley, D; Wang, X-Y; Ofek, E O; Cucchiara, A; Rau, A; Waxman, E; Simon, J D; Bock, D C-J; Milne, P A; Page, M J; Barentine, J C; Barthelmy, S D; Beardmore, A P; Bietenholz, M F; Brown, P; Burrows, A; Burrows, D N; Bryngelson, G; Byrngelson, G; Cenko, S B; Chandra, P; Cummings, J R; Fox, D B; Gal-Yam, A; Gehrels, N; Immler, S; Kasliwal, M; Kong, A K H; Krimm, H A; Kulkarni, S R; Maccarone, T J; Mészáros, P; Nakar, E; O'Brien, P T; Overzier, R A; de Pasquale, M; Racusin, J; Rea, N; York, D G

2008-05-22

Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of the explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the 'break-out' of the supernova shock wave from the progenitor star, and show that the inferred rate of such events agrees with that of all core-collapse supernovae. We predict that future wide-field X-ray surveys will catch each year hundreds of supernovae in the act of exploding.

The ignition of carbon detonations via converging shock waves in white dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Ken J.; Bildsten, Lars, E-mail: kenshen@astro.berkeley.edu, E-mail: bildsten@kitp.ucsb.edu

2014-04-10

The progenitor channel responsible for the majority of Type Ia supernovae is still uncertain. One emergent scenario involves the detonation of a He-rich layer surrounding a C/O white dwarf, which sends a shock wave into the core. The quasi-spherical shock wave converges and strengthens at an off-center location, forming a second, C-burning, detonation that disrupts the whole star. In this paper, we examine this second detonation of the double detonation scenario using a combination of analytic and numeric techniques. We perform a spatially resolved study of the imploding shock wave and outgoing detonation and calculate the critical imploding shock strengthsmore » needed to achieve a core C detonation. We find that He detonations in recent two-dimensional simulations yield converging shock waves that are strong enough to ignite C detonations in high-mass C/O cores, with the caveat that a truly robust answer requires multi-dimensional detonation initiation calculations. We also find that convergence-driven detonations in low-mass C/O cores and in O/Ne cores are harder to achieve and are perhaps unrealized in standard binary evolution.« less

Search for neutrinos from core-collapse supernova from the global network of detectors

NASA Astrophysics Data System (ADS)

Habig, Alec; Snews working Group

2010-01-01

The Supernova Early Warning System (SNEWS) is a cooperative effort between the world's neutrino detection experiments to spread the news that a star in our galaxy has just experienced a core-collapse event and is about to become a Type II Supernova. This project exploits the ~hours time difference between neutrinos promptly escaping the nascent supernova and photons which originate when the shock wave breaks through the stellar photosphere, to give the world a chance to get ready to observe such an exciting event at the earliest possible time. A coincidence trigger between experiments is used to eliminate potential local false alarms, allowing a rapid, automated alert.

Supernova remnant evolution in wind bubbles: A closer look at Kes 27

NASA Astrophysics Data System (ADS)

Dwarkadas, V. V.; Dewey, D.

2013-03-01

Massive Stars (>8M⊙) lose mass in the form of strong winds. These winds accumulate around the star, forming wind-blown bubbles. When the star explodes as a supernova (SN), the resulting shock wave expands within this wind-blown bubble, rather than the interstellar medium. The properties of the resulting remnant, its dynamics and kinematics, the morphology, and the resulting evolution, are shaped by the structure and properties of the wind-blown bubble. In this article we focus on Kes 27, a supernova remnant (SNR) that has been proposed by [1] to be evolving in a wind-blown bubble, explore its properties, and investigate whether the X-Ray properties could be ascribed to evolution of a SNR in a wind-blown bubble. Our initial model does not support the scenario proposed by [1], due to the fact that the reflected shock is expanding into much lower densities.

Potential for the Vishniac instability in ionizing shock waves propagating into cold gases

NASA Astrophysics Data System (ADS)

Robinson, A. P. L.; Pasley, J.

2018-05-01

The Vishniac instability was posited as an instability that could affect supernova remnants in their late stage of evolution when subject to strong radiative cooling, which can drive the effective ratio of specific heats below 1.3. The potential importance of this instability to these astrophysical objects has motivated a number of laser-driven laboratory studies. However, the Vishniac instability is essentially a dynamical instability that should operate independently of whatever physical processes happen to reduce the ratio of specific heats. In this paper, we examine the possibility that ionization and molecular dissociation processes can achieve this, and we show that this is possible for a certain range of shock wave Mach numbers for ionizing/dissociating shock waves propagating into cold atomic and molecular gases.

Detection of Supernova Neutrinos on the Earth for Large θ13

NASA Astrophysics Data System (ADS)

Xu, Jing; Huang, Ming-Yang; Hu, Li-Jun; Guo, Xin-Heng; Young, Bing-Lin

2014-02-01

Supernova (SN) neutrinos detected on the Earth are subject to the shock wave effects, the Mikheyev—Smirnov—Wolfenstein (MSW) effects, the neutrino collective effects and the Earth matter effects. Considering the recent experimental result about the large mixing angle θ13 (≃ 8.8°) provided by the Daya Bay Collaboration and applying the available knowledge for the neutrino conversion probability in the high resonance region of SN, PH, which is in the form of hypergeometric function in the case of large θ13, we deduce the expression of PH taking into account the shock wave effects. It is found that PH is not zero in a certain range of time due to the shock wave effects. After considering all the four physical effects and scanning relevant parameters, we calculate the event numbers of SN neutrinos for the “Garching” distribution of neutrino energy spectrum. From the numerical results, it is found that the behaviors of neutrino event numbers detected on the Earth depend on the neutrino mass hierarchy and neutrino spectrum parameters including the dimensionless pinching parameter βα (where α refers to neutrino flavor), the average energy , and the SN neutrino luminosities Lα. Finally, we give the ranges of SN neutrino event numbers that will be detected at the Daya Bay experiment.

Spherical shock due to point explosion with varying energy

NASA Astrophysics Data System (ADS)

Singh, J. B.; Srivastava, S. K.

1983-05-01

The motion of a perfect gas behind a weak or strong spherical point-explosion shock wave in a nonuniform rest atmosphere is investigated analytically for the case of variable flow energy. The self-similar solutions derived are also adaptable to a uniform expanding piston. The solution is applied to the isothermal case, and the results of numerical integration are presented in graphs showing the density, velocity, and pressure distributions for different values of delta. The findings are considered significant for investigations of sonic booms, laser production of plasmas, high-altitude nuclear detonations, supernova explosions, and the sudden expansion of the solar corona, and for the laboratory production of high temperatures using shock waves.

Evolution of Supernova Remnants

NASA Astrophysics Data System (ADS)

Arbutina, B.

2017-12-01

This book, both a monograph and a graduate textbook, is based on my original research and partly on the materials prepared earlier for the 2007 and 2008 IARS Astrophysics Summer School in Istanbul, AstroMundus course 'Supernovae and Their Remnants' that was held for the first time in 2011 at the Department of Astronomy, Faculty of Mathematics, University of Belgrade, and a graduate course 'Evolution of Supernova Remnants' that I teach at the aforementioned university. The first part Supernovae (introduction, thermonuclear supernovae, core-collapse supernovae) provides introductory information and explains the classification and physics of supernova explosions, while the second part Supernova remnants (introduction, shock waves, cosmic rays and particle acceleration, magnetic fields, synchrotron radiation, hydrodynamic and radio evolution of supernova remnants), which is the field I work in, is more detailed in scope i.e. technical/mathematical. Special attention is paid to details of mathematical derivations that often cannot be found in original works or available literature. Therefore, I believe it can be useful to both, graduate students and researchers interested in the field.

Parametric Study of Flow Patterns behind the Standing Accretion Shock Wave for Core-Collapse Supernovae

NASA Astrophysics Data System (ADS)

Iwakami, Wakana; Nagakura, Hiroki; Yamada, Shoichi

2014-05-01

In this study, we conduct three-dimensional hydrodynamic simulations systematically to investigate the flow patterns behind the accretion shock waves that are commonly formed in the post-bounce phase of core-collapse supernovae. Adding small perturbations to spherically symmetric, steady, shocked accretion flows, we compute the subsequent evolutions to find what flow pattern emerges as a consequence of hydrodynamical instabilities such as convection and standing accretion shock instability for different neutrino luminosities and mass accretion rates. Depending on these two controlling parameters, various flow patterns are indeed realized. We classify them into three basic patterns and two intermediate ones; the former includes sloshing motion (SL), spiral motion (SP), and multiple buoyant bubble formation (BB); the latter consists of spiral motion with buoyant-bubble formation (SPB) and spiral motion with pulsationally changing rotational velocities (SPP). Although the post-shock flow is highly chaotic, there is a clear trend in the pattern realization. The sloshing and spiral motions tend to be dominant for high accretion rates and low neutrino luminosities, and multiple buoyant bubbles prevail for low accretion rates and high neutrino luminosities. It is interesting that the dominant pattern is not always identical between the semi-nonlinear and nonlinear phases near the critical luminosity; the intermediate cases are realized in the latter case. Running several simulations with different random perturbations, we confirm that the realization of flow pattern is robust in most cases.

Equation-of-state dependent features in shock-oscillation modulated neutrino and gravitational-wave signals from supernovae

NASA Astrophysics Data System (ADS)

Marek, A.; Janka, H.-T.; Müller, E.

2009-03-01

We present two-dimensional (axisymmetric) neutrino-hydrodynamic simulations of the long-time accretion phase of a 15 M_⊙ progenitor star after core bounce and before the launch of a supernova explosion, when non-radial hydrodynamic instabilities like convection occur in different regions of the collapsing stellar core and the standing accretion shock instability (SASI) leads to large-amplitude oscillations of the stalled shock with a period of tens of milliseconds. Our simulations were performed with the Prometheus-Vertex code, which includes a multi-flavor, energy-dependent neutrino transport scheme and employs an effective relativistic gravitational potential. Testing the influence of a stiff and a soft equation of state for hot neutron star matter, we find that the non-radial mass motions in the supernova core impose a time variability on the neutrino and gravitational-wave signals with larger amplitudes, as well as higher frequencies in the case of a more compact nascent neutron star. After the prompt shock-breakout burst of electron neutrinos, a more compact accreting remnant produces higher neutrino luminosities and higher mean neutrino energies. The observable neutrino emission in the SASI sloshing direction exhibits a modulation of several ten percent in the luminosities and around 1 MeV in the mean energies with most power at typical SASI frequencies between roughly 20 and 100 Hz. The modulation is caused by quasi-periodic variations in the mass accretion rate of the neutron star in each hemisphere. At times later than ~50-100 ms after bounce, the gravitational-wave amplitude is dominated by the growing low-frequency (⪉200 Hz) signal associated with anisotropic neutrino emission. A high-frequency wave signal results from nonradial gas flows in the outer layers of the anisotropically accreting neutron star. Right after bounce such nonradial mass motions occur due to prompt post-shock convection in both considered cases and contribute mostly to the early wave production around 100 Hz. Later they are instigated by the SASI and by convective overturn that vigorously stir the neutrino-heating and cooling layers, and also by convective activity developing below the neutrinosphere. The gravitational-wave power then peaks at about 300-800 Hz, connected to changes in the mass quadrupole moment on a timescale of milliseconds. Distinctively higher spectral frequencies originate from the more compact and more rapidly contracting neutron star. Both the neutrino and gravitational-wave emission therefore carry information that is characteristic of the properties of the nuclear equation of state in the hot remnant. The detectability of the SASI effects in the neutrino and gravitational-wave signals is briefly discussed.

A New Mechanism of Magnetic Field Generation in Supernova Shock Waves and its Implication for Cosmic Ray Acceleration

NASA Astrophysics Data System (ADS)

Diamond, Patrick

2005-10-01

SNR shocks are the most probable source of galactic cosmic rays. We discuss the diffusive acceleration mechanism in terms of its potential to accelerate CRs to 10^18 eV, as observations imply. One possibility, currently discussed in the literature, is to resonantly generate a turbulent magnetic field via accelerated particles in excess of the background field. We indicate some difficulties of this scenario and suggest a different possibility, which is based on the generation of Alfven waves at the gyroradius scale at the background field level, with a subsequent transfer to longer scales via interaction with strong acoustic turbulence in the shock precursor. The acoustic turbulence in turn, may be generated by Drury instability or by parametric instability of the Alfven (A) waves. The essential idea is an A-->A+S decay instability process, where one of the interacting scatterers (i.e. the sound, or S-waves) are driven by the Drury instability process. This rapidly generates longer wavelength Alfven waves, which in turn resonate with high energy CRs thus binding them to the shock and enabling their further acceleration.

H-alpha images of the Cygnus Loop - A new look at shock-wave dynamics in an old supernova remnant

NASA Technical Reports Server (NTRS)

Fesen, Robert A.; Kwitter, Karen B.; Downes, Ronald A.

1992-01-01

Attention is given to deep H-alpha images of portions of the east, west, and southwest limbs of the Cygnus Loop which illustrate several aspects of shock dynamics in a multiphase interstellar medium. An H-alpha image of the isolated eastern shocked cloud reveals cloud deformation and gas stripping along the cloud's edges, shock front diffraction and reflection around the rear of the cloud, and interior remnant emission due to upstream shock reflection. A faint Balmer-dominated filament is identified 30 arcmin further west of the remnant's bright line of western radiative filaments. This detection indicates a far more westerly intercloud shock front position than previously realized, and resolves the nature of the weak X-ray, optical, and nonthermal radio emission observed west of NGC 6960. Strongly curved Balmer-dominated filaments along the remnant's west and southwest edge may indicate shock diffraction caused by shock wave passage in between clouds.

Stellar explosions from accreting white dwarfs

NASA Astrophysics Data System (ADS)

Moore, Kevin L.

Unstable thermonuclear burning on accreting white dwarfs (WDs) can lead to a wide variety of outcomes, and induce shock waves in several contexts. In classical and recurrent novae, a WD accreting hydrogen-rich material from a binary companion can experience thermonuclear runaways, ejecting mass into the interstellar/circumbinary environment at ~1000 km/s. This highly supersonic ejecta drives shock waves into the interstellar gas which may be relevant for sweeping out gas from globular clusters or forming circumstellar absorption regions in interacting supernovae. While runaway nuclear burning in novae releases enough energy for these objects to brighten by a factor of ~10 4 over roughly a weeklong outburst, it does not become dynamically unstable. In contrast, certain helium accretion scenarios may allow for dynamical burning modes, in part due to the higher temperature sensitivity of helium burning reactions and larger accreted envelopes. The majority of this thesis involves such dynamical burning modes, specifically detonations - shock waves sustained by nuclear energy release behind the shock front. We investigate when steady-state detonations are realizable in accreted helium layers on WDs, and model their strength and burning products using both semi-analytic and numerical models. We find the minimum helium layer thickness that will sustain a steady laterally propagating detonation and show that it depends on the density and composition of the helium layer, specifically 12 C and 16O. Though gravitationally unbound, the ashes still have unburned helium (~80% in the thinnest cases) and only reach up to heavy elements such as 40Ca, 44Ti, 48Cr, and 52Fe. It is rare for these thin shells to generate large amounts of radioactive isotopes necessary to power light curves, such as 56Ni. This has important implications on whether the unbound helium burning ashes may create faint and fast peculiar supernovae or events with virtually no radioactivity, as well as on off-center ignition of the underlying WD in the double detonation scenario for Type Ia supernovae.

The Core-Collapse Supernova-Black Hole Connection

NASA Astrophysics Data System (ADS)

O'Connor, Evan

The death of a massive star is typically associated with a bright optical transient known as a core-collapse supernova. However, there is growing evidence that not all massive stars end their lives with a brillant optical display, but rather in a whimper. These failed supernovae, or unnovae, result from the central engine failing to turn the initial implosion of the iron core into an explosion that launches the supernova shock wave, unbinds the majority of the star, and creates the supernova as we know it. In these unnovae, the failure of the central engine is soon followed by the collapse of the would-be neutron star into a stellar mass black hole. Instead of the bright optical display following successful supernovae, little to no optical emission is expected from typical failed supernovae as most of the material quietly accretes onto the black hole. This makes the hunt for failed supernovae difficult. In this chapter for the Handbook of Supernovae, I present the growing observational evidence for failed supernovae and discuss the current theoretical understanding of how and in what stars the supernova central engine fails.

A cosmic-ray-mediated shock in the solar system

NASA Technical Reports Server (NTRS)

Eichler, D.

1981-01-01

It is pointed out that the flare-induced blast wave of Aug. 4, 1972, the most violent disturbance in the solar wind on record, produced cosmic rays with an efficiency of about 50%. Such a high efficiency is predicted by the self-regulating production model of cosmic-ray origin in shocks. Most interplanetary shocks, according to simple theoretical analysis, are not strong enough to produce cosmic rays efficiently. However, if shock strength is the key parameter governing efficiency, as present interplanetary data suggest, then shocks from supernova blasts, quasar outbursts, and other violent astrophysical phenomena should be extremely efficient sources of cosmic rays.

Application of cosmic-ray shock theories to the Cygnus Loop - An alternative model

NASA Technical Reports Server (NTRS)

Boulares, Ahmed; Cox, Donald P.

1988-01-01

Steady state cosmic-ray shock models are investigated here in the light of observations of the Cygnus Loop supernova remnant. The predicted downstream temperature is derived for each model. The Cygnus Loop data and the application of the models to them, including wave dissipation, are presented. Heating rate and ionization fraction structures are provided along with an estimate of the cosmic-ray diffusion coefficient. It is found that the model of Voelk, Drury, and McKenzie (1984), in which the plasma waves are generated by the streaming instability of the cosmic rays and are dissipated into the gas, can be made consistent with some observed characteristics of the Cygnus Loop shocks. The model is used to deduce upstream densities and shock velocities and, compared to the usual pure gas shock interpretation, it is found that lower densities and approximately three times higher velocities are required.

Application of cosmic-ray shock theories to the Cygnus Loop - an alternative model

NASA Astrophysics Data System (ADS)

Boulares, Ahmed; Cox, Donald P.

1988-10-01

Steady state cosmic-ray shock models are investigated in light of observations of the Cygnus Loop supernova remnant. In this work the authors find that the model of Völk, Drury, and McKenzie, in which the plasma waves are generated by the streaming instability of the cosmic rays and are dissipated into the gas, can be made consistent with some observed characteristics of Cygnus Loop shocks. The waves heat the gas substantially in the cosmic-ray precursor, in addition to the usual heating in the (possibly weak) gas shock. The model is used to deduce upstream densities and shock velocities using known quantities for Cygnus Loop shocks. Compared to the usual pure gas shock interpretation, it is found that lower densities and approximately 3 times higher velocities are required. If the cosmic-ray models are valid, this could significantly alter our understanding of the Cygnus Loop's distance and age and of the energy released during the initial explosion.

A New Multi-dimensional General Relativistic Neutrino Hydrodynamics Code of Core-collapse Supernovae. III. Gravitational Wave Signals from Supernova Explosion Models

NASA Astrophysics Data System (ADS)

Müller, Bernhard; Janka, Hans-Thomas; Marek, Andreas

2013-03-01

We present a detailed theoretical analysis of the gravitational wave (GW) signal of the post-bounce evolution of core-collapse supernovae (SNe), employing for the first time relativistic, two-dimensional explosion models with multi-group, three-flavor neutrino transport based on the ray-by-ray-plus approximation. The waveforms reflect the accelerated mass motions associated with the characteristic evolutionary stages that were also identified in previous works: a quasi-periodic modulation by prompt post-shock convection is followed by a phase of relative quiescence before growing amplitudes signal violent hydrodynamical activity due to convection and the standing accretion shock instability during the accretion period of the stalled shock. Finally, a high-frequency, low-amplitude variation from proto-neutron star (PNS) convection below the neutrinosphere appears superimposed on the low-frequency trend associated with the aspherical expansion of the SN shock after the onset of the explosion. Relativistic effects in combination with detailed neutrino transport are shown to be essential for quantitative predictions of the GW frequency evolution and energy spectrum, because they determine the structure of the PNS surface layer and its characteristic g-mode frequency. Burst-like high-frequency activity phases, correlated with sudden luminosity increase and spectral hardening of electron (anti-)neutrino emission for some 10 ms, are discovered as new features after the onset of the explosion. They correspond to intermittent episodes of anisotropic accretion by the PNS in the case of fallback SNe. We find stronger signals for more massive progenitors with large accretion rates. The typical frequencies are higher for massive PNSs, though the time-integrated spectrum also strongly depends on the model dynamics.

TRIGGERING COLLAPSE OF THE PRESOLAR DENSE CLOUD CORE AND INJECTING SHORT-LIVED RADIOISOTOPES WITH A SHOCK WAVE. II. VARIED SHOCK WAVE AND CLOUD CORE PARAMETERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boss, Alan P.; Keiser, Sandra A., E-mail: boss@dtm.ciw.edu, E-mail: keiser@dtm.ciw.edu

2013-06-10

A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest solar system solids, including Type II supernovae (SNe), asymptotic giant branch (AGB) and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin SN shocks may be uniquely suited for the task. However,more » recent meteoritical studies have weakened the case for a direct SN injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that SN shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet (WR) star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave, by as much as a factor of {approx}10. The amount of gas and dust accreted from the post-shock wind can exceed that injected from the shock wave, with implications for the isotopic abundances expected for a SN source.« less

Generation of mesoscale magnetic fields and the dynamics of Cosmic Ray acceleration

NASA Astrophysics Data System (ADS)

Diamond, P. H.; Malkov, M. A.

The problem of the cosmic ray origin is discussed in connection with their acceleration in supernova remnant shocks. The diffusive shock acceleration mechanism is reviewed and its potential to accelerate particles to the maximum energy of (presumably) galactic cosmic rays (1018eV ) is considered. It is argued that to reach such energies, a strong magnetic field at scales larger than the particle gyroradius must be created as a result of the acceleration process, itself. One specific mechanism suggested here is based on the generation of Alfven wave at the gyroradius scale with a subsequent transfer to longer scales via interaction with strong acoustic turbulence in the shock precursor. The acoustic turbulence in turn, may be generated by Drury instability or by parametric instability of the Alfven waves. The generation mechanism is modulational instability of CR generated Alfven wave packets induced, in turn, by scattering off acoustic fluctuations in the shock precursor which are generated by Drury instability.

Hubble Sees Stars and a Stripe in Celestial Fireworks

NASA Image and Video Library

2017-12-08

Release date: July 1, 2008 SN 1006 Supernova Remnant (Hubble) A delicate ribbon of gas floats eerily in our galaxy. A contrail from an alien spaceship? A jet from a black-hole? Actually this image, taken by NASA's Hubble Space Telescope, is a very thin section of a supernova remnant caused by a stellar explosion that occurred more than 1,000 years ago. On or around May 1, 1006 A.D., observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, and surpassed Venus as the brightest object in the night time sky, only to be surpassed by the moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away. It wasn't until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred. In 1976, the first detection of exceedingly faint optical emission of the supernova remnant was reported, but only for a filament located on the northwest edge of the radio ring. A tiny portion of this filament is revealed in detail by the Hubble observation. The twisting ribbon of light seen by Hubble corresponds to locations where the expanding blast wave from the supernova is now sweeping into very tenuous surrounding gas. The hydrogen gas heated by this fast shock wave emits radiation in visible light. Hence, the optical emission provides astronomers with a detailed "snapshot" of the actual position and geometry of the shock front at any given time. Bright edges within the ribbon correspond to places where the shock wave is seen exactly edge on to our line of sight. Today we know that SN 1006 has a diameter of nearly 60 light-years, and it is still expanding at roughly 6 million miles per hour. Even at this tremendous speed, however, it takes observations typically separated by years to see significant outward motion of the shock wave against the grid of background stars. In the Hubble image as displayed, the supernova would have occurred far off the lower right corner of the image, and the motion would be toward the upper left. SN 1006 resides within our Milky Way Galaxy. Located more than 14 degrees off the plane of the galaxy's disk, there is relatively little confusion with other foreground and background objects in the field when trying to study this object. In the Hubble image, many background galaxies (orange extended objects) far off in the distant universe can be seen dotting the image. Most of the white dots are foreground or background stars in our Milky Way galaxy. This image is a composite of hydrogen-light observations taken with Hubble's Advanced Camera for Surveys in February 2006 and Wide Field Planetary Camera 2 observations in blue, yellow-green, and near-infrared light taken in April 2008. The supernova remnant, visible only in the hydrogen-light filter was assigned a red hue in the Heritage color image. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: W. Blair (Johns Hopkins University) To learn more about the Hubble Space Telescope go here: www.nasa.gov/mission_pages/hubble/main/index.html NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Parametric study of flow patterns behind the standing accretion shock wave for core-collapse supernovae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwakami, Wakana; Nagakura, Hiroki; Yamada, Shoichi, E-mail: wakana@heap.phys.waseda.ac.jp

2014-05-10

In this study, we conduct three-dimensional hydrodynamic simulations systematically to investigate the flow patterns behind the accretion shock waves that are commonly formed in the post-bounce phase of core-collapse supernovae. Adding small perturbations to spherically symmetric, steady, shocked accretion flows, we compute the subsequent evolutions to find what flow pattern emerges as a consequence of hydrodynamical instabilities such as convection and standing accretion shock instability for different neutrino luminosities and mass accretion rates. Depending on these two controlling parameters, various flow patterns are indeed realized. We classify them into three basic patterns and two intermediate ones; the former includes sloshingmore » motion (SL), spiral motion (SP), and multiple buoyant bubble formation (BB); the latter consists of spiral motion with buoyant-bubble formation (SPB) and spiral motion with pulsationally changing rotational velocities (SPP). Although the post-shock flow is highly chaotic, there is a clear trend in the pattern realization. The sloshing and spiral motions tend to be dominant for high accretion rates and low neutrino luminosities, and multiple buoyant bubbles prevail for low accretion rates and high neutrino luminosities. It is interesting that the dominant pattern is not always identical between the semi-nonlinear and nonlinear phases near the critical luminosity; the intermediate cases are realized in the latter case. Running several simulations with different random perturbations, we confirm that the realization of flow pattern is robust in most cases.« less

SNEWS The SuperNova Early Warning System

NASA Astrophysics Data System (ADS)

SNEWS Group

2005-06-01

SNEWS is a cooperative effort between the world's neutrino detection experiments to spread the news that a star in our galaxy has just experienced a core-collapse and is about to be seen as a Supernova. This project exploits the ˜hours time difference between neutrinos promptly escaping the nascent supernova and photons originating when the shock wave breaks through the stellar photosphere, to give the world a chance to get ready to observe such an exciting event at the earliest possible time. A coincidence trigger between experiments is used to eliminate potential local false alarms, allowing a rapid, automated alert. SNEWS is currently operational and ready, and this poster presents the procedures in use.

Order Amidst Chaos of Star's Explosion

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] Click on the image for movie of Order Amidst Chaos of Star's Explosion

This artist's animation shows the explosion of a massive star, the remains of which are named Cassiopeia A. NASA's Spitzer Space Telescope found evidence that the star exploded with some degree of order, preserving chunks of its onion-like layers as it blasted apart.

Cassiopeia A is what is known as a supernova remnant. The original star, about 15 to 20 times more massive than our sun, died in a cataclysmic 'supernova' explosion viewable from Earth about 340 years ago. The remnant is located 10,000 light-years away in the constellation Cassiopeia.

The movie begins by showing the star before it died, when its layers of elements (shown in different colors) were stacked neatly, with the heaviest at the core and the lightest at the top. The star is then shown blasting to smithereens. Spitzer found evidence that the star's original layers were preserved, flinging outward in all directions, but not at the same speeds. In other words, some chunks of the star sped outward faster than others, as illustrated by the animation.

The movie ends with an actual picture of Cassiopeia A taken by Spitzer. The colored layers containing different elements are seen next to each other because they traveled at different speeds.

The infrared observatory was able to see the tossed-out layers because they light up upon ramming into a 'reverse' shock wave created in the aftermath of the explosion. When a massive star explodes, it creates two types of shock waves. The forward shock wave darts out quickest, and, in the case of Cassiopeia A, is now traveling at supersonic speeds up to 7,500 kilometers per second (4,600 miles/second). The reverse shock wave is produced when the forward shock wave slams into a shell of surrounding material expelled before the star died. It tags along behind the forward shock wave at slightly slower speeds.

Chunks of the star that were thrown out fastest hit the shock wave sooner and have had more time to heat up to scorching temperatures previously detected by X-ray and visible-light telescopes. Chunks of the star that lagged behind hit the shock wave later, so they are cooler and radiate infrared light that was not seen until Spitzer came along. These lagging chunks are seen in false colors in the Spitzer picture of Cassiopeia A. They are made up of gas and dust containing neon, oxygen and aluminum -- elements from the middle layers of the original star.

The microphysics of collisionless shock waves.

PubMed

Marcowith, A; Bret, A; Bykov, A; Dieckman, M E; Drury, L O'C; Lembège, B; Lemoine, M; Morlino, G; Murphy, G; Pelletier, G; Plotnikov, I; Reville, B; Riquelme, M; Sironi, L; Novo, A Stockem

2016-04-01

Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

The microphysics of collisionless shock waves

NASA Astrophysics Data System (ADS)

Marcowith, A.; Bret, A.; Bykov, A.; Dieckman, M. E.; O'C Drury, L.; Lembège, B.; Lemoine, M.; Morlino, G.; Murphy, G.; Pelletier, G.; Plotnikov, I.; Reville, B.; Riquelme, M.; Sironi, L.; Stockem Novo, A.

2016-04-01

Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Akihiro; Maeda, Keiichi; Shigeyama, Toshikazu

A two-dimensional special relativistic radiation-hydrodynamics code is developed and applied to numerical simulations of supernova shock breakout in bipolar explosions of a blue supergiant. Our calculations successfully simulate the dynamical evolution of a blast wave in the star and its emergence from the surface. Results of the model with spherical energy deposition show a good agreement with previous simulations. Furthermore, we calculate several models with bipolar energy deposition and compare their results with the spherically symmetric model. The bolometric light curves of the shock breakout emission are calculated by a ray-tracing method. Our radiation-hydrodynamic models indicate that the early partmore » of the shock breakout emission can be used to probe the geometry of the blast wave produced as a result of the gravitational collapse of the iron core.« less

The state of clouds in a violent interstellar medium

NASA Astrophysics Data System (ADS)

Heathcote, S. R.; Brand, P. W. J. L.

1983-04-01

A highly approximate but simple model is developed which describes the interaction of a supernova blast wave with an interstellar cloud. The behavior of a cloud when exposed to conditions prevalent in a violent interstellar medium is examined using this model. Results show that after a cloud has been shocked it is rarely allowed sufficient time to return to pressure equilibrium with its surroundings before encountering a second shock. Thus, significant departures from pressure equilibrium are inevitable. It is determined that the disruption of a cloud by its passage through a blast wave is quite effective and the half life of clouds cannot greatly exceed the mean interval between shocks striking a given cloud. In addition, it is found that composite core-envelope clouds are not viable under typical conditions.

NASA's Swift Satellite Catches First Supernova in The Act of Exploding

NASA Astrophysics Data System (ADS)

2008-05-01

GREENBELT, Md.- Thanks to a fortuitous observation with NASA’s Swift satellite, astronomers for the first time have caught a star in the act of exploding. Astronomers have previously observed thousands of stellar explosions, known as supernovae, but they have always seen them after the fireworks were well underway. "For years we have dreamed of seeing a star just as it was exploding, but actually finding one is a once in a lifetime event," says team leader Alicia Soderberg, a Hubble and Carnegie-Princeton Fellow at Princeton University in Princeton, N.J. "This newly born supernova is going to be the Rosetta stone of supernova studies for years to come." A typical supernova occurs when the core of a massive star runs out of nuclear fuel and collapses under its own gravity to form an ultradense object known as a neutron star. The newborn neutron star compresses and then rebounds, triggering a shock wave that plows through the star’s gaseous outer layers and blows the star to smithereens. Astronomers thought for nearly four decades that this shock "break-out" will produce bright X-ray emission lasting a few minutes. X-ray Image X-ray Images But until this discovery, astronomers have never observed this signal. Instead, they have observed supernovae brightening days or weeks later, when the expanding shell of debris is energized by the decay of radioactive elements forged in the explosion. "Seeing the shock break-out in X-rays can give a direct view of the exploding star in the last minutes of its life and also provide a signpost to which astronomers can quickly point their telescopes to watch the explosion unfold," says Edo Berger, a Carnegie-Princeton Fellow at Princeton University. Soderberg's discovery of the first shock breakout can be attributed to luck and Swift's unique design. On January 9, 2008, Soderberg and Berger were using Swift to observe a supernova known as SN 2007uy in the spiral galaxy NGC 2770, located 90 million light-years from Earth in the constellation Lynx. At 9:33 a.m. EST they spotted an extremely bright 5-minute X-ray outburst in NGC 2770. They quickly recognized that the X-rays were coming from another location in the same galaxy. People Who Read This Also Read... Black Holes Have Simple Feeding Habits Jet Power and Black Hole Assortment Revealed in New Chandra Image Chandra Data Reveal Rapidly Whirling Black Holes Ghostly Glow Reveals a Hidden Class of Long-Wavelength Radio Emitters In a paper submitted to Nature, Soderberg and 38 colleagues show that the energy and pattern of the X-ray outburst is consistent with a shock wave bursting through the surface of the progenitor star. This marks the birth of the supernova now known as SN 2008D. Although astronomers were lucky that Swift was observing NGC 2770 just at the moment when SN 2008D’s shock wave was blowing up the star, Swift is well equipped to study such an event because of its multiple instruments observing in gamma rays, X-rays, and ultraviolet light. "It was a gift of nature for Swift to be observing that patch of sky when the supernova exploded. But thanks to Swift's flexibility, we have been able to trace its evolution in detail every day since," says Swift lead scientist Neil Gehrels of NASA’s Goddard Space Flight Center in Greenbelt, Md. Due to the significance of the X-ray outburst, Soderberg immediately mounted an international observing campaign to study SN 2008D. Observations were made with major telescopes such as the Hubble Space Telescope, the Chandra X-ray Observatory, the Very Large Array in New Mexico, the Gemini North telescope in Hawaii, the Keck I telescope in Hawaii, the 200-inch and 60-inch telescopes at the Palomar Observatory in California, and the 3.5-meter telescope at the Apache Point Observatory in New Mexico. The combined observations helped Soderberg and her colleagues pin down the energy of the initial X-ray outburst, which will help theorists better understand supernovae. The observations also show that SN 2008D is an ordinary Type Ibc supernova, which occurs when a massive, compact star explodes. Significantly, radio and X-ray observations found no evidence that a jet played a role in the explosion, ruling out a rare type of stellar explosion known as a gamma-ray burst. "This was a typical supernova," says Swift team member Stefan Immler of NASA Goddard. "The significance is not the explosion itself, but the fact that we were able to see the star blow up in real time, which gives us unprecedented insight into the explosion process."

Early Emission from Type Ia Supernovae

NASA Astrophysics Data System (ADS)

Rabinak, Itay; Livne, Eli; Waxman, Eli

2012-09-01

A unique feature of deflagration-to-detonation (DDT) white dwarf explosion models of supernovae of type Ia is the presence of a strong shock wave propagating through the outer envelope. We consider the early emission expected in such models, which is produced by the expanding shock-heated outer part of the ejecta and precedes the emission driven by radioactive decay. We expand on earlier analyses by considering the modification of the pre-detonation density profile by the weak shocks generated during the deflagration phase, the time evolution of the opacity, and the deviation of the post-shock equation of state from that obtained for radiation pressure domination. A simple analytic model is presented and shown to provide an acceptable approximation to the results of one-dimensional numerical DDT simulations. Our analysis predicts a ~103 s long UV/optical flash with a luminosity of ~1 to ~3 × 1039 erg s-1. Lower luminosity corresponds to faster (turbulent) deflagration velocity. The luminosity of the UV flash is predicted to be strongly suppressed at t > t drop ~ 1 hr due to the deviation from pure radiation domination.

Polarized Balmer line emission from supernova remnant shock waves efficiently accelerating cosmic rays

NASA Astrophysics Data System (ADS)

Shimoda, Jiro; Ohira, Yutaka; Yamazaki, Ryo; Laming, J. Martin; Katsuda, Satoru

2018-01-01

Linearly polarized Balmer line emissions from supernova remnant shocks are studied taking into account the energy loss of the shock owing to the production of non-thermal particles. The polarization degree depends on the downstream temperature and the velocity difference between upstream and downstream regions. The former is derived once the line width of the broad component of the H α emission is observed. Then, the observation of the polarization degree tells us the latter. At the same time, the estimated value of the velocity difference independently predicts adiabatic downstream temperature that is derived from Rankine Hugoniot relations for adiabatic shocks. If the actually observed downstream temperature is lower than the adiabatic temperature, there is a missing thermal energy which is consumed for particle acceleration. It is shown that a larger energy-loss rate leads to more highly polarized H α emission. Furthermore, we find that polarized intensity ratio of H β to H α also depends on the energy-loss rate and that it is independent of uncertain quantities such as electron temperature, the effect of Lyman line trapping and our line of sight.

Evidence from stable isotopes and 10Be for solar system formation triggered by a low-mass supernova

PubMed Central

Banerjee, Projjwal; Qian, Yong-Zhong; Heger, Alexander; Haxton, W C

2016-01-01

About 4.6 billion years ago, some event disturbed a cloud of gas and dust, triggering the gravitational collapse that led to the formation of the solar system. A core-collapse supernova, whose shock wave is capable of compressing such a cloud, is an obvious candidate for the initiating event. This hypothesis can be tested because supernovae also produce telltale patterns of short-lived radionuclides, which would be preserved today as isotopic anomalies. Previous studies of the forensic evidence have been inconclusive, finding a pattern of isotopes differing from that produced in conventional supernova models. Here we argue that these difficulties either do not arise or are mitigated if the initiating supernova was a special type, low in mass and explosion energy. Key to our conclusion is the demonstration that short-lived 10Be can be readily synthesized in such supernovae by neutrino interactions, while anomalies in stable isotopes are suppressed. PMID:27873999

Evidence from stable isotopes and 10Be for solar system formation triggered by a low-mass supernova

DOE PAGES

Banerjee, Projjwal; Qian, Yong -Zhong; Heger, Alexander; ...

2016-11-22

About 4.6 billion years ago, some event disturbed a cloud of gas and dust, triggering the gravitational collapse that led to the formation of the solar system. A core-collapse supernova, whose shock wave is capable of compressing such a cloud, is an obvious candidate for the initiating event. This hypothesis can be tested because supernovae also produce telltale patterns of short-lived radionuclides, which would be preserved today as isotopic anomalies. Previous studies of the forensic evidence have been inconclusive, finding a pattern of isotopes differing from that produced in conventional supernova models. Here we argue that these difficulties either domore » not arise or are mitigated if the initiating supernova was a special type, low in mass and explosion energy. Key to our conclusion is the demonstration that short-lived 10Be can be readily synthesized in such supernovae by neutrino interactions, while anomalies in stable isotopes are suppressed.« less

Evidence from stable isotopes and 10Be for solar system formation triggered by a low-mass supernova

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Projjwal; Qian, Yong -Zhong; Heger, Alexander

About 4.6 billion years ago, some event disturbed a cloud of gas and dust, triggering the gravitational collapse that led to the formation of the solar system. A core-collapse supernova, whose shock wave is capable of compressing such a cloud, is an obvious candidate for the initiating event. This hypothesis can be tested because supernovae also produce telltale patterns of short-lived radionuclides, which would be preserved today as isotopic anomalies. Previous studies of the forensic evidence have been inconclusive, finding a pattern of isotopes differing from that produced in conventional supernova models. Here we argue that these difficulties either domore » not arise or are mitigated if the initiating supernova was a special type, low in mass and explosion energy. Key to our conclusion is the demonstration that short-lived 10Be can be readily synthesized in such supernovae by neutrino interactions, while anomalies in stable isotopes are suppressed.« less

Electron injection by whistler waves in non-relativistic shocks

NASA Astrophysics Data System (ADS)

Riquelme, Mario A.; Spitkovsky, Anatoly

2012-04-01

Radio and X-ray observations of shocks in young supernova remnants (SNRs) reveal electron acceleration to non-thermal, ultra-relativistic energies (~ 10-100 TeV). This acceleration is usually assumed to happen via the diffusive shock acceleration (DSA) mechanism. However, the way in which electrons are initially energized or 'injected' into this acceleration process is an open question and the main focus of this work. We present our study of electron acceleration in nonrelativistic shocks using 2D and 3D particle-in-cell (PIC) plasma simulations. Our simulations show that significant non-thermal acceleration happens due to the growth of oblique whistler waves in the foot of quasi-perpendicular shocks. The obtained electron energy distributions show power law tails with spectral indices up to α ~ 3-4. Also, the maximum energies of the accelerated particles are consistent with the electron Larmor radii being comparable to that of the ions, indicating potential injection into the subsequent DSA process. This injection mechanism requires the shock waves to have fairly low Alfvénic Mach numbers, MA <20, which is consistent with the theoretical conditions for the growth of whistler waves in the shock foot (MA <(mi/me)1/2). Thus, if this mechanism is the only robust electron injection process at work in SNR shocks, then SNRs that display non-thermal emission must have significantly amplified upstream magnetic fields. Such field amplification is likely achieved by accelerated ions in these environments, so electron and ion acceleration in SNR shocks must be interconnected.

Collisionless Weibel shocks: Full formation mechanism and timing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bret, A.; Instituto de Investigaciones Energéticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real; Stockem, A.

2014-07-15

Collisionless shocks in plasmas play an important role in space physics (Earth's bow shock) and astrophysics (supernova remnants, relativistic jets, gamma-ray bursts, high energy cosmic rays). While the formation of a fluid shock through the steepening of a large amplitude sound wave has been understood for long, there is currently no detailed picture of the mechanism responsible for the formation of a collisionless shock. We unravel the physical mechanism at work and show that an electromagnetic Weibel shock always forms when two relativistic collisionless, initially unmagnetized, plasma shells encounter. The predicted shock formation time is in good agreement with 2Dmore » and 3D particle-in-cell simulations of counterstreaming pair plasmas. By predicting the shock formation time, experimental setups aiming at producing such shocks can be optimised to favourable conditions.« less

A cloud/particle model of the interstellar medium - Galactic spiral structure

NASA Technical Reports Server (NTRS)

Levinson, F. H.; Roberts, W. W., Jr.

1981-01-01

A cloud/particle model for gas flow in galaxies is developed that incorporates cloud-cloud collisions and supernovae as dominant local processes. Cloud-cloud collisions are the main means of dissipation. To counter this dissipation and maintain local dispersion, supernova explosions in the medium administer radial snowplow pushes to all nearby clouds. The causal link between these processes is that cloud-cloud collisions will form stars and that these stars will rapidly become supernovae. The cloud/particle model is tested and used to investigate the gas dynamics and spiral structures in galaxies where these assumptions may be reasonable. Particular attention is given to whether large-scale galactic shock waves, which are thought to underlie the regular well-delineated spiral structure in some galaxies, form and persist in a cloud-supernova dominated interstellar medium; this question is answered in the affirmative.

The Supernova Early Warning System (SNEWS)

NASA Astrophysics Data System (ADS)

Habig, A.; SNEWS Collaboration

2005-05-01

SNEWS is a cooperative effort between the world's neutrino detection experiments to spread the news that a star in our galaxy has just experienced a core-collapse event and is about to become a Type-II Supernova. This project exploits the ˜hours time difference between neutrinos promptly escaping the nascent supernova and photons which originate when the shock wave breaks through the stellar photosphere, to give the world a chance to get ready to observe such an exciting event at the earliest possible time. A coincidence trigger between experiments is used to eliminate potential local false alarms, allowing a rapid, automated alert. SNEWS is currently operational and ready, and this poster presents the procedures in use. SNEWS work is supported by NSF collaborative grant #0302166.

Observaciones combinadas XMM-Newton/Chandra del remanente de supernova G306.3-0.9

NASA Astrophysics Data System (ADS)

Filócomo, A.; Combi, J. A.; García, F.; Suárez, A. E.; Luque-Escamilla, P. L.; Parón, S.

2016-08-01

In this paper we study the spatial and spectral distribution of the physical and chemical properties of the supernova remnant G306.3-0.9 by using data of the X-rays telescopes XMM-Newton and Chandra, which we complement with radio and infrared information in order to study the morphology of the source and the effect of the shock wave in the interestelar medium. The results show a non-uniform morphology of the emission, dominated by thermal radiation with high values of Ne, Mg, S, Ca, Ar and Fe in the central region, typical of ejecta material. Also, using an infrared flux distribution, we could restrict the type of the progenitor responsible of the supernova phenomena.

Black Hole Formation and Fallback during the Supernova Explosion of a 40 M ⊙ Star

NASA Astrophysics Data System (ADS)

Chan, Conrad; Müller, Bernhard; Heger, Alexander; Pakmor, Rüdiger; Springel, Volker

2018-01-01

Fallback in core-collapse supernovae is considered a major ingredient for explaining abundance anomalies in metal-poor stars and the natal kicks and spins of black holes (BHs). We present a first 3D simulation of BH formation and fallback in an “aborted” neutrino-driven explosion of a 40 solar mass zero-metallicity progenitor from collapse to shock breakout. We follow the phase up to BH formation using the relativistic COCONUT-FMT code. For the subsequent evolution to shock breakout we apply the moving-mesh code AREPO to core-collapse supernovae for the first time. Our simulation shows that despite early BH formation, neutrino-heated bubbles can survive for tens of seconds before being accreted, leaving them sufficient time to transfer part of their energy to sustain the shock wave as is propagates through the envelope. Although the initial net energy (∼2 Bethe) of the neutrino-heated ejecta barely equals the binding energy of the envelope, 11 {M}ȯ of hydrogen are still expelled with an energy of 0.23 Bethe. We find no significant mixing and only a modest BH kick and spin, but speculate that stronger effects could occur for slightly more energetic explosions or progenitors with less tightly bound envelopes.

A distance estimate to the Cygnus Loop based on the distances to two stars located within the remnant

NASA Astrophysics Data System (ADS)

Fesen, Robert A.; Neustadt, Jack M. M.; Black, Christine S.; Milisavljevic, Dan

2018-04-01

Underlying nearly every quantitative discussion of the Cygnus Loop supernova remnant is uncertainty about its distance. Here, we present optical images and spectra of nebulosities around two stars whose mass-loss material appears to have interacted with the remnant's expanding shock front and thus can be used to estimate the Cygnus Loop's distance. Narrow passband images reveal a small emission-line nebula surrounding an M4 red giant near the remnant's eastern nebula NGC 6992. Optical spectra of the nebula show it to be shock-heated with significantly higher electron densities than seen in the remnant's filaments. This along with a bow-shaped morphology suggests it is likely red giant mass-loss material shocked and accelerated by passage of the Cygnus Loop's blast wave. We also identify a B7 V star located along the remnant's northwestern limb, which also appears to have interacted with the remnant's shock wave. It lies within a small arc of nebulosity in an unusually complex region of curved and distorted filaments along the remnant's northern shock front suggestive of a localized disturbance of the shock front due to the B star's stellar winds. Based on the assumption that these two stars lie inside the remnant, combined with an estimated distance to a molecular cloud situated along the remnant's western limb, we propose a distance to the Cygnus Loop of 1.0 ± 0.2 kpc. Although larger than several recent estimates of 500-800 pc, a distance ≃1 kpc helps resolve difficulties with the remnant's postshock cosmic ray and gas pressure ratio and estimated supernova explosion energy.

NASA's Hubble Sees A New Supernova Remnant Light Up

NASA Image and Video Library

2011-06-10

NASA image release June 10, 2011 Astronomers using NASA's Hubble Space Telescope are witnessing the unprecedented transition of a supernova to a supernova remnant, where light from an exploding star in a neighboring galaxy, the Large Magellanic Cloud, reached Earth in February 1987. Named Supernova 1987A, it was the closest supernova explosion witnessed in almost 400 years. The supernova's close proximity to Earth has allowed astronomers to study it in detail as it evolves. Now, the supernova debris, which has faded over the years, is brightening. This means that a different power source has begun to light the debris. The debris of SN 1987A is beginning to impact the surrounding ring, creating powerful shock waves that generate X-rays observed with NASA's Chandra X-ray Observatory. Those X-rays are illuminating the supernova debris and shock heating is making it glow in visible light. The results are being reported in the June 9, 2011, issue of the journal Nature by a team including Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics (CfA), who leads a long-term study of SN 1987A with Hubble. Since its launch in 1990, the Hubble telescope has provided a continuous record of the changes in SN 1987A. Credit: NASA, ESA, and P. Challis (Harvard-Smithsonian Center for Astrophysics) NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook Find us on Instagram

Model experiment of magnetic field amplification in laser-produced plasmas via the Richtmyer-Meshkov instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuramitsu, Y., E-mail: yasu@ncu.edu.tw; Moritaka, T.; Ohnishi, N.

2016-03-15

A model experiment of magnetic field amplification (MFA) via the Richtmyer-Meshkov instability (RMI) in supernova remnants (SNRs) was performed using a high-power laser. In order to account for very-fast acceleration of cosmic rays observed in SNRs, it is considered that the magnetic field has to be amplified by orders of magnitude from its background level. A possible mechanism for the MFA in SNRs is stretching and mixing of the magnetic field via the RMI when shock waves pass through dense molecular clouds in interstellar media. In order to model the astrophysical phenomenon in laboratories, there are three necessary factors formore » the RMI to be operative: a shock wave, an external magnetic field, and density inhomogeneity. By irradiating a double-foil target with several laser beams with focal spot displacement under influence of an external magnetic field, shock waves were excited and passed through the density inhomogeneity. Radiative hydrodynamic simulations show that the RMI evolves as the density inhomogeneity is shocked, resulting in higher MFA.« less

Gravitational-Wave and Neutrino Signals from Core-Collapse Supernovae with QCD Phase Transition

NASA Astrophysics Data System (ADS)

Zha, Shuai; Leung, Shing Chi; Lin, Lap Ming; Chu, Ming-Chung

Core-collapse supernovae (CCSNe) mark the catastrophic death of massive stars. We simulate CCSNe with a hybrid equations of state (EOS) containing a QCD (quantum chromodynamics) phase transition. The hybrid EOS incorporates the pure hadronic HShen EOS and the MIT Bag Model, with a Gibbs construction. Our two-dimensional hydrodynamics code includes a fifth-order shock capturing scheme WENO and models neutrino transport with the isotropic diffusion source approximation (IDSA). As the proto-neutron-star accretes matter and the core enters the mixed phase, a second collapse takes place due to softening of the EOS. We calculate the gravitational-wave (GW) and neutrino signals for this kind of CCSNe model. Future detection of these signals from CCSNe may help to constrain this scenario and the hybrid EOS.

Neutrino and Gravitational-Wave Signatures of Quark Stars

NASA Astrophysics Data System (ADS)

Chu, Ming-chung; Leung, Shing Chi; Lin, Lap Ming; Zha, Shuai

We study two types of supernovae — Type IA (SNIa) and Core-collapse supernovae (CCSNe), particularly how they may help to probe new physics. First, using a two-dimensional hydrodynamics code with a fifth-order shock capturing scheme, we simulate the explosions of dark matter admixed SNIa and find that the explosion energy and abundance of 56Ni produced are sensitive to the mass of admixed dark matter. A small admixture of dark matter may account for some sub-luminous SNIa observed. Second, by incorporating a hybrid equation of state (EOS) that includes a hadron-to-quark phase transition, we study possible formation of quark stars in CCSNe. We calculate the gravitational-wave and neutrino emissions from such a system, and we study the effects of the parameters in the EOS on such signals.

X-ray observations of the supernova remnant MSH 11-54

NASA Technical Reports Server (NTRS)

Agrawal, P. C.; Riegler, G. R.

1980-01-01

Soft X-ray observations of the X-ray source H1122-59 in the 0.4-2 keV band made with the low-energy detector 1 of the HEAO A-2 experiment are described. Based on positional coincidence, the source is identified with the supernova remnant MSH-11-54, thus confirming the report of Share et al. (1980). The object is a bright source in the 0.4-2 keV band with an X-ray flux of 9 x 10 to the -11th ergs/sq cm s near the earth. The measured source spectrum implies a plasma temperature of 4 million K and X-ray luminosity in the 0.4-2 keV band of 10 to the 37th ergs/s using a distance of 10 kpc for MSH 11-54. The X-ray observations, interpreted in terms of an adiabatic shock wave model, give a shock velocity of about 560 km/s and a supernova age of about 2300 yr, in good agreement with the age derived from the radio observations.

Vela X: A plerion or part of a shell?

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

1998-03-01

An analysis of the radio, optical, and X-ray observations of the supernova remnant (SNR) in Vela has led us to conclude that the radio source Vela X is part of the SNR shell. The high brightness of this radio source is assumed to be a result of the interaction of dome-shaped deformations (bubbles) on the SNR shell, which gives rise to bright radio filaments. The deformations could be produced by Richtmaier-Meshkov's instability, which develops during the impulsive acceleration of a shell of gas (swept up from the interstellar medium by the wind from a presupernova) by a shock wave (generated by a supernova explosion). The brightest radio filament and the X-ray jet extending along it are shown to be located in the region of interaction of two prominent bubbles on the SNR shell. We conclude that the X-ray jet, like Vela X, is part of the shell, and that it has its origin in the Mach reflection of two semispherical shock waves. Our estimate of the plasma temperature behind the front of the Mach wave matches the jet temperature. We also show that the large spread in the estimates of the spectral index for Vela X could be caused by the instrumental effect which arises during observations of extended radio sources with a nonuniform surface-brightness distribution.

The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giacalone, J.

We investigate the physics of charged-particle acceleration at spherical shocks moving into a uniform plasma containing a turbulent magnetic field with a uniform mean. This has applications to particle acceleration at astrophysical shocks, most notably, to supernovae blast waves. We numerically integrate the equations of motion of a large number of test protons moving under the influence of electric and magnetic fields determined from a kinematically defined plasma flow associated with a radially propagating blast wave. Distribution functions are determined from the positions and velocities of the protons. The unshocked plasma contains a magnetic field with a uniform mean andmore » an irregular component having a Kolmogorov-like power spectrum. The field inside the blast wave is determined from Maxwell’s equations. The angle between the average magnetic field and unit normal to the shock varies with position along its surface. It is quasi-perpendicular to the unit normal near the sphere’s equator, and quasi-parallel to it near the poles. We find that the highest intensities of particles, accelerated by the shock, are at the poles of the blast wave. The particles “collect” at the poles as they approximately adhere to magnetic field lines that move poleward from their initial encounter with the shock at the equator, as the shock expands. The field lines at the poles have been connected to the shock the longest. We also find that the highest-energy protons are initially accelerated near the equator or near the quasi-perpendicular portion of the shock, where the acceleration is more rapid.« less

Research Performance Progress Report: Diverging Supernova Explosion Experiments on NIF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plewa, Tomasz

2016-10-25

The aim of this project was to design a series of blast-wave driven Rayleigh-Taylor (RT) experiments on the National Ignition Facility (NIF). The experiments of this kind are relevant to mixing in core-collapse supernovae (ccSNe) and have the potential to address previously unanswered questions in high-energy density physics (HEDP) and astrophysics. The unmatched laser power of the NIF laser offers a unique chance to observe and study “new physics” like the mass extensions observed in HEDP RT experiments performed on the Omega laser [1], which might be linked to self-generated magnetic fields [2] and so far could not be reproducedmore » by numerical simulations. Moreover, NIF is currently the only facility that offers the possibility to execute a diverging RT experiment, which would allow to observe processes such as inter-shell penetration via turbulent mixing and shock-proximity effects (distortion of the shock by RT spikes).« less

Radio to Gamma-Ray Emission from Shell-Type Supernova Remnants: Predictions from Non-Linear Shock Acceleration Models

NASA Technical Reports Server (NTRS)

Baring, Matthew G.; Ellison, Donald C.; Reynolds, Stephen P.; Grenier, Isabelle A.; Goret, Philippe

1998-01-01

Supernova remnants (SNRs) are widely believed to be the principal source of galactic cosmic rays, produced by diffusive shock acceleration in the environs of the remnant's expanding blast wave. Such energetic particles can produce gamma-rays and lower energy photons via interactions with the ambient plasma. The recently reported observation of TeV gamma-rays from SN1006 by the CANGAROO Collaboration, combined with the fact that several unidentified EGRET sources have been associated with known radio/optical/X-ray-emitting remnants, provides powerful motivation for studying gamma-ray emission from SNRs. In this paper, we present results from a Monte Carlo simulation of non-linear shock structure and acceleration coupled with photon emission in shell-like SNRs. These non-linearities are a by-product of the dynamical influence of the accelerated cosmic rays on the shocked plasma and result in distributions of cosmic rays which deviate from pure power-laws. Such deviations are crucial to acceleration efficiency considerations and impact photon intensities and spectral shapes at all energies, producing GeV/TeV intensity ratios that are quite different from test particle predictions.

Space Science

NASA Image and Video Library

2004-10-07

Four hundred years ago, sky watchers, including the famous astronomer Johannes Kepler, best known as the discoverer of the laws of planetary motion, were startled by the sudden appearance of a new star in the western sky, rivaling the brilliance of the nearby planets. Modern astronomers, using NASA's three orbiting Great Observatories, are unraveling the mysteries of the expanding remains of Kepler's supernova, the last such object seen to explode in our Milky Way galaxy. When a new star appeared Oct. 9, 1604, observers could use only their eyes to study it. The telescope would not be invented for another four years. A team of modern astronomers has the combined abilities of NASA's Great Observatories, the Spritzer Space Telescope (SST), Hubble Space Telescope (HST), and Chandra X-Ray Observatory (CXO), to analyze the remains in infrared radiation, visible light, and X-rays. Visible-light images from Hubble's Advanced Camera for Surveys reveal where the supernova shock wave is slamming into the densest regions of surrounding gas. The astronomers used the SST to probe for material that radiates in infrared light, which shows heated microscopic dust particles that have been swept up by the supernova shock wave. The CXO data show regions of very hot gas. The combined image unveils a bubble-shaped shroud of gas and dust, 14 light-years wide and expanding at 4 million mph. There have been six known supernovas in our Milky Way over the past 1,000 years. Kepler's is the only one in which astronomers do not know what type of star exploded. By combining information from all three Great Observatories, astronomers may find the clues they need. Project management for both the HST and CXO programs is the responsibility of NASA’s Marshall Space Flight Center in Huntsville, Alabama.

Magnetogasdynamic spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes

NASA Astrophysics Data System (ADS)

Nath, G.; Vishwakarma, J. P.

2016-11-01

Similarity solutions are obtained for the flow behind a spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes, in the presence of a spatially decreasing azimuthal magnetic field. The shock wave is driven by a piston moving with time according to power law. The radiation is considered to be of the diffusion type for an optically thick grey gas model and the heat conduction is expressed in terms of Fourier's law for heat conduction. Similarity solutions exist only when the surrounding medium is of constant density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. It is shown that an increase of the gravitational parameter or the Alfven-Mach number or the parameter of the non-idealness of the gas decreases the compressibility of the gas in the flow-field behind the shock, and hence there is a decrease in the shock strength. The pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the center of symmetry. The shock waves in conducting non-ideal gas under gravitational field with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of a flare produced shock in the solar wind, central part of star burst galaxies, nuclear explosion etc. The solutions obtained can be used to interpret measurements carried out by space craft in the solar wind and in neighborhood of the Earth's magnetosphere.

Radio Observations Reveal a Smooth Circumstellar Environment Around the Extraordinary Type Ib Supernova 2012au

NASA Astrophysics Data System (ADS)

Kamble, Atish; Soderberg, Alicia M.; Chomiuk, Laura; Margutti, Raffaella; Medvedev, Mikhail; Milisavljevic, Dan; Chakraborti, Sayan; Chevalier, Roger; Chugai, Nikolai; Dittmann, Jason; Drout, Maria; Fransson, Claes; Nakar, Ehud; Sanders, Nathan

2014-12-01

We present extensive radio and X-ray observations of SN 2012au, an energetic, radio-luminous supernova of Type Ib that exhibits multi-wavelength properties bridging subsets of hydrogen-poor superluminous supernovae, hypernovae, and normal core-collapse supernovae. The observations closely follow models of synchrotron emission from a shock-heated circumburst medium that has a wind density profile (ρvpropr -2). We infer a sub-relativistic velocity for the shock wave v ≈ 0.2 c and a radius of r ≈ 1.4 × 1016cm at 25 days after the estimated date of explosion. For a wind velocity of 1000 km s-1, we determine the mass-loss rate of the progenitor to be \\dot{M} = 3.6 × 10-6 M⊙ yr-1, consistent with the estimates from X-ray observations. We estimate the total internal energy of the radio-emitting material to be E ≈ 1047 erg, which is intermediate to SN 1998bw and SN 2002ap. The evolution of the radio light curve of SN 2012au is in agreement with its interaction with a smoothly distributed circumburst medium and the absence of stellar shells ejected from previous outbursts out to r ≈ 1017 cm from the supernova site. We conclude that the bright radio emission from SN 2012au was not dissimilar from other core-collapse supernovae despite its extraordinary optical properties, and that the evolution of the SN 2012au progenitor star was relatively quiet, marked with a steady mass loss, during the final years preceding explosion.

ION ACCELERATION AT THE QUASI-PARALLEL BOW SHOCK: DECODING THE SIGNATURE OF INJECTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundberg, Torbjörn; Haynes, Christopher T.; Burgess, D.

Collisionless shocks are efficient particle accelerators. At Earth, ions with energies exceeding 100 keV are seen upstream of the bow shock when the magnetic geometry is quasi-parallel, and large-scale supernova remnant shocks can accelerate ions into cosmic-ray energies. This energization is attributed to diffusive shock acceleration; however, for this process to become active, the ions must first be sufficiently energized. How and where this initial acceleration takes place has been one of the key unresolved issues in shock acceleration theory. Using Cluster spacecraft observations, we study the signatures of ion reflection events in the turbulent transition layer upstream of the terrestrial bowmore » shock, and with the support of a hybrid simulation of the shock, we show that these reflection signatures are characteristic of the first step in the ion injection process. These reflection events develop in particular in the region where the trailing edge of large-amplitude upstream waves intercept the local shock ramp and the upstream magnetic field changes from quasi-perpendicular to quasi-parallel. The dispersed ion velocity signature observed can be attributed to a rapid succession of ion reflections at this wave boundary. After the ions’ initial interaction with the shock, they flow upstream along the quasi-parallel magnetic field. Each subsequent wavefront in the upstream region will sweep the ions back toward the shock, where they gain energy with each transition between the upstream and the shock wave frames. Within three to five gyroperiods, some ions have gained enough parallel velocity to escape upstream, thus completing the injection process.« less

Propagation of a shock wave in a radiating spherically symmetric distribution of matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrera, L.; Nunez, L.

1987-08-01

A method used to study the evolution of radiating spheres reported by Herrera et al. (1980) is extended to the case in which the sphere is divided in two regions by a shock wave front. The equations of state at both sides of the shock are different, and the solutions are matched on it via the Rankine-Hugoniot conditions. The outer-region metric is matched with a Vaidya solution on the boundary surface of the sphere. As an example of the procedure, two known solutions for radiating systems are considered. The matter distribution is free of singularities everywhere within the sphere andmore » a Gaussian-like pulse is assumed to carry out a fraction of the total mass. Exploding models are then obtained. Finally, the results are discussed in the light of recent work on gravitational collapse and supernovae. 29 references.« less

Shock wave physics and detonation physics — a stimulus for the emergence of numerous new branches in science and engineering

NASA Astrophysics Data System (ADS)

Krehl, Peter O. K.

2011-07-01

In the period of the Cold War (1945-1991), Shock Wave Physics and Detonation Physics (SWP&DP) — until the beginning of WWII mostly confined to gas dynamics, high-speed aerodynamics, and military technology (such as aero- and terminal ballistics, armor construction, chemical explosions, supersonic gun, and other firearms developments) — quickly developed into a large interdisciplinary field by its own. This rapid expansion was driven by an enormous financial support and two efficient feedbacks: the Terminal Ballistic Cycleand the Research& Development Cycle. Basic knowledge in SWP&DP, initially gained in the Classic Period(from 1808) and further extended in the Post-Classic Period(from the 1930s to present), is now increasingly used also in other branches of Science and Engineering (S&E). However, also independent S&E branches developed, based upon the fundamentals of SWP&DP, many of those developments will be addressed (see Tab. 2). Thus, shock wave and detonation phenomena are now studied within an enormous range of dimensions, covering microscopic, macroscopic, and cosmic dimensions as well as enormous time spans ranging from nano-/picosecond shock durations (such as produced by ultra-short laser pulses) to shock durations that continue for centuries (such as blast waves emitted from ancient supernova explosions). This paper reviews these developments from a historical perspective.

Spatially Resolved X-ray Spectroscopy of the Large Magellanic Cloud Supernova Remnant N132D

NASA Astrophysics Data System (ADS)

Plucinsky, Paul; Sharda, Piyush; Gaetz, Terrance; Kashyap, Vinay

2018-01-01

We perform detailed X-ray spectroscopy of the brightest Supernova Remnant (SNR), N132D, in the Large Magellanic Cloud (LMC) using observations taken by the Advanced CCD Imaging Spectrometer (ACIS) on the Chandra X-ray Observatory (Chandra). By studying the spectra of regions on the well-defined rim running from NW to NE, we determine an average abundance set for O, Ne, Mg, Si, S and Fe for the local LMC environment. We note that the elements other than Fe and Ne show significant trends across this region, implying they cannot be approximated by a single, constant value. We characterize the blast wave properties and find a simple plane parallel shock model is sufficient to explain the X-ray spectrum of the forward shock moving into ambient LMC material, with a shock velocity near 800 km/s and a shock age of 600-1100 years. We find evidence of enhanced Si near the western blast wave which would imply an asymmetric explosion. We fit a region near the central, optical O-rich knots which exhibits enhanced abundances of O, Ne, Mg, Si, and Fe. Comparison to nucleosynthesis models of the ratios of these elements indicates a progenitor mass of 28-35 solar masses, consistent with most previous estimates. Lastly, we find an intriguing presence of a very hot plasma with a temperature of ~4.5 keV (assuming a non-equilibrium ionization model) to explain the Fe-K emission which is centrally concentrated in the lower half of the remnant.

Supernova shock breakout from a red supergiant.

PubMed

Schawinski, Kevin; Justham, Stephen; Wolf, Christian; Podsiadlowski, Philipp; Sullivan, Mark; Steenbrugge, Katrien C; Bell, Tony; Röser, Hermann-Josef; Walker, Emma S; Astier, Pierre; Balam, Dave; Balland, Christophe; Carlberg, Ray; Conley, Alex; Fouchez, Dominique; Guy, Julien; Hardin, Delphine; Hook, Isobel; Howell, D Andrew; Pain, Reynald; Perrett, Kathy; Pritchet, Chris; Regnault, Nicolas; Yi, Sukyoung K

2008-07-11

Massive stars undergo a violent death when the supply of nuclear fuel in their cores is exhausted, resulting in a catastrophic "core-collapse" supernova. Such events are usually only detected at least a few days after the star has exploded. Observations of the supernova SNLS-04D2dc with the Galaxy Evolution Explorer space telescope reveal a radiative precursor from the supernova shock before the shock reached the surface of the star and show the initial expansion of the star at the beginning of the explosion. Theoretical models of the ultraviolet light curve confirm that the progenitor was a red supergiant, as expected for this type of supernova. These observations provide a way to probe the physics of core-collapse supernovae and the internal structures of their progenitor stars.

Surprisingly high-pressure shocks in the supernova remnant IC 443

NASA Technical Reports Server (NTRS)

Moorhouse, A.; Brand, P. W. J. L.; Geballe, T. R.; Burton, M. G.

1991-01-01

The intensities of several lines of molecular hydrogen have been measured from two regions of the supernova-remnant/molecular-cloud shock in IC 443. The lines measured have upper-state energies ranging from 7000 K to 23,000 K. Their relative intensities differ in the two regions, but are consistent with those predicted from the post-shock regions of simple jump-type shocks of different pressure. The pressures so derived are far higher than the pressure in the supernova remnant itself, and a possible reason for this discrepancy is discussed.

A HIRES analysis of the FIR emission of supernova remnants

NASA Technical Reports Server (NTRS)

Wang, Zhong

1994-01-01

The high resolution (HiRes) algorithm has been used to analyze the far infrared emission of shocked gas and dust in supernova remnants. In the case of supernova remnant IC 443, we find a very good match between the resolved features in the deconvolved images and the emissions of shocked gas mapped in other wavelengths (lines of H2, CO, HCO+, and HI). Dust emission is also found to be surrounding hot bubbles of supernova remnants which are seen in soft X-ray maps. Optical spectroscopy on the emission of the shocked gas suggests a close correlation between the FIR color and local shock speed, which is a strong function of the ambient (preshock) gas density. These provide a potentially effective way to identify regions of strong shock interaction, and thus facilitate studies of kinematics and energetics in the interstellar medium.

The Explosion Mechanism of Core-Collapse Supernovae: Progress in Supernova Theory and Experiments

DOE PAGES

Foglizzo, Thierry; Kazeroni, Rémi; Guilet, Jérôme; ...

2015-01-01

The explosion of core-collapse supernova depends on a sequence of events taking place in less than a second in a region of a few hundred kilometers at the center of a supergiant star, after the stellar core approaches the Chandrasekhar mass and collapses into a proto-neutron star, and before a shock wave is launched across the stellar envelope. Theoretical efforts to understand stellar death focus on the mechanism which transforms the collapse into an explosion. Progress in understanding this mechanism is reviewed with particular attention to its asymmetric character. We highlight a series of successful studies connecting observations of supernovamore » remnants and pulsars properties to the theory of core-collapse using numerical simulations. The encouraging results from first principles models in axisymmetric simulations is tempered by new puzzles in 3D. The diversity of explosion paths and the dependence on the pre-collapse stellar structure is stressed, as well as the need to gain a better understanding of hydrodynamical and MHD instabilities such as SASI and neutrino-driven convection. The shallow water analogy of shock dynamics is presented as a comparative system where buoyancy effects are absent. This dynamical system can be studied numerically and also experimentally with a water fountain. Lastly, we analyse the potential of this complementary research tool for supernova theory. We also review its potential for public outreach in science museums.« less

The Explosion Mechanism of Core-Collapse Supernovae: Progress in Supernova Theory and Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foglizzo, Thierry; Kazeroni, Rémi; Guilet, Jérôme

The explosion of core-collapse supernova depends on a sequence of events taking place in less than a second in a region of a few hundred kilometers at the center of a supergiant star, after the stellar core approaches the Chandrasekhar mass and collapses into a proto-neutron star, and before a shock wave is launched across the stellar envelope. Theoretical efforts to understand stellar death focus on the mechanism which transforms the collapse into an explosion. Progress in understanding this mechanism is reviewed with particular attention to its asymmetric character. We highlight a series of successful studies connecting observations of supernovamore » remnants and pulsars properties to the theory of core-collapse using numerical simulations. The encouraging results from first principles models in axisymmetric simulations is tempered by new puzzles in 3D. The diversity of explosion paths and the dependence on the pre-collapse stellar structure is stressed, as well as the need to gain a better understanding of hydrodynamical and MHD instabilities such as SASI and neutrino-driven convection. The shallow water analogy of shock dynamics is presented as a comparative system where buoyancy effects are absent. This dynamical system can be studied numerically and also experimentally with a water fountain. Lastly, we analyse the potential of this complementary research tool for supernova theory. We also review its potential for public outreach in science museums.« less

Neutrino Heating Drives a Supernova (Silent Animation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

When a neutron star forms, compression creates heat that generates neutrinos. When the star’s core collapses, a shock wave propagates around the star but stalls. The neutrinos reenergize a stalled shock wave, and the convection created leads to an asymmetric explosion that shoots elements into the cosmos. The heat content, or entropy, is shown, with greater entropy represented by “warmer” hues. At center is a volume rendering of the developing explosion above the newly formed neutron star (based on a simulation with the CHIMERA code); side images of orthogonal slices through the star reveal additional detail. The movie starts 100more » milliseconds after the formation of the neutron star, depicts the shockwave’s bounce and follows astrophysical events up to 432 milliseconds after the bounce.« less

Scientists Discover Supernova May Control Activity in the Center of Our Galaxy

NASA Astrophysics Data System (ADS)

2001-02-01

10 January 2001 -- Scientists using NASA's Chandra X-ray Observatory have discovered that an apparent supernova remnant in the center of our galaxy might help regulate a nearby supermassive black hole and that such relationships between supernova remnants and black holes might be common throughout the universe. The scientists studied Sagittarius A East, previously known by its ring-shaped radio emission, located nearly 26,000 light years from Earth in the constellation Sagittarius. Sgr A East appears to surround the black hole Sagittarius A* (denoted with an asterisk because it is a point source that emits radio waves) with its center offset by about six light years from that of the black hole. Using Chandra, scientists were able to separate Sgr A East from other complex structures for the first time in X-ray wavelengths. The properties they discovered support the long-standing hypothesis that Sgr A East is a single supernova remnant that exploded about 10,000 years ago. "With Chandra, we found hot gas concentrated within the larger radio shell of Sgr A East," said Yoshitomo Maeda, an astronomy and astrophysics research associate at Penn State who presented the research team's results at the 197th national meeting of the American Astronomical Society in San Diego, California, on 10 January 2001. "The gas is highly enriched by heavy elements, with four times more calcium and iron than the Sun, and that confirms earlier suspicions that Sgr A East is most likely a remnant of a supernova explosion. While dozens of supernova remnants are known in our galaxy, the proximity of Sgr A East to the black hole in the center of our galaxy makes it important." After a supernova explosion, scientists believe two shock waves are formed, with one moving inward and one outward. The inward shock wave heated up the ejecta that was detected with X-rays by the Advanced CCD Imaging Spectrometer (ACIS) aboard Chandra. The temperature of gas in that shock wave was measured at 20 million degrees by Chandra. Scientists believe the outward shock wave moved the cooler, heavier gas that comprises the intergalactic medium--compressing and plowing that gas past the black hole as the shock wave spread and feeding the black hole in the process. They believe the result was a period of intense feeding of material into the black hole, followed by a period of black hole "starvation." "The important question to be raised here is what effect the plowed gas has on its environment," said Frederick Baganoff, a research associate at Massachusetts Institute of Technology and lead scientist for Chandra's Galactic Center project. "It is possible that the plowed gas has passed over the supermassive black hole at some time in the recent past. During the passage, a lot of gas could have been captured by the black hole." When black holes pull matter inward, they are able to accelerate those particles to almost the speed of light. The matter accreting into a black hole releases a great deal of energy, much of it in X rays that can ionize the surrounding gas and make it visible with instruments such as ACIS. Because X-ray emissions from the black hole are weak at this time, scientists believe the shock wave already has passed by the black hole. "Radio astronomers already found that the gas in a halo surrounding Sgr A East and the supermassive black hole is largely ionized," said Mark Morris, professor of astronomy and physics at the University of California at Los Angeles. "If the gas plowed by the supernova remnant was pushed past the black hole, the spectacular interaction would very possibly have occurred as recently as a few hundred years ago, and the resulting flash of energy would likely have irradiated and ionized the surrounding gas. This could explain why the ionization of the gas still survives." In a broader sense, that activity might serve as a model for other black holes and other phenomena throughout the universe because the Chandra scientists suggest supernova explosions might regulate the activity of those phenomena. Many scientists believe black holes thrive at the center of most galaxies and when those black holes accrete material, scientists can detect an active galactic nucleus with X rays. According to the Chandra scientists, individual supernova explosions might be relevant for providing material that activates the accretion activity of black holes, thereby turning the active nucleus on and off. The Chandra observations were made 21 September 1999 using ACIS, which was conceived and developed for NASA by Penn State and Massachusetts Institute of Technology under the leadership of Gordon Garmire, Evan Pugh Professor of Astronomy and Astrophysics at Penn State. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. TRW, Inc., of Redondo Beach, California, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Massachusetts. The ACIS detector is a sophisticated version of the CCD detectors commonly used in digital cameras or video cameras. Chandra carries an X-ray telescope to focus the X-rays from objects in the sky. An X-ray telescope cannot work on the ground because X-rays are absorbed by the Earth's atmosphere. The Chandra X-ray Observatory is the third of NASA's "Great Observatories," following the Hubble Space Telescope and the Compton Gamma-Ray Observatory. Along with Maeda and Garmire, the Penn State contingent of collaborators for results of this research presented at the astronomical society meeting comprises: Niel Brandt, David Burrows, Eric Feigelson, and Leisa Townsley. Along with Baganoff and Morris, other collaborators include: Mark Bautz, John Doty, and George Ricker from Massachusetts Institute of Technology; and Steve Pravdo from the Jet Propulsion Laboratory. This research is supported by NASA contract NAS 8-38252 and, in part, by the Jet Propulsion Laboratory, under contract with NASA. Images associated with this release are available on the World Wide Web at: http://chandra.harvard.edu AND http://chandra.nasa.gov

Radio observations reveal a smooth circumstellar environment around the extraordinary type Ib supernova 2012au

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamble, Atish; Soderberg, Alicia M.; Margutti, Raffaella

2014-12-10

We present extensive radio and X-ray observations of SN 2012au, an energetic, radio-luminous supernova of Type Ib that exhibits multi-wavelength properties bridging subsets of hydrogen-poor superluminous supernovae, hypernovae, and normal core-collapse supernovae. The observations closely follow models of synchrotron emission from a shock-heated circumburst medium that has a wind density profile (ρ∝r {sup –2}). We infer a sub-relativistic velocity for the shock wave v ≈ 0.2 c and a radius of r ≈ 1.4 × 10{sup 16}cm at 25 days after the estimated date of explosion. For a wind velocity of 1000 km s{sup –1}, we determine the mass-loss ratemore » of the progenitor to be M-dot =3.6×10{sup −6} M{sub ⊙} yr{sup −1}, consistent with the estimates from X-ray observations. We estimate the total internal energy of the radio-emitting material to be E ≈ 10{sup 47} erg, which is intermediate to SN 1998bw and SN 2002ap. The evolution of the radio light curve of SN 2012au is in agreement with its interaction with a smoothly distributed circumburst medium and the absence of stellar shells ejected from previous outbursts out to r ≈ 10{sup 17} cm from the supernova site. We conclude that the bright radio emission from SN 2012au was not dissimilar from other core-collapse supernovae despite its extraordinary optical properties, and that the evolution of the SN 2012au progenitor star was relatively quiet, marked with a steady mass loss, during the final years preceding explosion.« less

NASA Scientists Witness a Supernova Cosmic Rite of Passage

NASA Astrophysics Data System (ADS)

2005-11-01

Scientists using NASA's Chandra X-ray Observatory have witnessed a cosmic rite of passage, the transition from a supernova to a supernova remnant, a process that has never been seen in much detail until now, leaving it poorly defined. A supernova is a massive star explosion; the remnant is the beautiful glowing shell that evolves afterwards. When does a supernova become supernova remnant? When does the shell appear and what powers its radiant glow? A science team led by Dr. Stefan Immler of NASA's Goddard Space Flight Center, Greenbelt, Md., has taken a fresh look at a supernova that exploded in 1970, called SN 1970G, just off the handle of the Big Dipper. This is the oldest supernova ever seen by X-ray telescopes. Chandra X-ray Image of SN 1970G Chandra X-ray Image of SN 1970G "Some astronomers have thought there's a moment when the supernova remnant magically turns on years after the supernova itself has faded away, when the shock wave of the explosion finally hits and lights up the interstellar medium," said Immler. "By contrast, our results show that a new supernova quickly and seamlessly evolves into a supernova remnant. The star's own debris, and not the interstellar medium gas, fuels the remnant." These results appear in The Astrophysical Journal, co-authored by Dr. Kip Kuntz, also of Goddard. They support previous Chandra observations of SN 1987A by Dr. Sangwook Park of Penn State. Using new data from Chandra and archived data from the European-led ROSAT and XMM-Newton observatories, Immler and Kuntz pieced together how SN 1970G evolved over the years. They found telltale signs of a supernova remnant - bright X-ray light - yet no evidence of interstellar gas, even across a distance around the site of the explosion 35 times larger than our solar system. Instead, the material that is heated by the supernova shock to glow in X-ray light, what we call the remnant, is from the stellar wind of the star itself and not distant gas in the interstellar medium. This wind, comprising energetic ions, was shed by the progenitor star thousands to million of years before the explosion. If this were from the interstellar medium, it would be much denser than this stellar wind. NOAO Optical Image of SN 1970G NOAO Optical Image of SN 1970G Immler and Kuntz next studied the density profiles of all other supernovae that have been detected over the past two decades. Sure enough, the low-density circumstellar matter from the stellar wind was the source of X-rays, not the interstellar medium. Immler said that historical supernova remnants such as Cassiopeia A, which exploded some 320 years ago, also show no signs of activity from the interstellar medium. This is more than just a name game, more than hypothetically changing SN 1970G to SNR 1970G. "We have to rethink this notion that a shock wave from the supernova crashes into the interstellar medium to create a supernova remnant," said Immler. "The luminous supernova remnants that we see can be created without the need of a dense interstellar medium. In fact, our study showed that all supernovae detected in X-rays over the past 25 years live in a low-density environment." SN 1970G is located in the galaxy M101, also called the Pinwheel Galaxy, a stunning spiral galaxy about 22 million light years away in the constellation Ursa Major, home of the Big Dipper. Although the galaxy itself is visible from dark skies with binoculars, telescopes cannot resolve much structure in SN 1970G, unlike for supernova remnants in our Milky Way galaxy. Discovered with an optical telescope in 1970, SN 1970G was not seen with X-ray telescopes until the 1990s. Immler's work at NASA Goddard is supported through the Universities Space Research Association. Kuntz is supported through University of Maryland, Baltimore County. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for the Agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

Once an Onion, Always an Onion (Artist Concept)

NASA Technical Reports Server (NTRS)

2006-01-01

This artist's concept illustrates a massive star before and after it blew up in a cataclysmic 'supernova' explosion. NASA's Spitzer Space Telescope found evidence that this star -- the remains of which are named Cassiopeia A -- exploded with some degree of order, preserving chunks of its onion-like layers as it blasted apart.

Cassiopeia A is located 10,000 light-years away in the constellation Cassiopeia. It was once a massive star 15 to 20 times larger than our sun. Its fiery death would have been viewable from Earth about 340 years ago.

The top figure shows the star before it died, when its layers of elements were stacked neatly, with the heaviest at the core and the lightest at the top. Spitzer found evidence that these layers were preserved when the star exploded, flinging outward in all directions, but not at the same speeds. As a result, some chunks of the layered material traveled farther out than others, as illustrated in the bottom drawing.

The infrared observatory was able to see the tossed-out layers, because they light up upon ramming into a 'reverse' shock wave created in the aftermath of the explosion. When a massive star explodes, it creates two types of shock waves. The forward shock wave darts out quickest, and, in the case of Cassiopeia A, is now traveling at supersonic speeds up to 7,500 kilometers per second (4,600 miles/second). The reverse shock wave is produced when the forward shock wave slams into a shell of surrounding material expelled before the star died. It tags along behind the forward shock wave at slightly slower speeds.

Chunks of the star that were thrown out fastest hit the shock wave sooner and have had more time to heat up to scorching temperatures previously detected by X-ray and visible-light telescopes. Chunks of the star that lagged behind hit the shock wave later, so they are cooler and radiate infrared light that was not seen until Spitzer came along. These lagging chunks are made up of gas and dust containing neon, oxygen and aluminum -- elements from the middle layers of the original star.

Nonrelativistic Perpendicular Shocks Modeling Young Supernova Remnants: Nonstationary Dynamics and Particle Acceleration at Forward and Reverse Shocks

NASA Astrophysics Data System (ADS)

Wieland, Volkmar; Pohl, Martin; Niemiec, Jacek; Rafighi, Iman; Nishikawa, Ken-Ichi

2016-03-01

For parameters that are applicable to the conditions at young supernova remnants, we present results of two-dimensional, three-vector (2D3V) particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at a 45^\\circ angle to the simulation plane to approximate three-dimensional (3D) physics. We developed an improved clean setup that uses the collision of two plasma slabs with different densities and velocities, leading to the development of two distinctive shocks and a contact discontinuity. The shock formation is mediated by Weibel-type filamentation instabilities that generate magnetic turbulence. Cyclic reformation is observed in both shocks with similar period, for which we note global variations due to shock rippling and local variations arising from turbulent current filaments. The shock rippling occurs on spatial and temporal scales produced by the gyro-motions of shock-reflected ions. The drift motion of electrons and ions is not a gradient drift, but is commensurate with {\\boldsymbol{E}}× {\\boldsymbol{B}} drift. We observe a stable supra-thermal tail in the ion spectra, but no electron acceleration because the amplitude of the Buneman modes in the shock foot is insufficient for trapping relativistic electrons. We see no evidence of turbulent reconnection. A comparison with other two-dimensional (2D) simulation results suggests that the plasma beta and the ion-to-electron mass ratio are not decisive for efficient electron acceleration, but the pre-acceleration efficacy might be reduced with respect to the 2D results once 3D effects are fully accounted for. Other microphysical factors may also play a part in limiting the amplitude of the Buneman waves or preventing the return of electrons to the foot region.

Multi-dimensional Core-Collapse Supernova Simulations with Neutrino Transport

NASA Astrophysics Data System (ADS)

Pan, Kuo-Chuan; Liebendörfer, Matthias; Hempel, Matthias; Thielemann, Friedrich-Karl

We present multi-dimensional core-collapse supernova simulations using the Isotropic Diffusion Source Approximation (IDSA) for the neutrino transport and a modified potential for general relativity in two different supernova codes: FLASH and ELEPHANT. Due to the complexity of the core-collapse supernova explosion mechanism, simulations require not only high-performance computers and the exploitation of GPUs, but also sophisticated approximations to capture the essential microphysics. We demonstrate that the IDSA is an elegant and efficient neutrino radiation transfer scheme, which is portable to multiple hydrodynamics codes and fast enough to investigate long-term evolutions in two and three dimensions. Simulations with a 40 solar mass progenitor are presented in both FLASH (1D and 2D) and ELEPHANT (3D) as an extreme test condition. It is found that the black hole formation time is delayed in multiple dimensions and we argue that the strong standing accretion shock instability before black hole formation will lead to strong gravitational waves.

Bridging the gap between supernovae and their remnants through multi-dimensional hydrodynamic modeling

NASA Astrophysics Data System (ADS)

Orlando, S.; Miceli, M.; Petruk, O.

2017-02-01

Supernova remnants (SNRs) are diffuse extended sources characterized by a complex morphology and a non-uniform distribution of ejecta. Such a morphology reflects pristine structures and features of the progenitor supernova (SN) and the early interaction of the SN blast wave with the inhomogeneous circumstellar medium (CSM). Deciphering the observations of SNRs might open the possibility to investigate the physical properties of both the interacting ejecta and the shocked CSM. This requires accurate numerical models which describe the evolution from the SN explosion to the remnant development and which connect the emission properties of the remnants to the progenitor SNe. Here we show how multi-dimensional SN-SNR hydrodynamic models have been very effective in deciphering observations of SNR Cassiopeia A and SN 1987A, thus unveiling the structure of ejecta in the immediate aftermath of the SN explosion and constraining the 3D pre-supernova structure and geometry of the environment surrounding the progenitor SN.

3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.

2006-01-01

Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets.

Supernova Fallback onto Magnetars and Propeller-powered Supernovae

NASA Astrophysics Data System (ADS)

Piro, Anthony L.; Ott, Christian D.

2011-08-01

We explore fallback accretion onto newly born magnetars during the supernova of massive stars. Strong magnetic fields (~1015 G) and short spin periods (~1-10 ms) have an important influence on how the magnetar interacts with the infalling material. At long spin periods, weak magnetic fields, and high accretion rates, sufficient material is accreted to form a black hole, as is commonly found for massive progenitor stars. When B <~ 5 × 1014 G, accretion causes the magnetar to spin sufficiently rapidly to deform triaxially and produces gravitational waves, but only for ≈50-200 s until it collapses to a black hole. Conversely, at short spin periods, strong magnetic fields, and low accretion rates, the magnetar is in the "propeller regime" and avoids becoming a black hole by expelling incoming material. This process spins down the magnetar, so that gravitational waves are only expected if the initial protoneutron star is spinning rapidly. Even when the magnetar survives, it accretes at least ≈0.3 M sun, so we expect magnetars born within these types of environments to be more massive than the 1.4 M sun typically associated with neutron stars. The propeller mechanism converts the ~1052 erg of spin energy in the magnetar into the kinetic energy of an outflow, which shock heats the outgoing supernova ejecta during the first ~10-30 s. For a small ~5 M sun hydrogen-poor envelope, this energy creates a brighter, faster evolving supernova with high ejecta velocities ~(1-3) × 104 km s-1 and may appear as a broad-lined Type Ib/c supernova. For a large >~ 10 M sun hydrogen-rich envelope, the result is a bright Type IIP supernova with a plateau luminosity of >~ 1043 erg s-1 lasting for a timescale of ~60-80 days.

Supernova Origin of Cosmic Rays from a γ-Ray Signal in the Constellation III Region of the Large Magellanic Cloud.

PubMed

Neronov, Andrii

2017-11-10

Cosmic rays could be produced via shock acceleration powered by supernovae. The supernova hypothesis implies that each supernova injects, on average, some 10^{50}  erg in cosmic rays, while the shock acceleration model predicts a power law cosmic ray spectrum with the slope close to 2. Verification of these predictions requires measurement of the spectrum and power of cosmic ray injection from supernova population(s). Here, we obtain such measurements based on γ-ray observation of the Constellation III region of the Large Magellanic Cloud. We show that γ-ray emission from this young star formation region originates from cosmic rays injected by approximately two thousand supernovae, rather than by a massive star wind powered by a superbubble predating supernova activity. Cosmic ray injection power is found to be (1.1_{-0.2}^{+0.5})×10^{50}  erg/supernova (for the estimated interstellar medium density 0.3  cm^{-3}). The spectrum is a power law with slope 2.09_{-0.07}^{+0.06}. This agrees with the model of particle acceleration at supernova shocks and provides a direct proof of the supernova origin of cosmic rays.

Spectrum and light curve of a supernova shock breakout through a thick Wolf-Rayet wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

Svirski, Gilad; Nakar, Ehud, E-mail: swirskig@post.tau.ac.il

Wolf-Rayet stars are known to eject winds. Thus, when a Wolf-Rayet star explodes as a supernova, a fast (≳ 40, 000 km s{sup –1}) shock is expected to be driven through a wind. We study the signal expected from a fast supernova shock propagating through an optically thick wind and find that the electrons behind the shock driven into the wind are efficiently cooled by inverse Compton over soft photons that were deposited by the radiation-mediated shock that crossed the star. Therefore, the bolometric luminosity is comparable to the kinetic energy flux through the shock, and the spectrum is foundmore » to be a power law, whose slope and frequency range depend on the number flux of soft photons available for cooling. Wolf-Rayet supernovae that explode through a thick wind have a high flux of soft photons, producing a flat spectrum, νF {sub ν} = Const, in the X-ray range of 0.1 ≲ T ≲ 50 keV. As the shock expands into an optically thin wind, the soft photons are no longer able to cool the shock that plows through the wind, and the bulk of the emission takes the form of a standard core-collapse supernova (without a wind). However, a small fraction of the soft photons is upscattered by the shocked wind and produces a transient unique X-ray signature.« less

X-Ray Emission from Supernova Remnants.

NASA Astrophysics Data System (ADS)

Sackville Hamilton, Andrew James

1984-12-01

This thesis deals with the x-ray spectra of supernova remnants (SNRs), and in particular the x-ray spectra of the two young Type I SNRs SN1006 and Tycho. Firstly an extensive grid of nonequilibrium model spectra of SNRs in the adiabatic blast wave stage of evolution is computed, and numerous diagnostics of the state and composi- tion of the blast wave plasma are plotted over parameter space. It is demonstrated that the spectrum of an adiabatic blast wave is a good approximation to several other model SNR structures in which emission is dominated by gas undergoing quasi steady state ioni- zation near a shock front, including the one-fluid isothermal blast wave similarity solution, and the reverse shock similarity solution advocated by Chevalier for the early evolution of Type I SNe. None of these structures appears able to account for the observed spectra of SN1006 or Tycho. A new similarity solution for the early time evolution of uniform ejecta moving into an external medium is presented. It is argued that the x-ray spectra of SN1006 and Tycho are consistent with emission mainly from a reverse shock into 1.4M(,o) of initially uniform density SN ejecta consisting of pure heavy elements, moving into a uniform medium. Satisfactory fits to the observed spectra are obtained with a two layer structure of ejecta, an outer layer of unprocessed material, and an inner layer of mixed processed heavy elements. The structure of ejecta inferred is similar for both SN1006 and Tycho, the marked difference between the two spectra being attributed largely to the lower density of the ambient medium around SN1006. The results are consistent with the theory of Type I SNe as exploded white dwarfs, and resolve the apparent problems of too little iron, and too much total mass, deduced by other authors from earlier analyses of the x-ray emission of SN1006 and Tycho. Various salient aspects of the physics of a shock-heated pure heavy element plasma are discussed.

Cosmic Ray Production in Supernovae

NASA Astrophysics Data System (ADS)

Bykov, A. M.; Ellison, D. C.; Marcowith, A.; Osipov, S. M.

2018-02-01

We give a brief review of the origin and acceleration of cosmic rays (CRs), emphasizing the production of CRs at different stages of supernova evolution by the first-order Fermi shock acceleration mechanism. We suggest that supernovae with trans-relativistic outflows, despite being rather rare, may accelerate CRs to energies above 10^{18} eV over the first year of their evolution. Supernovae in young compact clusters of massive stars, and interaction powered superluminous supernovae, may accelerate CRs well above the PeV regime. We discuss the acceleration of the bulk of the galactic CRs in isolated supernova remnants and re-acceleration of escaped CRs by the multiple shocks present in superbubbles produced by associations of OB stars. The effects of magnetic field amplification by CR driven instabilities, as well as superdiffusive CR transport, are discussed for nonthermal radiation produced by nonlinear shocks of all speeds including trans-relativistic ones.

THE ROLE OF THE DIFFUSIVE PROTONS IN THE GAMMA-RAY EMISSION OF SUPERNOVA REMNANT RX J1713.7–3946—A TWO-ZONE MODEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiao; Chen, Yang

2016-04-10

RX J1713.7−3946 is a prototype in the γ-ray-bright supernova remnants (SNRs) and is in continuing debates on its hadronic versus leptonic origin of the γ-ray emission. We explore the role played by the diffusive relativistic protons that escape from the SNR shock wave in the γ-ray emission, apart from the high-energy particles’ emission from the inside of the SNR. In the scenario that the SNR shock propagates in a clumpy molecular cavity, we consider that the γ-ray emission from the inside of the SNR may arise either from the inverse Compton scattering or from the interaction between the trapped energetic protons and themore » shocked clumps. The dominant origin between them depends on the electron-to-proton number ratio. The diffusive protons that escaped from the shock wave during the expansion history can provide an outer hadronic γ-ray component by bombarding the surrounding dense matter. The broadband spectrum can be well explained by this two-zone model, in which the γ-ray emission from the inside governs the TeV band, while the outer emission component substantially contributes to the GeV γ-rays. The two-zone model can also explain the TeV γ-ray radial brightness profile that significantly stretches beyond the nonthermal X-ray-emitting region. In the calculation, we present a simplified algorithm for Li and Chen's “accumulative diffusion” model for escaping protons and apply the Markov Chain Monte Carlo method to constrain the physical parameters.« less

Dust acoustic solitary and shock excitations in a Thomas-Fermi magnetoplasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahim, Z.; Qamar, A.; National Center for Physics

The linear and nonlinear properties of dust-acoustic waves are investigated in a collisionless Thomas-Fermi magnetoplasma, whose constituents are electrons, ions, and negatively charged dust particles. At dust time scale, the electron and ion number densities follow the Thomas-Fermi distribution, whereas the dust component is described by the classical fluid equations. A linear dispersion relation is analyzed to show that the wave frequencies associated with the upper and lower modes are enhanced with the variation of dust concentration. The effect of the latter is seen more strongly on the upper mode as compared to the lower mode. For nonlinear analysis, wemore » obtain magnetized Korteweg-de Vries (KdV) and Zakharov-Kuznetsov (ZK) equations involving the dust-acoustic solitary waves in the framework of reductive perturbation technique. Furthermore, the shock wave excitations are also studied by allowing dissipation effects in the model, leading to the Korteweg-de Vries-Burgers (KdVB) and ZKB equations. The analysis reveals that the dust-acoustic solitary and shock excitations in a Thomas-Fermi plasma are strongly influenced by the plasma parameters, e.g., dust concentration, dust temperature, obliqueness, magnetic field strength, and dust fluid viscosity. The present results should be important for understanding the solitary and shock excitations in the environments of white dwarfs or supernova, where dust particles can exist.« less

Ion Heating and Thermalization in a 3000 km/s Shock

NASA Astrophysics Data System (ADS)

Raymond, J. C.; Winkler, P. F.; Blair, W. P.; Laming, J. M.

2017-12-01

Collisionless shock waves can leave the plasma far from thermal equilibrium. Each particle species may have a different temperature, and the velocity distributions may be far from Maxwellian. We present HST/COS observations and MAGELLAN/IMACS of a 3000 km/s shock in the supernova remnant SN1006. The UV lines of He, C and N and the Hα profile show that the temperatures of H, He, C and N are mass-proportional to within the observational uncertainties. Thus there is no strong preferential heating and no strong transfer of energy among the ions. The electron temperature is about 0.05 as large as the proton temperature, and the H I distribution is non-Maxwellian. We briefly compare the results with theoretical expectations.

Monte Carlo study of neutrino acceleration in supernova shocks

NASA Technical Reports Server (NTRS)

Kazanas, D.; Ellison, D. C.

1981-01-01

The first order Fermi acceleration mechanism of cosmic rays in shocks may be at work for neutrinos in supernova shocks when the latter are at densities greater than 10 to the 13th g/cu cm, at which the core material is opaque to neutrinos. A Monte Carlo approach to study this effect is employed, and the emerging neutrino power law spectra are presented. The increased energy acquired by the neutrinos may facilitate their detection in supernova explosions and provide information about the physics of collapse.

Exposing Hierarchical Parallelism in the FLASH Code for Supernova Simulation on Summit and Other Architectures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papatheodore, Thomas L.; Messer, Bronson

Since roughly 100 million years after the big bang, the primordial elements hydrogen (H), helium (He), and lithium (Li) have been synthesized into heavier elements by thermonuclear reactions inside of the stars. The change in stellar composition resulting from these reactions causes stars to evolve over the course of their lives. Although most stars burn through their nuclear fuel and end their lives quietly as inert, compact objects, whereas others end in explosive deaths. These stellar explosions are called supernovae and are among the most energetic events known to occur in our universe. Supernovae themselves further process the matter ofmore » their progenitor stars and distribute this material into the interstellar medium of their host galaxies. In the process, they generate ∼1051 ergs of kinetic energy by sending shock waves into their surroundings, thereby contributing to galactic dynamics as well.« less

Electron Surfing Acceleration in High Mach Number Shocks

NASA Astrophysics Data System (ADS)

Hoshino, M.; Amano, T.; Matsumoto, Y.

2016-12-01

Many energetic events associated with shock waves have been argued in this context of the diffusive shock acceleration (DSA), and the origin of high-energy particles observed in astrophysical shocks are believed to be attributed to DSA. However, electron nonthermal acceleration still remains an unresolved issue of considerable interest. While cosmic rays of supernova remnant shocks with power-law spectra are believed to be produced by DSA, energetic electrons with a power-law energy spectrum are rarely ever observed at interplanetary shocks and at planetary bow shocks (e.g., Lario et al. 2003), and the diffusive-type acceleration seems to be necessarily malfunctioning in the heliosphere. The malfunctioning reason is thought to be a lack of pre-acceleration mechanism of supra-thermal electrons.In this presentation, we propose that the supra-thermal electrons can be generated by the mechanism of shock surfing acceleration (SSA) in a high Mach number magnetosonic shock. In the surfing mechanism, a series of large-amplitude electrostatic waves are excited by Buneman instability in the foot region under the interaction between the reflected ions and the incoming electrons, and it is argued that the electrons trapped in the electrostatic waves can be accelerated up to a relativistic energy (Hoshino and Shimada, 2002). Since the electron SSA has been studied based on one- or two-dimensional PIC simulations so far, SSA in three-dimensional system is questionable and remains an open question. We discuss based on our theoretical model and three-dimensional PIC simulation with a high-performance computing that the efficiency of SSA in three-dimensional system remains amazingly strong and plays an important role on the electron pre-acceleration/injection problem.

The 3D Death of a Massive Star

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2015-07-01

What happens at the very end of a massive star's life, just before its core's collapse? A group led by Sean Couch (California Institute of Technology and Michigan State University) claim to have carried out the first three-dimensional simulations of these final few minutes — revealing new clues about the factors that can lead a massive star to explode in a catastrophic supernova at the end of its life. A Giant Collapses In dying massive stars, in-falling matter bounces off the of collapsed core, creating a shock wave. If the shock wave loses too much energy as it expands into the star, it can stall out — but further energy input can revive it and result in a successful explosion of the star as a core-collapse supernova. In simulations of this process, however, theorists have trouble getting the stars to consistently explode: the shocks often stall out and fail to revive. Couch and his group suggest that one reason might be that these simulations usually start at core collapse assuming spherical symmetry of the progenitor star. Adding Turbulence Couch and his collaborators suspect that the key is in the final minutes just before the star collapses. Models that assume a spherically-symmetric star can't include the effects of convection as the final shell of silicon is burned around the core — and those effects might have a significant impact! To test this hypothesis, the group ran fully 3D simulations of the final three minutes of the life of a 15 solar-mass star, ending with core collapse, bounce, and shock-revival. The outcome was striking: the 3D modeling introduced powerful turbulent convection (with speeds of several hundred km/s!) in the last few minutes of silicon-shell burning. As a result, the initial structure and motions in the star just before core collapse were very different from those in core-collapse simulations that use spherically-symmetric initial conditions. The turbulence was then further amplified during collapse and formation of the shock, generating pressure that aided the shock expansion — which should ultimately help the star explode! The group cautions that their simulations are still very idealized, but these results clearly indicate that the 3D structure of massive stellar cores has an important impact on the core-collapse supernova mechanism. Citation Sean M. Couch et al. 2015 ApJ 808 L21 doi:10.1088/2041-8205/808/1/L21

A fast-evolving luminous transient discovered by K2/Kepler

NASA Astrophysics Data System (ADS)

Rest, A.; Garnavich, P. M.; Khatami, D.; Kasen, D.; Tucker, B. E.; Shaya, E. J.; Olling, R. P.; Mushotzky, R.; Zenteno, A.; Margheim, S.; Strampelli, G.; James, D.; Smith, R. C.; Förster, F.; Villar, V. A.

2018-04-01

For decades, optical time-domain searches have been tuned to find ordinary supernovae, which rise and fall in brightness over a period of weeks. Recently, supernova searches have improved their cadences and a handful of fast-evolving luminous transients have been identified1-5. These have peak luminosities comparable to type Ia supernovae, but rise to maximum in less than ten days and fade from view in less than one month. Here we present the most extreme example of this class of object thus far: KSN 2015K, with a rise time of only 2.2 days and a time above half-maximum of only 6.8 days. We show that, unlike type Ia supernovae, the light curve of KSN 2015K was not powered by the decay of radioactive elements. We further argue that it is unlikely that it was powered by continuing energy deposition from a central remnant (a magnetar or black hole). Using numerical radiation hydrodynamical models, we show that the light curve of KSN 2015K is well fitted by a model where the supernova runs into external material presumably expelled in a pre-supernova mass-loss episode. The rapid rise of KSN 2015K therefore probes the venting of photons when a hypersonic shock wave breaks out of a dense extended medium.

A surge of light at the birth of a supernova.

PubMed

Bersten, M C; Folatelli, G; García, F; Van Dyk, S D; Benvenuto, O G; Orellana, M; Buso, V; Sánchez, J L; Tanaka, M; Maeda, K; Filippenko, A V; Zheng, W; Brink, T G; Cenko, S B; de Jaeger, T; Kumar, S; Moriya, T J; Nomoto, K; Perley, D A; Shivvers, I; Smith, N

2018-02-21

It is difficult to establish the properties of massive stars that explode as supernovae. The electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase. Here we report the serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. The very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. We develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. This result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.

A surge of light at the birth of a supernova

NASA Astrophysics Data System (ADS)

Bersten, M. C.; Folatelli, G.; García, F.; van Dyk, S. D.; Benvenuto, O. G.; Orellana, M.; Buso, V.; Sánchez, J. L.; Tanaka, M.; Maeda, K.; Filippenko, A. V.; Zheng, W.; Brink, T. G.; Cenko, S. B.; de Jaeger, T.; Kumar, S.; Moriya, T. J.; Nomoto, K.; Perley, D. A.; Shivvers, I.; Smith, N.

2018-02-01

It is difficult to establish the properties of massive stars that explode as supernovae. The electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase. Here we report the serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. The very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. We develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. This result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.

Observation of a Hydrodynamically Driven, Radiative Precursor Shock

NASA Astrophysics Data System (ADS)

Keiter, P. A.; Drake, R. P.; Perry, T. S.; Robey, H.; Remington, B. A.; Iglesias, C. A.; Turner, N.; Stone, J.; Knauer, J.

2001-10-01

Many astrophysical systems, such as supernova remnants and jets, produce radiative-precursor shock waves. In a radiative-precursor shock, radiation from the shock ionizes and heats the medium ahead of it. The simulation of such systems requires that one treat both the emission and the absorption of the radiation. An important goal of this effort is to produce an experiment that can be modeled by astrophysical codes without implementing laser absorption physics into an astrophysical code. We report here the first measurements of a radiative-precursor shock in such an experiment. The experimental design is based on a past experiment[1,2] that used the Nova laser facility to simulate young supernova remnants. The target consists of a 60 νm CH plastic plug followed by a 150 νm vacuum gap and 2 mm of SiO2 aerogel foam. For the experiment, the density of the components and the laser-irradiation conditions are chosen so that the driven shock will produce an observable radiative precursor. We observed the radiative-precursor by using absorption spectroscopy. By backlighting the silicate aerogel foam with a thulium backlighter, we were able to observe both the 1s-2p and 1s-3p lines. These observations will allow us to determine the temperature profile in the precursor. 1. R.P. Drake, et al, Phys. Rev. Lett. 81, 2068 (1998). 2. R.P. Drake, et al., Phys. Plasmas, 7, 2142 (2000) Work supported by the U.S. Department of Energy both directly and through the Lawrence Livermore National Laboratory

X-ray emission from reverse-shocked ejecta in supernova remnants

NASA Technical Reports Server (NTRS)

Cioffi, Denis F.; Mckee, Christopher F.

1990-01-01

A simple physical model of the dynamics of a young supernova remnant is used to derive a straightforward kinematical description of the reverse shock. With suitable approximations, formulae can then be developed to give the X-ray emission of the reverse-shocked ejecta. The results are found to agree favorably with observations of SN1006.

Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Hardee, P.; Hededal, C.; Mizuno, Yosuke; Fishman, G. Jerry; Hartmann, D. H.

2006-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), supernova remnants, and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that particle acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration' is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different spectral properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations of relativistic jets and try to make a connection with observations.

Aspherical Supernovae and Oblique Shock Breakout

NASA Astrophysics Data System (ADS)

Afsariardchi, Niloufar; Matzner, Christopher D.

2017-02-01

In an aspherical supernova explosion, shock emergence is not simultaneous and non-radial flows develop near the stellar surface. Oblique shock breakouts tend to be easily developed in compact progenitors like stripped-envelop core collapse supernovae. According to Matzner et al. (2013), non-spherical explosions develop non-radial flows that alters the observable emission and radiation of a supernova explosion. These flows can limit ejecta speed, change the distribution of matter and heat of the ejecta, suppress the breakout flash, and most importantly engender collisions outside the star. We construct a global numerical FLASH hydrodynamic simulation in a two dimensional spherical coordinate, focusing on the non-relativistic, adiabatic limit in a polytropic envelope to see how these fundamental differences affect the early light curve of core-collapse SNe.

Spherization of the remnants of asymmetrical SN explosions in a uniform medium

NASA Astrophysics Data System (ADS)

Bisnovatyi-Kogan, G. S.; Blinnikov, S. I.

A 'snow-plow' approximation is used to project a spherical shape for a supernova remnant (SNR) after a shock wave has traveled through a uniform medium following an asymmetrical SN explosion. The asymmetry arises as magnetorotation causes the explosion. It is assumed that the main part of the mass remains in a thin layer after the explosion and that the layer can be described by 1,5-dimensional hydrodynamics. The cavity pressure inside the shock is assumed much greater than the pressure of the outside medium. The snow-plow model accounts for asymmetrical particle velocities in the expanding layer and the tangential velocity averaged across the shock. The equations are configured to conserve mass and momentum and have specific initial conditions. The calculations are in agreement with observations of Cas A.

Design and Construction of a Shock Tube Experiment for Multiphase Instability Experiments

NASA Astrophysics Data System (ADS)

Middlebrooks, John; Black, Wolfgang; Avgoustopoulos, Constantine; Allen, Roy; Kathakapa, Raj; Guo, Qiwen; McFarland, Jacob

2016-11-01

Hydrodynamic instabilities are important phenomena that have a wide range of practical applications in engineering and physics. One such instability, the shock driven multiphase instability (SDMI), arises when a shockwave accelerates an interface between two particle-gas mixtures with differing multiphase properties. The SDMI is present in high energy explosives, scramjets, and supernovae. A practical way of studying shock wave driven instabilities is through experimentation in a shock tube laboratory. This poster presentation will cover the design and data acquisition process of the University of Missouri's Fluid Mixing Shock Tube Laboratory. In the shock tube, a pressure generated shockwave is passed through a multiphase interface, creating the SDMI instability. This can be photographed for observation using high speed cameras, lasers, and advance imaging techniques. Important experimental parameters such as internal pressure and temperature, and mass flow rates of gases can be set and recorded by remotely controlled devices. The experimental facility provides the University of Missouri's Fluid Mixing Shock Tube Laboratory with the ability to validate simulated experiments and to conduct further inquiry into the field of shock driven multiphase hydrodynamic instabilities. Advisor.

History of Chandra X-Ray Observatory

NASA Image and Video Library

2004-08-23

This spectacular Chandra X-Ray Observatory (CXO) image of the supernova remnant Cassiopeia A is the most detailed image ever made of the remains of an exploded star. The one-million-second image shows a bright outer ring (green) 10 light years in diameter that marks the location of a shock wave generated by the supernova explosion. In the upper left corner is a large jet-like structure that protrudes beyond the shock wave, and a counter-jet can be seen on the lower right. The x-ray spectra show that the jets are rich in silicon atoms, and relatively poor in iron atoms. This indicates that the jets formed soon after the initial explosion of the star, otherwise, the jets should have contained large quantities of iron from the star’s central regions. The bright blue areas are composed almost purely of iron gas, which was produced in the central, hottest regions of the star and somehow ejected in a direction almost perpendicular to the jets. The bright source at the center of the image is presumed to be a neutron star created during the supernova. Unlike most others, this neutron star is quiet, faint, and so far shows no evidence of pulsed radiation. A working hypothesis is that the explosion that created Cassiopeia A produced high speed jets similar to, but less energetic than, the hyper nova jets thought to produce gamma-ray bursts. During the explosion, the star may have developed an extremely strong magnetic filed that helped to accelerate the jets and later stifled any pulsar wind activity. CXO project management is the responsibility of NASA’s Marshall Space Flight Center in Huntsville, Alabama.

Deepest Image of Exploded Star Uncovers Bipolar Jets

NASA Technical Reports Server (NTRS)

2004-01-01

This spectacular Chandra X-Ray Observatory (CXO) image of the supernova remnant Cassiopeia A is the most detailed image ever made of the remains of an exploded star. The one-million-second image shows a bright outer ring (green) 10 light years in diameter that marks the location of a shock wave generated by the supernova explosion. In the upper left corner is a large jet-like structure that protrudes beyond the shock wave, and a counter-jet can be seen on the lower right. The x-ray spectra show that the jets are rich in silicon atoms, and relatively poor in iron atoms. This indicates that the jets formed soon after the initial explosion of the star, otherwise, the jets should have contained large quantities of iron from the star's central regions. The bright blue areas are composed almost purely of iron gas, which was produced in the central, hottest regions of the star and somehow ejected in a direction almost perpendicular to the jets. The bright source at the center of the image is presumed to be a neutron star created during the supernova. Unlike most others, this neutron star is quiet, faint, and so far shows no evidence of pulsed radiation. A working hypothesis is that the explosion that created Cassiopeia A produced high speed jets similar to, but less energetic than, the hyper nova jets thought to produce gamma-ray bursts. During the explosion, the star may have developed an extremely strong magnetic filed that helped to accelerate the jets and later stifled any pulsar wind activity. CXO project management is the responsibility of NASA's Marshall Space Flight Center in Huntsville, Alabama.

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. V. Nonisothermal Collapse Regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boss, Alan P., E-mail: aboss@carnegiescience.edu

Recent meteoritical analyses support an initial abundance of the short-lived radioisotope (SLRI) {sup 60}Fe that may be high enough to require nucleosynthesis in a core-collapse supernova, followed by rapid incorporation into primitive meteoritical components, rather than a scenario where such isotopes were inherited from a well-mixed region of a giant molecular cloud polluted by a variety of supernovae remnants and massive star winds. This paper continues to explore the former scenario, by calculating three-dimensional, adaptive mesh refinement, hydrodynamical code (FLASH 2.5) models of the self-gravitational, dynamical collapse of a molecular cloud core that has been struck by a thin shockmore » front with a speed of 40 km s{sup −1}, leading to the injection of shock front matter into the collapsing cloud through the formation of Rayleigh–Taylor fingers at the shock–cloud intersection. These models extend the previous work into the nonisothermal collapse regime using a polytropic approximation to represent compressional heating in the optically thick protostar. The models show that the injection efficiencies of shock front materials are enhanced compared to previous models, which were not carried into the nonisothermal regime, and so did not reach such high densities. The new models, combined with the recent estimates of initial {sup 60}Fe abundances, imply that the supernova triggering and injection scenario remains a plausible explanation for the origin of the SLRIs involved in the formation of our solar system.« less

The first ten years of Swift supernovae

NASA Astrophysics Data System (ADS)

Brown, Peter J.; Roming, Peter W. A.; Milne, Peter A.

2015-09-01

The Swift Gamma Ray Burst Explorer has proven to be an incredible platform for studying the multiwavelength properties of supernova explosions. In its first ten years, Swift has observed over three hundred supernovae. The ultraviolet observations reveal a complex diversity of behavior across supernova types and classes. Even amongst the standard candle type Ia supernovae, ultraviolet observations reveal distinct groups. When the UVOT data is combined with higher redshift optical data, the relative populations of these groups appear to change with redshift. Among core-collapse supernovae, Swift discovered the shock breakout of two supernovae and the Swift data show a diversity in the cooling phase of the shock breakout of supernovae discovered from the ground and promptly followed up with Swift. Swift observations have resulted in an incredible dataset of UV and X-ray data for comparison with high-redshift supernova observations and theoretical models. Swift's supernova program has the potential to dramatically improve our understanding of stellar life and death as well as the history of our universe.

Onion-shell model of cosmic ray acceleration in supernova remnants

NASA Technical Reports Server (NTRS)

Bogdan, T. J.; Volk, H. J.

1983-01-01

A method is devised to approximate the spatially averaged momentum distribution function for the accelerated particles at the end of the active lifetime of a supernova remnant. The analysis is confined to the test particle approximation and adiabatic losses are oversimplified, but unsteady shock motion, evolving shock strength, and non-uniform gas flow effects on the accelerated particle spectrum are included. Monoenergetic protons are injected at the shock front. It is found that the dominant effect on the resultant accelerated particle spectrum is a changing spectral index with shock strength. High energy particles are produced in early phases, and the resultant distribution function is a slowly varying power law over several orders of magnitude, independent of the specific details of the supernova remnant.

SUPERNOVA FALLBACK ONTO MAGNETARS AND PROPELLER-POWERED SUPERNOVAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piro, Anthony L.; Ott, Christian D., E-mail: piro@caltech.edu, E-mail: cott@tapir.caltech.edu

2011-08-01

We explore fallback accretion onto newly born magnetars during the supernova of massive stars. Strong magnetic fields ({approx}10{sup 15} G) and short spin periods ({approx}1-10 ms) have an important influence on how the magnetar interacts with the infalling material. At long spin periods, weak magnetic fields, and high accretion rates, sufficient material is accreted to form a black hole, as is commonly found for massive progenitor stars. When B {approx}< 5 x 10{sup 14} G, accretion causes the magnetar to spin sufficiently rapidly to deform triaxially and produces gravitational waves, but only for {approx}50-200 s until it collapses to amore » black hole. Conversely, at short spin periods, strong magnetic fields, and low accretion rates, the magnetar is in the 'propeller regime' and avoids becoming a black hole by expelling incoming material. This process spins down the magnetar, so that gravitational waves are only expected if the initial protoneutron star is spinning rapidly. Even when the magnetar survives, it accretes at least {approx}0.3 M{sub sun}, so we expect magnetars born within these types of environments to be more massive than the 1.4 M{sub sun} typically associated with neutron stars. The propeller mechanism converts the {approx}10{sup 52} erg of spin energy in the magnetar into the kinetic energy of an outflow, which shock heats the outgoing supernova ejecta during the first {approx}10-30 s. For a small {approx}5 M{sub sun} hydrogen-poor envelope, this energy creates a brighter, faster evolving supernova with high ejecta velocities {approx}(1-3) x 10{sup 4} km s{sup -1} and may appear as a broad-lined Type Ib/c supernova. For a large {approx}> 10 M{sub sun} hydrogen-rich envelope, the result is a bright Type IIP supernova with a plateau luminosity of {approx}> 10{sup 43} erg s{sup -1} lasting for a timescale of {approx}60-80 days.« less

A New Gravitational-wave Signature from Standing Accretion Shock Instability in Supernovae

NASA Astrophysics Data System (ADS)

Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya

2016-09-01

We present results from fully relativistic three-dimensional core-collapse supernova simulations of a non-rotating 15{M}⊙ star using three different nuclear equations of state (EoSs). From our simulations covering up to ˜350 ms after bounce, we show that the development of the standing accretion shock instability (SASI) differs significantly depending on the stiffness of nuclear EoS. Generally, the SASI activity occurs more vigorously in models with softer EoS. By evaluating the gravitational-wave (GW) emission, we find a new GW signature on top of the previously identified one, in which the typical GW frequency increases with time due to an accumulating accretion to the proto-neutron star (PNS). The newly observed quasi-periodic signal appears in the frequency range from ˜100 to 200 Hz and persists for ˜150 ms before neutrino-driven convection dominates over the SASI. By analyzing the cycle frequency of the SASI sloshing and spiral modes as well as the mass accretion rate to the emission region, we show that the SASI frequency is correlated with the GW frequency. This is because the SASI-induced temporary perturbed mass accretion strikes the PNS surface, leading to the quasi-periodic GW emission. Our results show that the GW signal, which could be a smoking-gun signature of the SASI, is within the detection limits of LIGO, advanced Virgo, and KAGRA for Galactic events.

Shocked molecular gas and the origin of cosmic rays

NASA Astrophysics Data System (ADS)

Reach, William; Gusdorf, Antoine; Richter, Matthew

2018-06-01

When massive stars reach the end of their ability to remain stable with core nuclear fusion, they explode in supernovae that drive powerful shocks into their surroundings. Because massive stars form in and remain close to molecular clouds they often drive shocks into dense gas, which is now believed to be the origin of a significant fraction of galactic cosmic rays. The nature of the supernova-molecular cloud interaction is not well understood, though observations are gradually elucidating their nature. The range of interstellar densities, and the inclusion of circumstellar matter from the late-phase mass-loss of the stars before their explosions, leads to a wide range of possible appearances and outcomes. In particular, it is not even clear what speed or physical type of shocks are present: are they dense, magnetically-mediated shocks where H2 is not dissociated, or are they faster shocks that dissociate molecules and destroy some of the grains? SOFIA is observing some of the most significant (in terms of cosmic ray production potential and infrared energy output) supernova-molecular cloud interactions for measurement of the line widths of key molecular shocks tracers: H2, [OI], and CO. The presence of gas at speeds 100 km/s or greater would indicate dissociative shocks, while speeds 30 km/s and slower retain most molecules. The shock velocity is a key ingredient in modeling the interaction between supernovae and molecular clouds including the potential for formation of cosmic rays.

Multidimensional simulations of core-collapse supernovae with CHIMERA

NASA Astrophysics Data System (ADS)

Lentz, Eric J.; Bruenn, S. W.; Yakunin, K.; Endeve, E.; Blondin, J. M.; Harris, J. A.; Hix, W. R.; Marronetti, P.; Messer, O. B.; Mezzacappa, A.

2014-01-01

Core-collapse supernovae are driven by a multidimensional neutrino radiation hydrodynamic (RHD) engine, and full simulation requires at least axisymmetric (2D) and ultimately symmetry-free 3D RHD simulation. We present recent and ongoing work with our multidimensional RHD supernova code CHIMERA to understand the nature of the core-collapse explosion mechanism and its consequences. Recently completed simulations of 12-25 solar mass progenitors(Woosley & Heger 2007) in well resolved (0.7 degrees in latitude) 2D simulations exhibit robust explosions meeting the observationally expected explosion energy. We examine the role of hydrodynamic instabilities (standing accretion shock instability, neutrino driven convection, etc.) on the explosion dynamics and the development of the explosion energy. Ongoing 3D and 2D simulations examine the role that simulation resolution and the removal of the imposed axisymmetry have in the triggering and development of an explosion from stellar core collapse. Companion posters will explore the gravitational wave signals (Yakunin et al.) and nucleosynthesis (Harris et al.) of our simulations.

Time evolution of gamma rays from supernova remnants

NASA Astrophysics Data System (ADS)

Gaggero, Daniele; Zandanel, Fabio; Cristofari, Pierre; Gabici, Stefano

2018-04-01

We present a systematic phenomenological study focused on the time evolution of the non-thermal radiation - from radio waves to gamma rays - emitted by typical supernova remnants via hadronic and leptonic mechanisms, for two classes of progenitors: thermonuclear and core-collapse. To this aim, we develop a numerical tool designed to model the evolution of the cosmic ray spectrum inside a supernova remnant, and compute the associated multi-wavelength emission. We demonstrate the potential of this tool in the context of future population studies based on large collection of high-energy gamma-ray data. We discuss and explore the relevant parameter space involved in the problem, and focus in particular on their impact on the maximum energy of accelerated particles, in order to study the effectiveness and duration of the PeVatron phase. We outline the crucial role of the ambient medium through which the shock propagates during the remnant evolution. In particular, we point out the role of dense clumps in creating a significant hardening in the hadronic gamma-ray spectrum.

Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA

NASA Technical Reports Server (NTRS)

Indebetouw, R.; Matsuura, M.; Dwek, E.; Zanardo, G.; Barlow, M. J.; Baes, M.; Bouchet, P.; Burrows, D. N.; Chevalier, R.; Clayton, G. C.;

Exploding Stars and the Accelerating Universe

NASA Astrophysics Data System (ADS)

Kirshner, Robert P.

2012-01-01

Supernovae are exceptionally interesting astronomical objects: they punctuate the end of stellar evolution, create the heavy elements, and blast the interstellar gas with energetic shock waves. By studying supernovae, we can learn how these important aspects of cosmic evolution take place. Over the decades, we have learned that some supernovae are produced by gravitational collapse, and others by thermonuclear explosions. By understanding what supernovae are, or at least learning how they behave, supernovae explosions have been harnessed for the problem of measuring cosmic distances with some astonishing results. Carefully calibrated supernovae provide the best extragalactic distance indicators to probe the distances to galaxies and to measure the Hubble constant. Even more interesting is the evidence from supernovae that cosmic expansion has been speeding up over the last 5 billion years. We attribute this acceleration to a mysterious dark energy whose effects are clear, but whose nature is obscure. Combining the cosmic expansion history traced by supernovae with clues from galaxy clustering and cosmic geometry from the microwave background has produced today's standard, but peculiar, picture of a universe that is mostly dark energy, braked (with diminishing effect) by dark matter, and illuminated by a pinch of luminous baryons. In this talk, I will show how the attempt to understand supernovae, facilitated by ever-improving instruments, has led to the ability to measure the properties of dark energy. Looking ahead, the properties of supernovae as measured at infrared wavelengths seem to hold the best promise for more precise and accurate distances to help us understand the puzzle of dark energy. My own contribution to this work has been carried out in joyful collaboration with many excellent students, postdocs, and colleagues and with generous support from the places I have worked, the National Science Foundation, and from NASA.

The origin of the Crab Nebula and the electron capture supernova in 8-10 M solar mass stars

NASA Technical Reports Server (NTRS)

Nomoto, K.

1981-01-01

The chemical composition of the Crab Nebula is compared with several presupernova models. The small carbon and oxygen abundances in the helium-rich nebula are consistent with only the presupernova model of the star whose main sequence mass was MMS approximately 8-9.5 M. More massive stars contain too much carbon in the helium layer and smaller mass stars do not leave neutron stars. The progenitor star of the Crab Nebula lost appreciable part of the hydrogen-rich envelope before the hydrogen-rich and helium layers were mixed by convection. Finally it exploded as the electron capture supernova; the O+Ne+Mg core collapsed to form a neutron star and only the extended helium-rich envelope was ejected by the weak shock wave.

The shock process and light-element production in supernova envelopes

NASA Technical Reports Server (NTRS)

Brown, Lawrence E.; Dearborn, David S.; Schramm, David N.; Larsen, Jon T.; Kurokawa, Shin

1991-01-01

Detailed hydrodynamic modeling of the passage of supernova shocks through the hydrogen enevlopes of blue and red progenitor stars was carried out to explore the sensitivity to model conditions of light element production (specifically Li7 and B-11) which was noted by Dearborn, Schramm, Steigman and Truran (1989) (DSST). It is found that, for stellar models with M is less than or approximately 100 M solar mass, current state of the art supernova shocks do not produce significant light element yields by hydrodynamic processes alone. The dependence of this conclusion on stellar models and on shock strengths is explored. Preliminary implications for Galactic evolution of lithium are discussed, and it is suspected that intermediate mass red giant stars may be the most consistent production site for lithium.

The shock process and light element production in supernovae envelopes. Ph.D. Thesis - Chicago Univ.

NASA Technical Reports Server (NTRS)

Brown, Lawrence E.; Dearborn, David S.; Schramm, David N.; Larsen, Jon T.; Kurokawa, Shin

1990-01-01

Detailed hydrodynamic modeling of the passage of supernova shocks through the hydrogen envelopes of blue and red progenitor stars was carried out to explore the sensitivity to model conditions of light element production (specifically Li-7 and B-11) which was noted by Dearborn, Schramm, Steigman and Truran (1989) (DSST). It is found that, for stellar models with M is less than or approximately 100 M solar mass, current state of the art supernova shocks do not produce significant light element yields by hydrodynamic processes alone. The dependence of this conclusion on stellar models and on shock strengths is explored. Preliminary implications for Galactic evolution of lithium are discussed, and it is suspected that intermediate mass red giant stars may be the most consistent production site for lithium.

Co-production of Nitrogen-15 and Oxygen-18 in Explosive Helium Burning and Implications for Supernova Graphite Grains

NASA Astrophysics Data System (ADS)

Bojazi, Michael

My Masters research involves simulations of a supernova whereby a shock wave of constant Mach number is sent through a 15-solar-mass star evolved to the point of core-collapse. The resulting nucleosynthesis is examined with the intent of explaining the overproduction, relative to solar values, of nitrogen-15 and oxygen-18 abundances in supernova presolar graphite grains, as experimentally determined by Groopman et al. via a NanoSIMS analysis. We find such overabundances to be present in the helium-rich zone. Oxygen-18 is leftover from presupernova helium burning while nitrogen-15 is produced by explosive helium burning. Interestingly, anomalous excesses in molybdenum-95 and molybdenum-97 abundances in SiC X grains, discovered by Pellin et al. using the CHARISMA instrument, probably arise from explosive helium burning as well. These results signal the importance of the helium-rich zone for supernova presolar grain growth. We suggest that matter deep from the supernova, which is rich in iron-peak elements, gets injected into the helium-rich zone. Small TiC grains form in this material. These subgrains then traverse the helium-rich zone and serve as seeds for the growth of the graphite or SiC X grains.

Point-source and diffuse high-energy neutrino emission from Type IIn supernovae

NASA Astrophysics Data System (ADS)

Petropoulou, M.; Coenders, S.; Vasilopoulos, G.; Kamble, A.; Sironi, L.

2017-09-01

Type IIn supernovae (SNe), a rare subclass of core collapse SNe, explode in dense circumstellar media that have been modified by the SNe progenitors at their last evolutionary stages. The interaction of the freely expanding SN ejecta with the circumstellar medium gives rise to a shock wave propagating in the dense SN environment, which may accelerate protons to multi-PeV energies. Inelastic proton-proton collisions between the shock-accelerated protons and those of the circumstellar medium lead to multimessenger signatures. Here, we evaluate the possible neutrino signal of Type IIn SNe and compare with IceCube observations. We employ a Monte Carlo method for the calculation of the diffuse neutrino emission from the SN IIn class to account for the spread in their properties. The cumulative neutrino emission is found to be ˜10 per cent of the observed IceCube neutrino flux above 60 TeV. Type IIn SNe would be the dominant component of the diffuse astrophysical flux, only if 4 per cent of all core collapse SNe were of this type and 20-30 per cent of the shock energy was channeled to accelerated protons. Lower values of the acceleration efficiency are accessible by the observation of a single Type IIn SN as a neutrino point source with IceCube using up-going muon neutrinos. Such an identification is possible in the first year following the SN shock breakout for sources within 20 Mpc.

Enhancement of structure images of interstellar diamond microcrystals by image processing

NASA Technical Reports Server (NTRS)

O'Keefe, Michael A.; Hetherington, Crispin; Turner, John; Blake, David; Freund, Friedemann

1988-01-01

Image processed high resolution TEM images of diamond crystals found in oxidized acid residues of carbonaceous chondrites are presented. Two models of the origin of the diamonds are discussed. The model proposed by Lewis et al. (1987) supposes that the diamonds formed under low pressure conditions, whereas that of Blake et al (1988) suggests that the diamonds formed due to particle-particle collisions behind supernova shock waves. The TEM images of the diamond presented support the high pressure model.

Nonthermal X-Ray Emission from the Shell-Type Supernova Remnant G347.3-0.5

NASA Technical Reports Server (NTRS)

Slane, Patrick O.; Gaensler, Bryan M.; Dame, T. M.; Hughes, John P.; Plucinsky, Paul P.; Green, Anne

2002-01-01

Recent Advanced Spacecraft for Cosmology Astrophysics (ASCA) observations of G347.3-0.5, a supernova remnant (SNR) discovered in the ROSAT All-Sky Survey, reveal nonthermal emission from a region along the northwestern shell. Here we report on new pointed ASCA observations of G347.3-0.5 that confirm this result for all the bright shell regions and also reveal similar emission, although with slightly different spectral properties, from the remainder of the SNR. Curiously, no thermal X-ray emission is detected anywhere in the remnant. We derive limits on the amount of thermal emitting material present in G347.3-0.5 and present new radio continuum, CO, and infrared results that indicate that the remnant is distant and of moderate age. We show that our observations are broadly consistent with a scenario that has most of the supernova remnant shock wave still within the stellar wind bubble of its progenitor star, while part of it appears to be interacting with denser material. A point source at the center of the remnant has spectral properties similar to those expected for a neutron star and may represent the compact relic of the supernova progenitor.

Physical Conditions in Shocked Interstellar Gas Interacting with the Supernova Remnant IC 443

NASA Astrophysics Data System (ADS)

Ritchey, Adam M.; Federman, Steven Robert; Jenkins, Edward B.; Caprioli, Damiano; Wallerstein, George

2018-06-01

We present the results of a detailed investigation into the physical conditions in interstellar material interacting with the supernova remnant IC 443. Our analysis is based on an examination of high-resolution HST/STIS spectra of two stars probing predominantly neutral gas located both ahead of and behind the supernova shock front. The pre-shock neutral gas is characterized by densities and temperatures typical of diffuse interstellar clouds, while the post-shock material exhibits a range of more extreme physical conditions, including high temperatures (>104 K) in some cases, which may require a sudden heating event to explain. The ionization level is enhanced in the high-temperature post-shock material, which could be the result of enhanced radiation from shocks or from an increase in cosmic-ray ionization. The gas-phase abundances of refractory elements are also enhanced in the high-pressure gas, suggesting efficient destruction of dust grains by shock sputtering. Observations of highly-ionized species at very high velocity indicate a post-shock temperature of 107 K for the hot X-ray emitting plasma of the remnant’s interior, in agreement with studies of thermal X-ray emission from IC 443.

Supernova Remnant Science with AXIS

NASA Astrophysics Data System (ADS)

Williams, Brian J.; Yamaguchi, Hiroya; AXIS Science Team

2018-01-01

We present an overview of the supernova remnant (SNR) science that will be achieved with the Advanced X-ray Imaging Satellite (AXIS). AXIS follows in the footsteps of the spectacularly successful Chandra X-ray Observatory with similar or higher angular resolution and an order of magnitude more collecting area in the 0.3-10 keV band. These capabilities enable major advances in several areas of SNR science. These include, but are not limited to: 1) a more thorough spatial mapping of the ejecta products of both intermediate-mass and iron-group elements in core-collapse and Type Ia SNRs, particularly in remnants with a small diameter. The iron-group elements, specifically Cr, Mn, and Ni, are extremely important for constraining the explosion mechanism for SNe, but are generally weak and difficult to detect with Chandra, XMM-Newton, and Suzaku. 2) Studying the interface of a shock wave with the ambient ISM/CSM to constrain the degree of particle heating and acceleration at shock fronts. Chandra has only provided upper limits on shock precursor emission, and a detailed study of the thermal and nonthermal emission at the shock with greatly increased photon count rates will constrain the properties of the immediate post-shock plasma. 3) A high spatial resolution X-ray observatory will continue to build on the legacy begun by Chandra of studying the proper motion of young remnants. Directly measuring the dynamics of an SNR's evolution is crucial for understanding the explosion mechanism, and with the order of magnitude increase collecting area, we can measure the expansion of individual elemental species in the ejecta. 4) We will greatly increase the statistics of SNRs in nearby galaxies, going much faster and deeper than Chandra's observations. The increased depth of coverage would allow us to do spectroscopy in places where it was previously possible only to do rudimentary statistics. We can compare the local SNR population with the local star-formation rates for galaxies, important for supernova progenitor models. Finally, there is significant ancillary science that can be achieved by surveying nearby galaxies.

Interstellar gas and X-rays toward the Young supernova remnant RCW 86; pursuit of the origin of the thermal and non-thermal X-ray

NASA Astrophysics Data System (ADS)

Sano, H.; Reynoso, E. M.; Mitsuishi, I.; Nakamura, K.; Furukawa, N.; Mruganka, K.; Fukuda, T.; Yoshiike, S.; Nishimura, A.; Ohama, A.; Torii, K.; Kuwahara, T.; Okuda, T.; Yamamoto, H.; Tachihara, K.; Fukui, Y.

2017-09-01

We have analyzed the atomic and molecular gas using the 21 cm HI and 2.6/1.3 mm CO emissions toward the young supernova remnant (SNR) RCW 86 in order to identify the interstellar medium with which the shock waves of the SNR interact. We have found an HI intensity depression in the velocity range between -46 and - 28 kms-1 toward the SNR, suggesting a cavity in the interstellar medium. The HI cavity coincides with the thermal and non-thermal emitting X-ray shell. The thermal X-rays are coincident with the edge of the HI distribution, which indicates a strong density gradient, while the non-thermal X-rays are found toward the less dense, inner part of the HI cavity. The most significant non-thermal X-rays are seen toward the southwestern part of the shell where the HI gas traces the dense and cold component. We also identified CO clouds which are likely interacting with the SNR shock waves in the same velocity range as the HI, although the CO clouds are distributed only in a limited part of the SNR shell. The most massive cloud is located in the southeastern part of the shell, showing detailed correspondence with the thermal X-rays. These CO clouds show an enhanced CO J = 2- 1 / 1- 0 intensity ratio, suggesting heating/compression by the shock front. We interpret that the shock-cloud interaction enhances non-thermal X-rays in the southwest and the thermal X-rays are emitted by the shock-heated gas of density 10-100 cm-3. Moreover, we can clearly see an HI envelope around the CO cloud, suggesting that the progenitor had a weaker wind than the massive progenitor of the core-collapse SNR RX J1713.7-3949. It seems likely that the progenitor of RCW 86 was a system consisting of a white dwarf and a low-mass star with low-velocity accretion winds.

Large-eddy simulation of the passage of a shock wave through homogeneous turbulence

NASA Astrophysics Data System (ADS)

Braun, N. O.; Pullin, D. I.; Meiron, D. I.

2017-11-01

The passage of a nominally plane shockwave through homogeneous, compressible turbulence is a canonical problem representative of flows seen in supernovae, supersonic combustion engines, and inertial confinement fusion. The interaction of isotropic turbulence with a stationary normal shockwave is considered at inertial range Taylor Reynolds numbers, Reλ = 100 - 2500 , using Large Eddy Simulation (LES). The unresolved, subgrid terms are approximated by the stretched-vortex model (Kosovic et al., 2002), which allows self-consistent reconstruction of the subgrid contributions to the turbulent statistics of interest. The mesh is adaptively refined in the vicinity of the shock to resolve small amplitude shock oscillations, and the implications of mesh refinement on the subgrid modeling are considered. Simulations are performed at a range of shock Mach numbers, Ms = 1.2 - 3.0 , and turbulent Mach numbers, Mt = 0.06 - 0.18 , to explore the parameter space of the interaction at high Reynolds number. The LES shows reasonable agreement with linear analysis and lower Reynolds number direct numerical simulations. LANL Subcontract 305963.

Shock Driven Multiphase Instabilities in Scramjet Applications

NASA Astrophysics Data System (ADS)

McFarland, Jacob

2016-11-01

Shock driven multiphase instabilities (SDMI) arise in many applications from dust production in supernovae to ejecta distribution in explosions. At the limit of small, fast reacting particles the instability evolves similar to the Richtmyer-Meshkov (RM) instability. However, as additional particle effects such as lag, phase change, and collisions become significant the required parameter space becomes much larger and the instability deviates significantly from the RM instability. In scramjet engines the SDMI arises during a cold start where liquid fuel droplets are injected and processed by shock and expansion waves. In this case the particle evaporation and mixing is important to starting and sustaining combustion, but the particles are large and slow to react, creating significant multiphase effects. This talk will examine multiphase mixing in scramjet relevant conditions in 3D multiphase hydrodynamic simulations using the FLASH code from the University of Chicago FLASH center.

Spacelab

NASA Image and Video Library

1990-12-05

This image shows a part of the Cygnus loop supernova remnant, taken by the Ultraviolet Imaging Telescope (UIT) on the Astro Observatory during the Astro-1 mission (STS-35) on December 5, 1990. Pictured is a portion of the huge Cygnus loop, an array of interstellar gas clouds that have been blasted by a 900,000 mile per hour shock wave from a prehistoric stellar explosion, which occurred about 20,000 years ago, known as supernova. With ultraviolet and x-rays, astronomers can see emissions from extremely hot gases, intense magnetic fields, and other high-energy phenomena that more faintly appear in visible and infrared light or in radio waves that are crucial to deepening the understanding of the universe. The Astro Observatory was designed to explore the universe by observing and measuring the ultraviolet radiation from celestial objects. Three instruments make up the Astro Observatory: The Hopkins Ultraviolet Telescope (HUT), the Ultraviolet Imaging Telescope (UIT), and the Wisconsin Ultraviolet Photo-Polarimetry Experiment (WUPPE). The Marshall Space Flight Center had managment responsibilities for the Astro-1 mission. The Astro-1 Observatory was launched aboard the Space Shuttle Orbiter Columbia (STS-35) on December 2, 1990.

Correlated Signatures of Gravitational-wave and Neutrino Emission in Three-dimensional General-relativistic Core-collapse Supernova Simulations

NASA Astrophysics Data System (ADS)

Kuroda, Takami; Kotake, Kei; Hayama, Kazuhiro; Takiwaki, Tomoya

2017-12-01

We present results from general-relativistic (GR) three-dimensional (3D) core-collapse simulations with approximate neutrino transport for three nonrotating progenitors (11.2, 15, and 40 M ⊙) using different nuclear equations of state (EOSs). We find that the combination of progenitor’s higher compactness at bounce and the use of softer EOS leads to stronger activity of the standing accretion shock instability (SASI). We confirm previous predications that the SASI produces characteristic time modulations both in neutrino and gravitational-wave (GW) signals. By performing a correlation analysis of the SASI-modulated neutrino and GW signals, we find that the correlation becomes highest when we take into account the time-delay effect due to the advection of material from the neutrino sphere to the proto-neutron star core surface. Our results suggest that the correlation of the neutrino and GW signals, if detected, would provide a new signature of the vigorous SASI activity in the supernova core, which can be hardly seen if neutrino-convection dominates over the SASI.

X-ray Observations of Cosmic Ray Acceleration

NASA Technical Reports Server (NTRS)

Petre, Robert

2012-01-01

Since the discovery of cosmic rays, detection of their sources has remained elusive. A major breakthrough has come through the identification of synchrotron X-rays from the shocks of supernova remnants through imaging and spectroscopic observations by the most recent generation of X-ray observatories. This radiation is most likely produced by electrons accelerated to relativistic energy, and thus has offered the first, albeit indirect, observational evidence that diffusive shock acceleration in supernova remnants produces cosmic rays to TeV energies, possibly as high as the "knee" in the cosmic ray spectrum. X-ray observations have provided information about the maximum energy to which these shOCks accelerate electrons, as well as indirect evidence of proton acceleration. Shock morphologies measured in X-rays have indicated that a substantial fraction of the shock energy can be diverted into particle acceleration. This presentation will summarize what we have learned about cosmic ray acceleration from X-ray observations of supernova remnants over the past two decades.

Evolution of a superbubble blastwave in a magnetized medium

NASA Technical Reports Server (NTRS)

Ferriere, Katia M.; Zweibel, Ellen G.; Maclow, Mordecai-Mark

1990-01-01

Researchers investigate the effects of interstellar magnetic fields on the evolution and structure of interstellar superbubbles, using both analytic and numerical magnetohydrodynamic (MHD) calculations. These cavities of hot gas, surrounded by shells of cold dense material preceded by a shock wave result from the combined action of stellar winds and supernova explosions in OB associations. If the medium in which a superbubble goes off is homogeneous and unmagnetized, the blast wave expands isotropically. As the interstellar gas flows through the shock, it cools significantly and gets strongly compressed such that thermal pressure remains approximately equal to ram pressure. Hence, the swept up material is confined to a very thin shell. However, if the ambient medium is permeated by a uniform magnetic field B sub o approx. 3 mu G (typical value for the interstellar matter (ISM)), the configuration loses its spherical symmetry, and, due to magnetic pressure, the shell of swept up material does not remain thin. Researchers found the following qualitative differences: (1) Except in the immediate vicinity of the magnetic poles, the shell is supported by magnetic pressure. (2) The refraction of field lines at the shock and the thermal pressure gradient along the shell both contribute to accelerating the gas toward the equator. The resulting mass flux considerably decreases the column density at the magnetic poles. (3) Away from the poles, magnetic tension in the shell causes the field lines (particularly the inner boundary) to elongate in the direction of B sub o. In contrast, the shock wave radius increases with increasing theta. (4) The reduced inertia of a parcel in the polar neighborhood makes it easier to decelerate, and accounts for the dimple which appears at the poles in numerical simulations. This dimple also results from the necessity to call on intermediate shocks in order to insure a smooth transition between a purely thermal shock at the poles and a magnetic shock in the rest of the shell. (5) The shock wave propagates faster than in the absence of magnetic field, except near the poles where the reduced mass of the shell allows it to be more efficiently decelerated.

Multi-dimensional simulations of the expanding supernova remnant of SN 1987A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Potter, T. M.; Staveley-Smith, L.; Reville, B.

The expanding remnant from SN 1987A is an excellent laboratory for investigating the physics of supernovae explosions. There is still a large number of outstanding questions, such as the reason for the asymmetric radio morphology, the structure of the pre-supernova environment, and the efficiency of particle acceleration at the supernova shock. We explore these questions using three-dimensional simulations of the expanding remnant between days 820 and 10,000 after the supernova. We combine a hydrodynamical simulation with semi-analytic treatments of diffusive shock acceleration and magnetic field amplification to derive radio emission as part of an inverse problem. Simulations show that anmore » asymmetric explosion, combined with magnetic field amplification at the expanding shock, is able to replicate the persistent one-sided radio morphology of the remnant. We use an asymmetric Truelove and McKee progenitor with an envelope mass of 10 M {sub ☉} and an energy of 1.5 × 10{sup 44} J. A termination shock in the progenitor's stellar wind at a distance of 0.''43-0.''51 provides a good fit to the turn on of radio emission around day 1200. For the H II region, a minimum distance of 0.''63 ± 0.''01 and maximum particle number density of (7.11 ± 1.78) × 10{sup 7} m{sup –3} produces a good fit to the evolving average radius and velocity of the expanding shocks from day 2000 to day 7000 after explosion. The model predicts a noticeable reduction, and possibly a temporary reversal, in the asymmetric radio morphology of the remnant after day 7000, when the forward shock left the eastern lobe of the equatorial ring.« less

Multi-species first-principles simulations of particle acceleration at shocks

NASA Astrophysics Data System (ADS)

Caprioli, Damiano

Astrophysical shocks are known to be prominent sources of non-thermal particles and emission. In particular, strong shocks at supernova remnant blast waves are thought to accelerate Galactic cosmic rays (CRs) up to about 10^17eV via diffusive shock acceleration (DSA). The chemical composition of Galactic CRs, now measured with great accuracy by payloads and satellites, is reminiscent of that of the typical interstellar medium, although with some significant deviations. Observations reveal: 1) an electron/proton ratio of about 1% at about 10 GeV, (2) a general enhancement of the refractory elements relative to the volatile ones, (3) among the volatile elements, an enhancement of the heavier elements relative to the lighter ones, and (4) a discrepant hardening of CR nuclei heavier than hydrogen. Such peculiar trends contain precious information about the dependence of the acceleration process on the particle mass/charge ratio, a trend that has no theoretical counterpart in the DSA theory, yet. Building on our recent successes in modeling electron and proton DSA at non-relativistic astrophysical shocks via first-principles kinetic simulations, we will perform multispecies particle-in-cells simulations of such systems also including nuclei heavier than hydrogen, in order to investigate thermalization, injection, and acceleration of species with different mass/charge ratio. We will also analyze how the simulation outputs compare with the observed CR abundances, in order to build a model for DSA that accounts for the relative acceleration efficiency of energetic electrons, protons, and heavier ions. Finally, we will assess the possible contribution of accelerated heavy ions, especially helium, to the generation of magnetic turbulence via CR-driven instabilities - crucial to foster rapid particle energgization- and to the hadronic gamma-ray emission from young supernova remnants.

Two-Fluid Description of Collisionless Perpendicular Shocks

NASA Astrophysics Data System (ADS)

Gomez, D. O.; Morales, L. F.; Dmitruk, P.; Bertucci, C.

2017-12-01

Collisionless shocks are ubiquitous in space physics and astrophysics, such as the bow shocks formed by the solar wind in front of planets, the termination shock at the heliospheric boundary or the supernova shock fronts expanding in the interstellar plasma. Although the one-fluid magnetohydrodynamic framework provides a reasonable description of the large scale structures of the upstream and downstream plasmas, it falls short of providing an adequate description of the internal structure of the shock. A more comprehensive description of the inner and outer features of collisionless shocks would require the use of kinetic theory. Nonetheless, in the present work we show that a complete two-fluid framework (considering the role of both ions and electrons in the dynamics) can properly capture some of the features observed in real shocks. For the specific case of perpendicular shocks, i.e. cases in which the magnetic field is perpendicular to the shock normal, we integrate the one-dimensional two-fluid MHD equations numerically, to describe the generation of shocks and their spatial structure along the shock normal. Starting from finite amplitude fast-magnetosonic waves, our simulations show the generation of a stationary fast-magnetosonic shock. More importantly, we show that the ramp thickness is of the order of a few electron inertial lengths. The parallel and perpendicular components of the self-consistent electric field are derived, and their role in accelerating particles is discussed.

IceCube sensitivity for low-energy neutrinos from nearby supernovae

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Baum, V.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K. H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brown, A. M.; Buitink, S.; Caballero-Mora, K. S.; Carson, M.; Chirkin, D.; Christy, B.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; Cruz Silva, A. H.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; de Clercq, C.; Degner, T.; Demirörs, L.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Dunkman, M.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Góra, D.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, B.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jakobi, E.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kroll, G.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madsen, J.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Richard, A. S.; Richman, M.; Rodrigues, J. P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schulte, L.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Singh, K.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Stüer, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Zoll, M.; IceCube Collaboration

2011-11-01

This paper describes the response of the IceCube neutrino telescope located at the geographic south pole to outbursts of MeV neutrinos from the core collapse of nearby massive stars. IceCube was completed in December 2010 forming a lattice of 5160 photomultiplier tubes that monitor a volume of ~1 km3 in the deep Antarctic ice for particle induced photons. The telescope was designed to detect neutrinos with energies greater than 100 GeV. Owing to subfreezing ice temperatures, the photomultiplier dark noise rates are particularly low. Hence IceCube can also detect large numbers of MeV neutrinos by observing a collective rise in all photomultiplier rates on top of the dark noise. With 2 ms timing resolution, IceCube can detect subtle features in the temporal development of the supernova neutrino burst. For a supernova at the galactic center, its sensitivity matches that of a background-free megaton-scale supernova search experiment. The sensitivity decreases to 20 standard deviations at the galactic edge (30 kpc) and 6 standard deviations at the Large Magellanic Cloud (50 kpc). IceCube is sending triggers from potential supernovae to the Supernova Early Warning System. The sensitivity to neutrino properties such as the neutrino hierarchy is discussed, as well as the possibility to detect the neutronization burst, a short outbreak of \\barνe's released by electron capture on protons soon after collapse. Tantalizing signatures, such as the formation of a quark star or a black hole as well as the characteristics of shock waves, are investigated to illustrate IceCube's capability for supernova detection.

IceCube Sensitivity for Low-Energy Neutrinos from Nearby Supernovae

NASA Technical Reports Server (NTRS)

Stamatikos, M.; Abbasi, R.; Berghaus, P.; Chirkin, D.; Desiati, P.; Diaz-Velez, J.; Dumm, J. P.; Eisch, J.; Feintzeig, J.; Hanson, K.;

A physical model of mass ejection in failed supernovae

NASA Astrophysics Data System (ADS)

Coughlin, Eric R.; Quataert, Eliot; Fernández, Rodrigo; Kasen, Daniel

2018-06-01

During the core collapse of massive stars, the formation of the proto-neutron star is accompanied by the emission of a significant amount of mass energy (˜0.3 M⊙) in the form of neutrinos. This mass-energy loss generates an outward-propagating pressure wave that steepens into a shock near the stellar surface, potentially powering a weak transient associated with an otherwise-failed supernova. We analytically investigate this mass-loss-induced wave generation and propagation. Heuristic arguments provide an accurate estimate of the amount of energy contained in the outgoing sound pulse. We then develop a general formalism for analysing the response of the star to centrally concentrated mass loss in linear perturbation theory. To build intuition, we apply this formalism to polytropic stellar models, finding qualitative and quantitative agreement with simulations and heuristic arguments. We also apply our results to realistic pre-collapse massive star progenitors (both giants and compact stars). Our analytic results for the sound pulse energy, excitation radius, and steepening in the stellar envelope are in good agreement with full time-dependent hydrodynamic simulations. We show that prior to the sound pulses arrival at the stellar photosphere, the photosphere has already reached velocities ˜ 20-100 per cent of the local sound speed, thus likely modestly decreasing the stellar effective temperature prior to the star disappearing. Our results provide important constraints on the physical properties and observational appearance of failed supernovae.

EVIDENCE FOR PARTICLE ACCELERATION TO THE KNEE OF THE COSMIC RAY SPECTRUM IN TYCHO'S SUPERNOVA REMNANT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eriksen, Kristoffer A.; Hughes, John P.; Badenes, Carles

2011-02-20

Supernova remnants (SNRs) have long been assumed to be the source of cosmic rays (CRs) up to the 'knee' of the CR spectrum at 10{sup 15} eV, accelerating particles to relativistic energies in their blast waves by the process of diffusive shock acceleration (DSA). Since CR nuclei do not radiate efficiently, their presence must be inferred indirectly. Previous theoretical calculations and X-ray observations show that CR acceleration significantly modifies the structure of the SNR and greatly amplifies the interstellar magnetic field. We present new, deep X-ray observations of the remnant of Tycho's supernova (SN 1572, henceforth Tycho), which reveal amore » previously unknown, strikingly ordered pattern of non-thermal high-emissivity stripes in the projected interior of the remnant, with spacing that corresponds to the gyroradii of 10{sup 14}-10{sup 15} eV protons. Spectroscopy of the stripes shows the plasma to be highly turbulent on the (smaller) scale of the Larmor radii of TeV energy electrons. Models of the shock amplification of magnetic fields produce structure on the scale of the gyroradius of the highest energy CRs present, but they do not predict the highly ordered pattern we observe. We interpret the stripes as evidence for acceleration of particles to near the knee of the CR spectrum in regions of enhanced magnetic turbulence, while the observed highly ordered pattern of these features provides a new challenge to models of DSA.« less

A 3D View of a Supernova Remnant

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-06-01

The outlined regions mark the 57 knots in Tycho selected by the authors for velocity measurements. Magenta regions have redshifted line-of-sight velocities (moving away from us); cyan regions have blueshifted light-of-sight velocities (moving toward us). [Williams et al. 2017]The Tycho supernova remnant was first observed in the year 1572. Nearly 450 years later, astronomers have now used X-ray observations of Tycho to build the first-ever 3D map of a Type Ia supernova remnant.Signs of ExplosionsSupernova remnants are spectacular structures formed by the ejecta of stellar explosions as they expand outwards into the surrounding interstellar medium.One peculiarity of these remnants is that they often exhibit asymmetries in their appearance and motion. Is this because the ejecta are expanding into a nonuniform interstellar medium? Or was the explosion itself asymmetric? The best way we can explore this question is with detailed observations of the remnants.Histograms of the velocity in distribution of the knots in the X (green), Y (blue) and Z (red) directions (+Z is away from the observer). They show no evidence for asymmetric expansion of the knots. [Williams et al. 2017]Enter TychoTo this end, a team of scientists led by Brian Williams (Space Telescope Science Institute and NASA Goddard SFC) has worked to map out the 3D velocities of the ejecta in the Tycho supernova remnant. Tycho is a Type Ia supernova thought to be caused by the thermonuclear explosion of a white dwarf in a binary system that was destabilized by mass transfer from its companion.After 450 years of expansion, the remnant now has the morphological appearance of a roughly circular cloud of clumpy ejecta. The forward shock wave from the supernova, however, is known to have twice the velocity on one side of the shell as on the other.To better understand this asymmetry, Williams and collaborators selected a total of 57 knots in Tychos ejecta, spread out around the remnant. They then used 12 years of Chandra X-ray observations to measure both the knots proper motion in the plane of the sky and their line-of-sight velocity. These two measurements were then combined to build a full 3D map of the motion of the ejecta.3D hydrodynamical simulations of Tycho, stopped at the current epoch. These show that both initially smooth (top) and initially clumpy (bottom) ejecta models are consistent with the current observations of the morphology and dynamics of Tychos ejecta. [Adapted from Williams et al. 2017]Symmetry and ClumpsWilliams and collaborators found that the knots have total velocities that range from 2400 to 6600 km/s. Unlike the forward shock of the supernova, Tychos ejecta display no asymmetries in their motion which suggests that the explosion itself was symmetric. The more likely explanation is a density gradient in the interstellar medium, which could slow the shock wave on one side of the remnant without yet affecting the motion of the clumps of ejecta.As a final exploration, the authors attempt to address the origin of Tychos clumpiness. The fact that some of Tychos ejecta knots precede its outer edge has raised the question of whether the ejecta started out clumpy, or if they began smooth and only clumped during expansion. Williams and collaborators matched the morphological and dynamical data to simulations, demonstrating that neither scenario can be ruled out at this time.This first 3D map of a Type Ia supernova represents an important step in our ability to understand these stellar explosions. The authors suggest that well be able to expand on this map in the future with additional observations from Chandra, as well as with new data from future X-ray observatories that will be able to detect fainter emission.CitationBrian J. Williams et al 2017 ApJ 842 28. doi:10.3847/1538-4357/aa7384

Shock Acceleration of Electrons and Synchrotron Emission from the Dynamical Ejecta of Neutron Star Mergers

NASA Astrophysics Data System (ADS)

Lee, Shiu-Hang; Maeda, Keiichi; Kawanaka, Norita

2018-05-01

Neutron star mergers (NSMs) eject energetic subrelativistic dynamical ejecta into circumbinary media. Analogous to supernovae and supernova remnants, the NSM dynamical ejecta are expected to produce nonthermal emission by electrons accelerated at a shock wave. In this paper, we present the expected radio and X-ray signals by this mechanism, taking into account nonlinear diffusive shock acceleration (DSA) and magnetic field amplification. We suggest that the NSM is unique as a DSA site, where the seed relativistic electrons are abundantly provided by the decays of r-process elements. The signal is predicted to peak at a few 100–1000 days after the merger, determined by the balance between the decrease of the number of seed electrons and the increase of the dissipated kinetic energy, due to the shock expansion. While the resulting flux can ideally reach the maximum flux expected from near-equipartition, the available kinetic energy dissipation rate of the NSM ejecta limits the detectability of such a signal. It is likely that the radio and X-ray emission are overwhelmed by other mechanisms (e.g., an off-axis jet) for an observer placed in a jet direction (i.e., for GW170817). However, for an off-axis observer, to be discovered once a number of NSMs are identified, the dynamical ejecta component is predicted to dominate the nonthermal emission. While the detection of this signal is challenging even with near-future facilities, this potentially provides a robust probe of the creation of r-process elements in NSMs.

Linear analysis on the growth of non-spherical perturbations in supersonic accretion flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Kazuya; Yamada, Shoichi, E-mail: ktakahashi@heap.phys.waseda.ac.jp

We analyzed the growth of non-spherical perturbations in supersonic accretion flows. We have in mind an application to the post-bounce phase of core-collapse supernovae (CCSNe). Such non-spherical perturbations have been suggested by a series of papers by Arnett, who has numerically investigated violent convections in the outer layers of pre-collapse stars. Moreover, Couch and Ott demonstrated in their numerical simulations that such perturbations may lead to a successful supernova even for a progenitor that fails to explode without fluctuations. This study investigated the linear growth of perturbations during the infall onto a stalled shock wave. The linearized equations are solvedmore » as an initial and boundary value problem with the use of a Laplace transform. The background is a Bondi accretion flow whose parameters are chosen to mimic the 15 M {sub ☉} progenitor model by Woosley and Heger, which is supposed to be a typical progenitor of CCSNe. We found that the perturbations that are given at a large radius grow as they flow down to the shock radius; the density perturbations can be amplified by a factor of 30, for example. We analytically show that the growth rate is proportional to l, the index of the spherical harmonics. We also found that the perturbations oscillate in time with frequencies that are similar to those of the standing accretion shock instability. This may have an implication for shock revival in CCSNe, which will be investigated in our forthcoming paper in more detail.« less

Stochastic Acceleration of Galactic Cosmic Rays by Compressible Plasma Fluctuations in Supernova Shells

NASA Astrophysics Data System (ADS)

Zhang, Ming

2015-10-01

A theory of 2-stage acceleration of Galactic cosmic rays in supernova remnants is proposed. The first stage is accomplished by the supernova shock front, where a power-law spectrum is established up to a certain cutoff energy. It is followed by stochastic acceleration with compressible waves/turbulence in the downstream medium. With a broad \\propto {k}-2 spectrum for the compressible plasma fluctuations, the rate of stochastic acceleration is constant over a wide range of particle momentum. In this case, the stochastic acceleration process extends the power-law spectrum cutoff energy of Galactic cosmic rays to the knee without changing the spectral slope. This situation happens as long as the rate of stochastic acceleration is faster than 1/5 of the adiabatic cooling rate. A steeper spectrum of compressible plasma fluctuations that concentrate their power in long wavelengths will accelerate cosmic rays to the knee with a small bump before its cutoff in the comic-ray energy spectrum. This theory does not require a strong amplification of the magnetic field in the upstream interstellar medium in order to accelerate cosmic rays to the knee energy.

Acceleration of cosmic rays in supernova-remnants

NASA Technical Reports Server (NTRS)

Dorfi, E. A.; Drury, L. O.

1985-01-01

It is commonly accepted that supernova-explosions are the dominant source of cosmic rays up to an energy of 10 to the 14th power eV/nucleon. Moreover, these high energy particles provide a major contribution to the energy density of the interstellar medium (ISM) and should therefore be included in calculations of interstellar dynamic phenomena. For the following the first order Fermi mechanism in shock waves are considered to be the main acceleration mechanism. The influence of this process is twofold; first, if the process is efficient (and in fact this is the cas) it will modify the dynamics and evolution of a supernova-remnant (SNR), and secondly, the existence of a significant high energy component changes the overall picture of the ISM. The complexity of the underlying physics prevented detailed investigations of the full non-linear selfconsistent problem. For example, in the context of the energy balance of the ISM it has not been investigated how much energy of a SN-explosion can be transfered to cosmic rays in a time-dependent selfconsistent model. Nevertheless, a lot of progress was made on many aspects of the acceleration mechanism.

Core-Collapse Supernovae Explored by Multi-D Boltzmann Hydrodynamic Simulations

NASA Astrophysics Data System (ADS)

Sumiyoshi, Kohsuke; Nagakura, Hiroki; Iwakami, Wakana; Furusawa, Shun; Matsufuru, Hideo; Imakura, Akira; Yamada, Shoichi

We report the latest results of numerical simulations of core-collapse supernovae by solving multi-D neutrino-radiation hydrodynamics with Boltzmann equations. One of the longstanding issues of the explosion mechanism of supernovae has been uncertainty in the approximations of the neutrino transfer in multi-D such as the diffusion approximation and ray-by-ray method. The neutrino transfer is essential, together with 2D/3D hydrodynamical instabilities, to evaluate the neutrino heating behind the shock wave for successful explosions and to predict the neutrino burst signals. We tackled this difficult problem by utilizing our solver of the 6D Boltzmann equation for neutrinos in 3D space and 3D neutrino momentum space coupled with multi-D hydrodynamics adding special and general relativistic extensions. We have performed a set of 2D core-collapse simulations from 11M ⊙ and 15M ⊙ stars on K-computer in Japan by following long-term evolution over 400 ms after bounce to reveal the outcome from the full Boltzmann hydrodynamic simulations with a sophisticated equation of state with multi-nuclear species and updated rates for electron captures on nuclei.

Interacting supernovae from photoionization-confined shells around red supergiant stars

NASA Astrophysics Data System (ADS)

Mackey, Jonathan; Mohamed, Shazrene; Gvaramadze, Vasilii V.; Kotak, Rubina; Langer, Norbert; Meyer, Dominique M.-A.; Moriya, Takashi J.; Neilson, Hilding R.

2014-08-01

Betelgeuse, a nearby red supergiant, is a fast-moving star with a powerful stellar wind that drives a bow shock into its surroundings. This picture has been challenged by the discovery of a dense and almost static shell that is three times closer to the star than the bow shock and has been decelerated by some external force. The two physically distinct structures cannot both be formed by the hydrodynamic interaction of the wind with the interstellar medium. Here we report that a model in which Betelgeuse's wind is photoionized by radiation from external sources can explain the static shell without requiring a new understanding of the bow shock. Pressure from the photoionized wind generates a standing shock in the neutral part of the wind and forms an almost static, photoionization-confined shell. Other red supergiants should have much more massive shells than Betelgeuse, because the photoionization-confined shell traps up to 35 per cent of all mass lost during the red supergiant phase, confining this gas close to the star until it explodes. After the supernova explosion, massive shells dramatically affect the supernova light curve, providing a natural explanation for the many supernovae that have signatures of circumstellar interaction.

Interacting supernovae from photoionization-confined shells around red supergiant stars.

PubMed

Mackey, Jonathan; Mohamed, Shazrene; Gvaramadze, Vasilii V; Kotak, Rubina; Langer, Norbert; Meyer, Dominique M-A; Moriya, Takashi J; Neilson, Hilding R

2014-08-21

Betelgeuse, a nearby red supergiant, is a fast-moving star with a powerful stellar wind that drives a bow shock into its surroundings. This picture has been challenged by the discovery of a dense and almost static shell that is three times closer to the star than the bow shock and has been decelerated by some external force. The two physically distinct structures cannot both be formed by the hydrodynamic interaction of the wind with the interstellar medium. Here we report that a model in which Betelgeuse's wind is photoionized by radiation from external sources can explain the static shell without requiring a new understanding of the bow shock. Pressure from the photoionized wind generates a standing shock in the neutral part of the wind and forms an almost static, photoionization-confined shell. Other red supergiants should have much more massive shells than Betelgeuse, because the photoionization-confined shell traps up to 35 per cent of all mass lost during the red supergiant phase, confining this gas close to the star until it explodes. After the supernova explosion, massive shells dramatically affect the supernova light curve, providing a natural explanation for the many supernovae that have signatures of circumstellar interaction.

SN 1987A: A Unique Laboratory for Shock Physics

NASA Technical Reports Server (NTRS)

Sonneborn, George

2012-01-01

Supernova 1987 A is the brightest and nearest supernova observed since Kepler's SN1604, and is the only one close enough to resolve and directly observe the temporal growth of the ejecta. Over the past 25 years, intensive observations across the electromagnetic spectrum with observatories on the ground (Australia Telescope Compact Array, Gemini-S, Magellan, VLT) and in space (IUE, KAO, CGRO, Hubble, Chandra, Spitzer, Herschel) have given us an unprecedented view of the evolution of the debris of the supernova and of its shock interaction with circumstellar matter. The outer supernova debris, now expanding with velocities -8000 km/s, encountered the relatively dense circumstellar ring formed by presupernova mass loss starting in 1994. The resulting shock interaction has been manifested by: rapidly brightening UV-optical "hotspots", an expanding X-ray ring. an expanding ring of knotty non-thermal radio emission, and a ring of thermal IR emission from silicate dust. The recent evolution of these emissions reveal new details about the shock interaction, circumstellar material, and the star that exploded. Certain critical problems about SN 1987 A, such as the still undiscovered compact object formed in the explosion and the structure of the central debris, require the capabilities of JWST.

Perspectives on High-Energy-Density Physics

NASA Astrophysics Data System (ADS)

Drake, R. Paul

2008-11-01

Much of 21st century plasma physics will involve work to produce, understand, control, and exploit very non-traditional plasmas. High-energy density (HED) plasmas are often examples, variously involving strong Coulomb interactions and few particles per Debeye sphere, dominant radiation effects, strongly relativistic effects, or strongly quantum-mechanical behavior. Indeed, these and other modern plasma systems often fall outside the early standard theoretical definitions of ``plasma''. This presentation will focus on two types of HED plasmas that exhibit non-traditional behavior. Our first example will be the plasmas produced by extremely strong shock waves. Shock waves are present across the entire realm of plasma densities, often in space or astrophysical contexts. HED shock waves (at pressures > 1 Mbar) enable studies in many areas, from equations of state to hydrodynamics to radiation hydrodynamics. We will specifically consider strongly radiative shocks, in which the radiative energy fluxes are comparable to the mechanical energy fluxes that drive the shocks. Modern HED facilities can produce such shocks, which are also present in dense, energetic, astrophysical systems such as supernovae. These shocks are also excellent targets for advanced simulations due to their range of spatial scales and complex radiation transport. Our second example will be relativistic plasmas. In general, these vary from plasmas containing relativistic particle beams, produced for some decades in the laboratory, to the relativistic thermal plasmas present for example in pulsar winds. Laboratory HED relativistic plasmas to date have been those produced by laser beams of irradiance ˜ 10^18 to 10^22 W/cm^2 or by accelerator-produced HED electron beams. These have applications ranging from generation of intense x-rays to production of proton beams for radiation therapy to acceleration of electrons. Here we will focus on electron acceleration, a spectacular recent success and a rare example in which simplicity emerges from the complexity present in the plasma state.

The Saturnian Environment as a Unique Laboratory for Collisionless Shock Waves

NASA Astrophysics Data System (ADS)

Sulaiman, Ali; Masters, Adam; Dougherty, Michele; Burgess, David; Fujimoto, Masaki; Hospodarsky, George

2016-04-01

Collisionless shock waves are ubiquitous in the universe and fundamental to understanding the nature of collisionless plasmas. The interplay between particles (ions and electrons) and fields (electromagnetic) introduces a variety of both physical and geometrical parameters such as Mach numbers (e.g. MA, Mf), β, and θBn. These vary drastically from terrestrial to astrophysical regimes resulting in radically different characteristics of shocks. This poses two complexities. Firstly, separating the influences of these parameters on physical mechanisms such as energy dissipation. Secondly, correlating observations of shock waves over a wide range of each parameter, enough to span across different regimes. Investigating the latter has been restricted since the majority of studies on shocks at exotic regimes (such as supernova remnants) have been achieved either remotely or via simulations, but rarely by means of in-situ observations. It is not clear what happens in the higher MA regime. Here we show the parameter space of MA for all bow shock crossings from 2004-2012 as measured by the Cassini spacecraft. We found that the Saturnian bow shock exhibits characteristics akin to both terrestrial and astrophysical regimes (MA of order 100), which is principally controlled by the upstream magnetic field strength. Moreover, we estimated the θbn of each crossing and were able to further constrain the sample into categories of similar features. Our results demonstrate how MA plays a central role in controlling the onset of physical mechanisms in collisionless shocks, particularly reformation. While ongoing studies have investigated this process extensively both theoretically and via simulations, their observations remain few and far between. We show conclusive evidence for cyclic reformation controlled by specular ion reflection occurring at the predicted timescale of ˜0.3 τc, where τc is the ion gyroperiod. In addition, we experimentally underpin the relationship between reformation and MA and focus on the magnetic structure of such shocks to further show that for the same MA, a reforming shock exhibits stronger magnetic field amplification than a shock that is not reforming. We anticipate our comprehensive assessment to give deeper insight to high MA collisionless shocks and provide a broader scope for understanding the structures and mechanisms of collisionless shocks. This can potentially bridge the gap between more modest MA observed in near-Earth space and more exotic astrophysical regimes where shock processes play central roles.

Multidimensional neutrino-transport simulations of the core-collapse supernova central engine

NASA Astrophysics Data System (ADS)

O'Connor, Evan; Couch, Sean

2017-01-01

Core-collapse supernovae (CCSNe) mark the explosive death of a massive star. The explosion itself is triggered by the collapse of the iron core that forms near the end of a massive star's life. The core collapses to nuclear densities where the stiff nuclear equation of state halts the collapse and leads to the formation of the supernova shock. In many cases, this shock will eventually propagate throughout the entire star and produces a bright optical display. However, the path from shock formation to explosion has proven difficult to recreate in simulations. Soon after the shock forms, its outward propagation is stagnated and must be revived in order for the CCSNe to be successful. The leading theory for the mechanism that reenergizes the shock is the deposition of energy by neutrinos. In 1D simulations this mechanism fails. However, there is growing evidence that in 2D and 3D, hydrodynamic instabilities can assist the neutrino heating in reviving the shock. In this talk, I will present new multi-D neutrino-radiation-hydrodynamic simulations of CCSNe performed with the FLASH hydrodynamics package. I will discuss the efficacy of neutrino heating in our simulations and show the impact of the multi-D hydrodynamic instabilities.

X-Ray Measured Dynamics of Tycho's Supernova Remnant

NASA Technical Reports Server (NTRS)

Katsuda, Satoru; Petre, Robert; Hughes, John; Hwang, Una; Yamaguchi, Hiroya; Hayato, Asami; Mori, Koji; Tsunemi, Hiroshi

2010-01-01

We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0.''20 yr-1 (expansion index m = 0.33, where R = tm ) to 0.''40 yr-1 (m = 0.65) with azimuthal angle in 2000-2007 measurements, and 0.''14 yr-1 (m = 0.26) to 0.''40 yr-1 (m = 0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of [approx]0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0.''21-0.''31 yr-1 and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of [less, similar]0.2 cm-3.

Discovery of very-high-energy gamma-rays from the Galactic Centre ridge.

PubMed

Aharonian, F; Akhperjanian, A G; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Breitling, F; Brown, A M; Chadwick, P M; Chounet, L-M; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Ataï, A; Drury, L O'C; Dubus, G; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fontaine, G; Fuchs, Y; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; de Jager, O C; Khélifi, B; Klages, S; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemière, A; Lemoine-Goumard, M; Leroy, N; Lohse, T; Marcowith, A; Martin, J M; Martineau-Huynh, O; Masterson, C; McComb, T J L; de Naurois, M; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V; Saugé, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Spangler, D; Steenkamp, R; Stegmann, C; Tavernet, J-P; Terrier, R; Théoret, C G; Tluczykont, M; van Eldik, C; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J

2006-02-09

The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago.

Emission processes and dynamics of hot gases in astrophysics

NASA Technical Reports Server (NTRS)

Chevalier, Roger A.; Sarazin, Craig L.

1991-01-01

A detailed model was developed for Kepler's supernova remnant (SNR). Observations of the SNR revealed a strong interaction with the surrounding circumstellar medium, which was studied through both analytical and numerical calculations. Effects were studied of electron thermal conduction on the structure of radiative interstellar shock waves. An explanation is sought for the observed line emission from metal rich ejecta in SNR, incorporating atomic data. Light echoes around SN 1987A was also studied. Analysis of infrared and scattered circumstellar light echoes was accomplished with early observations to set limits on the mass of circumstellar dust. Work was completed on the emission from heavy element gas ejected in the supernova explosion of massive stars. It was assumed that a radioactive energy source was present and calculated the detailed heating and ionization of the gas. The evolution was studied of SNR in the very high pressure environment of a starburst galaxy.

Self-similar dynamic converging shocks - I. An isothermal gas sphere with self-gravity

NASA Astrophysics Data System (ADS)

Lou, Yu-Qing; Shi, Chun-Hui

2014-07-01

We explore novel self-similar dynamic evolution of converging spherical shocks in a self-gravitating isothermal gas under conceivable astrophysical situations. The construction of such converging shocks involves a time-reversal operation on feasible flow profiles in self-similar expansion with a proper care for the increasing direction of the specific entropy. Pioneered by Guderley since 1942 but without self-gravity so far, self-similar converging shocks are important for implosion processes in aerodynamics, combustion, and inertial fusion. Self-gravity necessarily plays a key role for grossly spherical structures in very broad contexts of astrophysics and cosmology, such as planets, stars, molecular clouds (cores), compact objects, planetary nebulae, supernovae, gamma-ray bursts, supernova remnants, globular clusters, galactic bulges, elliptical galaxies, clusters of galaxies as well as relatively hollow cavity or bubble structures on diverse spatial and temporal scales. Large-scale dynamic flows associated with such quasi-spherical systems (including collapses, accretions, fall-backs, winds and outflows, explosions, etc.) in their initiation, formation, and evolution are likely encounter converging spherical shocks at times. Our formalism lays an important theoretical basis for pertinent astrophysical and cosmological applications of various converging shock solutions and for developing and calibrating numerical codes. As examples, we describe converging shock triggered star formation, supernova explosions, and void collapses.

An integral condition for core-collapse supernova explosions

DOE PAGES

Murphy, Jeremiah W.; Dolence, Joshua C.

2017-01-10

Here, we derive an integral condition for core-collapse supernova (CCSN) explosions and use it to construct a new diagnostic of explodability. The fundamental challenge in CCSN theory is to explain how a stalled accretion shock revives to explode a star. In this manuscript, we assume that the shock revival is initiated by the delayed-neutrino mechanism and derive an integral condition for spherically symmetric shock expansion, v s > 0. One of the most useful one-dimensional explosion conditions is the neutrino luminosity and mass-accretion rate (more » $${L}_{\

Droplet and multiphase effects in a shock-driven hydrodynamic instability with reshock

NASA Astrophysics Data System (ADS)

Middlebrooks, John B.; Avgoustopoulos, Constantine G.; Black, Wolfgang J.; Allen, Roy C.; McFarland, Jacob A.

2018-06-01

Shock-driven multiphase instabilities (SDMI) are unique physical phenomena that have far-reaching applications in engineering and science such as high energy explosions, scramjet combustors, and supernovae events. The SDMI arises when a multiphase field is impulsively accelerated by a shock wave and evolves as a result of gradients in particle-gas momentum transfer. A new shock tube facility has been constructed to study the SDMI. Experiments were conducted to investigate liquid particle and multiphase effects in the SDMI. A multiphase cylindrical interface was created with water droplet laden air in our horizontal shock tube facility. The interface was accelerated by a Mach 1.66 shock wave, and its reflection from the end wall. The interface development was captured using laser illumination and a high-resolution CCD camera. Laser interferometry was used to determine the droplet size distribution. A particle filtration technique was used to determine mass loading within an interface and verify particle size distribution. The effects of particle number density, particle size, and a secondary acceleration (reshock) of the interface were noted. Particle number density effects were found comparable to Atwood number effects in the Richtmyer-Meshkov instability for small (˜ 1.7 {μ }m) droplets. Evaporation was observed to alter droplet sizes and number density, markedly after reshock. For large diameter droplets (˜ 10.7 {μ }m), diminished development was observed with larger droplets lagging far behind the interface. These lagging droplets were also observed to breakup after reshock into structured clusters of smaller droplets. Mixing width values were reported to quantify mixing effects seen in images.

Exploding Stars and Stripes

NASA Astrophysics Data System (ADS)

2011-03-01

The discovery of a pattern of X-ray "stripes" in the remains of an exploded star may provide the first direct evidence that a cosmic event can accelerate particles to energies a hundred times higher than achieved by the most powerful particle accelerator on Earth. This result comes from a very long observation of the Tycho supernova remnant with NASA's Chandra X-ray Observatory. It could explain how some of the extremely energetic particles bombarding the Earth, called cosmic rays, are produced. "We've seen lots of intriguing structures in supernova remnants, but we've never seen stripes before," said Kristoffer Eriksen, a postdoctoral researcher at Rutgers University who led the study. "This made us think very hard about what's happening in the blast wave of this powerful explosion." This latest study from Chandra provides support for a theory about how magnetic fields can be dramatically amplified in such blast waves. In this theory, the magnetic fields become highly tangled and the motions of the particles very turbulent near the expanding supernova shock wave at the front edge of the supernova remnant. High-energy charged particles can bounce back and forth across the shock wave repeatedly, gaining energy with each crossing. Theoretical models of the motion of the most energetic particles -- which are mostly protons -- are predicted to leave a messy network of holes and dense walls corresponding to weak and strong regions of magnetic fields, respectively. The X-ray stripes discovered by the Chandra researchers are thought to be regions where the turbulence is greater and the magnetic fields more tangled than surrounding areas, and may be the walls predicted by the theory. Electrons become trapped in these regions and emit X-rays as they spiral around the magnetic field lines. However, the regular and almost periodic pattern of the X-ray stripes was not predicted by the theory. "It was a big surprise to find such a neatly arranged set of stripes," said co-author Jack Hughes, professor of physics and astronomy at Rutgers. "We were not expecting so much order to appear in so much chaos. It could mean that the theory is incomplete, or that there's something else we don't understand." Assuming that the spacing between the X-ray stripes corresponds to the radius of the spiraling motion of the highest energy protons in the supernova remnant, the spacing corresponds to energies about 100 times higher than reached in the Large Hadron Collider. These energies equal the highest energies of cosmic rays thought to be produced in our Galaxy. Because cosmic rays are composed of charged particles, like protons and electrons, their direction of motion changes when they encounter magnetic fields throughout the galaxy. So, the origin of individual cosmic rays detected on Earth cannot be determined. Supernova remnants have long been considered a good candidate for producing the most energetic cosmic rays in our Galaxy. The protons can reach energies that are hundreds of times higher than the highest energy electrons, but since they do not radiate efficiently like the electrons, direct evidence for the acceleration of cosmic ray protons in supernova remnants has been lacking. These results also support the prediction that magnetic fields in interstellar space are greatly amplified in supernova remnants, but the difference between the observed and predicted structures means that other interpretations cannot be ruled out. "We were excited to discover these stripes because they might allow us to directly track, for the first time, the origin of the most energetic particles produced in our galaxy," said Eriksen. "But, we're not claiming victory yet." The Tycho supernova remnant is named for the famous Danish astronomer Tycho Brahe, who reported observing the supernova in 1572. Scientists think the explosion occurred when a white dwarf star grew in mass and exceeded its weight limit, forming a so-called Type Ia supernova. The Tycho remnant is located in the Milky Way, about 13,000 light years from Earth. "Supernova remnants are our best cosmic laboratories for understanding how nature accelerates the highest energy cosmic rays," said Roger Blandford of Stanford University, a noted expert in this field who was not involved with these findings. "These careful measurements provide a very strong clue as to what actually happens at these giant shock fronts." These results were published in the February 20th, 2011 issue of The Astrophysical Journal Letters. The other co-authors are Carles Badenes from Tel-Aviv University and the Weizmann Institute of Science in Israel, Robert Fesen from Dartmouth College, NH, Parviz Ghavamian from Space Telescope Science Institute, Baltimore, MD, David Moffett, from Furman University, Greenville, SC, Paul Plucinsky from Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, MA, Cara Rakowski from the Naval Research Laboratory, Washington, DC, Estela M. Reynoso from the Institute of Astronomy and Space Physics and University of Buenos Aires, Argentina and Patrick Slane from CfA. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass. More information, including images and other multimedia, can be found at: http://chandra.si.edu and http://chandra.nasa.gov

New Evidence Links Stellar Remains to Oldest Recorded Supernova

NASA Astrophysics Data System (ADS)

2006-09-01

Recent observations have uncovered evidence that helps to confirm the identification of the remains of one of the earliest stellar explosions recorded by humans. The new study shows that the supernova remnant RCW 86 is much younger than previously thought. As such, the formation of the remnant appears to coincide with a supernova observed by Chinese astronomers in 185 A.D. The study used data from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory, "There have been previous suggestions that RCW 86 is the remains of the supernova from 185 A.D.," said Jacco Vink of University of Utrecht, the Netherlands, and lead author of the study. "These new X-ray data greatly strengthen the case." When a massive star runs out of fuel, it collapses on itself, creating a supernova that can outshine an entire galaxy. The intense explosion hurls the outer layers of the star into space and produces powerful shock waves. The remains of the star and the material it encounters are heated to millions of degrees and can emit intense X-ray radiation for thousands of years. Animation of a Massive Star Explosion Animation of a Massive Star Explosion In their stellar forensic work, Vink and colleagues studied the debris in RCW 86 to estimate when its progenitor star originally exploded. They calculated how quickly the shocked, or energized, shell is moving in RCW 86, by studying one part of the remnant. They combined this expansion velocity with the size of the remnant and a basic understanding of how supernovas expand to estimate the age of RCW 86. "Our new calculations tell us the remnant is about 2,000 years old," said Aya Bamba, a coauthor from the Institute of Physical and Chemical Research (RIKEN), Japan. "Previously astronomers had estimated an age of 10,000 years." The younger age for RCW 86 may explain an astronomical event observed almost 2000 years ago. In 185 AD, Chinese astronomers (and possibly the Romans) recorded the appearance of a new bright star. The Chinese noted that it sparkled like a star and did not appear to move in the sky, arguing against it being a comet. Also, the observers noticed that the star took about eight months to fade, consistent with modern observations of supernovas. RCW 86 had previously been suggested as the remnant from the 185 AD event, based on the historical records of the object's position. However, uncertainties about the age provided significant doubt about the association. "Before this work I had doubts myself about the link, but our study indicates that the age of RCW 86 matches that of the oldest known supernova explosion in recorded history," said Vink. "Astronomers are used to referencing results from 5 or 10 years ago, so it's remarkable that we can build upon work from nearly 2000 years ago." The smaller age estimate for the remnant follows directly from a higher expansion velocity. By examining the energy distribution of the X-rays, a technique known as spectroscopy, the team found most of the X-ray emission was caused by high-energy electrons moving through a magnetic field. This is a well-known process that normally gives rise to low-energy radio emission. However, only very high shock velocities can accelerate the electrons to such high energies that X-ray radiation is emitted. "The energies reached in this supernova remnant are extremely high," said Andrei Bykov, another team member from the Ioffe Institute, St. Peterburg, Russia. "In fact, the particle energies are greater than what can be achieved by the most modern particle accelerators." The difference in age estimates for RCW 86 is due to differences in expansion velocities measured for the supernova remnant. The authors speculate that these variations arise because RCW 86 is expanding into an irregular bubble blown by a wind from the progenitor star before it exploded. In some directions, the shock wave has encountered a dense region outside the bubble and slowed down, whereas in other regions the shock remains inside the bubble and is still moving rapidly. These regions give the most accurate estimate of the age. The study describing these results appeared in the September 1 issue of The Astrophysical Journal Letters. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory, Cambridge, Mass., controls science and flight operations from the Chandra X-ray Center, Cambridge, Mass. XMM-Newton is an European Space Agency science mission managed at the European Space Research and Technology Centre, Noordwijk, the Netherlands for the Directorate of the Scientific Programme. Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

Newly Formed Dust in the Core-Collapse Supernova Remnant E0102

NASA Astrophysics Data System (ADS)

Ludwig, Bethany; Sandstrom, Karin; Bolatto, Alberto

2018-01-01

The mechanism of interstellar dust formation is a matter of continuing debate. In the very early universe, some high redshift galaxies are observed to have a substantial amount of dust. This has led to the suggestion that core collapse supernovae must be the producers of much of the dust in the universe. However, most observed supernova remnants (SNRs) in the local universe have measured dust yields far below the necessary levels. Cassiopeia A and SN 1987A are exceptions--in these young remnants, Herschel Space Observatory observations found large quantities of newly-formed dust. In these two cases, the SNR is young enough that the reverse shock has not yet interacted with most of the newly formed dust. To study supernova dust production, we observe SNR 1E0102.2-7219, which is approximately 1000 years old with a reverse shock that has only reached into a small part of its ejecta making it an excellent candidate to search for newly formed dust that has not yet been destroyed by those shocks. Using Herschel data, we carefully model the background around the remnant to remove emission that is unrelated to the SNR. We then measure the mass, temperature, and chemical composition of the dust by fitting the spectral energy distribution. Our findings reveal a substantial amount of previously undetected cold dust in the remnant, suggesting that indeed core collapse supernovae may host substantial amounts of newly formed dust, at least prior to the passage of the reverse shock.

High energy neutrinos and gamma-ray emission from supernovae in compact star clusters

NASA Astrophysics Data System (ADS)

Bykov, A. M.; Ellison, D. C.; Gladilin, P. E.; Osipov, S. M.

2017-01-01

Compact clusters of young massive stars are observed in the Milky Way and in starburst galaxies. The compact clusters with multiple powerful winds of young massive stars and supernova shocks are favorable sites for high-energy particle acceleration. We argue that expanding young supernova (SN) shells in compact stellar clusters can be very efficient PeV CR accelerators. At a stage when a supernova shock is colliding with collective fast winds from massive stars in a compact cluster the Fermi mechanism allows particle acceleration to energies well above the standard limits of diffusive shock acceleration in an isolated SNR. The energy spectrum of protons in such an accelerator is a hard power-law with a broad spectral upturn above TeV before a break at multi-PeV energies, providing a large energy flux in the high-energy end of the spectrum. The acceleration stage in the colliding shock flow lasts for a few hundred years after the supernova explosion producing high-energy CRs that escape the accelerator and diffuse through the ambient matter producing γ-rays and neutrinos in inelastic nuclear collisions. In starburst galaxies a sizeable fraction of core collapse supernovae is expected to occur in compact star clusters and therefore their high energy gamma-ray and neutrino spectra in the PeV energy regime may differ strongly from that of our Galaxy. To test the model with individual sources we briefly discuss the recent H.E.S.S. detections of gamma-rays from two potential candidate sources, Westerlund 1 and HESS J1806-204 in the Milky Way. We argue that this model of compact star clusters, with typical parameters, could produce a neutrino flux sufficient to explain a fraction of the recently detected IceCube South Pole Observatory neutrinos.

OXYGEN-RICH SUPERNOVA REMNANT IN THE LARGE MAGELLANIC CLOUD

NASA Technical Reports Server (NTRS)

2002-01-01

This is a NASA Hubble Space Telescope image of the tattered debris of a star that exploded 3,000 years ago as a supernova. This supernova remnant, called N132D, lies 169,000 light-years away in the satellite galaxy, the Large Magellanic Cloud. A Hubble Wide Field Planetary Camera 2 image of the inner regions of the supernova remnant shows the complex collisions that take place as fast moving ejecta slam into cool, dense interstellar clouds. This level of detail in the expanding filaments could only be seen previously in much closer supernova remnants. Now, Hubble's capabilities extend the detailed study of supernovae out to the distance of a neighboring galaxy. Material thrown out from the interior of the exploded star at velocities of more than four million miles per hour (2,000 kilometers per second) plows into neighboring clouds to create luminescent shock fronts. The blue-green filaments in the image correspond to oxygen-rich gas ejected from the core of the star. The oxygen-rich filaments glow as they pass through a network of shock fronts reflected off dense interstellar clouds that surrounded the exploded star. These dense clouds, which appear as reddish filaments, also glow as the shock wave from the supernova crushes and heats the clouds. Supernova remnants provide a rare opportunity to observe directly the interiors of stars far more massive than our Sun. The precursor star to this remnant, which was located slightly below and left of center in the image, is estimated to have been 25 times the mass of our Sun. These stars 'cook' heavier elements through nuclear fusion, including oxygen, nitrogen, carbon, iron etc., and the titanic supernova explosions scatter this material back into space where it is used to create new generations of stars. This is the mechanism by which the gas and dust that formed our solar system became enriched with the elements that sustain life on this planet. Hubble spectroscopic observations will be used to determine the exact chemical composition of this nuclear- processed material, and thereby test theories of stellar evolution. The image shows a region of the remnant 50 light-years across. The supernova explosion should have been visible from Earth's southern hemisphere around 1,000 B.C., but there are no known historical records that chronicle what would have appeared as a 'new star' in the heavens. This 'true color' picture was made by superposing images taken on 9-10 August 1994 in three of the strongest optical emission lines: singly ionized sulfur (red), doubly ionized oxygen (green), and singly ionized oxygen (blue). Photo credit: Jon A. Morse (STScI) and NASA Investigating team: William P. Blair (PI; JHU), Michael A. Dopita (MSSSO), Robert P. Kirshner (Harvard), Knox S. Long (STScI), Jon A. Morse (STScI), John C. Raymond (SAO), Ralph S. Sutherland (UC-Boulder), and P. Frank Winkler (Middlebury). Image files in GIF and JPEG format may be accessed via anonymous ftp from oposite.stsci.edu in /pubinfo: GIF: /pubinfo/GIF/N132D.GIF JPEG: /pubinfo/JPEG/N132D.jpg The same images are available via World Wide Web from links in URL http://www.stsci.edu/public.html.

Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A

NASA Technical Reports Server (NTRS)

Dwek, Eliahu; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, John; DeBuizer James M.; Gehrz, Robert D.; Kirshner, Robert P.; McCray, Richard;

A new equation of state for core-collapse supernovae based on realistic nuclear forces and including a full nuclear ensemble

NASA Astrophysics Data System (ADS)

Furusawa, S.; Togashi, H.; Nagakura, H.; Sumiyoshi, K.; Yamada, S.; Suzuki, H.; Takano, M.

2017-09-01

We have constructed a nuclear equation of state (EOS) that includes a full nuclear ensemble for use in core-collapse supernova simulations. It is based on the EOS for uniform nuclear matter that two of the authors derived recently, applying a variational method to realistic two- and three-body nuclear forces. We have extended the liquid drop model of heavy nuclei, utilizing the mass formula that accounts for the dependences of bulk, surface, Coulomb and shell energies on density and/or temperature. As for light nuclei, we employ a quantum-theoretical mass evaluation, which incorporates the Pauli- and self-energy shifts. In addition to realistic nuclear forces, the inclusion of in-medium effects on the full ensemble of nuclei makes the new EOS one of the most realistic EOSs, which covers a wide range of density, temperature and proton fraction that supernova simulations normally encounter. We make comparisons with the FYSS EOS, which is based on the same formulation for the nuclear ensemble but adopts the relativistic mean field theory with the TM1 parameter set for uniform nuclear matter. The new EOS is softer than the FYSS EOS around and above nuclear saturation densities. We find that neutron-rich nuclei with small mass numbers are more abundant in the new EOS than in the FYSS EOS because of the larger saturation densities and smaller symmetry energy of nuclei in the former. We apply the two EOSs to 1D supernova simulations and find that the new EOS gives lower electron fractions and higher temperatures in the collapse phase owing to the smaller symmetry energy. As a result, the inner core has smaller masses for the new EOS. It is more compact, on the other hand, due to the softness of the new EOS and bounces at higher densities. It turns out that the shock wave generated by core bounce is a bit stronger initially in the simulation with the new EOS. The ensuing outward propagations of the shock wave in the outer core are very similar in the two simulations, which may be an artifact, though, caused by the use of the same tabulated electron capture rates for heavy nuclei ignoring differences in the nuclear composition between the two EOSs in these computations.

Astro-1 Image Taken by Ultraviolet Imaging Telescope

NASA Technical Reports Server (NTRS)

1990-01-01

This image shows a part of the Cygnus loop supernova remnant, taken by the Ultraviolet Imaging Telescope (UIT) on the Astro Observatory during the Astro-1 mission (STS-35) on December 5, 1990. Pictured is a portion of the huge Cygnus loop, an array of interstellar gas clouds that have been blasted by a 900,000 mile per hour shock wave from a prehistoric stellar explosion, which occurred about 20,000 years ago, known as supernova. With ultraviolet and x-rays, astronomers can see emissions from extremely hot gases, intense magnetic fields, and other high-energy phenomena that more faintly appear in visible and infrared light or in radio waves that are crucial to deepening the understanding of the universe. The Astro Observatory was designed to explore the universe by observing and measuring the ultraviolet radiation from celestial objects. Three instruments make up the Astro Observatory: The Hopkins Ultraviolet Telescope (HUT), the Ultraviolet Imaging Telescope (UIT), and the Wisconsin Ultraviolet Photo-Polarimetry Experiment (WUPPE). The Marshall Space Flight Center had managment responsibilities for the Astro-1 mission. The Astro-1 Observatory was launched aboard the Space Shuttle Orbiter Columbia (STS-35) on December 2, 1990.

An explanation of the formation of the peculiar periphery of Tycho's supernova remnant

NASA Astrophysics Data System (ADS)

Fang, Jun; Yu, Huan; Zhang, Li

2018-02-01

Tycho's supernova remnant (SNR) has a periphery that clearly deviates from a spherical shape, based on X-ray and radio observations. The forward shock from the south-east to the north of the remnant has a deformed outline with a depression in the east, although in the west it is generally round and smooth. Moreover, at some locations in the shell, the supernova ejecta is located close to the forward shock, resulting in protrusions. Using 3D hydrodynamical simulations, we studied the dynamical evolution of the supernova ejecta in an inhomogeneous medium and the formation process of the profile of the forward shock. In order to reproduce the peculiar periphery of the remnant, we propose a model in which the supernova ejecta has evolved in a cavity blown by a latitude-dependent outflow. The results indicate that the depression to the east and the protrusion to the south-east on the observed periphery of the remnant can be generally reproduced if we assume a wind bubble driven by an anisotropic wind with a mass-loss rate of ˜10-7 M⊙ yr-1, a pole velocity of ˜100 km s-1, a duration of ˜105 yr prior to the supernova explosion, and a spatial velocity of ˜30 km s-1 of the progenitor with respect to the circumstellar medium. In conclusion, an explanation of the peculiar shape of the periphery of Tycho's SNR is that the supernova ejecta evolved in the cavity driven by a latitude-dependent wind.

Microscopic Processes in Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Nordlund, A.; Fredricksen, J.; Sol, H.; Niemiec, J.; Lyubarsky, Y.;

Particle Acceleration, Magnetic Field Generation, and Associated Emission in Collisionless Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.

2007-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron)jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Particle Acceleration, Magnetic Field Generation and Associated Emission in Collisionless Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K. I.; Ramirez-Ruiz, E.; Hardee, P.; Mizuno, Y.; Fishman. G. J.

2007-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Time-dependent shock acceleration of particles. Effect of the time-dependent injection, with application to supernova remnants

NASA Astrophysics Data System (ADS)

Petruk, O.; Kopytko, B.

2016-11-01

Three approaches are considered to solve the equation which describes the time-dependent diffusive shock acceleration of test particles at the non-relativistic shocks. At first, the solution of Drury for the particle distribution function at the shock is generalized to any relation between the acceleration time-scales upstream and downstream and for the time-dependent injection efficiency. Three alternative solutions for the spatial dependence of the distribution function are derived. Then, the two other approaches to solve the time-dependent equation are presented, one of which does not require the Laplace transform. At the end, our more general solution is discussed, with a particular attention to the time-dependent injection in supernova remnants. It is shown that, comparing to the case with the dominant upstream acceleration time-scale, the maximum momentum of accelerated particles shifts towards the smaller momenta with increase of the downstream acceleration time-scale. The time-dependent injection affects the shape of the particle spectrum. In particular, (I) the power-law index is not solely determined by the shock compression, in contrast to the stationary solution; (II) the larger the injection efficiency during the first decades after the supernova explosion, the harder the particle spectrum around the high-energy cutoff at the later times. This is important, in particular, for interpretation of the radio and gamma-ray observations of supernova remnants, as demonstrated on a number of examples.

The X-Ray Light Curve of the Very Luminous Supernova SN 1978K in NGC 1313

NASA Astrophysics Data System (ADS)

Schlegel, Eric M.; Petre, R.; Colbert, E. J. M.

1996-01-01

We present the 0.5-2.0 keV light curve of the X-ray luminous supernova SN 1978K in NGC 1313, based on six ROSAT observations spanning 1990 July to t994 July. SN 1978K is one of a few supernovae or supernova remnants that are very luminous (˜1039-1040 ergs s-1) in the X-ray, optical, and radio bands, and the first, at a supernova age of 10-20 yr, for which sufficient data exist to create an X-ray light curve. The X-ray flux is approximately constant over the 4 yr sampled by our observations, which were obtained 12-16 yr after the initial explosion. Three models exist to explain the large X-ray luminosity: pulsar input, a reverse shock running back into the expanding debris of the supernova, and the outgoing shock crushing of cloudlets in the debris field. Based upon calculations of Chevalier & Fransson, a pulsar cannot provide sufficient energy to produce the soft X-ray luminosity. Based upon the models and the light curve to date, it is not possible to discern the evolutionary phase of the supernova.

X-Ray Illumination of the Ejecta of Supernova 1987A

NASA Technical Reports Server (NTRS)

Larsson, J.; Fransson, C.; Oestlin, G.; Groeningsson, P.; Jerkstrand, A.; Kozma, C.; Sollerman, J.; Challis, P.; Kirshner, R. P.; Chevalier, R. A.;

Broadband Observations and Modeling of the Shell-Type Supernova Remnant G347.3-0.5

NASA Technical Reports Server (NTRS)

Ellison, Donald C.; Slane, Patrick O.; Gaensler, Bryan M.

2002-01-01

The supernova remnant G347.3-0.5 emits a featureless power law in X-rays, thought to indicate shock acceleration of electrons to high energies. We here produce a broadband spectrum of the bright northwest limb of this source by combining radio observations from the Australia Telescope Compact Array (ATCA), X-ray observations from the Advanced Satellite for Cosmology and Astrophysics (ASCA), and TeV gamma-ray observations from the CANGAROO imaging Cerenkov telescope. We assume that this emission is produced by an electron population generated by diffusive shock acceleration at the remnant forward shock. The nonlinear aspects of the particle acceleration force a connection between the widely different wavelength bands and between the electrons and the unseen ions, presumably accelerated simultaneously with the electrons. This allows us to infer the relativistic proton spectrum and estimate ambient parameters such as the supernova explosion energy, magnetic field, matter density in the emission region, and efficiency of the shock acceleration process. We find convincing evidence that the shock acceleration is efficient, placing greater than 25% of the shock kinetic energy flux into relativistic ions. Despite this high efficiency, the maximum electron and proton energies, while depending somewhat on assumptions for the compression of the magnetic field in the shock, are well below the observed 'knee' at 10(exp 15) eV in the Galactic cosmic-ray spectrum.

Evidence for Cocoon Emission from the Early Light Curve of SSS17a

NASA Astrophysics Data System (ADS)

Piro, Anthony L.; Kollmeier, Juna A.

2018-03-01

Swope Supernova Survey 2017a (SSS17a) was discovered as the first optical counterpart to the gravitational wave event GW170817. Although its light curve on the timescale of weeks roughly matches the expected luminosity and red color of an r-process powered transient, the explanation for the blue emission from high velocity material over the first few days is not as clear. Here we show that the power-law evolution of the luminosity, temperature, and photospheric radius during these early times can be explained by cooling of shock-heated material around the neutron star merger. This heating is likely from the interaction of the gamma-ray burst jet with merger debris, the so-called cocoon emission. We summarize the properties of this emission and provide formulae that can be used to study future detections of shock cooling from merging neutron stars. This argues that optical transient surveys should search for such early, blue light if they wish to find off-axis gamma-ray bursts and double neutron star gravitational wave events as soon as possible after the merger.

The Dynamics of Very High Alfvén Mach Number Shocks in Space Plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundberg, Torbjörn; Burgess, David; Scholer, Manfred

2017-02-10

Astrophysical shocks, such as planetary bow shocks or supernova remnant shocks, are often in the high or very-high Mach number regime, and the structure of such shocks is crucial for understanding particle acceleration and plasma heating, as well inherently interesting. Recent magnetic field observations at Saturn’s bow shock, for Alfvén Mach numbers greater than about 25, have provided evidence for periodic non-stationarity, although the details of the ion- and electron-scale processes remain unclear due to limited plasma data. High-resolution, multi-spacecraft data are available for the terrestrial bow shock, but here the very high Mach number regime is only attained onmore » extremely rare occasions. Here we present magnetic field and particle data from three such quasi-perpendicular shock crossings observed by the four-spacecraft Cluster mission. Although both ion reflection and the shock profile are modulated at the upstream ion gyroperiod timescale, the dominant wave growth in the foot takes place at sub-proton length scales and is consistent with being driven by the ion Weibel instability. The observed large-scale behavior depends strongly on cross-scale coupling between ion and electron processes, with ion reflection never fully suppressed, and this suggests a model of the shock dynamics that is in conflict with previous models of non-stationarity. Thus, the observations offer insight into the conditions prevalent in many inaccessible astrophysical environments, and provide important constraints for acceleration processes at such shocks.« less

The Dynamics of Very High Alfvén Mach Number Shocks in Space Plasmas

NASA Astrophysics Data System (ADS)

Sundberg, Torbjörn; Burgess, David; Scholer, Manfred; Masters, Adam; Sulaiman, Ali H.

2017-02-01

Astrophysical shocks, such as planetary bow shocks or supernova remnant shocks, are often in the high or very-high Mach number regime, and the structure of such shocks is crucial for understanding particle acceleration and plasma heating, as well inherently interesting. Recent magnetic field observations at Saturn’s bow shock, for Alfvén Mach numbers greater than about 25, have provided evidence for periodic non-stationarity, although the details of the ion- and electron-scale processes remain unclear due to limited plasma data. High-resolution, multi-spacecraft data are available for the terrestrial bow shock, but here the very high Mach number regime is only attained on extremely rare occasions. Here we present magnetic field and particle data from three such quasi-perpendicular shock crossings observed by the four-spacecraft Cluster mission. Although both ion reflection and the shock profile are modulated at the upstream ion gyroperiod timescale, the dominant wave growth in the foot takes place at sub-proton length scales and is consistent with being driven by the ion Weibel instability. The observed large-scale behavior depends strongly on cross-scale coupling between ion and electron processes, with ion reflection never fully suppressed, and this suggests a model of the shock dynamics that is in conflict with previous models of non-stationarity. Thus, the observations offer insight into the conditions prevalent in many inaccessible astrophysical environments, and provide important constraints for acceleration processes at such shocks.

ISS-Lobster: A Proposed Wide-Field X-Ray Telescope on the International Space Station

NASA Technical Reports Server (NTRS)

Camp, Jordan

2012-01-01

The Lobster wide-field imaging telescope combines simultaneous high FOV, high sensitivity and good position resolution. These characteristics can open the field of X-Ray time domain astronomy, which will study many interesting transient sources, including tidal disruptions of stars, supernova shock breakouts, and high redshift gamma-ray bursts. Also important will be its use for the X-ray follow-up of gravitational wave detections. I will describe our present effort to propose the Lobster concept for deployment on the International Space Station through a NASA Mission of Opportunity this fall.

First targeted search for gravitational-wave bursts from core-collapse supernovae in data of first-generation laser interferometer detectors

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corpuz, A.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalmus, P.; Kalogera, V.; Kamaretsos, I.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Loew, K.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lück, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, K. N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Pereira, R.; Perreca, A.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Santamaria, L.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J. L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; ZadroŻny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

2016-11-01

We present results from a search for gravitational-wave bursts coincident with two core-collapse supernovae observed optically in 2007 and 2011. We employ data from the Laser Interferometer Gravitational-wave Observatory (LIGO), the Virgo gravitational-wave observatory, and the GEO 600 gravitational-wave observatory. The targeted core-collapse supernovae were selected on the basis of (1) proximity (within approximately 15 Mpc), (2) tightness of observational constraints on the time of core collapse that defines the gravitational-wave search window, and (3) coincident operation of at least two interferometers at the time of core collapse. We find no plausible gravitational-wave candidates. We present the probability of detecting signals from both astrophysically well-motivated and more speculative gravitational-wave emission mechanisms as a function of distance from Earth, and discuss the implications for the detection of gravitational waves from core-collapse supernovae by the upgraded Advanced LIGO and Virgo detectors.

X-ray astrophysics: Constraining thermal conductivity in intracluster gas in clusters of galaxies and placing limits on progenitor systems of Type Ia supernovae

NASA Astrophysics Data System (ADS)

Russell, Brock Richard

X-ray astrophysics provides a great many opportunities to study astronomical structures with large energies or high temperatures. This dissertation will describe two such applications: the use of Swift X-ray Telescope (XRT) data to analyze the interaction between a supernova shock and the circumstellar medium, and the use of a straightforward computer simulation to model the dynamics of intracluster gas in clusters of galaxies and constrain the thermal conduction coefficient. Stars emit stellar wind at varying rates throughout their lifetimes. This wind populates the circumstellar medium (CSM) with gas. When the supernova explodes, the shock wave propogates outward through this CSM and heats it to X-ray emitting temperatures. By analyzing X-ray observations of the immediate post-supernova environment, we are able to determine whether any significant CSM is present. By stacking a large number of Swift observations of SNe Ia, we increase the sensitivity. We find no X-rays, with an upper limit of 1.7 x 1038 erg s-1 and a 3 sigma upper limit on the mass loss rate of progenitor systems 1.1 x 10-6 solar masses per year x (vw)/(10 km s -1). This low upper limit precludes a massive progenitor as the binary companion in the supernova progenitor system, unless that star is in Roche lobe overflow. The hot Intracluster Medium (ICM) is composed of tenuous gas which is gravitationally-bound to the cluster of galaxies. This gas is not initially of uniform temperature, and experiences thermal conduction while maintaining hydrostatic equilibrium. However, magnetic field lines present in the ionized gas inhibit the full thermal conduction. In this dissertation, we present the results of a new one-dimensional simulation that models this conduction (and includes cooling while maintaining hydrostatic equilibrium). By comparing the results of this model with the observed gas temperature profiles and recent accurate constraints on the scatter of the gas fraction, we are able to constrain the thermal conductivity. Our results suggest that conduction factors are not higher than 10% of full Spitzer conduction for hot, relaxed clusters.

Supernova Remnants As Laboratories For Determining The Properties Of Ejecta Dust And The Processing Of Dust Grains In Shocks

NASA Astrophysics Data System (ADS)

Dwek, Eli; Temim, Tea

Recent infrared satellites, such as the Spitzer, Herschel, and WISE, have obtained a wealth of spectral and broadband data on the infrared (IR) emission from dust in supernova remnants (SNRs). Supernovae (SNe) are important producers of newly condensed dust during the early free-expansion phase of their evolution, and the dominant destroyers of dust during the subsequent remnant phase of their evolution. The infrared observations hold the key for determining their role in the origin and evolution of dust in the universe. We propose to model the composition, abundance, and size distribution of the dust in select Galactic and Magellanic Cloud remnants. As explained in detail below, the remnants were selected for the availability of IR and X-ray observations. All selected remnants have Spitzer IRS spectral data in the 5-35 μm regions which allow us to determine the effect of grain processing in the shock. Some have spectral maps that allow the distinction between the IR emission from SN-condensed and swept up circumstellar and interstellar dust. All remnants have also been covered by Spitzer, Herschel, and WISE imaging, and have existing X-ray Chandra and/or XMM observations. The dust in some remnants is radiatively-heated by a pulsar wind nebula, and in others collisionally- heated by shocked X-ray or line emitting gas. We will use physical models to calculate the radiative and collisional heating of SNR dust, the equilibrium or fluctuating dust temperatures, and the resulting IR emission for various dust compositions and size distributions. Specific examples of Cas A, SN1987A, the Crab Nebula, and Puppis A, are discussed in detail to illustrate our modeling approach. Our study will be the first comprehensive and physical analysis of a large sample of SNRs in different evolutionary states and different astrophysical environments. They will cover a wide range of interactions between the dust grains and their surroundings, including the radioactively- powered and/or shocked SN ejecta, hard X-rays and EUV radiation fields, and shocked circumstel- lar/interstellar gas. Our study will shed light on the evolution of dust grains from their explosive formation sites, through their violent injection into the ISM, and ultimate demise or survival as they travel through a network of interstellar shock waves. It will constitute a major advance in our understanding of the origin and evolution of dust in the Milky Way, in galaxies in general, and especially in the early universe.

Implications of supernova remnant origin model of galactic cosmic rays on gamma rays from young supernova remnants

NASA Astrophysics Data System (ADS)

Banik, Prabir; Bhadra, Arunava

2017-06-01

It is widely believed that Galactic cosmic rays are originated in supernova remnants (SNRs), where they are accelerated by a diffusive shock acceleration (DSA) process in supernova blast waves driven by expanding SNRs. In recent theoretical developments of the DSA theory in SNRs, protons are expected to accelerate in SNRs at least up to the knee energy. If SNRs are the true generators of cosmic rays, they should accelerate not only protons but also heavier nuclei with the right proportions, and the maximum energy of the heavier nuclei should be the atomic number (Z ) times the mass of the proton. In this work, we investigate the implications of the acceleration of heavier nuclei in SNRs on energetic gamma rays produced in the hadronic interaction of cosmic rays with ambient matter. Our findings suggest that the energy conversion efficiency has to be nearly double for the mixed cosmic ray composition compared to that of pure protons to explain observations. In addition, the gamma-ray flux above a few tens of TeV would be significantly higher if cosmic ray particles could attain energies Z times the knee energy in lieu of 200 TeV, as suggested earlier for nonamplified magnetic fields. The two stated maximum energy paradigms will be discriminated in the future by upcoming gamma-ray experiments like the Cherenkov telescope array (CTA).

Fizzlers

NASA Astrophysics Data System (ADS)

Imamura, James

2008-05-01

Type II Supernovae are produced by the collapse of the cores of massive stars at the ends of their nuclear lifetimes. The basic picture for the outburst mechanism of Type II Supernova explosions is rather secure with only the details of the shock generation and the outburst uncertain. However, broad issues remain concerning our understanding of Type II Supernovae when the less studied, but more general case of rotating and/or magnetic progenitor stars is considered. That rotation and magnetic fields may play large roles in core collapse has been suggested for almost 40 years dating from the discovery that pulsars, the remnants of Type II Supernovae, are strongly magnetic, rapidly rotating neutron stars. This fact has been further reinforced by the discovery of the class of neutron stars with ultra-strong magnetic fields known as Magnetars. The role that rotation plays in core collapse can be appreciated by noting that stable, stationary, degenerate equilibrium configurations are possible only for stars with central density ρc 10^4-10^9 g cm-3 (white dwarf densities) and ρc 10^14-10^15 g cm-3 (neutron star densities). Nonrotating objects with ρc between that of white dwarfs (typical of the densities of the precollapse cores of Type II Supernovae) and neutron stars are unstable to radial collapse because of the low effective γ of their equations-of-state (EOS) (see Shapiro & & Teukolsky 1983). Stars at intermediate ρc may be stabilized against collapse by rapid rotation. This possibility gives rise to what were coined fizzlers by Gold (1974) to describe fizzled core collapses of massive rotating stars through formation of rotation-supported stars with densities intermediate between those of the white dwarf-like precollapse core and a neutron star. Interest in fizzlers waned in the 1980s when it was showed that, although fizzlers could exist, they only occupied a small part of the precollapse core parameter space for cold equations-of-state (EOS). Interest in fizzlers was revived in the late 1990s when it was found that fizzlers could form under a wider range of conditions than had been suggested if hot dense EOSs were considered. Observationally, interest in fizzlers was also driven by the recognition that fizzlers could lead to the generation of gravitational wave emission in Type II Supernovae, emission potentially observable by LIGO, the Laser Interferometer Gravitational Wave Observatory), and other gravitational wave observatories, and that fizzlers could perhaps play roles in the γ-ray burster phenomenon and the formation of strange stars. We review the properties of fizzlers and consider their applications to LIGO, strange stars, and Magnetars.

Acquiring information about neutrino parameters by detecting supernova neutrinos

NASA Astrophysics Data System (ADS)

Huang, Ming-Yang; Guo, Xin-Heng; Young, Bing-Lin

2010-08-01

We consider the supernova shock effects, the Mikheyev-Smirnov-Wolfenstein effects, the collective effects, and the Earth matter effects in the detection of type II supernova neutrinos on the Earth. It is found that the event number of supernova neutrinos depends on the neutrino mass hierarchy, the neutrino mixing angle θ13, and neutrino masses. Therefore, we propose possible methods to identify the mass hierarchy and acquire information about θ13 and neutrino masses by detecting supernova neutrinos. We apply these methods to some current neutrino experiments.

Observing the Next Galactic Supernova

NASA Astrophysics Data System (ADS)

Adams, Scott M.; Kochanek, C. S.; Beacom, John F.; Vagins, Mark R.; Stanek, K. Z.

2013-12-01

No supernova (SN) in the Milky Way has been observed since the invention of the optical telescope, instruments for other wavelengths, neutrino detectors, or gravitational wave observatories. It would be a tragedy to miss the opportunity to fully characterize the next one. To aid preparations for its observations, we model the distance, extinction, and magnitude probability distributions of a successful Galactic core-collapse supernova (ccSN), its shock breakout radiation, and its massive star progenitor. We find, at very high probability (sime 100%), that the next Galactic SN will easily be detectable in the near-IR and that near-IR photometry of the progenitor star very likely (sime 92%) already exists in the Two Micron All Sky Survey. Most ccSNe (98%) will be easily observed in the optical, but a significant fraction (43%) will lack observations of the progenitor due to a combination of survey sensitivity and confusion. If neutrino detection experiments can quickly disseminate a likely position (~3°), we show that a modestly priced IR camera system can probably detect the shock breakout radiation pulse even in daytime (64% for the cheapest design). Neutrino experiments should seriously consider adding such systems, both for their scientific return and as an added and internal layer of protection against false triggers. We find that shock breakouts from failed ccSNe of red supergiants may be more observable than those of successful SNe due to their lower radiation temperatures. We review the process by which neutrinos from a Galactic ccSN would be detected and announced. We provide new information on the EGADS system and its potential for providing instant neutrino alerts. We also discuss the distance, extinction, and magnitude probability distributions for the next Galactic Type Ia supernova (SN Ia). Based on our modeled observability, we find a Galactic ccSN rate of 3.2^{+7.3}_{-2.6} per century and a Galactic SN Ia rate of 1.4^{+1.4}_{-0.8} per century for a total Galactic SN rate of 4.6^{+7.4}_{-2.7} per century is needed to account for the SNe observed over the last millennium, which implies a Galactic star formation rate of 3.6^{+8.3}_{-3.0} M ⊙ yr-1.

X-Ray Mosaic of Milky Way Taken by the Chandra X-Ray Observatory

NASA Technical Reports Server (NTRS)

2001-01-01

The Chandra X-Ray Observatory (CXO) has made a sturning, high-energy panorama of the central regions of our Milky Way galaxy. The findings are an important step toward understanding the most active area of the Milky Way as well as other galaxies throughout the universe. This 400 by 900-light-year mosaic of several CXO images reveals hundreds of white dwarf stars, neutron stars, and black holes bathed in an incandescent fog of miltimillion-degree gas. The diffuse x-ray emission seems to be related to the turmoil and density of matter in the inner Milky Way. Stars are forming there at a much more rapid rate than in the galactic 'suburbs.' Many of the most massive stars in the galaxy are located in the galactic center and are furiously boiling off their outer layers in searing stellar winds. Supernova explosions are far more common in the region and send shock waves booming through the inner galaxy. The super massive black hole at the center of the galaxy is located inside the bright white patch in the center of the image. The colors indicate x-ray energy bands-red (low), green (medial), and blue (high). A supernova occurs when a massive star has used up its nuclear fuel and the pressure drops in the central core of the star. The matter in the core is crushed by gravity to higher and higher densities, and temperatures reach billions of degrees. Under these extreme conditions, nuclear reactions occur violently and catastrophically reversing the collapse. A thermonuclear shock wave races through the now expanding stellar debris, fusing lighter elements into heavier ones and producing a brilliant visual outburst. (Photo credit: NASA/UMass/D. Wang et al)

Neutrino-Driven Explosions

NASA Astrophysics Data System (ADS)

Janka, Hans-Thomas

The question why and how core-collapse supernovae (SNe) explode is one of the central and most long-standing riddles of stellar astrophysics. Solving this problem is crucial for deciphering the supernova (SN) phenomenon; for predicting its observable signals such as light curves and spectra, nucleosynthesis yields, neutrinos, and gravitational waves; for defining the role of SNe in the dynamical and chemo-dynamical evolution of galaxies; and for explaining the birth conditions and properties of neutron stars (NSs) and stellar-mass black holes. Since the formation of such compact remnants releases over hundred times more energy in neutrinos than the kinetic energy of the SN explosion, neutrinos can be the decisive agents for powering the SN outburst. According to the standard paradigm of the neutrino-driven mechanism, the energy transfer by the intense neutrino flux to the medium behind the stagnating core bounce shock, assisted by violent hydrodynamic mass motions (sometimes subsumed by the term "turbulence"), revives the outward shock motion and thus initiates the SN explosion. Because of the weak coupling of neutrinos in the region of this energy deposition, detailed, multidimensional hydrodynamic models including neutrino transport and a wide variety of physics are needed to assess the viability of the mechanism. Owing to advanced numerical codes and increasing supercomputer power, considerable progress has been achieved in our understanding of the physical processes that have to act in concert for the success of neutrino-driven explosions. First studies begin to reveal observational implications and avenues to test the theoretical picture by data from individual SNe and SN remnants but also from population-integrated observables. While models will be further refined, a real breakthrough is expected through the next galactic core-collapse SN, when neutrinos and gravitational waves can be used to probe the conditions deep inside the dying star.

History of Chandra X-Ray Observatory

NASA Image and Video Library

2001-07-01

The Chandra X-Ray Observatory (CXO) has made a sturning, high-energy panorama of the central regions of our Milky Way galaxy. The findings are an important step toward understanding the most active area of the Milky Way as well as other galaxies throughout the universe. This 400 by 900-light-year mosaic of several CXO images reveals hundreds of white dwarf stars, neutron stars, and black holes bathed in an incandescent fog of miltimillion-degree gas. The diffuse x-ray emission seems to be related to the turmoil and density of matter in the inner Milky Way. Stars are forming there at a much more rapid rate than in the galactic "suburbs." Many of the most massive stars in the galaxy are located in the galactic center and are furiously boiling off their outer layers in searing stellar winds. Supernova explosions are far more common in the region and send shock waves booming through the inner galaxy. The super massive black hole at the center of the galaxy is located inside the bright white patch in the center of the image. The colors indicate x-ray energy bands-red (low), green (medial), and blue (high). A supernova occurs when a massive star has used up its nuclear fuel and the pressure drops in the central core of the star. The matter in the core is crushed by gravity to higher and higher densities, and temperatures reach billions of degrees. Under these extreme conditions, nuclear reactions occur violently and catastrophically reversing the collapse. A thermonuclear shock wave races through the now expanding stellar debris, fusing lighter elements into heavier ones and producing a brilliant visual outburst. (Photo credit: NASA/UMass/D. Wang et al)

Pulsar Wind Bubble Blowout from a Supernova

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blondin, John M.; Chevalier, Roger A., E-mail: blondin@ncsu.edu

For pulsars born in supernovae, the expansion of the shocked pulsar wind nebula is initially in the freely expanding ejecta of the supernova. While the nebula is in the inner flat part of the ejecta density profile, the swept-up, accelerating shell is subject to the Rayleigh–Taylor instability. We carried out two- and three-dimensional simulations showing that the instability gives rise to filamentary structure during this initial phase but does not greatly change the dynamics of the expanding shell. The flow is effectively self-similar. If the shell is powered into the outer steep part of the density profile, the shell ismore » subject to a robust Rayleigh–Taylor instability in which the shell is fragmented and the shocked pulsar wind breaks out through the shell. The flow is not self-similar in this phase. For a wind nebula to reach this phase requires that the deposited pulsar energy be greater than the supernova energy, or that the initial pulsar period be in the ms range for a typical 10{sup 51} erg supernova. These conditions are satisfied by some magnetar models for Type I superluminous supernovae. We also consider the Crab Nebula, which may be associated with a low energy supernova for which this scenario applies.« less

NASA Space Observatories Glimpse Faint Afterglow of Nearby Stellar Explosion

NASA Astrophysics Data System (ADS)

2005-10-01

Intricate wisps of glowing gas float amid a myriad of stars in this image created by combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory. The gas is a supernova remnant, cataloged as N132D, ejected from the explosion of a massive star that occurred some 3,000 years ago. This titanic explosion took place in the Large Magellanic Cloud, a nearby neighbor galaxy of our own Milky Way. The complex structure of N132D is due to the expanding supersonic shock wave from the explosion impacting the interstellar gas of the LMC. Deep within the remnant, the Hubble visible light image reveals a crescent-shaped cloud of pink emission from hydrogen gas, and soft purple wisps that correspond to regions of glowing oxygen emission. A dense background of colorful stars in the LMC is also shown in the Hubble image. The large horseshoe-shaped gas cloud on the left-hand side of the remnant is glowing in X-rays, as imaged by Chandra. In order to emit X-rays, the gas must have been heated to a temperature of about 18 million degrees Fahrenheit (10 million degrees Celsius). A supernova-generated shock wave traveling at a velocity of more than four million miles per hour (2,000 kilometers per second) is continuing to propagate through the low-density medium today. The shock front where the material from the supernova collides with ambient interstellar material in the LMC is responsible for these high temperatures. Chandra image of N132D Chandra image of N132D, 2002 It is estimated that the star that exploded as a supernova to produce the N132D remnant was 10 to 15 times more massive than our own Sun. As fast-moving ejecta from the explosion slam into the cool, dense interstellar clouds in the LMC, complex shock fronts are created. A supernova remnant like N132D provides a rare opportunity for direct observation of stellar material, because it is made of gas that was recently hidden deep inside a star. Thus it provides information on stellar evolution and the creation of chemical elements such as oxygen through nuclear reactions in their cores. Such observations also help reveal how the interstellar medium (the gas that occupies the vast spaces between the stars) is enriched with chemical elements because of supernova explosions. Later on, these elements are incorporated into new generations of stars and their accompanying planets. Visible only from Earth's southern hemisphere, the LMC is an irregular galaxy lying about 160,000 light-years from the Milky Way. The supernova remnant appears to be about 3,000 years old, but since its light took 160,000 years to reach us, the explosion actually occurred some 163,000 years ago. This composite image of N132D was created by the Hubble Heritage team from visible-light data taken in January 2004 with Hubble's Advanced Camera for Surveys, and X-ray images obtained in July 2000 by Chandra's Advanced CCD Imaging Spectrometer. This marks the first Hubble Heritage image that combines pictures taken by two separate space observatories. The Hubble data include color filters that sample starlight in the blue, green, and red portions of the spectrum, as well as the pink emission from glowing hydrogen gas. The Chandra data are assigned blue in the color composite, in accordance with the much higher energy of the X-rays, emitted from extremely hot gas. This gas does not emit a significant amount of optical light, and was only detected by Chandra. Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Acknowledgment: J.C. Green (Univ. of Colorado) and the Cosmic Origins Spectrograph (COS) GTO team; NASA/CXO/SAO Electronic image files, video, illustrations and additional information are available at: http://hubblesite.org/news/2005/30 http://heritage.stsci.edu/2005/30 The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

A Deep X-Ray View of the Synchrotron-dominated Supernova Remnant G330.2+1.0

NASA Astrophysics Data System (ADS)

Williams, Brian J.; Hewitt, John W.; Petre, Robert; Temim, Tea

2018-03-01

We present moderately deep (125 ks) XMM-Newton observations of supernova remnant G330.2+1.0. This remnant is one of only a few known that fall into the “synchrotron-dominated” category, with the emission almost entirely dominated by a nonthermal continuum. Previous X-ray observations could only characterize the spectra of a few regions. Here, we examine the spectra from 14 regions surrounding the entire rim, finding that the spectral properties of the nonthermal emission do not vary significantly in any systematic way from one part of the forward shock to another, unlike several other remnants of this class. We confirm earlier findings that the power-law index, Γ, ranges from about 2.1–2.5, while the absorbing column density is generally between (2.0–2.6) × 1022 cm‑2. Fits with the srcut model find values of the roll-off frequency in the range of 1017.1–1017.5 Hz, implying energies of accelerated electrons of ∼100 TeV. These values imply a high shock velocity of ∼4600 km s‑1, favoring a young age of the remnant. Diffuse emission from the interior is nonthermal in origin as well, and fits to these regions yield similar values to those along the rim, also implying a young age. Thermal emission is present in the east, and the spectrum is consistent with a ∼650 km s‑1 shock wave encountering interstellar or circumstellar material with a density of ∼1 cm‑3.

Dust Destruction in the Supernova Remnant N49: Additional WiFeS Integral Field data AnalysisRachel Quigley, Rachael Huxford, Parviz Ghavamian, Mike Dopita

NASA Astrophysics Data System (ADS)

Quigley, Rachel; Ghavamian, Parviz

2018-01-01

Abstract:The supernova remnant N49, located in the Large Magellanic Cloud (LMC), is widely researched because of its relatively young age and its location near a dense, dusty molecular cloud in the interstellar medium (ISM). N49 has entered into its radiative phase more quickly than to be expected for the age of this remnant. As a consequence, N49 is showing signs that the diffuse hot interior is starting to cool and recombine. Using existing integral field spectra of SNR N49, different Fe emission lines and other spectral lines were extracted via python tools, following a similar approach to Dopita et al. (2016). At optical wavelengths, the dependence of [OIII]5007/4363 ratio on shock velocity is evident. This diagnostic is important because the [OIII]-emitting zone in low-velocity shocks of the cooling post-shock gas is hot. As the shock velocity increases, the temperature indicated by the [OIII] parameter falls. The dependence of Fe depletion lines on shock velocity is rather weak. Using [FeIII]:[OIII] diagnostic, the properties of dust destruction and production of dust in the SNR can be determined. Using this method, line ratios for other emission lines can be compared to the MAPPINGS predictions of Allen et al. (2008) to study the range of shock speeds present in the supernova remnant, where radiative shocks are driven into interstellar gas.

Pair production of helicity-flipped neutrinos in supernovae

NASA Technical Reports Server (NTRS)

Perez, Armando; Gandhi, Raj

1989-01-01

The emissivity was calculated for the pair production of helicity-flipped neutrinos, in a way that can be used in supernova calculations. Also presented are simple estimates which show that such process can act as an efficient energy-loss mechanism in the shocked supernova core, and this fact is used to extract neutrino mass limits from SN 1987A neutrino observations.

A CR-HYDRO-NEI MODEL OF MULTI-WAVELENGTH EMISSION FROM THE VELA JR. SUPERNOVA REMNANT (SNR RX J0852.0-4622)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Shiu-Hang; Nagataki, Shigehiro; Slane, Patrick O.

Based largely on energy budget considerations and the observed cosmic-ray (CR) ionic composition, supernova remnant (SNR) blast waves are the most likely sources of CR ions with energies at least up to the 'knee' near 10{sup 15} eV. Shocks in young shell-type TeV-bright SNRs are surely producing TeV particles, but the emission could be dominated by ions producing {pi}{sup 0}-decay emission or electrons producing inverse Compton gamma rays. Unambiguously identifying the GeV-TeV emission process in a particular SNR will not only help pin down the origin of CRs, it will also add significantly to our understanding of the diffusive shockmore » acceleration (DSA) mechanism and improve our understanding of supernovae and the impact SNRs have on the circumstellar medium. In this study, we investigate the Vela Jr. SNR, an example of TeV-bright non-thermal SNRs. We perform hydrodynamic simulations coupled with nonlinear DSA and non-equilibrium ionization near the forward shock to confront currently available multi-wavelength data. We find, with an analysis similar to that used earlier for SNR RX J1713.7-3946, that self-consistently modeling the thermal X-ray line emission with the non-thermal continuum in our one-dimensional model strongly constrains the fitting parameters, and this leads convincingly to a leptonic origin for the GeV-TeV emission for Vela Jr. This conclusion is further supported by applying additional constraints from observation, including the radial brightness profiles of the SNR shell in TeV gamma rays, and the spatial variation of the X-ray synchrotron spectral index. We will discuss implications of our models on future observations by the next-generation telescopes.« less

Equation of State Dependent Dynamics and Multi-messenger Signals from Stellar-mass Black Hole Formation

NASA Astrophysics Data System (ADS)

Pan, Kuo-Chuan; Liebendörfer, Matthias; Couch, Sean M.; Thielemann, Friedrich-Karl

2018-04-01

We investigate axisymmetric black hole (BH) formation and its gravitational wave (GW) and neutrino signals with self-consistent core-collapse supernova simulations of a non-rotating 40 M ⊙ progenitor star using the isotropic diffusion source approximation for the neutrino transport and a modified gravitational potential for general relativistic effects. We consider four different neutron star (NS) equations of state (EoS): LS220, SFHo, BHBΛϕ, and DD2, and study the impact of the EoS on BH formation dynamics and GW emission. We find that the BH formation time is sensitive to the EoS from 460 to >1300 ms and is delayed in multiple dimensions for ∼100–250 ms due to the finite entropy effects. Depending on the EoS, our simulations show the possibility that shock revival can occur along with the collapse of the proto-neutron star (PNS) to a BH. The gravitational waveforms contain four major features that are similar to previous studies but show extreme values: (1) a low-frequency signal (∼300–500 Hz) from core-bounce and prompt convection, (2) a strong signal from the PNS g-mode oscillation among other features, (3) a high-frequency signal from the PNS inner-core convection, and (4) signals from the standing accretion shock instability and convection. The peak frequency at the onset of BH formation reaches to ∼2.3 kHz. The characteristic amplitude of a 10 kpc object at peak frequency is detectable but close to the noise threshold of the Advanced LIGO and KAGRA, suggesting that the next-generation GW detector will need to improve the sensitivity at the kHz domain to better observe stellar-mass BH formation from core-collapse supernovae or failed supernovae.

Detection of supernova neutrinos at spallation neutron sources

NASA Astrophysics Data System (ADS)

Huang, Ming-Yang; Guo, Xin-Heng; Young, Bing-Lin

2016-07-01

After considering supernova shock effects, Mikheyev-Smirnov-Wolfenstein effects, neutrino collective effects, and Earth matter effects, the detection of supernova neutrinos at the China Spallation Neutron Source is studied and the expected numbers of different flavor supernova neutrinos observed through various reaction channels are calculated with the neutrino energy spectra described by the Fermi-Dirac distribution and the “beta fit” distribution respectively. Furthermore, the numerical calculation method of supernova neutrino detection on Earth is applied to some other spallation neutron sources, and the total expected numbers of supernova neutrinos observed through different reactions channels are given. Supported by National Natural Science Foundation of China (11205185, 11175020, 11275025, 11575023)

A high-resolution X-ray image of Puppis A - Inhomogeneities in the interstellar medium

NASA Technical Reports Server (NTRS)

Petre, R.; Kriss, G. A.; Winkler, P. F.; Canizares, C. R.

1982-01-01

Eleven HRI exposures from the Einstein Observatory are assembled into an 0.1-4 keV image of the Puppis A supernova remnant which displays a complex morphology that may reflect the structure of the shocked interstellar medium. In addition to showing a density gradient of a factor greater than four across the approximately 30 pc diameter of the remnant perpendicular to the galactic plane, a shell of X-ray emission is seen surrounding the northern half of Puppis A, coincident with the radio shell, whose edge brightness profile indicates direct hot plasma heating by the blast wave rather than evaporation from clouds. The interior structure of the supernova remnant suggests inhomogeneities whose sizes range over 0.1-5 pc, but with moderate density contrast. Although isolated clouds of 10-30/cu cm density are responsible for the two brightest X-ray features, they represent only a small fraction of the Puppis A mass.

Image of the Supernova Remnant Cassiopeia A Taken by the High Energy Astronomy Observatory (HEAO)-2

NASA Technical Reports Server (NTRS)

1980-01-01

This x-ray photograph of the Supernova remnant Cassiopeia A, taken with the High Energy Astronomy Observatory (HEAO) 2/Einstein Observatory, shows that the regions with fast moving knots of material in the expanding shell are bright and clear. A faint x-ray halo, just outside the bright shell, is interpreted as a shock wave moving ahead of the expanding debris. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO-2, designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center, was launched aboard an Atlas/Centaur launch vehicle on November 13, 1978.

Convective instabilities in SN 1987A

NASA Technical Reports Server (NTRS)

Benz, Willy; Thielemann, Friedrich-Karl

1990-01-01

Following Bandiera (1984), it is shown that the relevant criterion to determine the stability of a blast wave, propagating through the layers of a massive star in a supernova explosion, is the Schwarzschild (or Ledoux) criterion rather than the Rayleigh-Taylor criterion. Both criteria coincide only in the incompressible limit. Results of a linear stability analysis are presented for a one-dimensional (spherical) explosion in a realistic model for the progenitor of SN 1987A. When applying the Schwarzschild criterion, unstable regions get extended considerably. Convection is found to develop behind the shock, with a characteristic growth rate corresponding to a time scale much smaller than the shock traversal time. This ensures that efficient mixing will take place. Since the entire ejected mass is found to be convectively unstable, Ni can be transported outward, even into the hydrogen envelope, while hydrogen can be mixed deep into the helium core.

Chondrites and the Protoplanetary Disk, Part 3

NASA Technical Reports Server (NTRS)

2004-01-01

Contents include the following: Ca-, Al-Rich Inclusions and Ameoboid Olivine Aggregates: What We Know and Don t Know About Their Origin. Aluminium-26 and Oxygen Isotopic Distributions of Ca-Al-rich Inclusions from Acfer 214 CH Chondrite. The Trapping Efficiency of Helium in Fullerene and Its Implicatiion to the Planetary Science. Constraints on the Origin of Chondritic Components from Oxygen Isotopic Compositions. Role of Planetary Impacts in Thermal Processing of Chondrite Materials. Formation of the Melilite Mantle of the Type B1 CAIs: Flash Heating or Transport? The Iodine-Xenon System in Outer and Inner Portions of Chondrules from the Unnamed Antarctic LL3 Chondrite. Nucleosynthesis of Short-lived Radioactivities in Massive Stars. The Two-Fluid Analysis of the Kelvin-Helmholtz Instability in the Dust Layer of a Protoplanetary Disk: A Possible Path to the Planetesimal Formation Through the Gravitational Instability. Shock-Wave Heating Model for Chonodrule Formation: Heating Rate and Cooling Rate Constraints. Glycine Amide Hydrolysis with Water and OH Radical: A Comparative DFT Study. Micron-sized Sample Preparation for AFM and SEM. AFM, FE-SEM and Optical Imaging of a Shocked L/LL Chondrite: Implications for Martensite Formation and Wave Propagation. Infrared Spectroscopy of Chondrites and Their Components: A Link Between Meteoritics and Astronomy? Mid-Infrared Spectroscopy of CAI and Their Mineral Components. The Origin of Iron Isotope Fractionation in Chondrules, CAIs and Matrix from Allende (CV3) and Chainpur (LL3) Chondrites. Protoplanetary Disk Evolution: Early Results from Spitzer. Kinetics of Evaporation-Condensation in a Melt-Solid System and Its Role on the Chemical Composition and Evolution of Chondrules. Oxygen Isotope Exchange Recorded Within Anorthite Single Crystal in Vigarano CAI: Evidence for Remelting by High Temperature Process in the Solar Nebula. Chondrule Forming Shock Waves in Solar Nebula by X-Ray Flares. Organic Globules with Anormalous Nitrogen Isotopic Compositions in the Tagish Lake Meteorite: Products of Primitive Organic Reactions. Yet Another Chondrule Formation Scenario. CAIs are Not Supernova Condensates. Microcrystals and Amorphous Material in Comets and Primitive Meteorites: Keys to Understanding Processes in the Early Solar System. A Nearby Supernova Injected Short-lived Radionuclides into Our Protoplanetary Disk. REE+Y Systematics in CC and UOC Chondrules. Meteoritic Constraints on Temperatures, Pressures, Cooling Rates, Chemical Compositions, and Modes of Condensation in the Solar Nebula. The I-Xe Record of Long Equilibration in Chondrules from the Unnamed Antarctic Meteorite L3/LL3. Early Stellar Evolution.

High energy neutrinos from gamma-ray bursts with precursor supernovae.

PubMed

Razzaque, Soebur; Mészáros, Peter; Waxman, Eli

2003-06-20

The high energy neutrino signature from proton-proton and photo-meson interactions in a supernova remnant shell ejected prior to a gamma-ray burst provides a test for the precursor supernova, or supranova, model of gamma-ray bursts. Protons in the supernova remnant shell and photons entrapped from a supernova explosion or a pulsar wind from a fast-rotating neutron star remnant provide ample targets for protons escaping the internal shocks of the gamma-ray burst to interact and produce high energy neutrinos. We calculate the expected neutrino fluxes, which can be detected by current and future experiments.

Iron line emission from a high temperature plasma in Cas A

NASA Technical Reports Server (NTRS)

Pravdo, S. H.; Becker, R. H.; Boldt, E. A.; Holt, S. S.; Rothschild, R. E.; Serlemitsos, P. J.; Swank, J. H.

1976-01-01

The X-ray spectrum of Cassiopeia A was observed for several days by the proportional counter experiment on board OSO-8. The high energy ( 5 keV) data are fit well by a thermal spectrum. A narrow iron line which is predicted by the thermal model is also observed. The low energy (2-5 keV) data show an excess over the high temperature component which is consistent with the presence of an additional low temperature thermal component. Iron abundance in the source relative to normal cosmic abundance is discussed, as in the relation of this observation to shock wave and multi-component thermal models for supernova remnants.

Summer School on Interstellar Processes: Abstracts of contributed papers

NASA Technical Reports Server (NTRS)

Hollenbach, D. J. (Editor); Thronson, H. A., Jr. (Editor)

1986-01-01

The Summer School on Interstellar Processes was held to discuss the current understanding of the interstellar medium and to analyze the basic physical processes underlying interstellar phenomena. Extended abstracts of the contributed papers given at the meeting are presented. Many of the papers concerned the local structure and kinematics of the interstellar medium and focused on such objects as star formation regions, molecular clouds, HII regions, reflection nebulae, planetary nebulae, supernova remnants, and shock waves. Other papers studied the galactic-scale structure of the interstellar medium either in the Milky Way or other galaxies. Some emphasis was given to observations of interstellar grains and

Proton impact charge transfer on hydantoin - Prebiotic implications

NASA Astrophysics Data System (ADS)

Bacchus-Montabonel, Marie-Christine

2016-11-01

Formation and destruction of prebiotic compounds in astrophysical environments is a major issue in reactions concerning the origin of life. Detection of hydantoin in laboratory irradiation of interstellar ice analogues has confirmed evidence of this prebiotic compound and its stability to UV radiation or collisions may be crucial. Considering the different astrophysical environments, we have investigated theoretically proton-induced collisions with hydantoin in a wide energy range, from eV in the interstellar medium, up to keV for processes involving solar wind or supernovae shock-waves protons. Results are compared to previous investigations and qualitative trends on damage under spatial radiations are suggested.

History of Chandra X-Ray Observatory

NASA Image and Video Library

2000-09-20

This Chandra image reveals, in detail, the turbulent debris created by a supernova explosion that was observed by the Danish Astronomer Tycho Brahe in the year 1572. The colors show different x-ray energies, with red, green, and blue representing low, medium, and high energies, respectively. Most likely caused by the destruction of a white dwarf star, a shock wave produced by the expanding debris is outlined by the sharp blue circular arcs of 20 million degree Celsius gas seen on the outer rim. The stellar debris, visible only by x-ray, has a temperature of about 10 million degrees, and shows up as mottled yellow, green, and red fingers of gas.

Simulating cosmic ray physics on a moving mesh

NASA Astrophysics Data System (ADS)

Pfrommer, C.; Pakmor, R.; Schaal, K.; Simpson, C. M.; Springel, V.

2017-03-01

We discuss new methods to integrate the cosmic ray (CR) evolution equations coupled to magnetohydrodynamics on an unstructured moving mesh, as realized in the massively parallel AREPO code for cosmological simulations. We account for diffusive shock acceleration of CRs at resolved shocks and at supernova remnants in the interstellar medium (ISM) and follow the advective CR transport within the magnetized plasma, as well as anisotropic diffusive transport of CRs along the local magnetic field. CR losses are included in terms of Coulomb and hadronic interactions with the thermal plasma. We demonstrate the accuracy of our formalism for CR acceleration at shocks through simulations of plane-parallel shock tubes that are compared to newly derived exact solutions of the Riemann shock-tube problem with CR acceleration. We find that the increased compressibility of the post-shock plasma due to the produced CRs decreases the shock speed. However, CR acceleration at spherically expanding blast waves does not significantly break the self-similarity of the Sedov-Taylor solution; the resulting modifications can be approximated by a suitably adjusted, but constant adiabatic index. In first applications of the new CR formalism to simulations of isolated galaxies and cosmic structure formation, we find that CRs add an important pressure component to the ISM that increases the vertical scaleheight of disc galaxies and thus reduces the star formation rate. Strong external structure formation shocks inject CRs into the gas, but the relative pressure of this component decreases towards halo centres as adiabatic compression favours the thermal over the CR pressure.

A Highly Ordered Magnetic Field in a Crushed Pulsar Wind Nebula in G327.1-1.1

NASA Astrophysics Data System (ADS)

Ma, Yik Ki; Ng, Chi-Yung; Bucciantini, Niccolò; Gaensler, Bryan M.; Slane, Patrick O.; Temim, Tea

2015-01-01

A significant fraction of a pulsar's spin-down luminosity is in the form of a relativistic magnetized particle outflow known as a pulsar wind. Confinement of the wind by the ambient medium creates a synchrotron-emitting bubble called a pulsar wind nebula (PWN). Studies of PWNe is important for understanding the physics of relativistic shocks and particle acceleration. Simulations suggest that a PWN will be crushed by the reverse shock of its surrounding supernova remnant at an age of ~10^4 yr, resulting in a turbulent environment. However, given the short timescale of the interaction stage, only a few such systems are observed.We present radio polarization observations of the PWN in supernova remnant G327.1-1.1, taken with the Australia Telescope Compact Array. Previous works suggest that this system has recently interacted with the supernova reverse shock, providing a rare example for the study of magnetic field in a crushed PWN. We found a highly ordered magnetic field in the PWN, which is unexpected given the presumed turbulent interior of the nebula. This suggests that the magnetic pressure in the PWN could play an important role in the interaction with supernova reverse shock.The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.YKM and CYN are supported by a ECS grant of the Hong Kong Government under HKU 709713P

Multimessenger Predictions from 3D General-Relativistic Core-Collapse Supernovae Models

NASA Astrophysics Data System (ADS)

Kotake, Kei; Kuroda, Takami; Hayama, Kazuhiro

2017-02-01

In this contribution, we present results from fully general-relativistic three-dimensional (3D) simulations of a non-rotating 15M ⊙ star using different nuclear equations of state (EOSs). We show that the SASI (standing-accretion-shock-instability) activity occurs much more vigorously in models with softer EOS. By performing detailed analysis of the gravitational-wave (GW) emission, we find a new GW signature that is produced predominantly by the SASI-induced downflows to the proto-neutron star. We discuss the detectability of the GW signal by performing a coherent network analysis where multiple detectors including LIGO Hanford, LIGO Livingston, VIRGO, and KAGRA are considered. We point out that the GW signal, whose typical frequency is in the best sensitivity range of the laser-interferometers, could potentially provide the live broadcast that pictures how the supernova shock is dancing in the core. The detection horizon of the signal is estimated as 2~3 kpc for the current generation detectors, which can extend up to ~100 kpc for the third generation detectors like Cosmic Explorer. We furthermore perform a correlation analysis between the SASI-modulated GW and neutrino signals. Our results show that the time correlation of the two signals becomes highest when we take into account the travel timescale of adverting material from the (average) neutrino-sphere to the proto-neutron star surface.

SUPRATHERMAL ELECTRONS AT SATURN'S BOW SHOCK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masters, A.; Dougherty, M. K.; Sulaiman, A. H.

2016-07-20

The leading explanation for the origin of galactic cosmic rays is particle acceleration at the shocks surrounding young supernova remnants (SNRs), although crucial aspects of the acceleration process are unclear. The similar collisionless plasma shocks frequently encountered by spacecraft in the solar wind are generally far weaker (lower Mach number) than these SNR shocks. However, the Cassini spacecraft has shown that the shock standing in the solar wind sunward of Saturn (Saturn's bow shock) can occasionally reach this high-Mach number astrophysical regime. In this regime Cassini has provided the first in situ evidence for electron acceleration under quasi-parallel upstream magneticmore » conditions. Here we present the full picture of suprathermal electrons at Saturn's bow shock revealed by Cassini . The downstream thermal electron distribution is resolved in all data taken by the low-energy electron detector (CAPS-ELS, <28 keV) during shock crossings, but the higher energy channels were at (or close to) background. The high-energy electron detector (MIMI-LEMMS, >18 keV) measured a suprathermal electron signature at 31 of 508 crossings, where typically only the lowest energy channels (<100 keV) were above background. We show that these results are consistent with the theory in which the “injection” of thermal electrons into an acceleration process involves interaction with whistler waves at the shock front, and becomes possible for all upstream magnetic field orientations at high Mach numbers like those of the strong shocks around young SNRs. A future dedicated study will analyze the rare crossings with evidence for relativistic electrons (up to ∼1 MeV).« less

Suprathermal Electrons at Saturn's Bow Shock

NASA Astrophysics Data System (ADS)

Masters, A.; Sulaiman, A. H.; Sergis, N.; Stawarz, L.; Fujimoto, M.; Coates, A. J.; Dougherty, M. K.

2016-07-01

The leading explanation for the origin of galactic cosmic rays is particle acceleration at the shocks surrounding young supernova remnants (SNRs), although crucial aspects of the acceleration process are unclear. The similar collisionless plasma shocks frequently encountered by spacecraft in the solar wind are generally far weaker (lower Mach number) than these SNR shocks. However, the Cassini spacecraft has shown that the shock standing in the solar wind sunward of Saturn (Saturn's bow shock) can occasionally reach this high-Mach number astrophysical regime. In this regime Cassini has provided the first in situ evidence for electron acceleration under quasi-parallel upstream magnetic conditions. Here we present the full picture of suprathermal electrons at Saturn's bow shock revealed by Cassini. The downstream thermal electron distribution is resolved in all data taken by the low-energy electron detector (CAPS-ELS, <28 keV) during shock crossings, but the higher energy channels were at (or close to) background. The high-energy electron detector (MIMI-LEMMS, >18 keV) measured a suprathermal electron signature at 31 of 508 crossings, where typically only the lowest energy channels (<100 keV) were above background. We show that these results are consistent with the theory in which the “injection” of thermal electrons into an acceleration process involves interaction with whistler waves at the shock front, and becomes possible for all upstream magnetic field orientations at high Mach numbers like those of the strong shocks around young SNRs. A future dedicated study will analyze the rare crossings with evidence for relativistic electrons (up to ˜1 MeV).

Neutrino oscillations in magnetically driven supernova explosions

NASA Astrophysics Data System (ADS)

Kawagoe, Shio; Takiwaki, Tomoya; Kotake, Kei

2009-09-01

We investigate neutrino oscillations from core-collapse supernovae that produce magnetohydrodynamic (MHD) explosions. By calculating numerically the flavor conversion of neutrinos in the highly non-spherical envelope, we study how the explosion anisotropy has impacts on the emergent neutrino spectra through the Mikheyev-Smirnov-Wolfenstein effect. In the case of the inverted mass hierarchy with a relatively large θ13 (sin2 2θ13 gtrsim 10-3), we show that survival probabilities of bar nue and νe seen from the rotational axis of the MHD supernovae (i.e., polar direction), can be significantly different from those along the equatorial direction. The event numbers of bar nue observed from the polar direction are predicted to show steepest decrease, reflecting the passage of the magneto-driven shock to the so-called high-resonance regions. Furthermore we point out that such a shock effect, depending on the original neutrino spectra, appears also for the low-resonance regions, which could lead to a noticeable decrease in the νe signals. This reflects a unique nature of the magnetic explosion featuring a very early shock-arrival to the resonance regions, which is in sharp contrast to the neutrino-driven delayed supernova models. Our results suggest that the two features in the bar nue and νe signals, if visible to the Super-Kamiokande for a Galactic supernova, could mark an observational signature of the magnetically driven explosions, presumably linked to the formation of magnetars and/or long-duration gamma-ray bursts.

The Efficiency of Magnetic Field Amplification at Shocks by Turbulence

NASA Technical Reports Server (NTRS)

Ji, Suoqing; Oh, S. Peng; Ruszkowsi, M.; Markevitch, M.

2016-01-01

Turbulent dynamo field amplification has often been invoked to explain the strong field strengths in thin rims in supernova shocks (approx.100 micrograms) and in radio relics in galaxy clusters (approx. micrograms). We present high-resolution magnetohydrodynamic simulations of the interaction between pre-shock turbulence, clumping and shocks, to quantify the conditions under which turbulent dynamo amplification can be significant. We demonstrate numerically converged field amplification which scales with Alfven Mach number, B/B0 varies as MA, up to MA approx.150.This implies that the post-shock field strength is relatively independent of the seed field. Amplification is dominated by compression at low MA, and stretching (turbulent amplification) at high MA. For high MA, the B-field grows exponentially and saturates at equipartition with turbulence, while the vorticity jumps sharply at the shock and subsequently decays; the resulting field is orientated predominately along the shock normal (an effect only apparent in 3D and not 2D). This agrees with the radial field bias seen in supernova remnants. By contrast, for low MA, field amplification is mostly compressional, relatively modest, and results in a predominantly perpendicular field. The latter is consistent with the polarization seen in radio relics. Our results are relatively robust to the assumed level of gas clumping. Our results imply that the turbulent dynamo may be important for supernovae, but is only consistent with the field strength, and not geometry, for cluster radio relics. For the latter, this implies strong pre-existing B-fields in the ambient cluster outskirts.

Imprints of the ejecta-companion interaction in Type Ia supernovae: main-sequence, subgiant, and red giant companions

NASA Astrophysics Data System (ADS)

Boehner, P.; Plewa, T.; Langer, N.

2017-02-01

We study supernova ejecta-companion interactions in a sample of realistic semidetached binary systems representative of Type Ia supernova progenitor binaries in a single-degenerate scenario. We model the interaction process with the help of a high-resolution hydrodynamic code assuming cylindrical symmetry. We find that the ejecta hole has a half-opening angle of 40-50° with the density by a factor of 2-4 lower, in good agreement with the previous studies. Quantitative differences from the past results in the amounts and kinematics of the stripped companion material and levels of contamination of the companion with the ejecta material can be explained by different model assumptions and effects due to numerical diffusion. We analyse and, for the first time, provide simulation-based estimates of the amounts and of the thermal characteristics of the shock-heated material responsible for producing a prompt, soft X-ray emission. Besides the shocked ejecta material, considered in the original model by Kasen, we also account for the stripped, shock-heated envelope material of stellar companions, which we predict partially contributes to the prompt emission. The amount of the energy deposited in the envelope is comparable to the energy stored in the ejecta. The total energy budget available for the prompt emission is by a factor of about 2-4 smaller than originally predicted by Kasen. Although the shocked envelope has a higher characteristic temperature than the shocked ejecta, the temperature estimates of the shocked material are in good agreement with the Kasen's model. The hottest shocked plasma is produced in the subgiant companion case.

New Relativistic Particle-In-Cell Simulation Studies of Prompt and Early Afterglows from GRBs

NASA Technical Reports Server (NTRS)

Nishikawa, Ken-ichi; Hardee, P.; Mizuno, Y.; Zhang, B.; Medvedev, M.; Hartmann, D.; Fishman, J. F.; Preece, R.

2008-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Microscopic Processes On Radiation from Accelerated Particles in Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Hardee, P. E.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Sol, H.; Niemiec, J.; Pohl, M.; Nordlund, A.; Fredriksen, J.;

The impact of supernova fragments on the evolution of multisupernova remnants

NASA Technical Reports Server (NTRS)

Franco, J.; Ferrara, A.; Rozyczka, M.; Tenorio-Tgale, G.; Cox, D. P.

1993-01-01

Analytical approximations and 2D hydrodynamical simulations are used to examine the interaction of supernova fragments with the internal structure of large multisupernova remnants (MSRs). The fragments are thermalized by reverse shocks generated in the interaction with the MSR interior, which is assumed to be hot and rarefied. The evolution is divided into two stages: before and after reaching a reference distance, R(E), from the explosion site. As the density of the expanding fragment drops, the reverse shock accelerates, and, when the distance R(E) is reached, it begins to effectively erode the fragment. At some selected evolutionary times, the X-ray emission from the shocked fragment is also calculated. The direct bombardment of the MRS shell by the shocked fragment has a series of important consequences: it excites, punctures, and deforms the expanding shell.

The Death of a Star: Supernova 1987a. NASA Educational Briefs for the Upper Elementary-Level Classroom.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Washington, DC.

This material discusses supernova, the violent death of a massive star, at a level appropriate for upper elementary students. Background information on Supernova 1987a is presented. Observation techniques using visible light, ultraviolet waves, radio waves, neutrinos, X-rays, and gamma-rays are described. A vocabulary list, 11 questions, and 6…

Influence of Non-spherical Initial Stellar Structure on the Core-Collapse Supernova Mechanism

NASA Astrophysics Data System (ADS)

Couch, Sean M.

I review the state of investigation into the impact that nonspherical stellar progenitor structure has on the core-collapse supernova mechanism. Although modeling stellar evolution relies on 1D spherically symmetric calculations, massive stars are not truly spherical. In the stellar evolution codes, this fact is accounted for by "fixes" such as mixing length theory and attendant modifications. Of particular relevance to the supernova mechanism, the Si- and O-burning shells surrounding the iron core at the point of collapse can be violently convective, with convective speeds of hundreds of km s-1. It has recently been shown by a number of groups that the presence of nonspherical perturbations in the layers surrounding the collapsing iron core can have a favorable impact on the likelihood for shock revival and explosion via the neutrino heating mechanism. This is due in large part to the strengthening of turbulence behind the stalled shock due to the presence of finite amplitude seed perturbations to speed the growth of convection which drives the post-shock turbulence. Efforts are now underway to simulate the final minutes of stellar evolution to core-collapse in 3D with the aim to generate realistic multidimensional initial conditions for use in simulations of the supernova mechanism.

9500 Nights of Mid-Infrared Observations of SN 1987A: the birth of the remnant

NASA Astrophysics Data System (ADS)

Bouchet, Patrice; Danziger, John

2014-01-01

The one-in-a-life-time event Supernova SN 1987A, the brightest supernova seen since Kepler's in 1604, has given us a unique opportunity to study the mechanics of a supernova explosion and now to witness the birth of a supernova remnant. A violent encounter is underway between the fastest-moving debris and the circumstellar ring: shocks excite ``hotspots''. ATCA/ANTF, Gemini, VLT, HST, Spitzer, Chandra, and recently ALMA observations have been so far organized to help understanding the several emission mechanisms at work. In the mid-infrared SN 1987A has transformed from a SN with the bulk of its radiation from the ejecta to a SNR whose emission is dominated by the interaction of the blast wave with the surrounding interstellar medium, a process in which kinetic energy is converted into radiative energy. Currently this remnant emission is dominated by material in or near the inner equatorial ring (ER). We give here a brief history of our mid-infrared observations, and present our last data obtained with the SPITZER infrared satellite and the ESO VLT and Gemini telescopes: we show how together with Chandra observations, they contribute to the understanding of this fascinating object. We argue also that our imaging observations suggest that warm dust is still present in the ejecta, and we dispute the presence of huge amount of very cold dust in it, as it has been claimed on the basis of data obtained with the HERSCHELl satellite.

DISCOVERY OF X-RAY EMISSION FROM SUPERNOVA 1970G WITH CHANDRA: FILLING THE VOID BETWEEN SUPERNOVAE AND SUPERNOVA REMNANTS

NASA Technical Reports Server (NTRS)

Immler, Stefan; Kuntz, K. D.

2005-01-01

We report the discovery of X-ray emission from SN 1970G in M101, 35 yr after its outburst, using deep X-ray imaging with the Chundra X-Ray Observatory. The Chandra ACIS spectrum shows that the emission is soft (52 keV) and characteristic of the reverse-shock region. The X-ray luminosity, Lo,,, = (1.1 3 0.2) x lo3# ergs s-1, is likely caused by the interaction of the supernova shock with dense circumstellar matter. If the material was deposited by the stellar wind from the progenitor, a mass-loss rate of M = (2.6 ? 0.4) x M, yr-I (v,/lO km s-I) is inferred. Utilizing the high-resolution Chandra ACIS data of SN 1970G and its environment, we reconstruct the X-ray lightcurve from previous ROSAT HRI, PSPC, and XMM-Newton EPIC observations, and find a best-fit linear rate of decline of L cc t-# with index s = 2.7 t 0.9 over a period of -20-35 yr after the outburst. As the oldest supernova detected in X-rays, SN 1970G allows, for the first time, direct observation of the transition from a supenova to its supernova remnant phase.

The shocking development of lithium (and boron) in supernovae

NASA Technical Reports Server (NTRS)

Dearborn, David S. P.; Schramm, David N.; Steigman, Gary; Truran, James

1989-01-01

It is shown that significant amounts of Li-7 and B-11 are produced in Type 2 supernovae. The synthesis of these rare elements occurs as the supernova shock traverses the base of the hydrogen envelope burning He-3 to masses 7 and 11 via alpha capture. The yields in this process are sufficient to account for the difference in lithium abundance observed between Pop 2 and Pop 1 stars. Since lithium (and boron) would, in this manner, be created in the same stars that produce the bulk of the heavy elements, the lithium abundance even in old Pop 1 stars would be high (as observed). The B-11 production may remedy the long-standing problem of the traditional spallation scenario to account for the observed isotopic ratio of boron. Observational consequences of this mechanism are discussed, including the evolution of lithium and boron isotope ratios in the Galaxy and the possible use of the boron yields to constrain the number of blue progenitor Type 2 supernovae.

The rebirth of Supernova 1987A : a study of the ejecta-ring collision

NASA Astrophysics Data System (ADS)

Gröningsson, Per

Supernovae are some of the most energetic phenomena in the Universe and they have throughout history fascinated people as they appeared as new stars in the sky. Supernova (SN) 1987A exploded in the nearby satellite galaxy, the Large Magellanic Cloud (LMC), at a distance of only 168,000 light years. The proximity of SN 1987A offers a unique opportunity to study the medium surrounding the supernova in great detail. Powered by the dynamical interaction of the ejecta with the inner circumstellar ring, SN 1987A is dramatically evolving at all wavelengths on time scales less than a year. This makes SN 1987A a great ``laboratory'' for studies of shock physics. Repeated observations of the ejecta-ring collision have been carried out using the UVES echelle spectrograph at VLT. This thesis covers seven epochs of high resolution spectra taken between October 1999 and November 2007. Three different emission line components are identified from the spectra. A narrow (~10 km/s) velocity component emerges from the unshocked ring. An intermediate (~250 km/s) component arises in the shocked ring, and a broad component extending to ~15,000 km/s comes from the reverse shock. Thanks to the high spectral resolution of UVES, it has been possible to separate the shocked from the unshocked ring emission. For the unshocked gas, ionization stages from neutral up to Ne V and Fe VII were found. The line fluxes of the low-ionization lines decline during the period of the observations. However, the fluxes of the [O III] and [Ne III] lines appear to increase and this is found to be consistent with the heating of the pre-shock gas by X-rays from the shock interactions. The line emission from the ejecta-ring collision increases rapidly as more gas is swept up by the shocks. This emission comes from ions with a range of ionization stages (e.g., Fe II-XIV). The low-ionization lines show an increase in their line widths which is consistent with that these lines originate from radiative shocks. The high-ionization line profiles (Fe X-XIV) initially show larger spectral widths, which indicates that at least a fraction of the emission comes from non-radiative shocks.

Weibel instability mediated collisionless shocks using intense laser-driven plasmas

NASA Astrophysics Data System (ADS)

Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald; Fernandez, Juan; Ma, Wenjun; Schreiber, Jorg; LANL Collaboration; LMU Team

2016-10-01

The origin of cosmic rays remains a long-standing challenge in astrophysics and continues to fascinate physicists. It is believed that ``collisionless shocks'' - where the particle Coulomb mean free path is much larger that the shock transition - are a dominant source of energetic cosmic rays. These shocks are ubiquitous in astrophysical environments such as gamma-ray bursts, supernova remnants, pulsar wind nebula and coronal mass ejections from the sun. Several spacecraft observations have revealed acceleration of charged particles, mostly electrons, to very high energies with in the shock front. There is now also clear observational evidence that supernova remnant shocks accelerate both protons and electrons. The understanding of the microphysics behind collisionless shocks and their particle acceleration is tightly related with nonlinear basic plasma processes and remains a grand challenge. In this poster, we will present results from recent experiments at the LANL Trident laser facility studying collisionless shocks using intense ps laser (80J, 650 fs - peak intensity of 1020 W/cm2) driven near-critical plasmas using carbon nanotube foam targets. A second short pulse laser driven protons from few microns thick aluminum foil is used to image the laser-driven plasma.

Cosmic Ray Acceleration from Multiple Galactic Wind Shocks

NASA Astrophysics Data System (ADS)

Cotter, Cory; Bustard, Chad; Zweibel, Ellen

2018-01-01

Cosmic rays still have an unknown origin. Many mechanisms have been suggested for their acceleration including quasars, pulsars, magnetars, supernovae, supernova remnants, and galactic termination shocks. The source of acceleration may be a mixture of these and a different mixture in different energy regimes. Using numerical simulations, we investigate multiple shocks in galactic winds as potential cosmic rays sources. By having shocks closer to the parent galaxy, more particles may diffuse back to the disk instead of being blown out in the wind, as found in Bustard, Zweibel, and Cotter (2017, ApJ) and also Merten, Bustard, Zweibel, and Tjus (to be submitted to ApJ). Specifically, this flux of cosmic rays could contribute to the unexplained "shin" region between the well-known "knee" and "ankle" of the cosmic ray spectrum. We would like to acknowledge support from the National Science Foundation (NSF) Graduate Research Fellowship Program under grant No. DGE-125625 and NSF grant No. AST-1616037.

Chandra Finds Oxygen and Neon Ring in Ashes of Exploded Star

NASA Astrophysics Data System (ADS)

2000-01-01

NASA's Chandra X-ray Observatory has revealed an expanding ring-like structure of oxygen and neon that was hurled into space by the explosion of a massive star. The image of E0102-72 provides unprecedented details about the creation and dispersal of heavy elements necessary to form planets like Earth. The results were reported by Professor Claude Canizares of the Massachusetts Institute of Technology (MIT), Cambridge, at the 195th national meeting of the American Astronomical Society in Atlanta, Ga. Drs. Kathryn Flanagan, David Davis, and John Houck of MIT collaborated with Canizares in this investigation. E0102-72 is the remnant of a supernova explosion located in our neighbor galaxy, the Small Magellanic Cloud, nearly 200,000 light years away. It was created by the explosion of a star that was more than ten times as massive as our Sun. We are seeing the aftermath of the explosion a thousand or more years after the outburst. Shock waves are heating gas to temperatures of nearly 10 million degrees, so it glows with X-rays that are detected by Chandra's instruments. By using the High Energy Transmission Grating Spectrometer (HETG), astronomers were able to pinpoint the distribution of each chemical element individually and measure the velocities of different parts of the expanding ring. They also show the shock wave in a kind of "freeze-frame," revealing the progressive heating of the stellar matter as it plows into the surrounding gas. This is the first time such detailed X-ray information has ever been obtained for a supernova remnant, and should provide critical clues to the nature of supernovas. The grating spectrometer, which was built by an MIT team led by Canizares, spreads the X-rays according to their wavelength, giving distinct images of the object at specific wavelengths characteristic of each chemical element. Small wavelength shifts caused by the Doppler effect are used to measure the expansion velocities of each element independently. "We've been studying these supernova remnants for decades, but now we're getting the kind of information we need to really test the theories," said Canizares. "Understanding supernovas helps us to learn about the processes that formed chemical elements like those which are found on Earth and are necessary for life," said Flanagan. Most of the oxygen in the universe, for example, is synthesized in the interiors of relatively few massive stars like the one being studied here. When they explode, they expel the newly manufactured elements which become part of the raw material for new stars and planets. The amount of oxygen in the E0102-72 ring is enough for thousands of solar systems. By measuring the expansion velocity of the ring, the team can estimate the amount of energy liberated in the explosion. The expansion energy would be enough to power the Sun for 3 billion years. The ring has more complex structure and motion than can be explained by current simplified theories, suggesting complexity in the explosion itself or in the surrounding interstellar matter. The supernova remnant also provides a laboratory for atomic physics. The observations show how the atoms in the expelled matter behave when heated to such high temperatures. The images reveal the progressive stripping of electrons from the atoms after the super-sonic shock wave has passed. The Chandra observation was taken using the HETG in conjunction with the Advanced CCD Imaging Spectrometer (ACIS) on September 28 and October 10, 1999. ACIS was built by Pennsylvania State University, University Park, and the Massachusetts Institute of Technology, Cambridge. To follow Chandra's progress or download images visit the Chandra sites at http://chandra.harvard.edu/photo/2000/0015/index.html AND http://chandra.nasa.gov NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. TRW, Inc., Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass. High resolution digital versions of the X-ray image (JPG, 300 dpi TIFF ) and other information associated with this release are available on the Internet at: http://chandra.harvard.edu Further information on the HETG may be found at: http://space.mit.edu/CSR/hetg_info.html

The Los Alamos Supernova Light Curve Project: Current Projects and Future Directions

NASA Astrophysics Data System (ADS)

Wiggins, Brandon Kerry; Los Alamos Supernovae Research Group

2015-01-01

The Los Alamos Supernova Light Curve Project models supernovae in the ancient and modern universe to determine the luminosities of observability of certain supernovae events and to explore the physics of supernovae in the local universe. The project utilizes RAGE, Los Alamos' radiation hydrodynamics code to evolve the explosions of progenitors prepared in well-established stellar evolution codes. RAGE allows us to capture events such as shock breakout and collisions of ejecta with shells of material which cannot be modeled well in other codes. RAGE's dumps are then ported to LANL's SPECTRUM code which uses LANL's OPLIB opacities database to calculate light curves and spectra. In this paper, we summarize our recent work in modeling supernovae.

SN 1987 A: A Unique Laboratory for Shock Physics

NASA Technical Reports Server (NTRS)

Sonneborn, George

2012-01-01

Supernova 1987 A has given us an unprecedented view of the evolution of the explosion debris and its interaction with circumstellar matter. The outer supernova debris, now expanding with velocities approx.8000 km/s, encountered the relatively dense circumstellar ring formed by presupernova mass loss in the early 1990s. The shock interaction is manifested by UV-optical "hotspots", an expanding X-ray ring, an expanding ring of knotty non-thermal radio emission, and a ring of thermal IR emission from silicate dust Recent ultraviolet observations of the emissions from the reverse shock and the ring with the HST/COS reveal new details about the shock interaction. Lyman alpha emission from the reverse shock is much stronger than H alpha and they have different emission morphologies, pointing to different emission mechanisms. The reverse shock was detected for the first time in C IV 1550. The N V to C IV brightness ratio indicates the N/C abundance ratio in the expanding debris is about 100X solar, about 3X N/C in the inner ring.

Kiso Supernova Survey (KISS): Survey strategy

NASA Astrophysics Data System (ADS)

Morokuma, Tomoki; Tominaga, Nozomu; Tanaka, Masaomi; Mori, Kensho; Matsumoto, Emiko; Kikuchi, Yuki; Shibata, Takumi; Sako, Shigeyuki; Aoki, Tsutomu; Doi, Mamoru; Kobayashi, Naoto; Maehara, Hiroyuki; Matsunaga, Noriyuki; Mito, Hiroyuki; Miyata, Takashi; Nakada, Yoshikazu; Soyano, Takao; Tarusawa, Ken'ichi; Miyazaki, Satoshi; Nakata, Fumiaki; Okada, Norio; Sarugaku, Yuki; Richmond, Michael W.; Akitaya, Hiroshi; Aldering, Greg; Arimatsu, Ko; Contreras, Carlos; Horiuchi, Takashi; Hsiao, Eric Y.; Itoh, Ryosuke; Iwata, Ikuru; Kawabata, Koji S.; Kawai, Nobuyuki; Kitagawa, Yutaro; Kokubo, Mitsuru; Kuroda, Daisuke; Mazzali, Paolo; Misawa, Toru; Moritani, Yuki; Morrell, Nidia; Okamoto, Rina; Pavlyuk, Nikolay; Phillips, Mark M.; Pian, Elena; Sahu, Devendra; Saito, Yoshihiko; Sano, Kei; Stritzinger, Maximilian D.; Tachibana, Yutaro; Taddia, Francesco; Takaki, Katsutoshi; Tateuchi, Ken; Tomita, Akihiko; Tsvetkov, Dmitry; Ui, Takahiro; Ukita, Nobuharu; Urata, Yuji; Walker, Emma S.; Yoshii, Taketoshi

2014-12-01

The Kiso Supernova Survey (KISS) is a high-cadence optical wide-field supernova (SN) survey. The primary goal of the survey is to catch the very early light of a SN, during the shock breakout phase. Detection of SN shock breakouts combined with multi-band photometry obtained with other facilities would provide detailed physical information on the progenitor stars of SNe. The survey is performed using a 2.2° × 2.2° field-of-view instrument on the 1.05-m Kiso Schmidt telescope, the Kiso Wide Field Camera (KWFC). We take a 3-min exposure in g-band once every hour in our survey, reaching magnitude g ˜ 20-21. About 100 nights of telescope time per year have been spent on the survey since 2012 April. The number of the shock breakout detections is estimated to be of the order of 1 during our three-year project. This paper summarizes the KISS project including the KWFC observing setup, the survey strategy, the data reduction system, and CBET-reported SNe discovered so far by KISS.

The Contribution of Stellar Winds to Cosmic Ray Production

NASA Astrophysics Data System (ADS)

Seo, Jeongbhin; Kang, Hyesung; Ryu, Dongsu

2018-04-01

Massive stars blow powerful stellar winds throughout their evolutionary stages from the main sequence to Wolf-Rayet phases. The wind mechanical energy of a massive star deposited to the interstellar medium can be comparable to the explosion energy of a core-collapse supernova that detonates at the end of its life In this study, we estimate the kinetic energy deposition by massive stars in our Galaxy by considering the integrated Galactic initial mass function and modeling the stellar wind luminosity. The mass loss rate and terminal velocity of stellar winds during the main sequence, red supergiant, and Wolf-Rayet stages are estimated by adopting theoretical calculations and observational data published in the literature. We find that the total stellar wind luminosity by all massive stars in the Galaxy is about Lw ≈ 1.1×1041 ergs, which is about 1/4 of the power of supernova explosions, LSN ≈ 4.8×1041 ergs. If we assume that ˜1-1% of the wind luminosity could be converted to Galactic cosmic rays (GCRs) through collisonless shocks such as termination shocks in stellar bubbles and superbubbles, colliding-wind shocks in binaries, and bow-shocks of massive runaway stars, stellar winds are expected to make a significant contribution to GCR production, though lower than that of supernova remnants.

Broad-band emission properties of central engine powered supernova ejecta interacting with a circumstellar medium

NASA Astrophysics Data System (ADS)

Suzuki, Akihiro; Maeda, Keiichi

2018-04-01

We investigate broad-band emission from supernova ejecta powered by a relativistic wind from a central compact object. A recent two-dimensional hydrodynamic simulation studying the dynamical evolution of supernova ejecta with a central energy source has revealed that outermost layers of the ejecta are accelerated to mildly relativistic velocities because of the breakout of a hot bubble driven by the energy injection. The outermost layers decelerate as they sweep a circumstellar medium surrounding the ejecta, leading to the formation of the forward and reverse shocks propagating in the circumstellar medium and the ejecta. While the ejecta continue to release the internal energy as thermal emission from the photosphere, the energy dissipation at the forward and reverse shock fronts gives rise to non-thermal emission. We calculate light curves and spectral energy distributions of thermal and non-thermal emission from central engine powered supernova ejecta embedded in a steady stellar wind with typical mass loss rates for massive stars. The light curves are compared with currently available radio and X-ray observations of hydrogen-poor superluminous supernovae, as well as the two well-studied broad-lined Ic supernovae, 1998bw and 2009bb, which exhibit bright radio emission indicating central engine activities. We point out that upper limits on radio luminosities of nearby superluminous supernovae may indicate the injected energy is mainly converted to thermal radiation rather than creating mildly relativistic flows owing to photon diffusion time scales comparable to the injection time scale.

Models for Supernovae and Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Woosley, Stan

Supernovae and gamma-ray bursts are the brightest stellar mass explosions in the universe. As such, they serve as cosmic beacons for probing cosmic structure and diagnosing the properties of stars and the universe when it was young. They also produce black holes and neutron stars, interesting in themselves as laboratories where exotic physics comes into play, and they make the elements from which life arises. Consequently, supernovae and gamma-ray bursts are subject to intense study by many NASA missions. We propose focused studies in five areas of supernova research that are directly relevant to NASA's missions, especially SWIFT, HST, JWST, and planning for WFIRST. Our specific topics are a) models for Type Ia supernovae; b) extreme supernovae and first supernovae; c) magnetar-powered supernovae; d) ultra-long duration gamma-ray bursts; and e) shock breakout in supernovae. These phenomena all have in common their importance to NASA missions and the fact that they can be studied using similar tools - computer codes that do radiation hydrodynamics. Our two principal codes, KEPLER (one-dimension) and CASTRO (one to three dimensions), have been honed to the task by years of supernova modeling, and have some unique capabilities. Type Ia supernovae have long been of interest to NASA, but their importance has increased lately because of their utility in determining cosmic distances and because a string of recent observational breakthroughs has severely limited their progenitors. Responding to these developments, we propose to focus on a class of model we have previously neglected, the merger of two white dwarfs. The mergers will be studied with KEPLER and CASTRO in one and two dimensions, and the spectra and light curves determined. The library of model results will be useful in interpreting the results of present NASA missions and planning new ones. A second important area of investigation will be the study of first generation stars and the supernovae that they produce. These stars may have been born more massive than nowadays, and certainly died more massive if mass loss depends upon metallicity. We will explore the bright signal from shock breakout in these stars, a signal that should be detectable even after traversing almost all the universe. We will also study a particular class of ultra-luminous supernovae resulting from the collisions of shells ejected by repeated thermonuclear explosions in very massive stars, the so called ``pulsational pair instability supernovae''. Shock break out will also be studied in more nearby stars using the large library of supernova models we have computed over the years. And we will study the effects that the black holes and neutron stars have on the light emitted by the supernovae that made them. If the outer layers of the star that made the black hole rotate too fast to fall straight into the hole, a long duration (minutes to days) gamma-ray burst can result. If the neutron star has an exceptionally strong magnetic field and rotates rapidly, it may contribute to the supernova light curve. In some cases the supernova would be ultraluminous. Finding compelling evidence for either of these effects would have important implications for how supernovae and gamma-ray bursts work. We are seeking support for one month's summer salary for the PI and full time support for a graduate student. The student is already at UCSC and working on similar projects.

Gravitational waves and core-collapse supernovae

NASA Astrophysics Data System (ADS)

Bisnovatyi-Kogan, G. S.; Moiseenko, S. G.

2017-11-01

A mechanism of formation of gravitational waves in the Universe is considered for a nonspherical collapse of matter. Nonspherical collapse results are presented for a uniform spheroid of dust and a finite-entropy spheroid. Numerical simulation results on core-collapse supernova explosions are presented for the neutrino and magneto-rotational models. These results are used to estimate the dimensionless amplitude of the gravitational wave with a frequency ν ~ 1300 Hz, radiated during the collapse of the rotating core of a pre-supernova with a mass of 1.2 M⊙ (calculated by the authors in 2D). This estimate agrees well with many other calculations (presented in this paper) that have been done in 2D and 3D settings and which rely on more exact and sophisticated calculations of the gravitational wave amplitude. The formation of the large-scale structure of the Universe in the Zel’dovich pancake model involves the emission of very long-wavelength gravitational waves. The average amplitude of these waves is calculated from the simulation, in the uniform spheroid approximation, of the nonspherical collapse of noncollisional dust matter, which imitates dark matter. It is noted that a gravitational wave radiated during a core-collapse supernova explosion in our Galaxy has a sufficient amplitude to be detected by existing gravitational wave telescopes.

The Dawn of a New Era for Supernova 1987a

NASA Image and Video Library

2017-12-08

Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987. Since that first sighting, SN 1987A has continued to fascinate astronomers with its spectacular light show. Located in the nearby Large Magellanic Cloud, it is the nearest supernova explosion observed in hundreds of years and the best opportunity yet for astronomers to study the phases before, during, and after the death of a star. "The 30 years' worth of observations of SN 1987A are important because they provide insight into the last stages of stellar evolution," said Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and the Gordon and Betty Moore Foundation in Palo Alto, California. The latest data from these powerful telescopes indicate that SN 1987A has passed an important threshold. The supernova shock wave is moving beyond the dense ring of gas produced late in the life of the pre-supernova star when a fast outflow or wind from the star collided with a slower wind generated in an earlier red giant phase of the star's evolution. What lies beyond the ring is poorly known at present, and depends on the details of the evolution of the star when it was a red giant. Read more: go.nasa.gov/2lEgs8M NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Shock waves; Proceedings of the 18th International Symposium, Sendai, Japan, July 21-26, 1991. Vols. 1 & 2

NASA Astrophysics Data System (ADS)

Takayama, Kazuyoshi

Various papers on shock waves are presented. The general topics addressed include: shock wave structure, propagation, and interaction; shock wave reflection, diffraction, refraction, and focusing; shock waves in condensed matter; shock waves in dusty gases and multiphase media; hypersonic flows and shock waves; chemical processes and related combustion phenomena; explosions, blast waves, and laser initiation of shock waves; shock tube technology and instrumentation; CFD of shock wave phenomena; medical applications and biological effects; industrial applications.

Particle Acceleration and Radiation associated with Magnetic Field Generation from Relativistic Collisionless Shocks

NASA Technical Reports Server (NTRS)

Nishikawa, K.; Hardee, P. E.; Richardson, G. A.; Preece, R. D.; Sol, H.; Fishman, G. J.

2003-01-01

Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. While some Fermi acceleration may occur at the jet front, the majority of electron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Diffuse gamma-ray emission from self-confined cosmic rays around Galactic sources

NASA Astrophysics Data System (ADS)

D'Angelo, Marta; Morlino, Giovanni; Amato, Elena; Blasi, Pasquale

2018-02-01

The propagation of particles accelerated at supernova remnant shocks and escaping the parent remnants is likely to proceed in a strongly non-linear regime, due to the efficient self-generation of Alfvén waves excited through streaming instability near the sources. Depending on the amount of neutral hydrogen present in the regions around the sites of supernova explosions, cosmic rays may accumulate an appreciable grammage in the same regions and get self-confined for non-negligible times, which in turn results in an enhanced rate of production of secondaries. Here we calculate the contribution to the diffuse gamma-ray background due to the overlap along lines of sight of several of these extended haloes as due to pion production induced by self-confined cosmic rays. We find that if the density of neutrals is low, the haloes can account for a substantial fraction of the diffuse emission observed by Fermi-Large Area Telescope (LAT), depending on the orientation of the line of sight with respect to the direction of the Galactic Centre.

A Quick Look at Supernova 1987A

NASA Image and Video Library

2017-02-24

On February 24, 1987, astronomers in the southern hemisphere saw a supernova in the Large Magellanic Cloud. This new object was dubbed “Supernova 1987A” and was the brightest stellar explosion seen in over four centuries. Chandra has observed Supernova 1987A many times and the X-ray data reveal important information about this object. X-rays from Chandra have shown the expanding blast wave from the original explosion slamming into a ring of material expelled by the star before it exploded. The latest Chandra data reveal the blast wave has moved beyond the ring into a region that astronomers do not know much about. These observations can help astronomers learn how supernovas impact their environments and affect future generations of stars and planets.

The Progenitor of Tycho’s Supernova was Not Hot and Luminous

NASA Astrophysics Data System (ADS)

Ghavamian, Parviz; Woods, T. E.; Gilfanov, M.; Badenes, C.; T. E. Woods, C. Badenes, M. Gilfanov

2018-01-01

Canonical accretion models of Type Ia supernovae predict that a hot and luminous progenitor will ionize the surrounding gas out to a radius of ∼10–100 pc for ∼100,000 years after the explosion. Tycho’s supernova of 1572 was a Type Ia explosion which produced a remnant that is currently interacting with neutral gas in the form of Balmer-dominated shocks. From analysis of these shocks and photoionization calculations, we have placed stringent upper limits on the temperature and luminosity of the progenitor of Tycho’s supernova. Hot, luminous progenitors that would have produced a greater hydrogen ionization fraction than that measured at the current SNR radius (∼3 parsecs) can thus be excluded. This rules out steadily nuclear-burning white dwarfs (i..e, supersoft X-ray sources), as well as disk emission from a Chandrasekhar-mass white dwarf accreting 1E-8 solar masses per year (recurrent novae). The lack of a Stromgren sphere around Tycho’s SNR is consistent with a double degenerate explosion, although other more exotic scenarios may be possible.

Mapping the Supernova-Rich Fireworks Galaxy NGC 6946

NASA Astrophysics Data System (ADS)

Patton, Locke; Levesque, Emily

2018-01-01

Supernovae (SNe) are the spectacularly violent deaths of evolved young massive stars, which expel a shock wave into the intergalactic medium that in turn can spark star formation and disperse heavy elements into their host galaxy. While a SN event can be classified by its spectral signature, determining the nature of a SN progenitor depends upon chance photometry taken prior to the event. By turning to the study of SN host environments and their surrounding interstellar medium within the unique and rare population of galaxies that have hosted three or more SN events within the last century, we are granted the opportunity to study the locations and environmental properties of stellar populations prone to supernova progenitor production. Using moderate-resolution optical slit spectra taken with the Apache Point Observatory 3.5m DIS spectrograph, our goal is to map metallicity, ionization parameter, and star formation rates using emission line diagnostic ratios across each SN-rich galaxy. Dubbed the “Fireworks Galaxy” at a distance of 5.6 ± 1.5 Mpc, NGC 6946 is of particular interest as it has uniquely produced ten core-collapse supernovae (CCSNe) and several other massive star transients within the last century. We present spatially-resolved metallicity and star formation rate (SFR) maps of NGC 6946, tracing fifty-five slit orientations which span the face of the galaxy and cover all CCSN host sites. Future work will include both stellar population synthesis modelling to determine stellar populations, ages, and SFR histories in NGC 6946 and a further expansion of this analysis to the other SN-rich host galaxies in our sample.

Anomalous cosmic ray fluxes in diffusive shock acceleration processes in the heliosphere and in planetary and WR-nebulae

NASA Astrophysics Data System (ADS)

Yeghikyan, Ararat

2018-04-01

Based on the analogy between interacting stellar winds of planetary nebulae and WR-nebulae, on the one hand, and the heliosphere and the expanding envelopes of supernovae, on the other, an attempt is made to calculate the differential intensity of the energetic protons accelerated to energies of 100 MeV by the shock wave. The proposed one-parameter formula for estimating the intensity at 1-100 MeV, when applied to the heliosphere, shows good agreement with the Voyager-1 data, to within a factor of less than 2. The same estimate for planetary (and WR-) nebulae yields a value 7-8 (3-4) orders of magnitude higher than the mean galactic intensity value. The obtained estimate of the intensity of energetic protons in mentioned kinds of nebulae was used to estimate the doses of irradiation of certain substances, in order to show that such accelerated particles play an important role in radiation-chemical transformations in such nebulae.

Constraining the Origin and Heating Mechanism of Dust in Type IIn Supernovae

NASA Astrophysics Data System (ADS)

Fox, Ori; Skrutskie, Michael; Chevalier, Roger; Moseley, Samuel Harvey

2011-05-01

More than any other supernova subclass, Type IIn supernovae tend to exhibit late-time (>100 days) infrared emission from warm dust. Identifying the origin and heating mechanism of the dust provides an important probe of the supernova explosion, circumstellar environment, and progenitor system. Yet mid-infrared observations, which span the peak of the thermal emission, are rare. Two years ago, we executed a warm Spitzer survey (P60122) of sixty-eight Type IIn events from the past ten years. The survey uncovered nine supernovae with unreported late-time infrared excesses, in some cases more than 5 years post-explosion. From this single epoch of data, and ground-based optical data, we have determined the likely origin of the mid-infrared emission to be pre-existing dust that is continuously heated by optical emission generated by ongoing circumstellar interaction between the forward shock and circumstellar medium. Furthermore, we noticed an emerging trend suggests these supernovae ``turn off'' at ~1000-2000 days post-discovery once the forward shock overruns the dust shell. Now is the ideal time to build upon this work with a second epoch of observations, which will be necessary to constrain our models. If we catch even a single supernova turning off between the first and second epochs of observation, we will be able to both measure the size of the circumstellar dust shell and characterize of the supernova progenitor system. We can obtain all the necessary data in only 9.3 hours of observation. Our team has extensive experience in infrared supernovae observations. We have already published two papers on one Type IIn supernovae (SN 2005ip) and authored two successful proposal for Spitzer observations of this subclass. This is an ideal application for the Spitzer warm mission, as the 3.6 and 4.5 micron bands span the peak of the thermal emission and provide the necessary constraints on the dust temperature, mass, and luminosity.

An in situ Comparison of Electron Acceleration at Collisionless Shocks under Differing Upstream Magnetic Field Orientations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masters, A.; Dougherty, M. K.; Sulaiman, A. H.

A leading explanation for the origin of Galactic cosmic rays is acceleration at high-Mach number shock waves in the collisionless plasma surrounding young supernova remnants. Evidence for this is provided by multi-wavelength non-thermal emission thought to be associated with ultrarelativistic electrons at these shocks. However, the dependence of the electron acceleration process on the orientation of the upstream magnetic field with respect to the local normal to the shock front (quasi-parallel/quasi-perpendicular) is debated. Cassini spacecraft observations at Saturn’s bow shock have revealed examples of electron acceleration under quasi-perpendicular conditions, and the first in situ evidence of electron acceleration at amore » quasi-parallel shock. Here we use Cassini data to make the first comparison between energy spectra of locally accelerated electrons under these differing upstream magnetic field regimes. We present data taken during a quasi-perpendicular shock crossing on 2008 March 8 and during a quasi-parallel shock crossing on 2007 February 3, highlighting that both were associated with electron acceleration to at least MeV energies. The magnetic signature of the quasi-perpendicular crossing has a relatively sharp upstream–downstream transition, and energetic electrons were detected close to the transition and immediately downstream. The magnetic transition at the quasi-parallel crossing is less clear, energetic electrons were encountered upstream and downstream, and the electron energy spectrum is harder above ∼100 keV. We discuss whether the acceleration is consistent with diffusive shock acceleration theory in each case, and suggest that the quasi-parallel spectral break is due to an energy-dependent interaction between the electrons and short, large-amplitude magnetic structures.« less

A Fast-Evolving, Luminous Transient Discovered by K2/Kepler

NASA Astrophysics Data System (ADS)

Rest, Armin; Garnavich, Peter; Khatami, David; Kasen, Daniel; Tucker, Brad; Shaya, Edward; Olling, Robert; Mushotzky, Richard; Zenteno, Alfredo; Margheim, Steven; Strampelli, Giovanni Maria; James, David; Smith, Chris; Forster, Francisco; Villar, Ashley

2018-01-01

For decades optical time-domain searches have been tuned to find ordinary supernovae, which rise and fall in brightness over a period of weeks. Recently, supernova searches have improved their cadences and a handful of fast-evolving luminous transients (FELTs) have been identified. FELTs have peak luminosities comparable to type Ia supernovae, but rise to maximum in <10 days and fade from view in <30 days. Here we present the most extreme example of this class thus far, KSN2015K, with a rise time of only 2.2 days and a time above half-maximum of only 6.8 days. Possible energy sources for KSN2015K are the decay of radioactive elements, a central engine powered by accretion/magnetic fields, or hydrodynamic shock. We show that KSN2015K's luminosity makes it unlikely to be powered by radioactive isotopes, and we find that the shock breakout into a dense wind most likely energized the transient.

Molecular Diagnostics of Supernova Remnant Shocks

NASA Astrophysics Data System (ADS)

Lazendic, J. S.; Wardle, M.; Green, A. J.; Whiteoak, J. B.; Burton, M. G.

We have undertaken a study of radio and infrared molecular-line emission towards several SNRs in order to investigate molecular signatures of SNR shocks, and to test models for OH maser production in SNRs. Here we present results on G349.7+0.2.

The Status of Multi-Dimensional Core-Collapse Supernova Models

NASA Astrophysics Data System (ADS)

Müller, B.

2016-09-01

Models of neutrino-driven core-collapse supernova explosions have matured considerably in recent years. Explosions of low-mass progenitors can routinely be simulated in 1D, 2D, and 3D. Nucleosynthesis calculations indicate that these supernovae could be contributors of some lighter neutron-rich elements beyond iron. The explosion mechanism of more massive stars remains under investigation, although first 3D models of neutrino-driven explosions employing multi-group neutrino transport have become available. Together with earlier 2D models and more simplified 3D simulations, these have elucidated the interplay between neutrino heating and hydrodynamic instabilities in the post-shock region that is essential for shock revival. However, some physical ingredients may still need to be added/improved before simulations can robustly explain supernova explosions over a wide range of progenitors. Solutions recently suggested in the literature include uncertainties in the neutrino rates, rotation, and seed perturbations from convective shell burning. We review the implications of 3D simulations of shell burning in supernova progenitors for the `perturbations-aided neutrino-driven mechanism,' whose efficacy is illustrated by the first successful multi-group neutrino hydrodynamics simulation of an 18 solar mass progenitor with 3D initial conditions. We conclude with speculations about the impact of 3D effects on the structure of massive stars through convective boundary mixing.

DES14X3taz: A TYPE I SUPERLUMINOUS SUPERNOVA SHOWING A LUMINOUS, RAPIDLY COOLING INITIAL PRE-PEAK BUMP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, M.; Sullivan, M.; D’Andrea, C. B.

2016-02-03

We present DES14X3taz, a new hydrogen-poor superluminous supernova (SLSN-I) discovered by the Dark Energy Survey (DES) supernova program, with additional photometric data provided by the Survey Using DECam for Superluminous Supernovae. Spectra obtained using Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy on the Gran Telescopio CANARIAS show DES14X3taz is an SLSN-I at z = 0.608. Multi-color photometry reveals a double-peaked light curve: a blue and relatively bright initial peak that fades rapidly prior to the slower rise of the main light curve. Our multi-color photometry allows us, for the first time, to show that the initial peak cools frommore » 22,000 to 8000 K over 15 rest-frame days, and is faster and brighter than any published core-collapse supernova, reaching 30% of the bolometric luminosity of the main peak. No physical Ni-56-powered model can fit this initial peak. We show that a shock-cooling model followed by a magnetar driving the second phase of the light curve can adequately explain the entire light curve of DES14X3taz. Models involving the shock-cooling of extended circumstellar material at a distance of similar or equal to 400 R-circle dot are preferred over the cooling of shock-heated surface layers of a stellar envelope. We compare DES14X3taz to the few double-peaked SLSN-I events in the literature. Although the rise. times and characteristics of these initial peaks differ, there exists the tantalizing possibility that they can be explained by one physical interpretation« less

DES14X3taz: A type I superluminous supernova showing a luminous, rapidly cooling initial pre-peak bump

DOE PAGES

Smith, M.

2016-02-03

Here, we present DES14X3taz, a new hydrogen-poor superluminous supernova (SLSN-I) discovered by the Dark Energy Survey (DES) supernova program, with additional photometric data provided by the Survey Using DECam for Superluminous Supernovae. Spectra obtained using Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy on the Gran Telescopio CANARIAS show DES14X3taz is an SLSN-I at z = 0.608. Multi-color photometry reveals a double-peaked light curve: a blue and relatively bright initial peak that fades rapidly prior to the slower rise of the main light curve. Our multi-color photometry allows us, for the first time, to show that the initial peak cools from 22,000more » to 8000 K over 15 rest-frame days, and is faster and brighter than any published core-collapse supernova, reaching 30% of the bolometric luminosity of the main peak. No physical (56)Ni-powered model can fit this initial peak. We show that a shock-cooling model followed by a magnetar driving the second phase of the light curve can adequately explain the entire light curve of DES14X3taz. Models involving the shock-cooling of extended circumstellar material at a distance of ≃400 R ⊙ are preferred over the cooling of shock-heated surface layers of a stellar envelope. We compare DES14X3taz to the few double-peaked SLSN-I events in the literature. Although the rise times and characteristics of these initial peaks differ, there exists the tantalizing possibility that they can be explained by one physical interpretation.« less

Triggering Star Formation: From the Pillars of Creation to the Formation of Our Solar System

NASA Astrophysics Data System (ADS)

Gritschneder, Matthias; Lin, Douglas N. C.

We study the evolution of molecular clouds under the influence of ionizing radiation. We propose that the Pipe Nebula is an HII region shell swept up by the B2 IV β Cephei star θ Ophiuchi. After reviewing the recent observations, we perform a series of analytical calculations. We are able to show that the current size, mass and pressure of the region can be explained in this scenario. The Pipe Nebula can be best described by a three phase medium in pressure equilibrium. The pressure support is provided by the ionized gas and mediated by an atomic component to confine the cores at the observed current pressure. We then present simulations on the future evolution as soon as the massive star explodes in a supernova. We show that a surviving core at the border of the HII-region (D = 5 pc) is getting enriched sufficiently with supernova material and is triggered into collapse fast enough to be consistent with the tight constraints put by meteoritic data of e.g.26Al on the formation of our Solar System. We therefore propose that the formation of the Solar System was triggered by the shock wave of a type IIa supernova interacting with surviving cold structures similar to the Pillars of Creation at the border of HII-regions.

Astrophysical fluid dynamics

NASA Astrophysics Data System (ADS)

Ogilvie, Gordon I.

2016-06-01

> These lecture notes and example problems are based on a course given at the University of Cambridge in Part III of the Mathematical Tripos. Fluid dynamics is involved in a very wide range of astrophysical phenomena, such as the formation and internal dynamics of stars and giant planets, the workings of jets and accretion discs around stars and black holes and the dynamics of the expanding Universe. Effects that can be important in astrophysical fluids include compressibility, self-gravitation and the dynamical influence of the magnetic field that is `frozen in' to a highly conducting plasma. The basic models introduced and applied in this course are Newtonian gas dynamics and magnetohydrodynamics (MHD) for an ideal compressible fluid. The mathematical structure of the governing equations and the associated conservation laws are explored in some detail because of their importance for both analytical and numerical methods of solution, as well as for physical interpretation. Linear and nonlinear waves, including shocks and other discontinuities, are discussed. The spherical blast wave resulting from a supernova, and involving a strong shock, is a classic problem that can be solved analytically. Steady solutions with spherical or axial symmetry reveal the physics of winds and jets from stars and discs. The linearized equations determine the oscillation modes of astrophysical bodies, as well as their stability and their response to tidal forcing.

Ablative stabilization of Rayleigh-Taylor instabilities resulting from a laser-driven radiative shock

NASA Astrophysics Data System (ADS)

Huntington, C. M.; Shimony, A.; Trantham, M.; Kuranz, C. C.; Shvarts, D.; Di Stefano, C. A.; Doss, F. W.; Drake, R. P.; Flippo, K. A.; Kalantar, D. H.; Klein, S. R.; Kline, J. L.; MacLaren, S. A.; Malamud, G.; Miles, A. R.; Prisbrey, S. T.; Raman, K. S.; Remington, B. A.; Robey, H. F.; Wan, W. C.; Park, H.-S.

2018-05-01

The Rayleigh-Taylor (RT) instability is a common occurrence in nature, notably in astrophysical systems like supernovae, where it serves to mix the dense layers of the interior of an exploding star with the low-density stellar wind surrounding it, and in inertial confinement fusion experiments, where it mixes cooler materials with the central hot spot in an imploding capsule and stifles the desired nuclear reactions. In both of these examples, the radiative flux generated by strong shocks in the system may play a role in partially stabilizing RT instabilities. Here, we present experiments performed on the National Ignition Facility, designed to isolate and study the role of radiation and heat conduction from a shock front in the stabilization of hydrodynamic instabilities. By varying the laser power delivered to a shock-tube target with an embedded, unstable interface, the radiative fluxes generated at the shock front could be controlled. We observe decreased RT growth when the shock significantly heats the medium around it, in contrast to a system where the shock did not produce significant heating. Both systems are modeled with a modified set of buoyancy-drag equations accounting for ablative stabilization, and the experimental results are consistent with ablative stabilization when the shock is radiative. This result has important implications for our understanding of astrophysical radiative shocks and supernova radiative hydrodynamics [Kuranz et al., Nature Communications 9(1), 1564 (2018)].

COS Observations of SN1987A

NASA Astrophysics Data System (ADS)

McCray, Richard; France, K.; Kirshner, R. P.; SAINTS Collaboration

2012-01-01

We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (v - 300 km/s) emission lines from the circumstellar ring, broad (v - 10 - 20 × 103 km/s) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise (> 40 per resolution element) broad Ly α emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at - > 1350 A can be explained by H I 2-photon (2s 2S1/2 - 1s 2S1/2) emission from the same region. We confirm our earlier, tentative detection of N V -1240 emission from the reverse shock and we present the first detections of broad He II 1640, C IV -1550, and N IV] 1486 emission lines from the reverse shock. The helium abundance in the high velocity material is He/H = 0.14 +/- 0.06. The N V/H line ratio requires partial ion-electron equilibration (Te/Tp - 0.14 - 0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result we attribute to continued CNO processing in the supernova progenitor subsequent to the expulsion of the circumstellar ring.

Circumstellar X-ray Emission from SN1978K

NASA Astrophysics Data System (ADS)

Schlegel, Eric M.; Colbert, E.; Petre, R.

1995-02-01

We present the X-ray light curve in the 0.2 2.4 keV band based on fiveROSAT observations of SN1978K in NGC 1313. The X-ray emission is believed to arise from the interaction of the reverse shock and the expanding debris from the supernova. The reverse shock becomes established after the outgoing shock runs into circumstellar matter.

Shocks in Dense Clouds in the Vela Supernova Remnant: FUSE

NASA Technical Reports Server (NTRS)

Nichols, Joy; Sonneborn, George (Technical Monitor)

2002-01-01

We have obtained 8 LWRS FUSE spectra to study a recently identified interaction of the Vela supernova remnant with a dense cloud region along its western edge. The goal is to quantify the temperature, ionization, density, and abundance characteristics associated with this shock/dense cloud interface by means of UV absorption line studies. Our detection of high-velocity absorption line C I at +90 to +130 km/s with IUE toward a narrow region interior to the Vela SNR strongly suggests the Vela supernova remnant is interacting with a dense ISM or molecular cloud. The shock/dense cloud interface is suggested by (1) the rarity of detection of high-velocity C I seen in IUE spectra, (2) its very limited spatial distribution in the remnant, and (3) a marked decrease in X-ray emission in the region immediately west of the position of these stars where one also finds a 100 micron emission ridge in IRAS images. We have investigated the shock physics and general properties of this interaction region through a focussed UV absorption line study using FUSE spectra. We have FUSE data on OVI absorption lines observed toward 8 stars behind the Vela supernova remnant (SNR). We compare the OVI observations with IUE observations of CIV absorption toward the same stars. Most of the stars, which are all B stars, have complex continua making the extraction of absorption lines difficult. Three of the stars, HD 72088, HD 72089 and HD 72350, however, are rapid rotators (v sin i less than 100 km/s) making the derivation of absorption column densities much easier. We have measured OVI and CIV column densities for the "main component" (i.e. the low velocity component) for these stars. In addition, by removing the H2 line at 1032.35A (121.6 km/s relative to OVI), we find high velocity components of OVI at approximately 150 km/s that we attribute to the shock in the Vela SNR. The column density ratios and magnitudes are compared to both steady shock models and results of hydrodynamical SNR modeling. We find that the models require the shock to be relatively slow (approximately 100 - 170 km/s) to match the FUSE data. We discuss the implications of our results for models of the evolution of the Vela SNR.

Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets and Supernova Remnants

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Hartmann, D. H.; Hardee, P.; Hededal, C.; Mizunno, Y.; Fishman, G. J.

2006-01-01

We performed numerical simulations of particle acceleration, magnetic field generation, and emission from shocks in order to understand the observed emission from relativistic jets and supernova remnants. The investigation involves the study of collisionless shocks, where the Weibel instability is responsible for particle acceleration as well as magnetic field generation. A 3-D relativistic particle-in-cell (RPIC) code has been used to investigate the shock processes in electron-positron plasmas. The evolution of theWeibe1 instability and its associated magnetic field generation and particle acceleration are studied with two different jet velocities (0 = 2,5 - slow, fast) corresponding to either outflows in supernova remnants or relativistic jets, such as those found in AGNs and microquasars. Slow jets have intrinsically different structures in both the generated magnetic fields and the accelerated particle spectrum. In particular, the jet head has a very weak magnetic field and the ambient electrons are strongly accelerated and dragged by the jet particles. The simulation results exhibit jitter radiation from inhomogeneous magnetic fields, generated by the Weibel instability, which has different spectral properties than standard synchrotron emission in a homogeneous magnetic field.

Interaction of Supernova Blast Waves with Wind-Driven Shells: Formation of "Jets", "Bullets", "Ears", Etc.

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

Most of middle-aged supernova remnants (SNRs) have a distorted and complicated appearance which cannot be explained in the framework of the Sedov-Taylor model. We consider three typical examples of such SNRs (Vela SNR, MSH15-52, G309.2-00.6) and show that their structure could be explained as a result of interaction of a supernova (SN) blast wave with the ambient medium preprocessed by the action of the SN progenitor's wind and ionized emission.

Dynamics of supernova driven superbubbles

NASA Astrophysics Data System (ADS)

Yadav, Naveen; Mukherjee, Dipanjan; Sharma, Prateek; Nath, Biman

2015-08-01

Energy injection by supernovae is believed to be one of the primary sources which powers the expansion of supershells. There is a qualitative difference between isolated supernovae (SNe) and overlapping SNe. For typical interstellar medium (ISM) conditions an isolated supernova loses most of the injected mechanical energy by 1 Myr. In contrast, for SNe going off in bubbles the radiative losses are much smaller. While the outer shock going off in the dense ISM (~1 cm-3) becomes radiative well before 1 Myr, there is a strong non-radiative termination shock that keeps the bubble over-pressured till the lifetime of the OB association (10s of Myr; Sharma et al. 2014). This has relevance for supernova feedback in galaxy formation simulations. In our previous 1-D treatment all the SNe were assumed to occur at the same location in space. It was found that a steady wind inside the bubble (Chevalier & Clegg 1985) can occur only if the number of SNe is large (>~104) and a supernova going off inside the bubble can thermalize within the termination shock. In the present work we study the effect of SNe separated in both space and time using 3-D hydrodynamic simulations with radiative cooling. If the separation between SNe is larger than the remnant’s radius at the time it becomes radiative, SNe are in the isolated regime. The explosion energy is deposited as thermal energy in a uniform, static interstellar medium (ISM) with temperature 104 K, corresponding to the warm neutral medium. The key parameters of our idealized setup are the ISM density (ngas), the number of SNe (N★) and the spatial separation between SNe (Rcl). The shock radius when it becomes radiative depends on the ISM density and number of SNe. We obtain the critical values of the key parameters (ngas, N★, Rcl) which lead to the formation of a superbubble. e.g., at least 103 SNe are required to maintain an over-pressured bubble at 20 Myr in an ISM with 1 cm-3 similarly 102 SNe going off within a region of 100 pc in an ISM with 1 cm-3 are effectively in the isolated regime. We also compare our simulation results with observational data on superbubbles.

Shock tubes and waves; Proceedings of the Thirteenth International Symposium, Niagara Falls, NY, July 6-9, 1981

NASA Astrophysics Data System (ADS)

Treanor, C. E.; Hall, J. G.

1982-10-01

The present conference on shock tubes and waves considers shock tube drivers, luminous shock tubes, shock tube temperature and pressure measurement, shock front distortion in real gases, nonlinear standing waves, transonic flow shock wave turbulent boundary interactions, wall roughness effects on reflected shock bifurcation, argon thermal conductivity, pattern generation in gaseous detonations, cylindrical resonators, shock tunnel-produced high gain lasers, fluid dynamic aspects of laser-metal interaction, and the ionization of argon gas behind reflected shock waves. Also discussed are the ionization relaxation of shock-heated plasmas and gases, discharge flow/shock tube studies of singlet oxygen, rotational and vibrational relaxation, chemiluminescence thermal and shock wave decomposition of hydrogen cyanide and hydrogen azide, shock wave structure in gas-particle mixtures at low Mach numbers, binary nucleation in a Ludwieg tube, shock liquefaction experiments, pipeline explosions, the shock wave ignition of pulverized coal, and shock-initiated methane combustion.

The Betelgeuse Project II: Asteroseismology

NASA Astrophysics Data System (ADS)

Nance, S.; Sullivan, J. M.; Diaz, M.; Wheeler, J. Craig

2018-06-01

We explore the question of whether the interior state of massive red supergiant supernova progenitors can be effectively probed with asteroseismology. We have computed a suite of ten models with ZAMS masses from 15 to 25 M⊙ in intervals of 1 M⊙ including the effects of rotation, with the stellar evolutionary code MESA. We estimate characteristic frequencies and convective luminosities of convective zones at two illustrative stages, core helium burning and off-center convective carbon burning. We also estimate the power that might be delivered to the surface to modulate the luminous output considering various efficiencies and dissipation mechanisms. The inner convective regions should generate waves with characteristic periods of ˜ 20 days in core helium burning, ˜10 days in helium shell burning, and 0.1 to 1 day in shell carbon burning. Acoustic waves may avoid both shock and diffusive dissipation relatively early in core helium burning throughout most of the structure. In shell carbon burning, years before explosion, the signal generated in the helium shell might in some circumstances be weak enough to avoid shock dissipation, but is subject to strong thermal dissipation in the hydrogen envelope. Signals from a convective carbon-burning shell are very likely to be even more severely damped by within the envelope. In the most optimistic case, early in core helium burning, waves arriving close to the surface could represent luminosity fluctuations of a few millimagnitudes, but the conditions in the very outer reaches of the envelope suggest severe thermal damping there.

Assessment of renal injury with a clinical dual head lithotriptor delivering 240 shock waves per minute.

PubMed

Handa, Rajash K; McAteer, James A; Evan, Andrew P; Connors, Bret A; Pishchalnikov, Yuri A; Gao, Sujuan

2009-02-01

Lithotriptors with 2 treatment heads deliver shock waves along separate paths. Firing 1 head and then the other in alternating mode has been suggested as a strategy to treat stones twice as rapidly as with conventional shock wave lithotripsy. Because the shock wave rate is known to have a role in shock wave lithotripsy induced injury, and given that treatment using 2 separate shock wave sources exposes more renal tissue to shock wave energy than treatment with a conventional lithotriptor, we assessed renal trauma in pigs following treatment at rapid rate (240 shock waves per minute and 120 shock waves per minute per head) using a Duet lithotriptor (Direx Medical Systems, Petach Tikva, Israel) fired in alternating mode. Eight adult female pigs (Hardin Farms, Danville, Indiana) each were treated with sham shock wave lithotripsy or 2,400 shock waves delivered in alternating mode (1,200 shock waves per head, 120 shock waves per minute per head and 240 shock waves per minute overall at a power level of 10) to the lower renal pole. Renal functional parameters, including glomerular filtration rate and effective renal plasma flow, were determined before and 1 hour after shock wave lithotripsy. The kidneys were perfusion fixed in situ and the hemorrhagic lesion was quantified as a percent of functional renal volume. Shock wave treatment resulted in no significant change in renal function and the response was similar to the functional response seen in sham shock wave treated animals. In 6 pigs treated with alternating mode the renal lesion was small at a mean +/- SEM of 0.22% +/- 0.09% of functional renal volume. Kidney tissue and function were minimally affected by a clinical dose of shock waves delivered in alternating mode (120 shock waves per minute per head and 240 shock waves per minute overall) with a Duet lithotriptor. These observations decrease concern that dual head lithotripsy at a rapid rate is inherently dangerous.

Shock tubes and waves; Proceedings of the Sixteenth International Symposium, Rheinisch-Westfaelische Technische Hochschule, Aachen, Federal Republic of Germany, July 26-31, 1987

NASA Astrophysics Data System (ADS)

Groenig, Hans

Topics discussed in this volume include shock wave structure, propagation, and interaction; shocks in condensed matter, dusty gases, and multiphase media; chemical processes and related combustion and detonation phenomena; shock wave reflection, diffraction, and focusing; computational fluid dynamic code development and shock wave application; blast and detonation waves; advanced shock tube technology and measuring technique; and shock wave applications. Papers are presented on dust explosions, the dynamics of shock waves in certain dense gases, studies of condensation kinetics behind incident shock waves, the autoignition mechanism of n-butane behind a reflected shock wave, and a numerical simulation of the focusing process of reflected shock waves. Attention is also given to the equilibrium shock tube flow of real gases, blast waves generated by planar detonations, modern diagnostic methods for high-speed flows, and interaction between induced waves and electric discharge in a very high repetition rate excimer laser.

Supernova VLBI

NASA Astrophysics Data System (ADS)

Bartel, N.

2009-08-01

We review VLBI observations of supernovae over the last quarter century and discuss the prospect of imaging future supernovae with space VLBI in the context of VSOP-2. From thousands of discovered supernovae, most of them at cosmological distances, ˜50 have been detected at radio wavelengths, most of them in relatively nearby galaxies. All of the radio supernovae are Type II or Ib/c, which originate from the explosion of massive progenitor stars. Of these, 12 were observed with VLBI and four of them, SN 1979C, SN 1986J, SN 1993J, and SN 1987A, could be imaged in detail, the former three with VLBI. In addition, supernovae or young supernova remnants were discovered at radio wavelengths in highly dust-obscured galaxies, such as M82, Arp 299, and Arp 220, and some of them could also be imaged in detail. Four of the supernovae so far observed were sufficiently bright to be detectable with VSOP-2. With VSOP-2 the expansion of supernovae can be monitored and investigated with unsurpassed angular resolution, starting as early as the time of the supernova's transition from its opaque to transparent stage. Such studies can reveal, in a movie, the aftermath of a supernova explosion shortly after shock break out.

Fast time variations of supernova neutrino signals from 3-dimensional models

DOE PAGES

Lund, Tina; Wongwathanarat, Annop; Janka, Hans -Thomas; ...

2012-11-19

Here, we study supernova neutrino flux variations in the IceCube detector, using 3D models based on a simplified neutrino transport scheme. The hemispherically integrated neutrino emission shows significantly smaller variations compared with our previous study of 2D models, largely because of the reduced activity of the standing accretion shock instability in this set of 3D models which we interpret as a pessimistic extreme. For the studied cases, intrinsic flux variations up to about 100 Hz frequencies could still be detected in a supernova closer than about 2 kpc.

Light-curve and spectral properties of ultrastripped core-collapse supernovae leading to binary neutron stars

NASA Astrophysics Data System (ADS)

Moriya, Takashi J.; Mazzali, Paolo A.; Tominaga, Nozomu; Hachinger, Stephan; Blinnikov, Sergei I.; Tauris, Thomas M.; Takahashi, Koh; Tanaka, Masaomi; Langer, Norbert; Podsiadlowski, Philipp

2017-04-01

We investigate light-curve and spectral properties of ultrastripped core-collapse supernovae. Ultrastripped supernovae are the explosions of heavily stripped massive stars that lost their envelopes via binary interactions with a compact companion star. They eject only ˜0.1 M⊙ and may be the main way to form double neutron-star systems that eventually merge emitting strong gravitational waves. We follow the evolution of an ultrastripped supernova progenitor until iron core collapse and perform explosive nucleosynthesis calculations. We then synthesize light curves and spectra of ultrastripped supernovae using the nucleosynthesis results and present their expected properties. Ultrastripped supernovae synthesize ˜0.01 M⊙ of radioactive 56Ni, and their typical peak luminosity is around 1042 erg s-1 or -16 mag. Their typical rise time is 5-10 d. Comparing synthesized and observed spectra, we find that SN 2005ek, some of the so-called calcium-rich gap transients, and SN 2010X may be related to ultrastripped supernovae. If these supernovae are actually ultrastripped supernovae, their event rate is expected to be about 1 per cent of core-collapse supernovae. Comparing the double neutron-star merger rate obtained by future gravitational-wave observations and the ultrastripped supernova rate obtained by optical transient surveys identified with our synthesized light-curve and spectral models, we will be able to judge whether ultrastripped supernovae are actually a major contributor to the binary neutron-star population and provide constraints on binary stellar evolution.

VLBI of supernovae and gamma-ray bursts

NASA Astrophysics Data System (ADS)

Bartel, N.; Karimi, B.; Bietenholz, M. F.

2017-04-01

Supernovae and gamma-ray bursts (GRBs) are among the brightest events in the universe. Excluding Type Ia supernovae and short GRBs, they are the result of the core collapse of a massive star with material being ejectedwith speeds of several 1000 km/s to nearly the speed of light, and with a neutron star or a black hole left over as the compact remnant of the explosion. Synchrotron radiation in the radio is generated in a shell when the ejecta interact with the surrounding medium and possibly also in the central region near the compact remnant itself. VLBI has allowed resolving some of these sources and monitoring their expansion in detail, thereby revealing characteristics of the dying star, the explosion, the expanding shock front, and the expected compact remnant. We report on updates of some of the most interesting results that have been obtained with VLBI so far. Movies of supernovae are available from our website. They show the evolution from shortly after the explosion to decades thereafter, in one case revealing an emerging compact central source, which may be associated with shock interaction near the explosion center or with the stellar corpse itself, a neutron star or a black hole.

Non-linear acceleration at supernova remnant shocks and the hardening in the cosmic ray spectrum

NASA Astrophysics Data System (ADS)

Recchia, S.; Gabici, S.

2018-02-01

In the last few years, several experiments have shown that the cosmic ray spectrum below the knee is not a perfect power law. In particular, the proton and helium spectra show a spectral hardening by ˜0.1-0.2 in spectral index at particle energies of ˜ 200-300 GeV nucleon-1. Moreover, the helium spectrum is found to be harder than that of protons by ˜0.1 and some evidence for a similar hardening was also found in the spectra of heavier elements. Here, we consider the possibility that the hardening may be the result of a dispersion in the slope of the spectrum of cosmic rays accelerated at supernova remnant shocks. Such a dispersion is indeed expected within the framework of non-linear theories of diffusive shock acceleration, which predict steeper (harder) particle spectra for larger (smaller) cosmic ray acceleration efficiencies.

Observing supernova 1987A with the refurbished Hubble Space Telescope.

PubMed

France, Kevin; McCray, Richard; Heng, Kevin; Kirshner, Robert P; Challis, Peter; Bouchet, Patrice; Crotts, Arlin; Dwek, Eli; Fransson, Claes; Garnavich, Peter M; Larsson, Josefin; Lawrence, Stephen S; Lundqvist, Peter; Panagia, Nino; Pun, Chun S J; Smith, Nathan; Sollerman, Jesper; Sonneborn, George; Stocke, John T; Wang, Lifan; Wheeler, J Craig

2010-09-24

Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 with the use of the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Lyα and Hα lines from shock emission continue to brighten, whereas their maximum velocities continue to decrease. We observe broad, blueshifted Lyα, which we attribute to resonant scattering of photons emitted from hot spots on the equatorial ring. We also detect N v λλ1239, 1243 angstrom line emission, but only to the red of Lyα. The profiles of the N v lines differ markedly from that of Hα, suggesting that the N4+ ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock.

Collisionless Shocks and Particle Acceleration.

NASA Astrophysics Data System (ADS)

Malkov, M.

2016-12-01

Collisionless shocks emerged in the 50s and 60s of the last century as an important branch of plasma physics and have remained ever since. New applications pose new challenges to our understanding of collisionless shock mechanisms. Particle acceleration in astrophysical settings, primarily studied concerning the putative origin of cosmic rays (CR) in supernova remnant (SNR) shocks, stands out with the collisionless shock mechanism being the key. Among recent laboratory applications, a laser-based tabletop proton accelerator is an affordable compact alternative to big synchrotron accelerators. The much-anticipated proof of cosmic ray (CR) acceleration in supernova remnants is hindered by our limited understanding of collisionless shock mechanisms. Over the last decade, dramatically improved observations were puzzling the theorists with unexpected discoveries. The difference between the helium/carbon and proton CR rigidity (momentum to charge ratio) spectra, seemingly inconsistent with the acceleration and propagation theories, and the perplexing positron excess in the 10-300 GeV range are just two recent examples. The latter is now also actively discussed in the particle physics and CR communities as a possible signature of decay or annihilation of hypothetical dark matter particles. By considering an initial (injection) phase of a diffusive shock acceleration mechanism, including particle reflection off the shock front - where an elemental similarity of particle dynamics does not apply - I will discuss recent suggestions of how to address the new data from the collisionless shock perspective. The backreaction of accelerated particles on the shock structure, its environment, and visibility across the electromagnetic spectrum from radio to gamma rays is another key aspect of collisionless shock that will be discussed.

Interacting Supernovae: Types IIn and Ibn

NASA Astrophysics Data System (ADS)

Smith, Nathan

Supernovae that show evidence of strong shock interaction between their ejecta and pre-existing slower circumstellar material (CSM) constitute an interesting, diverse, and still poorly understood category of explosive transients. The chief reason they are extremely interesting is because they tell us that in a subset of stellar deaths, the progenitor star becomes wildly unstable in the years, decades, or centuries before explosion. This is something that has not been included in standard stellar evolution models but may significantly change the end product and yield of that evolution and complicates our attempts to map SNe to their progenitors. Another reason they are interesting is because CSM interaction is an efficient engine for making bright transients, allowing superluminous transients to arise from normal SN explosion energy, and transients of normal supernova luminosity to arise from sub-energetic explosions or low radioactivity yield. CSM interaction shrouds the fast ejecta in bright shock emission, obscuring our view of the underlying explosion, and the radiation hydrodynamics is challenging to model. The CSM interaction may also be highly nonspherical, perhaps linked to binary interaction in the progenitor system. In some cases, these complications make it difficult to tell the difference between a core-collapse and thermonuclear explosion or to discern between a nonterminal eruption, failed supernova, or weak supernova. Efforts to uncover the physical parameters of individual events and connections to progenitor stars make this a rapidly evolving topic that challenges paradigms of stellar evolution.

Hard X-ray Emission and Efficient Particle Acceleration by Supernova Remnants

NASA Astrophysics Data System (ADS)

Vink, Jacco

2009-05-01

I discuss the non-thermal X-ray emission from young supernova remnants. Over the last decade it has become clear from both X-ray and γ-ray observations that young supernovae accelerate particles up to 100 TeV. In soft X-rays the accelerated >10 TeV electrons produce synchrotron radiation, coming from narrow filaments located at the shock fronts. The width of these filaments shows that the magnetic fields are relatively high, thus providing evidence for magnetic field amplification. The synchrotron radiation of several remnants is known to extend into the hard X-ray regime. In particular Cas A, has a spectrum that appears as a power law up to almost 100 TeV. This is very surprising, as a steepening is expected going from the soft to the hard X-ray band. The spectrum is likely a result of many superimposed individual spectra, each steepening at different energies. This implies considerable spatial variation in hard X-rays, an obvious target for Simbol-X. The variations will be important to infer local shock acceleration properties, but also magnetic field fluctuations may cause spatial and temporal variations. Finally, I draw the attention to super bubbles and supernovae as sources of cosmic rays. As such they may be sources of hard X-ray emission. In particular, supernovae exploding inside the dense red supergiants winds of their progenitors ares promising candidates for hard X-ray emission.

Gravitational wave asteroseismology with protoneutron stars

NASA Astrophysics Data System (ADS)

Sotani, Hajime; Takiwaki, Tomoya

2016-08-01

We examine the time evolution of the frequencies of the gravitational wave after the bounce within the framework of relativistic linear perturbation theory using the results of one-dimensional numerical simulations of core-collapse supernovae. Protoneutron star models are constructed in such a way that the mass and the radius of the protoneutron star become equivalent to the results obtained from the numerical simulations. Then we find that the frequencies of gravitational waves radiating from protoneutron stars strongly depend on the mass and the radius of protoneutron stars, but almost independently of the profiles of the electron fraction and the entropy per baryon inside the star. Additionally, we find that the frequencies of gravitational waves can be characterized by the square root of the average density of the protoneutron star irrespective of the progenitor models, which are completely different from the empirical formula for cold neutron stars. The dependence of the spectra on the mass and the radius is different from that of the g -mode: the oscillations around the surface of protoneutron stars due to the convection and the standing accretion-shock instability. Careful observation of these modes of gravitational waves can determine the evolution of the mass and the radius of protoneutron stars after core bounce. Furthermore, the expected frequencies of gravitational waves are around a few hundred hertz in the early stages after bounce, which must be a good candidate for the ground-based gravitational wave detectors.

Radiative transfer calculations of ultra-relativistic shock breakout in circumstellar medium: Dependence on the central engine activity

NASA Astrophysics Data System (ADS)

Ohtani, Yukari; Suzuki, Akihiro; Shigeyama, Toshikazu

2015-08-01

Core collapse supernovae radiate bright X-ray or UV flashes imediately after their explosion, because shock waves emerge on the surfaces of the progenitors. Due to their short duration, a very small number of such events (so called shock breakouts) have been observed, and the maximum shock velocities are likely to be significantly smaller than the speed of light. In principle, we can consider the shocks with ultra-relativistic velocities breakout stellar surfaces and generate gamma-ray photons. A recently popular theory of gamma-ray bursts argues that the thermal radiation produced in the jet may play important roles in the prompt emission. Therefore, for understanding of the relation between jets and the central engine, studying properties of breakouts in the relativistic limit will be interesting. To obtain some information concerning the temporal evolution of the photospheric emission from jets, we make a radiative transfer calculation of ultra-relativistic shock breakout in circumstellar medium by using a Monte Carlo method. We use a self-similar solution constructed by Blandford & McKee (1976), in which the shock Lorentz factor is assumed to follow a simple power law relation determined by the central engine activity. By comparing the calculation results of the accelerating shock and the decelerating shock, we find that influence of the beaming effect and the scattering angular distribution cause two apparent differences in light curves and temporal spectral evolution. One is that the ratio of the time between the onset and the peak to the duration is much smaller in light curves of decelerating shocks. The other one is that the spectral shape does not significantly change with time if the shock accelerates, otherwise the first half of the emerging photons contains much more high energy photons (above 1 MeV) than the second half.

The shocking properties of supersonic flows: Dependence of the thermal overstability on M, α, and Tc / T0

NASA Astrophysics Data System (ADS)

Pittard, J. M.; Dobson, M. S.; Durisen, R. H.; Dyson, J. E.; Hartquist, T. W.; O'Brien, J. T.

2005-07-01

We present hydrodynamical calculations of radiative shocks with low Mach numbers and find that the well-known global overstability can occur if the temperature exponent (α) of the cooling is sufficiently negative. We find that the stability of radiative shocks increases with decreasing Mach number, with the result that M=2 shocks require α ⪉ -1.2 in order to be overstable. Such values occur within a limited temperature range of many cooling curves. We observe that Mach numbers of order 100 are needed before the strong shock limit of α_cr ≈ 0.4 is reached, and we discover that the frequency of oscillation of the fundamental mode also has a strong Mach number dependence. We find that feedback between the cooling region and the cold dense layer (CDL) further downstream is a function of Mach number, with stronger feedback and oscillation of the boundary between the CDL and the cooling region occuring at lower Mach numbers. This feedback can be quantified in terms of the reflection coefficient of sound waves, and in those cases where the cooling layer completely disappears at the end of each oscillation cycle, the initial velocity of the waves driven into the upstream pre-shock flow and into the downstream CDL, and the velocity of the the boundary between the CDL and the cooling layer, can be understood in terms of the solution to the Riemann problem. An interesting finding is that the stability properties of low Mach number shocks can be dramatically altered if the shocked gas is able to cool to temperatures less than the pre-shock value (i.e. when χ < 1, where χ is the ratio of the temperature of the cold dense layer to the pre-shock temperature). In such circumstances, low Mach number shocks have values of α_cr which are comparable to values obtained for higher Mach number shocks when χ = 1. For instance, α_cr=-0.1 when M=2 and χ=0.1, comparable to that when M=10 and χ=1. Thus, it is probable that low Mach number astrophysical shocks will be overstable in a variety of situations. We also explore the effect of different assumptions for the initial hydrodynamic set up and the type of boundary condition imposed downstream, and find that the properties of low Mach number shocks are relatively insensitive to these issues. The results of this work are relevant to astrophysical shocks with low Mach numbers, such as supernova remnants (SNRs) immersed in a hot interstellar medium (e.g., within a starburst region), and shocks in molecular clouds, where time-dependent chemistry can lead to overstability.

Are pulsars spun up or down by SASI spiral modes?

NASA Astrophysics Data System (ADS)

Kazeroni, Rémi; Guilet, Jérôme; Foglizzo, Thierry

2017-10-01

Pulsars may either be spun up or down by hydrodynamic instabilities during the supernova explosion of massive stars. Besides rapidly rotating cases related to bipolar explosions, stellar rotation may affect the explosion of massive stars in the more common situations where the centrifugal force is minor. Using 2D simulations of a simplified set-up in cylindrical geometry, we examine the impact of rotation on the standing accretion shock instability (SASI) and the corotation instability, also known as low-T/|W|. The influence of rotation on the saturation amplitude of these instabilities depends on the specific angular momentum in the accretion flow and the ratio of the shock to the neutron star radii. The spiral mode of SASI becomes more vigorous with faster rotation only if this ratio is large enough. A corotation instability develops at large rotation rates and impacts the dynamics more dramatically, leading to a strong one-armed spiral wave. Non-axisymmetric instabilities are able to redistribute angular momentum radially and affect the pulsar spin at birth. A systematic study of the relationship between the core rotation period of the progenitor and the initial pulsar spin is performed. Stellar rotation rates for which pulsars are spun up or down by SASI are estimated. Rapidly spinning progenitors are modestly spun down by spiral modes, less than ˜30 per cent, when a corotation instability develops. Given the observational constraints on pulsar spin periods at birth, this suggests that rapid rotation might not play a significant hydrodynamic role in most core-collapse supernovae.

Shock wave treatment in medicine.

PubMed

Shrivastava, S K; Kailash

2005-03-01

Extracorporeal shock wave therapy in orthopedics and traumatology is still a young therapy method. Since the last few years the development of shock wave therapy has progressed rapidly. Shock waves have changed the treatment of urolithiasis substantially. Today shock waves are the first choice to treat kidney and urethral stones. Urology has long been the only medical field for shock waves in medicine. Meanwhile shock waves have been used in orthopedics and traumatology to treat insertion tendinitis, avascular necrosis of the head of femur and other necrotic bone alterations. Another field of shock wave application is the treatment of tendons, ligaments and bones on horses in veterinary medicine. In the present paper we discuss the basic theory and application of shock waves and its history in medicine. The idea behind using shock wave therapy for orthopedic diseases is the stimulation of healing in tendons, surrounding tissue and bones.

Enhanced kidney stone fragmentation by short delay tandem conventional and modified lithotriptor shock waves: a numerical analysis.

PubMed

Tham, Leung-Mun; Lee, Heow Pueh; Lu, Chun

2007-07-01

We evaluated the effectiveness of modified lithotriptor shock waves using computer models. Finite element models were used to simulate the propagation of lithotriptor shock waves in human renal calculi in vivo. Kidney stones were assumed to be spherical, homogeneous, isotropic and linearly elastic, and immersed in a continuum fluid. Single and tandem shock wave pulses modified to intensify the collapse of cavitation bubbles near the stone surface to increase fragmentation efficiency and suppress the expansion of intraluminal bubbles for decreased vascular injury were analyzed. The effectiveness of the modified shock waves was assessed by comparing the states of loading in the renal calculi induced by these shock waves to those produced by conventional shock waves. Our numerical simulations revealed that modified shock waves produced marginally lower stresses in spherical renal calculi than those produced by conventional shock waves. Tandem pulses of conventional or modified shock waves produced peak stresses in the front and back halves of the renal calculi. However, the single shock wave pulses generated significant peak stresses in only the back halves of the renal calculi. Our numerical simulations suggest that for direct stress wave induced fragmentation modified shock waves should be as effective as conventional shock waves for fragmenting kidney stones. Also, with a small interval of 20 microseconds between the pulses tandem pulse lithotripsy using modified or conventional shock waves could be considerably more effective than single pulse lithotripsy for fragmenting kidney stones.

Conditions for shock revival by neutrino heating in core-collapse supernovae

NASA Astrophysics Data System (ADS)

Janka, H.-Th.

2001-03-01

Energy deposition by neutrinos can rejuvenate the stalled bounce shock and can provide the energy for the supernova explosion of a massive star. This neutrino-heating mechanism, though investigated by numerical simulations and analytic studies, is not finally accepted or proven as the trigger of the explosion. Part of the problem is that different groups have obtained seemingly discrepant results, and the complexity of the hydrodynamic models often hampers a clear and simple interpretation of the results. This demands a deeper theoretical understanding of the requirements of a successful shock revival. A toy model is developed here for discussing the neutrino heating phase analytically. The neutron star atmosphere between the neutrinosphere and the supernova shock can well be considered to be in hydrostatic equilibrium, with a layer of net neutrino cooling below the gain radius and a layer of net neutrino heating above. Since the mass infall rate to the shock is in general different from the rate at which gas is advected into the neutron star, the mass in the gain layer varies with time. Moreover, the gain layer receives additional energy input by neutrinos emitted from the neutrinosphere and the cooling layer. Therefore the determination of the shock evolution requires a time-dependent treatment. To this end the hydrodynamical equations of continuity and energy are integrated over the volume of the gain layer to obtain conservation laws for the total mass and energy in this layer. The radius and velocity of the supernova shock can then be calculated from global properties of the gain layer as solutions of an initial value problem, which expresses the fact that the behavior of the shock is controlled by the cumulative effects of neutrino heating and mass accumulation in the gain layer. The described toy model produces steady-state accretion and mass outflow from the nascent neutron star as special cases. The approach is useful to illuminate the conditions that can lead to delayed explosions and in this sense supplements detailed numerical simulations. On grounds of the model developed here, a criterion is derived for the requirements of shock revival. It confirms the existence of a minimum neutrino luminosity that is needed for shock expansion, but also demonstrates the importance of a sufficiently large mass infall rate to the shock. If the neutrinospheric luminosity or accretion rate by the shock are too low, the shock is weakened because the gain layer loses more mass than is resupplied by inflow. On the other hand, very high infall rates damp the shock expansion and above some threshold, the development of positive total energy in the neutrino-heating layer is prevented. Time-dependent solutions for the evolution of the gain layer show that the total specific energy transferred to nucleons by neutrinos is limited by about 1052 erg Msun-1 ( ~ 5 MeV per nucleon). This excludes the possibility of very energetic explosions by the neutrino-heating mechanism, because the typical mass in the gain layer is about 0.1 Msun and does not exceed a few tenths of a solar mass. The toy model also allows for a crude discussion of the global effects of convective energy transport in the neutrino-heating layer. Transfer of energy from the region of maximum heating to radii closer behind the shock mainly reduces the loss of energy by the inward flow of neutrino-heated matter through the gain radius.

Interaction of a supernova shock with two interstellar clouds

NASA Astrophysics Data System (ADS)

Hansen, J. F.; McKee, C. F.

2005-10-01

The interaction of supernova shocks and interstellar clouds is an important astrophysical phenomenon since it can result in stellar and planetary formation. Our experiments attempt to simulate this mass-loading as it occurs when a shock passes through interstellar clouds. We drive a strong shock using a 5 kJ laser into a foam-filled cylinder with embedded Al spheres (diameter D=120 μm) simulating interstellar clouds. The density ratio between Al and foam is ˜9. We have previously reported on the interaction between shock and a single cloud, and the ensuing Kelvin-Helmholtz and Widnall instabilities. We now report on experiments under way in which two clouds are placed side by side. Cloud separation (center to center) is either 1.2xD or 1.5xD. Initial results for 1.2xD show that cloud material merges and travels further downstream than in the single cloud case. For 1.5xD, material does not merge, but the clouds tilt toward each other. Work performed under the auspices of the Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.

Exploring the X-ray Morphology of the Supernova Remnant Kes 27 using Numerical Simulations

NASA Astrophysics Data System (ADS)

Dwarkadas, Vikram; Dewey, D.

2013-04-01

Kesteven 27 is a member of the class of thermal composite or mixed-morphology remnants, which can show thermal X-ray emission extending all the way in towards the center. The Chandra image shows two incomplete shell-like features in the north-eastern half, with brightness fading towards the southwest. The X-ray and radio structure led Chen et al. (2008) to suggest that the morphology represents a supernova remnant expanding in a windblown bubble. The two X-ray rings represent the outer shock of the supernova remnant, and a reflected shock arising from collision with a dense shell. Using numerical simulations followed by a computation of the X-ray emission, we explore this possibility. Our initial modeling suggests that the scenario discussed by Chen et al. (2008) may not work. We suggest and discuss modifications to this scenario that may be able to reproduce the observed morphology, and the implications for thermal composite remnants.

HST-COS Observations on Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock

NASA Technical Reports Server (NTRS)

France, Kevin; McCray, Richard; Penton, Steven V.; Kirshner, Robert P.; Challis, Peter; Laming, J. Martin; Bouchet, Patrice; Chevalier, Roger; Garnavich, Peter M.; Fransson, Claes;

The Distribution of Radioactive 44Ti in Cassiopeia A

DOE PAGES

Grefenstette, Brian W.; Fryer, Christopher Lee; Harrison, Fiona A.; ...

2016-12-27

The distribution of elements produced in the inner-most layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially-resolved spectroscopic analyses of the 44Ti ejecta which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44Ti ejecta. We nd an initial 44Ti mass of 1.54±0.21x10 -4 M which has a present day average momentum direction of 340°±15° projected on to the plane of themore » sky (measured clockwise from Celestial North) and tilted by 58°±20° into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object. We find some 44Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to the reverse shock. Where we observe 44Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44Ti in some regions by at least a factor of two, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.« less

The Distribution of Radioactive 44Ti in Cassiopeia A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grefenstette, Brian W.; Fryer, Christopher Lee; Harrison, Fiona A.

The distribution of elements produced in the inner-most layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially-resolved spectroscopic analyses of the 44Ti ejecta which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44Ti ejecta. We nd an initial 44Ti mass of 1.54±0.21x10 -4 M which has a present day average momentum direction of 340°±15° projected on to the plane of themore » sky (measured clockwise from Celestial North) and tilted by 58°±20° into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object. We find some 44Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to the reverse shock. Where we observe 44Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44Ti in some regions by at least a factor of two, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.« less

Supernova of 1006 (G327.6+14.6)

NASA Astrophysics Data System (ADS)

Katsuda, Satoru

SN 1006 (G327.6 + 14.6) was the brightest supernova (SN) witnessed in human history. As of 1000 years later, it stands out as an ideal laboratory to study Type Ia SNe and shocks in supernova remnants (SNRs). The present state of knowledge about SN 1006 is reviewed in this article. No star consistent with a surviving companion expected in the traditional single-degenerate scenario has been found, which favors a double-degenerate scenario for the progenitor of SN 1006. Both unshocked and shocked SN ejecta have been probed through absorption lines in ultraviolet spectra of a few background sources and thermal X-ray emission, respectively. The absorption studies suggest that the amount of iron is < 0.16 M⊙, which is significantly less than the range for normal SNe Ia. On the other hand, analyses of X-ray data reveal the distribution of shocked ejecta to be highly asymmetric especially for iron. Therefore, most of iron might have escaped from the ultraviolet background sources. Another important aspect with SN 1006 is that it was the first SNR in which synchrotron X-ray emission was detected from shells of the remnant, providing evidence that electrons are accelerated up to ˜ 100 TeV energies at forward shocks. The bilateral symmetry of the synchrotron emission (bright in northeastern and southwestern limbs) is likely due to a polar cap geometry. The broadband (radio, X-ray, and gamma ray) spectral energy distribution suggests that the gamma ray emission is predominantly leptonic. At the northwestern shock, evidence for extreme, but less than mass-proportional, temperature non-equilibration has been found by optical, ultraviolet, and X-ray observations.

High-energy Emission from the Composite Supernova Remnant MSH 15-56

NASA Technical Reports Server (NTRS)

Temim, Tea; Slane, Patrick; Castro, Daniel; Plucinsky, Paul; Gelfand, Joseph; Dickel, John R.

2013-01-01

MSH 1556 (G326.3-1.8) is a composite supernova remnant (SNR) that consists of an SNR shell and a displaced pulsar wind nebula (PWN) in the radio. We present XMM-Newton and Chandra X-ray observations of the remnant that reveal a compact source at the tip of the radio PWN and complex structures that provide evidence for mixing of the supernova (SN) ejecta with PWN material following a reverse shock interaction. The X-ray spectra are well fitted by a non-thermal power-law model whose photon index steepens with distance from the presumed pulsar, and a thermal component with an average temperature of 0.55 keV. The enhanced abundances of silicon and sulfur in some regions, and the similar temperature and ionization timescale, suggest that much of the X-ray emission can be attributed to SN ejecta that have either been heated by the reverse shock or swept up by the PWN. We find one region with a lower temperature of 0.3 keV that appears to be in ionization equilibrium.Assuming the Sedov model, we derive a number of SNR properties, including an age of 16,500 yr. Modeling of the gamma-ray emission detected by Fermi shows that the emission may originate from the reverse shock-crushed PWN.

The impact of different interstellar medium structures on the dynamical evolution of supernova remnants

NASA Astrophysics Data System (ADS)

Wang, Yueyang; Bao, Biwen; Yang, Chuyuan; Zhang, Li

2018-05-01

The dynamical properties of supernova remnants (SNRs) evolving with different interstellar medium structures are investigated through performing extensive two-dimensional magnetohydrodynamic (MHD) simulations in the cylindrical symmetry. Three cases of different interstellar medium structures are considered: the uniform medium, the turbulent medium and the cloudy medium. Large-scale density and magnetic fluctuations are calculated and mapped into the computational domain before simulations. The clouds are set by random distribution in advance. The above configuration allows us to study the time-dependent dynamical properties and morphological evolution of the SNR evolving with different ambient structures, along with the development of the instabilities at the contact discontinuity. Our simulation results indicate that remnant morphology deviates from symmetry if the interstellar medium contains clouds or turbulent density fluctuations. In the cloudy medium case, interactions between the shock wave and clouds lead to clouds' fragmentation. The magnetic field can be greatly enhanced by stretching field lines with a combination of instabilities while the width of amplification region is quite different among the three cases. Moreover, both the width of amplification region and the maximum magnetic-field strength are closely related to the clouds' density.

Panchromatic Observations of SN2011dh Point to a Compact Progenitor Star

NASA Technical Reports Server (NTRS)

Soderberg, A. M.; Margutti, R.; Zauerer, B. A.; Krauss, M.; Katz, B.; Chomiuk, L.; Dittmann, J. A.; Nakar, E.; Sakamoto, T.; Kawai, N.;

Simulations of Rayleigh Taylor Instabilities in the presence of a Strong Radiative shock

NASA Astrophysics Data System (ADS)

Trantham, Matthew; Kuranz, Carolyn; Shvarts, Dov; Drake, R. P.

2016-10-01

Recent Supernova Rayleigh Taylor experiments on the National Ignition Facility (NIF) are relevant to the evolution of core-collapse supernovae in which red supergiant stars explode. Here we report simulations of these experiments using the CRASH code. The CRASH code, developed at the University of Michigan to design and analyze high-energy-density experiments, is an Eulerian code with block-adaptive mesh refinement, multigroup diffusive radiation transport, and electron heat conduction. We explore two cases, one in which the shock is strongly radiative, and another with negligible radiation. The experiments in all cases produced structures at embedded interfaces by the Rayleigh Taylor instability. The weaker shocked environment is cooler and the instability grows classically. The strongly radiative shock produces a warm environment near the instability, ablates the interface, and alters the growth. We compare the simulated results with the experimental data and attempt to explain the differences. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, Grant Number DE-NA0002956.

PROPER MOTIONS AND BRIGHTNESS VARIATIONS OF NONTHERMAL X-RAY FILAMENTS IN THE CASSIOPEIA A SUPERNOVA REMNANT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patnaude, Daniel J.; Fesen, Robert A.

2009-05-20

We present Chandra ACIS X-ray observations of the Galactic supernova remnant Cassiopeia A taken in 2007 December. Combining these data with previous archival Chandra observations taken in 2000, 2002, and 2004, we estimate the remnant's forward shock velocity at various points around the outermost shell to range between 4200 and 5200 {+-} 500 km s{sup -1}. Using these results together with previous analyses of Cas A's X-ray emission, we present a model for the evolution of Cas A and find that it's expansion is well fit by a {rho}{sub ej} {proportional_to} r {sup -(7-9)} ejecta profile running into a circumstellarmore » wind. We further find that while the position of the reverse shock in this model is consistent with that measured in the X-rays, in order to match the forward shock velocity and radius we had to assume that {approx} 30% of the explosion energy has gone into accelerating cosmic rays at the forward shock. The new X-ray images also show that brightness variations can occur for some forward shock filaments like that seen for several nonthermal filaments seen projected in the interior of the remnant. Spectral fits to exterior forward shock filaments and interior nonthermal filaments show that they exhibit similar spectra. This together with similar flux variations suggests that interior nonthermal filaments might be simply forward shock filaments seen in projection and not located at the reverse shock as has been recently proposed.« less

Electron acceleration at localized wave structures in the solar corona (German Title: Elektronenbeschleunigung an lokalen Wellenstrukturen in der Sonnenkorona)

NASA Astrophysics Data System (ADS)

Miteva, Rositsa Stoycheva

2007-07-01

Our dynamic Sun manifests its activity by different phenomena: from the 11-year cyclic sunspot pattern to the unpredictable and violent explosions in the case of solar flares. During flares, a huge amount of the stored magnetic energy is suddenly released and a substantial part of this energy is carried by the energetic electrons, considered to be the source of the nonthermal radio and X-ray radiation. One of the most important and still open question in solar physics is how the electrons are accelerated up to high energies within (the observed in the radio emission) short time scales. Because the acceleration site is extremely small in spatial extent as well (compared to the solar radius), the electron acceleration is regarded as a local process. The search for localized wave structures in the solar corona that are able to accelerate electrons together with the theoretical and numerical description of the conditions and requirements for this process, is the aim of the dissertation. Two models of electron acceleration in the solar corona are proposed in the dissertation: I. Electron acceleration due to the solar jet interaction with the background coronal plasma (the jet--plasma interaction) A jet is formed when the newly reconnected and highly curved magnetic field lines are relaxed by shooting plasma away from the reconnection site. Such jets, as observed in soft X-rays with the Yohkoh satellite, are spatially and temporally associated with beams of nonthermal electrons (in terms of the so-called type III metric radio bursts) propagating through the corona. A model that attempts to give an explanation for such observational facts is developed here. Initially, the interaction of such jets with the background plasma leads to an (ion-acoustic) instability associated with growing of electrostatic fluctuations in time for certain range of the jet initial velocity. During this process, any test electron that happen to feel this electrostatic wave field is drawn to co-move with the wave, gaining energy from it. When the jet speed has a value greater or lower than the one, required by the instability range, such wave excitation cannot be sustained and the process of electron energization (acceleration and/or heating) ceases. Hence, the electrons can propagate further in the corona and be detected as type III radio burst, for example. II. Electron acceleration due to attached whistler waves in the upstream region of coronal shocks (the electron--whistler--shock interaction) Coronal shocks are also able to accelerate electrons, as observed by the so-called type II metric radio bursts (the radio signature of a shock wave in the corona). From in-situ observations in space, e.g., at shocks related to co-rotating interaction regions, it is known that nonthermal electrons are produced preferably at shocks with attached whistler wave packets in their upstream regions. Motivated by these observations and assuming that the physical processes at shocks are the same in the corona as in the interplanetary medium, a new model of electron acceleration at coronal shocks is presented in the dissertation, where the electrons are accelerated by their interaction with such whistlers. The protons inflowing toward the shock are reflected there by nearly conserving their magnetic moment, so that they get a substantial velocity gain in the case of a quasi-perpendicular shock geometry, i.e, the angle between the shock normal and the upstream magnetic field is in the range 50--80 degrees. The so-accelerated protons are able to excite whistler waves in a certain frequency range in the upstream region. When these whistlers (comprising the localized wave structure in this case) are formed, only the incoming electrons are now able to interact resonantly with them. But only a part of these electrons fulfill the the electron--whistler wave resonance condition. Due to such resonant interaction (i.e., of these electrons with the whistlers), the electrons are accelerated in the electric and magnetic wave field within just several whistler periods. While gaining energy from the whistler wave field, the electrons reach the shock front and, subsequently, a major part of them are reflected back into the upstream region, since the shock accompanied with a jump of the magnetic field acts as a magnetic mirror. Co-moving with the whistlers now, the reflected electrons are out of resonance and hence can propagate undisturbed into the far upstream region, where they are detected in terms of type II metric radio bursts. In summary, the kinetic energy of protons is transfered into electrons by the action of localized wave structures in both cases, i.e., at jets outflowing from the magnetic reconnection site and at shock waves in the corona. Die Sonne ist ein aktiver Stern, was sich nicht nur in den allseits bekannten Sonnenflecken, sondern auch in Flares manifestiert. Während Flares wird eine große Menge gespeicherter, magnetischer Energie in einer kurzen Zeit von einigen Sekunden bis zu wenigen Stunden in der Sonnenkorona freigesetzt. Dabei werden u.a. energiereiche Elektronen erzeugt, die ihrerseits nichtthermische Radio- und Röntgenstrahlung, wie sie z.B. am Observatorium für solare Radioastronomie des Astrophysikalischen Instituts Potsdam (AIP) in Tremsdorf und durch den NASA-Satelliten RHESSI beobachtet werden, erzeugen. Da diese Elektronen einen beträchtlichen Anteil der beim Flare freigesetzten Energie tragen, ist die Frage, wie Elektronen in kurzer Zeit auf hohe Energien in der Sonnenkorona beschleunigt werden, von generellem astrophysikalischen Interesse, da solche Prozesse auch in anderen Sternatmosphären und kosmischen Objekten, wie z.B. Supernova-Überresten, stattfinden. In der vorliegenden Dissertation wird die Elektronenbeschleunigung an lokalen Wellenstrukturen im Plasma der Sonnenkorona untersucht. Solche Wellen treten in der Umgebung der magnetischen Rekonnektion, die als ein wichtiger Auslöser von Flares angesehen wird, und in der Nähe von Stoßwellen, die infolge von Flares erzeugt werden, auf. Generell werden die Elektronen als Testteilchen behandelt. Sie werden durch ihre Wechselwirkung mit den elektrischen und magnetischen Feldern, die mit den Plasmawellen verbunden sind, beschleunigt. Infolge der magnetischen Rekonnektion als Grundlage des Flares werden starke Plasmaströmungen (sogenannte Jets) erzeugt. Solche Jets werden im Licht der weichen Röntgenstrahlung, wie z.B. durch den japanischen Satelliten YOHKOH, beobachtet. Mit solchen Jets sind solare Typ III Radiobursts als Signaturen von energiereichen Elektronenstrahlen in der Sonnenkorona verbunden. Durch die Wechselwirkung eines Jets mit dem umgebenden Plasma werden lokal elektrische Felder erzeugt, die ihrerseits Elektronen beschleunigen können. Dieses hier vorgestellte Szenarium kann sehr gut die Röntgen- und Radiobeobachtungen von Jets und den damit verbundenen Elektronenstrahlen erklären. An koronalen Stoßwellen, die infolge Flares entstehen, werden Elektronen beschleunigt, deren Signatur man in der solaren Radiostrahlung in Form von sogenannten Typ II Bursts beobachten kann. Stoßwellen in kosmischen Plasmen können mit Whistlerwellen (ein spezieller Typ von Plasmawellen) verbunden sein. In der vorliegenden Arbeit wird ein Szenarium vorgestellt, das aufzeigt, wie solche Whistlerwellen an koronalen Stoßwellen erzeugt werden und durch ihre resonante Wechselwirkung mit den Elektronen dieselben beschleunigen. Dieser Prozess ist effizienter als bisher vorgeschlagene Mechanismen und kann deshalb auch auf andere Stoßwellen im Kosmos, wie z.B. an Supernova-Überresten, zur Erklärung der dort erzeugten Radio- und Röntgenstrahlung dienen.

21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Extracorporeal shock wave lithotripter. 876.5990... shock wave lithotripter. (a) Identification. An extracorporeal shock wave lithotripter is a device that focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney...

21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Extracorporeal shock wave lithotripter. 876.5990... shock wave lithotripter. (a) Identification. An extracorporeal shock wave lithotripter is a device that focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney...

21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Extracorporeal shock wave lithotripter. 876.5990... shock wave lithotripter. (a) Identification. An extracorporeal shock wave lithotripter is a device that focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney...

IUE investigations of SN 1987A

NASA Technical Reports Server (NTRS)

Kirshner, Robert P.

1989-01-01

IUE observations of the SN 1987A began shortly after the discovery and have been frequent through 1988 and 1989, using the fine error sensor for photometry, low dispersion spectra for the supernova spectrum, and high dispersion observations for the interstellar medium when the supernova was bright and for circumstellar gas surrounding the supernova as the initial event faded. The UV data were very useful in determining which star exploded, assessing the ionizing pulse produced as the shock hit the surface of the star, and in constraining the stellar evolution that preceded the explosion through observations of a circumstellar shell.

The methodology of the search for a correlated signal from a supernova explosion using the data of gravitational wave detectors and neutrino observatories

NASA Astrophysics Data System (ADS)

Gromov, M. B.

2017-11-01

The proposed methodology developed in cooperation of the LIGO, VIRGO, Borexino, LVD, and IceCube collaborations is based on a joint analysis of data from neutrino and gravitational wave detectors which record corresponding radiations, almost undistorted by the interstellar medium and propagating with similar speeds. This approach allows to increase the reliability of observations, detect the so-called Silent supernovae and explore the properties and generation mechanisms of gravitational waves.

Five Years of Mid-Infrared Evolution of the Remnant of SN 1987A: The Encounter Between the Blast Wave and the Dusty Equatorial Ring

NASA Technical Reports Server (NTRS)

Dwek, Eli; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, I. John; De Buizer, James M.; Gehrz, Robert D.; Park, Sangwook; Polomski, Elisha F.;

Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Pair Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Mizuno, Y.

2005-01-01

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created by relativistic pair jets are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet propagating through an ambient plasma with and without initial magnetic fields. The growth rates of the Weibel instability depends on the distribution of pair jets. Simulations show that the Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Cosmic physics data analysis program

NASA Technical Reports Server (NTRS)

Wilkes, R. Jeffrey

1993-01-01

A data analysis program was carried out to investigate the intensity, propagation, and origin of primary Cosmic Ray Galactic electrons. Scanning was carried out on two new balloon flight experiments as well as the border area of previous experiments. The identification and evaluation of the energies of the primary electrons were carried out. A new analysis of these data were incorporated into an overall evaluation of the roll of electrons in the problem of the origin of cosmic rays. Recent measurements indicate that the earth may be within the expanding Geminga supernova shock wave which is expected to have a major effect upon the propagation and the energy spectrum of galactic electrons. Calculations with the Geminga model indicate that the cut-off energy may be very close to the observed highest energy electrons in our analysis.

Preheat Measurements for Supernova Hydrodynamics Experiments

NASA Astrophysics Data System (ADS)

Krauland, Christine; Kuranz, Carolyn; Drake, Paul; Grosskopf, Mike; Campbell, Duncan

2007-11-01

The use of multi-kilojoule, ns lasers to launch shock waves has become a standard method for initiating hydrodynamic experiments in the field of Laboratory Astrophysics. However, the intense laser ablation that creates moving plasma also leads to the production of unwanted energetic x-rays and suprathermal electrons, both of which can be sources of material preheating. In principle, this preheat can alter the conditions of the experimental setup prior to the desired experiment actually taking place. At the University of Michigan, ongoing Rayleigh-Taylor instability experiments are defined by precise initial conditions, and potential deformation due to preheat could greatly affect their accuracy. An experiment devised and executed in an attempt to assess the preheat in this specific case will be presented, along with the quantitative analysis of the data obtained.

THE UNREASONABLE WEAKNESS OF R -PROCESS COSMIC RAYS IN THE NEUTRON-STAR-MERGER NUCLEOSYNTHESIS SCENARIO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kyutoku, Koutarou; Ioka, Kunihito, E-mail: koutarou.kyutoku@riken.jp

We reach the robust conclusion that, by combining the observed cosmic rays of r -process elements with the fact that the velocity of the neutron-star-merger ejecta is much higher than that of the supernova ejecta, either (1) the reverse shock in the neutron-star-merger ejecta is a very inefficient accelerator that converts less than 0.003% of the ejecta kinetic energy to the cosmic-ray energy or (2) the neutron star merger is not the origin of the Galactic r -process elements. We also find that the acceleration efficiency should be less than 0.1% for the reverse shock of the supernova ejecta withmore » observed cosmic rays lighter than the iron.« less

Amplification and attenuation of shock wave strength caused by homogeneous isotropic turbulence

NASA Astrophysics Data System (ADS)

Tanaka, K.; Watanabe, T.; Nagata, K.; Sasoh, A.; Sakai, Y.; Hayase, T.

2018-03-01

We study the pressure increase across a planar shock wave with shock Mach numbers Ms of 1.1, 1.3, and 1.5 propagating through homogeneous isotropic turbulence at a low turbulent Mach number (Mt ˜ 10-4) based on direct numerical simulations (DNSs). Fluctuation in the pressure increase, Δp', on a given shock ray is induced by turbulence around the ray. A local amplification of the shock wave strength, measured with the pressure increase, is caused by the velocity fluctuation opposed to the shock wave propagating direction with a time delay, while the velocity in the opposite direction attenuates the shock wave strength. The turbulence effects on the shock wave are explained based on shock wave deformation due to turbulent shearing motions. The spatial distribution of Δp' on the shock wave has a characteristic length of the order of the integral scale of turbulence. The influence of turbulent velocity fluctuation at a given location on Δp' becomes most significant after the shock wave propagates from the location for a distance close to the integral length scale for all shock Mach numbers, demonstrating that the shock wave properties possess strong memory even during the propagation in turbulence. A lower shock Mach number Ms results in a smaller rms value of Δp', stronger influences on Δp' by turbulence far away from the shock ray, and a larger length scale in the spatial profile of Δp' on the shock wave. Relative intensity of Δp' increases with [Mt/(Ms-1 ) ] α, where DNS and experimental results yield α ≈ 0.73.

Hard X-ray Emission and Efficient Particle Acceleration by Supernova Remnants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vink, Jacco

I discuss the non-thermal X-ray emission from young supernova remnants. Over the last decade it has become clear from both X-ray and {gamma}-ray observations that young supernovae accelerate particles up to 100 TeV. In soft X-rays the accelerated >10 TeV electrons produce synchrotron radiation, coming from narrow filaments located at the shock fronts. The width of these filaments shows that the magnetic fields are relatively high, thus providing evidence for magnetic field amplification.The synchrotron radiation of several remnants is known to extend into the hard X-ray regime. In particular Cas A, has a spectrum that appears as a power lawmore » up to almost 100 TeV. This is very surprising, as a steepening is expected going from the soft to the hard X-ray band. The spectrum is likely a result of many superimposed individual spectra, each steepening at different energies. This implies considerable spatial variation in hard X-rays, an obvious target for Simbol-X. The variations will be important to infer local shock acceleration properties, but also magnetic field fluctuations may cause spatial and temporal variations.Finally, I draw the attention to super bubbles and supernovae as sources of cosmic rays. As such they may be sources of hard X-ray emission. In particular, supernovae exploding inside the dense red supergiants winds of their progenitors ares promising candidates for hard X-ray emission.« less

1051 Ergs: The Evolution of Shell Supernova Remnants

DTIC Science & Technology

1997-11-15

progress in these matters . For convenience, and also to avoid conventional labels (e.g., “Sedov”), most of the workshop was organized around chron...setting the stage,” so that many preliminary matters had been resolved or focused. The web site continues to be acces- sible for review of the...acting with circumstellar matter (Chevalier 1982b). The inter- action between the supernova ejecta and circumstellar matter generates a double-shock

High-energy particle acceleration in the shell of a supernova remnant.

PubMed

Aharonian, F A; Akhperjanian, A G; Aye, K-M; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Berghaus, P; Bernlöhr, K; Bolz, O; Boisson, C; Borgmeier, C; Breitling, F; Brown, A M; Gordo, J Bussons; Chadwick, P M; Chitnis, V R; Chounet, L-M; Cornils, R; Costamante, L; Degrange, B; Djannati-Ataï, A; Drury, L O'C; Ergin, T; Espigat, P; Feinstein, F; Fleury, P; Fontaine, G; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Goret, P; Guy, J; Hadjichristidis, C; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; De Jager, O C; Jung, I; Khélifi, B; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemoine, M; Lemière, A; Leroy, N; Lohse, T; Marcowith, A; Masterson, C; McComb, T J L; De Naurois, M; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pohl, M; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Redondo, I; Reimer, A; Reimer, O; Ripken, J; Rivoal, M; Rob, L; Rolland, L; Rowell, G; Sahakian, V; Saugé, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Steenkamp, R; Stegmann, C; Tavernet, J-P; Théoret, C G; Tluczykont, M; Van Der Walt, D J; Vasileiadis, G; Vincent, P; Visser, B; Völk, H J; Wagner, S J

2004-11-04

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy gamma-rays of TeV energies (1 TeV = 10(12) eV). We present a TeV gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

The Distribution of Radioactive Ti-44 in Cassiopeia A

NASA Technical Reports Server (NTRS)

Grefenstette, Brian W.; Fryer, Chris L.; Harrison, Fiona A.; Boggs, Steven E.; Delaney, Tracey; Laming, J. Martin; Reynolds, Stephen P.; Alexander, David M.; Barret, Didier; Zhang, William W.;

Progenitor-dependent Explosion Dynamics in Self-consistent, Axisymmetric Simulations of Neutrino-driven Core-collapse Supernovae

NASA Astrophysics Data System (ADS)

Summa, Alexander; Hanke, Florian; Janka, Hans-Thomas; Melson, Tobias; Marek, Andreas; Müller, Bernhard

2016-07-01

We present self-consistent, axisymmetric core-collapse supernova simulations performed with the Prometheus-Vertex code for 18 pre-supernova models in the range of 11-28 M ⊙, including progenitors recently investigated by other groups. All models develop explosions, but depending on the progenitor structure, they can be divided into two classes. With a steep density decline at the Si/Si-O interface, the arrival of this interface at the shock front leads to a sudden drop of the mass-accretion rate, triggering a rapid approach to explosion. With a more gradually decreasing accretion rate, it takes longer for the neutrino heating to overcome the accretion ram pressure and explosions set in later. Early explosions are facilitated by high mass-accretion rates after bounce and correspondingly high neutrino luminosities combined with a pronounced drop of the accretion rate and ram pressure at the Si/Si-O interface. Because of rapidly shrinking neutron star radii and receding shock fronts after the passage through their maxima, our models exhibit short advection timescales, which favor the efficient growth of the standing accretion-shock instability. The latter plays a supportive role at least for the initiation of the re-expansion of the stalled shock before runaway. Taking into account the effects of turbulent pressure in the gain layer, we derive a generalized condition for the critical neutrino luminosity that captures the explosion behavior of all models very well. We validate the robustness of our findings by testing the influence of stochasticity, numerical resolution, and approximations in some aspects of the microphysics.

PROGENITOR-DEPENDENT EXPLOSION DYNAMICS IN SELF-CONSISTENT, AXISYMMETRIC SIMULATIONS OF NEUTRINO-DRIVEN CORE-COLLAPSE SUPERNOVAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Summa, Alexander; Hanke, Florian; Janka, Hans-Thomas

We present self-consistent, axisymmetric core-collapse supernova simulations performed with the Prometheus-Vertex code for 18 pre-supernova models in the range of 11–28 M {sub ⊙}, including progenitors recently investigated by other groups. All models develop explosions, but depending on the progenitor structure, they can be divided into two classes. With a steep density decline at the Si/Si–O interface, the arrival of this interface at the shock front leads to a sudden drop of the mass-accretion rate, triggering a rapid approach to explosion. With a more gradually decreasing accretion rate, it takes longer for the neutrino heating to overcome the accretion rammore » pressure and explosions set in later. Early explosions are facilitated by high mass-accretion rates after bounce and correspondingly high neutrino luminosities combined with a pronounced drop of the accretion rate and ram pressure at the Si/Si–O interface. Because of rapidly shrinking neutron star radii and receding shock fronts after the passage through their maxima, our models exhibit short advection timescales, which favor the efficient growth of the standing accretion-shock instability. The latter plays a supportive role at least for the initiation of the re-expansion of the stalled shock before runaway. Taking into account the effects of turbulent pressure in the gain layer, we derive a generalized condition for the critical neutrino luminosity that captures the explosion behavior of all models very well. We validate the robustness of our findings by testing the influence of stochasticity, numerical resolution, and approximations in some aspects of the microphysics.« less

Proceedings of the 15th International Symposium on Shock Waves and Shock Tubes

NASA Astrophysics Data System (ADS)

Bershader, Daniel; Hanson, Ronald

1986-09-01

One hundred ten papers were presented in 32 sessions. Topics included: The application of Hook-method spectroscopy to the diagnosis of shock-heated gases. The nonintrusive destruction of kidney stones by underwater focused shock waves. Several of the papers reflect the recent and continuing interest in shock wave phenomena in dusty gases and other multiphase and heterogeneous systems, including chemically reactive configurations. The major subject areas were: shock propagation and interactions; shock-general chemical kinetics; shock computation, modeling, and stability problems; shock wave aerodynamics; experimental methods; shocks in multiphase and heterogeneous media; high energy gas excitation and wave phenomena; and technical applications and shocks in condensed matter.

Dust in a Type Ia Supernova Progenitor: Spitzer Spectroscopy of Kepler's Supernova Remnant

NASA Technical Reports Server (NTRS)

Williams, Brian J.; Borkowski, Kazimierz; Reynolds, Stephen P.; Ghavamian, Parviz; Blair, William P.; Long, Knox S.; Sankrit, Ravi

2012-01-01

Characterization of the relatively poorly-understood progenitor systems of Type Ia supernovae is of great importance in astrophysics, particularly given the important cosmological role that these supernovae play. Kepler's Supernova Remnant, the result of a Type Ia supernova, shows evidence for an interaction with a dense circumstellar medium (CSM), suggesting a single-degenerate progenitor system. We present 7.5-38 micron IR spectra of the remnant, obtained with the Spitzer Space Telescope, dominated by emission from warm dust. Broad spectral features at 10 and 18 micron, consistent with various silicate particles, are seen throughout. These silicates were likely formed in the stellar outflow from the progenitor system during the AGB stage of evolution, and imply an oxygen-rich chemistry. In addition to silicate dust, a second component, possibly carbonaceous dust, is necessary to account for the short-wavelength IRS and IRAC data. This could imply a mixed chemistry in the atmosphere of the progenitor system. However, non-spherical metallic iron inclusions within silicate grains provide an alternative solution. Models of collisionally-heated dust emission from fast shocks (> 1000 km/s) propagating into the CSM can reproduce the majority of the emission associated with non-radiative filaments, where dust temperatures are approx 80-100 K, but fail to account for the highest temperatures detected, in excess of 150 K. We find that slower shocks (a few hundred km/s) into moderate density material (n(sub o) approx 50-100 / cubic cm) are the only viable source of heating for this hottest dust. We confirm the finding of an overall density gradient, with densities in the north being an order of magnitude greater than those in the south.

Constraining the Origin and Heating Mechanism of Dust in Type IIn Supernovae

NASA Astrophysics Data System (ADS)

Fox, Ori; Skrutskie, Michael; Filippenko, Alex

2012-12-01

More than any other supernova subclass, Type IIn supernovae tend to exhibit late-time (>1 year) infrared emission from warm dust. Identifying the origin and heating mechanism of the dust provides an important probe of the supernova explosion, circumstellar environment, and progenitor system. Yet mid-infrared observations, which span the peak of the thermal emission, are rare. Three years ago, we executed a warm Spitzer survey (P60122) that uncovered a unique sample of ten supernovae with unreported late-time infrared excesses, in some cases more than 5 years post-explosion. The data from this single epoch are most consistent with a pre-existing dust shell that is continuously heated by visible and/or X-ray emission generated by ongoing shock interaction. Furthermore, the lack of any detections beyond ~2000 days suggests the dust is destroyed once the forward shock overruns the pre-existing shell. The actual shell sizes remain unknown, however, since the derived blackbody radii offer only lower limits. Last year, we obtained second epoch observations of these ten re-discovered SNe IIn (plus the well-studied Type IIn SN 2010jl). The project aimed for non-detections to constrain the light-curve ``turn-off'' times and, thereby, the shell sizes and progenitor mass-loss models. Only two SNe (2005gn and 2008J), however, went undetected. The other nine SNe remain bright at mid-IR wavelengths, which means the dust shell radii are larger than expected. Here we propose continued monitoring of these nine SNe IIn to constrain the size of the circumstellar dust shell and characterize the supernova progenitor system. We can obtain all the necessary data in only 6.1 hours of observation.

Potential applications of low-energy shock waves in functional urology.

PubMed

Wang, Hung-Jen; Cheng, Jai-Hong; Chuang, Yao-Chi

2017-08-01

A shock wave, which carries energy and can propagate through a medium, is a type of continuous transmitted sonic wave with a frequency of 16 Hz-20 MHz. It is accompanied by processes involving rapid energy transformations. The energy associated with shock waves has been harnessed and used for various applications in medical science. High-energy extracorporeal shock wave therapy is the most successful application of shock waves, and has been used to disintegrate urolithiasis for 30 years. At lower energy levels, however, shock waves have enhanced expression of vascular endothelial growth factor, endothelial nitric oxide synthase, proliferating cell nuclear antigen, chemoattractant factors and recruitment of progenitor cells; shock waves have also improved tissue regeneration. Low-energy shock wave therapy has been used clinically with musculoskeletal disorders, ischemic cardiovascular disorders and erectile dysfunction, through the mechanisms of neovascularization, anti-inflammation and tissue regeneration. Furthermore, low-energy shock waves have been proposed to temporarily increase tissue permeability and facilitate intravesical drug delivery. The present review article provides information on the basics of shock wave physics, mechanisms of action on the biological system and potential applications in functional urology. © 2017 The Japanese Urological Association.

New Evidence for Efficient Collisionless Heating of Electrons at the Reverse Shock of a Young Supernova Remnant

NASA Technical Reports Server (NTRS)

Yamaguchi, Hiroya; Eriksen, Kristoffer A.; Badenes, Carles; Hughes, John P.; Brickhouse, Nancy S.; Foster, Adam R.; Patnaude, Daniel J.; Petre, Robert; Slane, Patrick O.; Smith, Randall K.

2013-01-01

Although collisionless shocks are ubiquitous in astrophysics, certain key aspects of them are not well understood. In particular, the process known as collisionless electron heating, whereby electrons are rapidly energized at the shock front, is one of the main open issues in shock physics. Here, we present the first clear evidence for efficient collisionless electron heating at the reverse shock of Tycho's supernova remnant (SNR), revealed by Fe K diagnostics using high-quality X-ray data obtained by the Suzaku satellite. We detect K beta (3p yields 1s) fluorescence emission from low-ionization Fe ejecta excited by energetic thermal electrons at the reverse shock front, which peaks at a smaller radius than Fe K alpha (2p yields 1s) emission dominated by a relatively highly ionized component. Comparisons with our hydrodynamical simulations imply instantaneous electron heating to a temperature 1000 times higher than expected from Coulomb collisions alone. The unique environment of the reverse shock, which is propagating with a high Mach number into rarefied ejecta with a low magnetic field strength, puts strong constraints on the physical mechanism responsible for this heating and favors a cross-shock potential created by charge deflection at the shock front. Our sensitive observation also reveals that the reverse shock radius of this SNR is about 10% smaller than the previous measurement using the Fe K alpha morphology from the Chandra observations. Since strong Fe K beta fluorescence is expected only from low-ionization plasma where Fe ions still have many 3p electrons, this feature is key to diagnosing the plasma state and distribution of the immediate postshock ejecta in a young SNR.

Shock wave attenuation by grids and orifice plates

NASA Astrophysics Data System (ADS)

Britan, A.; Igra, O.; Ben-Dor, G.; Shapiro, H.

2006-11-01

The interaction of weak shock waves with porous barriers of different geometries and porosities is examined. Installing a barrier inside the shock tube test section will cause the development of the following wave pattern upon a head-on collision between the incident shock wave and the barrier: a reflected shock from the barrier and a transmitted shock propagating towards the shock tube end wall. Once the transmitted shock wave reaches the end wall it is reflected back towards the barrier. This is the beginning of multiple reflections between the barrier and the end wall. This full cycle of shock reflections/interactions resulting from the incident shock wave collision with the barrier can be studied in a single shock tube test. A one-dimensional (1D), inviscid flow model was proposed for simulating the flow resulting from the initial collision of the incident shock wave with the barrier. Fairly good agreement is found between experimental findings and simulations based on a 1D flow model. Based on obtained numerical and experimental findings an optimal design procedure for shock wave attenuator is suggested. The suggested attenuator may ensure the safety of the shelter’s ventilation systems.

Jet formation of SF6 bubble induced by incident and reflected shock waves

NASA Astrophysics Data System (ADS)

Zhu, Yuejin; Yu, Lei; Pan, Jianfeng; Pan, Zhenhua; Zhang, Penggang

2017-12-01

The computational results of two different cases on the evolution of the shock-SF6 heavy bubble interaction are presented. The shock focusing processes and jet formation mechanisms are analyzed by using the high resolution of computation schemes, and the influence of reflected shock waves is also investigated. It is concluded that there are two steps in the shock focusing process behind the incident shock wave, and the density and pressure values increase distinctly when the shock focusing process is completed. The local high pressure and vorticities in the vicinity of the downstream pole can propel the formation of the jet behind the incident shock wave. In addition, the gas is with the rightward velocity before the reflected shock wave impinges on the bubble; therefore, the evolutions of the waves and the bubble are more complicated when the reflected shock wave impinges on the SF6 bubble. Furthermore, the different end wall distances would affect the deformation degree of the bubble before the interaction of the reflected shock wave; therefore, the different left jet formation processes are found after the impingement of reflected shock waves when L = 27 mm. The local high pressure zones in the vicinity of the left bubble interface and the impingement of different shock waves can induce the local gas to shift the rightward velocity to the leftward velocity, which can further promote the formation of jets.

Magnetic Field Amplification in Supernova Remnants

NASA Astrophysics Data System (ADS)

Xu, Siyao; Lazarian, Alex

2017-12-01

Based on the new findings on the turbulent dynamo in Xu & Lazarian, we examine the magnetic field amplification in the context of supernova remnants. Due to the strong ion-neutral collisional damping in the weakly ionized interstellar medium, the dynamo in the preshock turbulence remains in the damping kinematic regime, which leads to a linear-in-time growth of the magnetic field strength. The resultant magnetic field structure enables effective diffusion upstream and shock acceleration of cosmic rays to energies above the “knee.” Differently, the nonlinear dynamo in the postshock turbulence leads to a linear-in-time growth of the magnetic energy due to the turbulent magnetic diffusion. Given a weak initial field strength in the postshock region, the magnetic field saturates at a significant distance from the shock front as a result of the inefficiency of the nonlinear dynamo. This result is in a good agreement with existing numerical simulations and well explains the X-ray spots detected far behind the shock front.

Celestial paleontology: The legacy of dying stars

NASA Astrophysics Data System (ADS)

Hart, Alexa H.

2013-03-01

In their death throes, stars dole out their atmospheric material to the interstellar medium in dramatic stellar winds and spectacular explosions. The details of this profound metamorphosis, from star to remnant, play a key role in the next generation of star formation as well as the energetic and chemical evolution of galaxies and the universe as a whole. Dying stars are thought to be the source of all of the nuclei heavier than iron in the universe, as well as more complex molecules, such as carbon chains, which form the backbone of life as we know it. High mass Wolf-Rayet stars are likely progenitors of many types of Supernova, yet due to observational constraints we lack the most basic information about most of them: rather they are part of binary systems. This information is key to the determination of rather or not these stars will go supernova, since depending on its nature the companion can either draw mass off the Wolf-Rayet star, effectively quenching the march to explosion, or feed material onto the Wolf-Rayet star, speeding its demise as a supernova. Models of galactic evolution depend sensitively on the frequency of supernova for several reasons: they inject a great deal of energy into the Interstellar medium, they are the only known producers of nuclei heavier than nickel, and the shock waves that they create can stimulate star formation. In turn, the energy generated by supernova explosions drives the galactic wind, the heavier elements now present in the Interstellar Medium increase the efficiency of star formation, and the groups of new stars formed in the wake of a shock are thought to lead to the development of spiral arms in galaxies. In addition, because high mass stars are so short-lived, they can cycle through hundreds of generations in the time it takes one solar-type star's to evolve. Though intermediate mass stars merely fizzle out in comparison, they are pivotal to the evolution of the universe because they make up over 97% of the stars that have had enough time to evolve off the Main Sequence since the Big Bang. These stars produce more than half of the carbon in the universe as well as much of the nitrogen, oxygen, and more complex molecules such as aromatic rings of carbon. This process, often referred to as chemical enrichment, strongly affects the star formation rates and the characteristics of the next generation of stars. In this work, we explore the contributions of these two classes of stars to our own galaxy: we quantify the nature of the chemical enrichment to the Milky Way from a large sample of intermediate mass stars, and determine the binary status of a sample of Wolf-Rayet stars in the Milky Way.

The rise-time of Type II supernovae

NASA Astrophysics Data System (ADS)

González-Gaitán, S.; Tominaga, N.; Molina, J.; Galbany, L.; Bufano, F.; Anderson, J. P.; Gutierrez, C.; Förster, F.; Pignata, G.; Bersten, M.; Howell, D. A.; Sullivan, M.; Carlberg, R.; de Jaeger, T.; Hamuy, M.; Baklanov, P. V.; Blinnikov, S. I.

2015-08-01

We investigate the early-time light curves of a large sample of 223 Type II supernovae (SNe II) from the Sloan Digital Sky Survey and the Supernova Legacy Survey. Having a cadence of a few days and sufficient non-detections prior to explosion, we constrain rise-times, i.e. the durations from estimated first to maximum light, as a function of effective wavelength. At rest-frame g' band (λeff = 4722 Å), we find a distribution of fast rise-times with median of (7.5 ± 0.3) d. Comparing these durations with analytical shock models of Rabinak & Waxman and Nakar & Sari, and hydrodynamical models of Tominaga et al., which are mostly sensitive to progenitor radius at these epochs, we find a median characteristic radius of less than 400 solar radii. The inferred radii are on average much smaller than the radii obtained for observed red supergiants (RSG). Investigating the post-maximum slopes as a function of effective wavelength in the light of theoretical models, we find that massive hydrogen envelopes are still needed to explain the plateaus of SNe II. We therefore argue that the SN II rise-times we observe are either (a) the shock cooling resulting from the core collapse of RSG with small and dense envelopes, or (b) the delayed and prolonged shock breakout of the collapse of an RSG with an extended atmosphere or embedded within pre-SN circumstellar material.

GRB 120422A: a Low-Luminosity Gamma-Ray Burst Driven by a Central Engine

NASA Technical Reports Server (NTRS)

Zhang, Bin-Bin; Fan, Yi-Zhong; Shen, Rong-Feng; Xu, Dong; Zhang, Fu-Wen; Wei, Da-Ming; Burrows, David N.; Zhang, Bing; Gehrels, Neil

2012-01-01

GRB 120422A is a low-luminosity gamma-ray burst (GRB) associated with a bright supernova, which distinguishesitself by its relatively short T(sub 90) (approximately 5 s) and an energetic and steep-decaying X-ray tail. We analyze the Swift BurstAlert Telescope and X-ray Telescope data and discuss the physical implications. We show that the steep declineearly in the X-ray light curve can be interpreted as the curvature tail of a late emission episode around 58-86 s,with a curved instantaneous spectrum at the end of the emission episode. Together with the main activity in thefirst 20 s and the weak emission from 40 s to 60 s, the prompt emission is variable, which points to a centralengine origin in contrast to a shock-breakout origin, which is used to interpret some other nearby low-luminosity supernova GRBs. Both the curvature effect model and interpreting the early shallow decay as the coasting externalforward shock emission in a wind medium provide a constraint on the bulk Lorentz factor to be around several.Comparing the properties ofGRB 120422A and other supernova GRBs,we find that themain criterion to distinguish engine-driven GRBs from shock-breakout GRBs is the time-averaged -ray luminosity. Engine-driven GRBs likelyhave a luminosity above approximately 10(sup 48) erg s(sup -1).

Energy Dependence of Synchrotron X-Ray Rims in Tycho's Supernova Remnant

NASA Technical Reports Server (NTRS)

Tran, Aaron; Williams, Brian J.; Petre, Robert; Ressler, Sean M.; Reynolds, Stephen P.

2015-01-01

Several young supernova remnants exhibit thin X-ray bright rims of synchrotron radiation at their forward shocks. Thin rims require strong magnetic field amplification beyond simple shock compression if rim widths are only limited by electron energy losses. But, magnetic field damping behind the shock could produce similarly thin rims with less extreme field amplification. Variation of rim width with energy may thus discriminate between competing influences on rim widths. We measured rim widths around Tycho's supernova remnant in 5 energy bands using an archival 750 ks Chandra observation. Rims narrow with increasing energy and are well described by either loss-limited or damped scenarios, so X-ray rim width-energy dependence does not uniquely specify a model. But, radio counterparts to thin rims are not loss-limited and better reflect magnetic field structure. Joint radio and X-ray modeling favors magnetic damping in Tycho's SNR with damping lengths approximately 1-5% of remnant radius and magnetic field strengths approximately 50-400 micron G assuming Bohm diffusion. X-ray rim widths are approximately 1% of remnant radius, somewhat smaller than inferred damping lengths. Electron energy losses are important in all models of X-ray rims, suggesting that the distinction between loss-limited and damped models is blurred in soft X-rays. All loss-limited and damping models require magnetic fields approximately greater than 20 micron G, arming the necessity of magnetic field amplification beyond simple compression.

Far UV Observations of Interstellar Shocks

NASA Technical Reports Server (NTRS)

Raymond, John C.

1998-01-01

This grant covered analysis of Hopkins Ultraviolet Telescope data from the Astro-2 mission. The proposed research was aimed primarily at SNR shock waves, but the ASTRO-2 GO program was intended to make the GOs part of the instrument teams. The grant therefore covered extensive travel to Marshall Space Flight Center for mission simulations and the mission itself. In keeping with the unique nature of the ASTRO-2 GO program, I participated actively in the instrument team's investigations of HH objects and cataclysmic variables. Over the course of the Astro-2 mission, we obtained good observations of the supernova remnants SN1006 (1 position), Vela (3 positions), the Cygnus Loop (7 positions) and 0519-69 in the LMC (1 position) as part of this GI program, along with Puppis A (1 position), Vela (1 position), the Cygnus Loop (7 positions) and the Schweizer- Middleditch star (HUT PI program on SNRS). We also observed the Herbig-Haro object HH2 and about a dozen cataclysmic variables, including magnetic systems and dwarf novae. This GI grant covered modest travel for data analysis. We anticipate submitting papers on the non-radiative shock in northern Cygnus Loop, on the LMC Balmer-dominated remnant LMC 0519-69, on the radiative shocks in the Eastern Cygnus Loop (the XA region), and on the cataclysmic variable YZ Cnc over the course of the coming year. We have obtained extensive supporting data from ground-based telescopes for the Cygnus Loop spectra.

Constraints on Cosmic-ray Acceleration Efficiency in Balmer Shocks of Two Young Type Ia Supernova Remnants in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Hovey, Luke; Hughes, John P.; McCully, Curtis; Pandya, Viraj; Eriksen, Kristoffer

2018-01-01

We present results from an optical study of two young Balmer-dominated remnants of SNIa in the Large Magellanic Cloud, 0509-67.5 and 0519-69.0, in an attempt to search for signatures of efficient cosmic-ray (CR) acceleration. We combine proper motion measurements from HST with corresponding optical spectroscopic measurements of the Hα line at multiple rim positions from VLT/FORS2 and SALT/RSS and compare our results to published Balmer shock models. Analysis of the optical spectra result in broad Hα widths in the range of 1800-4000 km s-1 for twelve separate Balmer-dominated filaments that show no evidence for forbidden line emission, the corresponding shock speeds from proper motion measurements span a range of 1600-8500 km s-1. Our measured values of shock speeds and broad Hα widths in 0509-67.5 and 0519-69.0 are fit well with a Balmer shock model that does not include effects of efficient CR acceleration. We determine an upper limit of 7%/Χ (95% confidence) on the CR acceleration efficiency for our ensemble of data points, where Χ is the ionization fraction of the pre-shock gas. The upper limits on the individual remnants are 6%/Χ (0509-67.5) and 11%/Χ (0519-69.0). These upper limits are below the integrated CR acceleration efficiency in the Tycho supernova remnant, where the shocks predominantly show little Hα emission, indicating that Balmer-dominated shocks are not efficient CR accelerators.

Prolonged electron accelerations at a high-Mach-number, quasi-perpendicular shock

NASA Astrophysics Data System (ADS)

Matsumoto, Y.; Amano, T.; Kato, T.; Hoshino, M.

2016-12-01

Elucidating acceleration mechanisms of charged particles have been of great interests in laboratory, space, and astrophysical plasmas. Among other mechanisms, a collision-less shock is thought as an efficient particle accelerator. The idea has been strengthened by radio, X-ray, and gamma-ray observations of astrophysical objects such as supernova remnant shocks, where it has been indicated that protons and electrons are efficiently accelerated to TeV energies at such very strong shock waves. Efficient electron accelerations at high-Mach-number shocks was also suggested recently by in-situ measurements at the Saturn's bow shock. Motivated by these circumstances, laboratory experiments using high-power laser facilities emerge to provide a new platform to tackle these problems.Numerical simulations have revealed that electrons can be efficiently heated and accelerated via so-called the shock surfing acceleration mechanism in which electron-scale Buneman instability played key roles. Recently, Matsumoto et al. [2015] proposed a stochastic acceleration mechanism by turbulent reconnection in the shock transition region through excitation of the ion Weibel instability. In order to deal with the two different acceleration mechanisms in a self-consistent system, we examined 3D PIC simulations of a quasi-perpendicular, high-Mach-number shock. We successfully followed a long term evolution in which two different acceleration mechanisms coexist in the 3D shock structure. The Buneman instability is strongly excited ahead of the shock front in the same manner as have been found in 2D simulations. The surfing acceleration is found to be very effective in the present 3D system. In the transition region, the ion-beam Weibel instability generated strong magnetic field turbulence in 3D space. Energetic electrons, which initially experienced the surfing acceleration, undergo pitch-angle diffusion by interacting with the turbulent fields and thus stay in the upstream regions. The ion Weibel turbulence is essentially the key to prolonged acceleration processes which can produce relativistic particles with energies more than 1000 times the initial kinetic energy. We present how such relativistic electrons are produced during traveling in the 3D shock structure.

Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen

PubMed Central

Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

2016-01-01

The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

PubMed

Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

2016-01-01

The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.

Neutrino Observation of Core Collapse Supernovae

NASA Astrophysics Data System (ADS)

Nakazato, Ken'ichiro

The event rate of the supernova neutrinos are predicted for the future SK-Gd experiment. With an eye on the neutron tagging by Gd, the energy and angular distributions are calculated both for tagged events from inverse β decay reaction and untagged events from other reactions. As a result, it is indicated that the shock revival in the supernova is detectable through the decrease of the event rate and decline of the average energy of events. It is also implied that a careful treatment for the neutrino spectra is needed to investigate the untagged events owing to the high neutrino threshold energy of 16O reactions.

Pulsar recoil by large-scale anisotropies in supernova explosions.

PubMed

Scheck, L; Plewa, T; Janka, H-Th; Kifonidis, K; Müller, E

2004-01-09

Assuming that the neutrino luminosity from the neutron star core is sufficiently high to drive supernova explosions by the neutrino-heating mechanism, we show that low-mode (l=1,2) convection can develop from random seed perturbations behind the shock. A slow onset of the explosion is crucial, requiring the core luminosity to vary slowly with time, in contrast to the burstlike exponential decay assumed in previous work. Gravitational and hydrodynamic forces by the globally asymmetric supernova ejecta were found to accelerate the remnant neutron star on a time scale of more than a second to velocities above 500 km s(-1), in agreement with observed pulsar proper motions.

RESONANT AMPLIFICATION OF TURBULENCE BY THE BLAST WAVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zankovich, A. M.; Kovalenko, I. G., E-mail: ilya.g.kovalenko@gmail.com

2015-02-10

We discuss the idea of whether spherical blast waves can amplify by a nonlocal resonant hydrodynamic mechanism inhomogeneities formed by turbulence or phase segregation in the interstellar medium. We consider the problem of a blast-wave-turbulence interaction in the Linear Interaction Approximation. Mathematically, this is an eigenvalue problem for finding the structure and amplitude of eigenfunctions describing the response of the shock-wave flow to forced oscillations by external perturbations in the ambient interstellar medium. Linear analysis shows that the blast wave can amplify density and vorticity perturbations for a wide range of length scales with amplification coefficients of up to 20,more » with increasing amplification the larger the length. There also exist resonant harmonics for which the gain becomes formally infinite in the linear approximation. Their orbital wavenumbers are within the range of macro- (l ∼ 1), meso- (l ∼ 20), and microscopic (l > 200) scales. Since the resonance width is narrow (typically, Δl < 1), resonance should select and amplify discrete isolated harmonics. We speculate on a possible explanation of an observed regular filamentary structure of regularly shaped round supernova remnants such as SNR 1572, 1006, or 0509-67.5. Resonant mesoscales found (l ≈ 18) are surprisingly close to the observed scales (l ≈ 15) of ripples in the shell's surface of SNR 0509-67.5.« less

Effects of shock strength on shock turbulence interaction

NASA Technical Reports Server (NTRS)

Lee, Sangsan

1993-01-01

Direct numerical simulation (DNS) and linear analysis (LIA) of isotropic turbulence interacting with a shock wave are performed for several upstream shock normal Mach numbers (M(sub 1)). Turbulence kinetic energy (TKE) is amplified across the shock wave, but this amplification tends to saturate beyond M(sub 1) = 3.0. TKE amplification and Reynolds stress anisotropy obtained in DNS are consistent with LIA predictions. Rapid evolution of TKE immediate downstream of the shock wave persists for all shock strengths and is attributed to the transfer between kinetic and potential modes of turbulence energy through acoustic fluctuations. Changes in energy spectra and various length scales across the shock wave are predicted by LIA, which is consistent with DNS results. Most turbulence length scales decrease across the shock. Dissipation length scale (rho-bar q(exp 3) / epsilon), however, increases slightly for shock waves with M(sub 1) less than 1.65. Fluctuations in thermodynamic variables behind the shock wave stay nearly isentropic for M(sub 1) less than 1.2 and deviate significantly from isentropy for the stronger shock waves due to large entropy fluctuation generated through the interaction.

A unified model of supernova driven by magnetic monopoles

NASA Astrophysics Data System (ADS)

Peng, Qiu-He; Liu, Jing-Jing; Chou, Chih-Kang

2017-12-01

In this paper, we first discuss a series of important but puzzling physical mechanisms concerning the energy source, various kinds of core collapsed supernovae explosion mechanisms during central gravitational collapse in astrophysics. We also discuss the puzzle of possible association of γ -ray burst with gravitational wave perturbation, the heat source for the molten interior of the core of the Earth and finally the puzzling problem of the cooling of white dwarfs. We then make use of the estimations for the space flux of magnetic monopoles (hereafter MMs) and nucleon decay induced by MMs (called the Rubakov-Callen (RC) effect) to obtain the luminosity due to the RC effect. In terms of the formula for this RC luminosity, we present a unified treatment for the heat source of the Earth's core, the energy source for the white dwarf interior, various kinds of core collapsed supernovae (Type II Supernova (SNII), Type Ib Supernova (SNIb), Type Ic Supernova (SNIc), Super luminous supernova (SLSN)), and the production mechanism for γ -ray burst. This unified model can also be used to reasonably explain the possible association of the short γ -ray burst detected by the Fermi γ -ray Burst Monitoring Satellite (GBM) with the LIGO gravitational wave event GW150914 in September 2015.

Current topics in shock waves; Proceedings of the International Symposium on Shock Waves and Shock Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989

NASA Astrophysics Data System (ADS)

Kim, Yong W.

Various papers on shock waves are presented. The general topics addressed include: shock formation, focusing, and implosion; shock reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and shock-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and shock propagation through particle suspension; boundary layers and blast simulation; computational methods and numerical simulation.

Youngest Stellar Explosion in Our Galaxy Discovered

NASA Astrophysics Data System (ADS)

2008-05-01

Astronomers have found the remains of the youngest supernova, or exploded star, in our Galaxy. The supernova remnant, hidden behind a thick veil of gas and dust, was revealed by the National Science Foundation's Very Large Array (VLA) and NASA's Chandra X-Ray Observatory, which could see through the murk. The object is the first example of a "missing population" of young supernova remnants. 1985 and 2008 VLA Images Move cursor over image to blink. VLA Images of G1.9+0.3 in 1985 and 2008: Circle for size comparison. CREDIT: Green, et al., NRAO/AUI/NSF From observing supernovae in other galaxies, astronomers have estimated that about three such stellar explosions should occur in our Milky Way every century. However, the most recent one known until now occurred around 1680, creating the remnant called Cassiopeia A. The newly-discovered object is the remnant of an explosion only about 140 years ago. "If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions in the Milky Way that are younger than Cassiopeia A," said David Green of the University of Cambridge in the UK, who led the VLA study. "It's great to finally track one of them down." Supernova explosions, which mark the violent death of a star, release tremendous amounts of energy and spew heavy elements such as calcium and iron into interstellar space. They thus seed the clouds of gas and dust from which new stars and planets are formed and, through their blast shocks, can even trigger such formation. The lack of evidence for young supernova remnants in the Milky Way had caused astronomers to wonder if our Galaxy, which appears otherwise normal, differed in some unknown way from others. Alternatively, scientists thought that the "missing" Milky Way supernovae perhaps indicated that their understanding of the relationship between supernovae and other galactic processes was in error. The astronomers made their discovery by measuring the expansion of the debris from the star's explosion. They did this by comparing images of the object, called G1.9+0.3, made more than two decades apart. In 1985, astronomers led by Green observed G1.9+0.3 with the VLA and identified it as a supernova remnant. At that time, they estimated its age as between 400 and 1,000 years. It is near the center of our Galaxy, roughly 25,000 light-years from Earth. In 2007, another team of astronomers, led by Stephen Reynolds of North Carolina State University, observed the object with the Chandra X-Ray Observatory. To their surprise, their image showed the object to be about 16 percent larger than in the 1985 VLA image. "This is a huge difference. It means the explosion debris is expanding very quickly, which in turn means the object is much younger than we originally thought," Reynolds explained. However, this expansion measurement came from comparing a radio image to an X-ray image. To make an "apples to apples" comparison, the scientists sought and were quickly granted observing time on the VLA. "I've never seen a large astronomical institution move so fast," said Reynolds. Their new VLA observations confirmed the supernova remnant's rapid expansion. The discovery provides scientists with a valuable source of new information about exploding stars. "Our previous situation was as if someone studying humans could look at babies and at adults, but could not study teenagers. Now, we're filling in that gap," said Reynolds. The object already has provided surprises. The velocities of its explosion debris and extreme energies of its particles are unprecedented. "No other object in the Galaxy has properties like this," said Reynolds. "Finding G1.9+0.3 is extremely important for learning more about how some stars explode and what happens in the aftermath," he added. The discovery was possible because radio and X-ray telescopes, unlike visible-light telescopes, can penetrate the thick clouds of gas and dust in our Galaxy. "Looking out of the Milky Way, we can see some supernova explosions with optical telescopes across half of the Universe, but when they're in this murk, we can miss them in our own cosmic back yard," Reynolds said. "Fortunately, the expanding gas cloud from the explosion shines brightly in radio waves and X-rays for thousands of years. X-ray and radio telescopes can see through all that obscuration and show us what we've been missing," he added. Because of the obscuration, no one could have seen the original explosion 140 years ago. The astronomers are reporting their results in papers published in the Astrophysical Journal Letters and Monthly Notices of the Royal Astronomical Society. Background Information: Supernova Explosions Supernova explosions are the violent death throes of stars. These explosions release in one event as much energy as is being released by all the rest of the stars in a galaxy -- typically 100 billion or so. Supernovae seen in other galaxies can outshine the rest of their galaxy for days. The supernovae that have occurred in our own Galaxy and were not obscured by the gas and dust that obscured G1.9+0.3 have often provided a spectacular sight. Historical records indicate that ancient astronomers noted supernova explosions at least as early as A.D. 393, and probably earlier. The pre-telescopic astronomers Tycho Brahe and Johannes Kepler made extensive observations of supernovae in 1572 and 1604. Chinese astronomers noted that a supernova in 1054 was bright enough to be seen in the daytime. A supernova in 1006 remained visible for two years. Supernovae that result from the deaths of stars much more massive than the Sun enrich the galaxy with chemical elements that are produced in the cores of those stars before they explode. The heavy elements, such as carbon, oxygen, iron, siicon and calcium, that make up planets and their inhabitants were made available by supernova explosions. In addition to enriching the material between stars with heavy elements, supernovae stir up that material through the shock energy of the explosion. This is thought to help trigger the process of star formation in interstellar clouds of gas and dust. Many astronomers believe that our own Solar System is the result of such a supernova shock. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Underwater electrical wire explosion: Shock wave from melting being overtaken by shock wave from vaporization

NASA Astrophysics Data System (ADS)

Li, Liuxia; Qian, Dun; Zou, Xiaobing; Wang, Xinxin

2018-05-01

The shock waves generated by an underwater electrical wire explosion were investigated. A microsecond time-scale pulsed current source was used to trigger the electrical explosion of copper wires with a length of 5 cm and a diameter of 200 μm. The energy-storage capacitor was charged to a relatively low energy so that the energy deposited onto the wire was not large enough to fully vaporize the whole wire. Two shock waves were recorded with a piezoelectric gauge that was located at a position of 100 mm from the exploding wire. The first and weak shock wave was confirmed to be the contribution from wire melting, while the second and stronger shock wave was the contribution from wire vaporization. The phenomenon whereby the first shock wave generated by melting being overtaken by the shock wave due to vaporization was observed.

A numerical study of fundamental shock noise mechanisms. Ph.D. Thesis - Cornell Univ.

NASA Technical Reports Server (NTRS)

Meadows, Kristine R.

1995-01-01

The results of this thesis demonstrate that direct numerical simulation can predict sound generation in unsteady aerodynamic flows containing shock waves. Shock waves can be significant sources of sound in high speed jet flows, on helicopter blades, and in supersonic combustion inlets. Direct computation of sound permits the prediction of noise levels in the preliminary design stage and can be used as a tool to focus experimental studies, thereby reducing cost and increasing the probability of a successfully quiet product in less time. This thesis reveals and investigates two mechanisms fundamental to sound generation by shocked flows: shock motion and shock deformation. Shock motion is modeled by the interaction of a sound wave with a shock. During the interaction, the shock wave begins to move and the sound pressure is amplified as the wave passes through the shock. The numerical approach presented in this thesis is validated by the comparison of results obtained in a quasi-one dimensional simulation with linear theory. Analysis of the perturbation energy demonstrated for the first time that acoustic energy is generated by the interaction. Shock deformation is investigated by the numerical simulation of a ring vortex interacting with a shock. This interaction models the passage of turbulent structures through the shock wave. The simulation demonstrates that both acoustic waves and contact surfaces are generated downstream during the interaction. Analysis demonstrates that the acoustic wave spreads cylindrically, that the sound intensity is highly directional, and that the sound pressure level increases significantly with increasing shock strength. The effect of shock strength on sound pressure level is consistent with experimental observations of shock noise, indicating that the interaction of a ring vortex with a shock wave correctly models a dominant mechanism of shock noise generation.

Bubbles, Bow Shocks and B Fields: The Interplay Between Neutron Stars and Their Environments

NASA Astrophysics Data System (ADS)

Gaensler, Bryan M.

2006-12-01

Young neutron stars embody Nature's extremes: they spin incredibly rapidly, move through space at enormous velocities, and are imbued with unimaginably strong magnetic fields. Since their progenitor stars do not have any of these characteristics, these properties are presumably all imparted to a neutron star during or shortly after the supernova explosion in which it is formed. This raises two fundamental questions: how do neutron stars attain these extreme parameters, and how are their vast reservoirs of energy then dissipated? I will explain how multi-wavelength observations of the environments of neutron stars not only provide vital forensic evidence on the physics of supernova core collapse, but also spectacularly reveal the winds, jets, shocks and outflows through which these remarkable objects couple to their surroundings.

High-energy extracorporeal shock wave therapy as a treatment for chronic noninsertional Achilles tendinopathy.

PubMed

Furia, John P

2008-03-01

High-energy extracorporeal shock wave therapy has been shown to be an effective treatment for chronic insertional Achilles tendinopathy. The results of high-energy shock wave therapy for chronic noninsertional Achilles tendinopathy have not been determined. Shock wave therapy is an effective treatment for noninsertional Achilles tendinopathy. Case control study; Level of evidence, 3. Thirty-four patients with chronic noninsertional Achilles tendinopathy were treated with a single dose of high-energy shock wave therapy (shock wave therapy group; 3000 shocks; 0.21 mJ/mm(2); total energy flux density, 604 mJ/mm(2)). Thirty-four patients with chronic noninsertional Achilles tendinopathy were treated not with shock wave therapy but with additional forms of nonoperative therapy (control group). All shock wave therapy procedures were performed using regional anesthesia. Evaluation was by change in visual analog score and by Roles and Maudsley score. One month, 3 months, and 12 months after treatment, the mean visual analog scores for the control and shock wave therapy groups were 8.4 and 4.4 (P < .001), 6.5 and 2.9 (P < .001), and 5.6 and 2.2 (P < .001), respectively. At final follow-up, the number of excellent, good, fair, and poor results for the shock wave therapy and control groups were 12 and 0 (P < .001), 17 and 9 (P < .001), 5 and 17 (P < .001), and 0 and 8 (P < .001), respectively. A chi(2) analysis revealed that the percentage of patients with excellent ("1") or good ("2") Roles and Maudsley scores, that is, successful results, 12 months after treatment was statistically greater in the shock wave therapy group than in the control group (P < .001). Shock wave therapy is an effective treatment for chronic noninsertional Achilles tendinopathy.

Three dimensional core-collapse supernova simulated using a 15 M ⊙ progenitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lentz, Eric J.; Bruenn, Stephen W.; Hix, W. Raphael

We have performed ab initio neutrino radiation hydrodynamics simulations in three and two spatial dimensions (3D and 2D) of core-collapse supernovae from the same 15 M⊙ progenitor through 440 ms after core bounce. Both 3D and 2D models achieve explosions; however, the onset of explosion (shock revival) is delayed by ~100 ms in 3D relative to the 2D counterpart and the growth of the diagnostic explosion energy is slower. This is consistent with previously reported 3D simulations utilizing iron-core progenitors with dense mantles. In the ~100 ms before the onset of explosion, diagnostics of neutrino heating and turbulent kinetic energymore » favor earlier explosion in 2D. During the delay, the angular scale of convective plumes reaching the shock surface grows and explosion in 3D is ultimately lead by a single, large-angle plume, giving the expanding shock a directional orientation not dissimilar from those imposed by axial symmetry in 2D simulations. Finally, we posit that shock revival and explosion in the 3D simulation may be delayed until sufficiently large plumes form, whereas such plumes form more rapidly in 2D, permitting earlier explosions.« less

Three dimensional core-collapse supernova simulated using a 15 M ⊙ progenitor

DOE PAGES

Lentz, Eric J.; Bruenn, Stephen W.; Hix, W. Raphael; ...

2015-07-10

We have performed ab initio neutrino radiation hydrodynamics simulations in three and two spatial dimensions (3D and 2D) of core-collapse supernovae from the same 15 M⊙ progenitor through 440 ms after core bounce. Both 3D and 2D models achieve explosions; however, the onset of explosion (shock revival) is delayed by ~100 ms in 3D relative to the 2D counterpart and the growth of the diagnostic explosion energy is slower. This is consistent with previously reported 3D simulations utilizing iron-core progenitors with dense mantles. In the ~100 ms before the onset of explosion, diagnostics of neutrino heating and turbulent kinetic energymore » favor earlier explosion in 2D. During the delay, the angular scale of convective plumes reaching the shock surface grows and explosion in 3D is ultimately lead by a single, large-angle plume, giving the expanding shock a directional orientation not dissimilar from those imposed by axial symmetry in 2D simulations. Finally, we posit that shock revival and explosion in the 3D simulation may be delayed until sufficiently large plumes form, whereas such plumes form more rapidly in 2D, permitting earlier explosions.« less

Seismic excitation by space shuttles

USGS Publications Warehouse

Kanamori, H.; Mori, J.; Sturtevant, B.; Anderson, D.L.; Heaton, T.

1992-01-01

Shock waves generated by the space shuttles Columbia (August 13, 1989), Atlantis (April 11, 1991) and Discovery (September 18, 1991) on their return to Edwards Air Force Base, California, were recorded by TERRAscope (Caltech's broadband seismic network), the Caltech-U.S.G.S Southern California Seismic Network (SCSN), and the University of Southern California (USC) Los Angeles Basin Seismic Network. The spatial pattern of the arrival times exhibits hyperbolic shock fronts from which the path, velocity and altitude of the space shuttle could be determined. The shock wave was acoustically coupled to the ground, converted to a seismic wave, and recorded clearly at the broadband TERRAscope stations. The acoustic coupling occurred very differently depending on the conditions of the Earth's surface surrounding the station. For a seismic station located on hard bedrock, the shock wave (N wave) was clearly recorded with little distortion. Aside from the N wave, very little acoustic coupling of the shock wave energy to the ground occurred at these sites. The observed N wave record was used to estimate the overpressure of the shock wave accurately; a pressure change of 0.5 to 2.2 mbars was obtained. For a seismic station located close to the ocean or soft sedimentary basins, a significant amount of shock wave energy was transferred to the ground through acoustic coupling of the shock wave and the oceanic Rayleigh wave. A distinct topography such as a mountain range was found effective to couple the shock wave energy to the ground. Shock wave energy was also coupled to the ground very effectively through large man made structures such as high rise buildings and offshore oil drilling platforms. For the space shuttle Columbia, in particular, a distinct pulse having a period of about 2 to 3 seconds was observed, 12.5 s before the shock wave, with a broadband seismograph in Pasadena. This pulse was probably excited by the high rise buildings in downtown Los Angeles which were simultaneously hit by the space shuttle shock waves. The proximity of the natural periods of the high rise buildings and the modal periods of the Los Angeles basin enabled efficient energy transfer from shock wave to seismic wave. ?? 1992 Springer-Verlag.

Integral Field Spectroscopy of Balmer-dominated Shocks in the Magellanic Cloud Supernova Remnant N103B

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghavamian, Parviz; Seitenzahl, Ivo R.; Dopita, M. A.

2017-10-01

We present results of integral field spectroscopy of Balmer-dominated shocks in the LMC supernova remnant (SNR) N103B, carried out using the Wide Field Integral Spectrograph (WiFeS ) on the 2.3 m telescope at the Siding Spring Observatory in Australia. Existing X-ray studies of N103B have indicated an SN Ia origin. Radiative shock emission from clumpy material surrounding the SNR may result from interaction of the forward shock with relic stellar wind material, possibly implicating a thermonuclear explosion in a single-degenerate binary system. The recently discovered Balmer-dominated shocks mark the impact of the forward shock with low density, partially neutral CSMmore » gas, and form a partial shell encircling clumps of material exhibiting radiative shocks. The WiFeS spectra of N103B reveal broad H α emission having a width as high as 2350 km s{sup −1} along the northern rim, and both H α and H β broad profiles having widths around 1300 km s{sup −1} along the southern rim. Fits to the H α line profiles indicate that in addition to the usual broad and narrow emission components, a third component of intermediate width exists in these Balmer-dominated shocks, ranging from around 125 km s{sup −1} up to 225 km s{sup −1} in width. This is consistent with predictions of recent Balmer-dominated shock models, which predict that an intermediate-width component will be generated in a fast neutral precursor. We derive a Sedov age of approximately 685 ± 20 years for N103B from the Balmer-dominated spectra, consistent with the young age of 380–860 years estimated from light echo studies.« less

Non-radial instabilities and progenitor asphericities in core-collapse supernovae

NASA Astrophysics Data System (ADS)

Müller, B.; Janka, H.-Th.

2015-04-01

Since core-collapse supernova simulations still struggle to produce robust neutrino-driven explosions in 3D, it has been proposed that asphericities caused by convection in the progenitor might facilitate shock revival by boosting the activity of non-radial hydrodynamic instabilities in the post-shock region. We investigate this scenario in depth using 42 relativistic 2D simulations with multigroup neutrino transport to examine the effects of velocity and density perturbations in the progenitor for different perturbation geometries that obey fundamental physical constraints (like the anelastic condition). As a framework for analysing our results, we introduce semi-empirical scaling laws relating neutrino heating, average turbulent velocities in the gain region, and the shock deformation in the saturation limit of non-radial instabilities. The squared turbulent Mach number, , reflects the violence of aspherical motions in the gain layer, and explosive runaway occurs for ≳ 0.3, corresponding to a reduction of the critical neutrino luminosity by ˜ 25 per cent compared to 1D. In the light of this theory, progenitor asphericities aid shock revival mainly by creating anisotropic mass flux on to the shock: differential infall efficiently converts velocity perturbations in the progenitor into density perturbations δρ/ρ at the shock of the order of the initial convective Mach number Maprog. The anisotropic mass flux and ram pressure deform the shock and thereby amplify post-shock turbulence. Large-scale (ℓ = 2, ℓ = 1) modes prove most conducive to shock revival, whereas small-scale perturbations require unrealistically high convective Mach numbers. Initial density perturbations in the progenitor are only of the order of Ma_prog^2 and therefore play a subdominant role.

On the local time dependence of the bow shock wave structure

NASA Technical Reports Server (NTRS)

Olson, J. V.; Holzer, R. E.

1974-01-01

In the first 6 months after its launch, Ogo 3 crossed the earth's bow shock over 500 times. From this group, a set of 494 shock crossings were chosen for analysis. These crossings, as they were recorded by the UCLA/JPL search coil magnetometer, were scanned and classified according to the nature of the plasma waves detected near the shock. More than 85% of the shocks detected fell into a single category showing the predominance of two independent wave trains near the shock, the higher frequency appearing upstream and the lower downstream. The other 15%, which constitute an upper limit, appear to be composed of shocks dominated by a single wave pattern and of chaotic shocks showing no orderly progression of wave frequencies as the shock was penetrated. This division of wave pattern was found to occur at all local times, that is, in all regions where the satellite penetrated the shock.

Shock waves in weakly compressed granular media.

PubMed

van den Wildenberg, Siet; van Loo, Rogier; van Hecke, Martin

2013-11-22

We experimentally probe nonlinear wave propagation in weakly compressed granular media and observe a crossover from quasilinear sound waves at low impact to shock waves at high impact. We show that this crossover impact grows with the confining pressure P0, whereas the shock wave speed is independent of P0-two hallmarks of granular shocks predicted recently. The shocks exhibit surprising power law attenuation, which we model with a logarithmic law implying that shock dissipation is weak and qualitatively different from other granular dissipation mechanisms. We show that elastic and potential energy balance in the leading part of the shocks.

ORTHO-TO-PARA RATIO STUDIES OF SHOCKED H{sub 2} GAS IN THE TWO SUPERNOVA REMNANTS IC 443 AND HB 21

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shinn, Jong-Ho; Moon, Dae-Sik; Lee, Ho-Gyu, E-mail: jhshinn@kasi.re.kr, E-mail: hglee@astron.s.u-tokyo.ac.jp, E-mail: moon@astro.utoronto.ca

2012-11-01

We present near-infrared (2.5-5.0 {mu}m) spectral studies of shocked H{sub 2} gas in two supernova remnants, IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with the Infrared Camera aboard the AKARI satellite. At the energy range 7000 K {approx}< E({upsilon},J) {approx}< 20,000 K, the shocked H{sub 2} gas in IC 443 shows an ortho-to-para ratio (OPR) of 2.4{sup +0.3} {sub -0.2}, which is significantly lower than the equilibrium value 3, suggesting the existence of non-equilibrium OPR. The shocked gas in HB 21 also indicates a potential non-equilibrium OPRmore » in the range of 1.8-2.0. The level populations are well described by the power-law thermal admixture model with a single OPR, where the temperature integration range is 1000-4000 K. We conclude that the obtained non-equilibrium OPR probably originates from the reformed H{sub 2} gas of dissociative J-shocks, considering several factors such as the shock combination requirement, the line ratios, and the possibility that H{sub 2} gas can form on grains with a non-equilibrium OPR. We also investigate C-shocks and partially dissociative J-shocks as the origin of the non-equilibrium OPR. However, we find that they are incompatible with the observed ionic emission lines for which dissociative J-shocks are required to explain. The difference in the collision energy of H atoms on grain surfaces would give rise to the observed difference between the OPRs of IC 443 and HB 21, if dissociative J-shocks are responsible for the H{sub 2} emission. Our study suggests that dissociative J-shocks can produce shocked H{sub 2} gas with a non-equilibrium OPR.« less

Numerical analysis on interactions of vortex, shock wave, and exothermal reaction in a supersonic planar shear layer laden with droplets

NASA Astrophysics Data System (ADS)

Ren, Zhaoxin; Wang, Bing; Zheng, Longxi

2018-03-01

The analysis on the interactions of a large-scale shearing vortex, an incident oblique shock wave, and a chemical reaction in a planar shear layer is performed by numerical simulations. The reacting flows are obtained by directly solving the multi-species Navier-Stokes equations in the Eulerian frame, and the motions of individual point-mass fuel droplets are tracked in the Lagrangian frame considering the two-way coupling. The influences of shock strength and spray equivalence ratio on the shock-vortex interaction and the induced combustion are further studied. Under the present conditions, the incident shock is distorted by the vortex evolution to form the complicated waves including an incident shock wave, a multi-refracted wave, a reflected wave, and a transmitted wave. The local pressure and temperature are elevated by the shock impingement on the shearing vortex, which carries flammable mixtures. The chemical reaction is mostly accelerated by the refracted shock across the vortex. Two different exothermal reaction modes could be distinguished during the shock-vortex interaction as a thermal mode, due to the additional energy from the incident shock, and a local quasi detonation mode, due to the coupling of the refracted wave with reaction. The former mode detaches the flame and shock wave, whereas the latter mode tends to occur when the incident shock strength is higher and local equivalence ratio is higher approaching to the stoichiometric value. The numerical results illustrate that those two modes by shock-vortex interaction depend on the structure of the post-shock flame kernel, which may be located either in the vortex-braids of post-shock flows or in the shock-vortex interaction regime.

On the interplay between cosmological shock waves and their environment

NASA Astrophysics Data System (ADS)

Martin-Alvarez, Sergio; Planelles, Susana; Quilis, Vicent

2017-05-01

Cosmological shock waves are tracers of the thermal history of the structures in the Universe. They play a crucial role in redistributing the energy within the cosmic structures and are also amongst the main ingredients of galaxy and galaxy cluster formation. Understanding this important function requires a proper description of the interplay between shocks and the different environments where they can be found. In this paper, an Adaptive Mesh Refinement (AMR) Eulerian cosmological simulation is analysed by means of a shock-finding algorithm that allows to generate shock wave maps. Based on the population of dark matter halos and on the distribution of density contrast in the simulation, we classify the shocks in five different environments. These range from galaxy clusters to voids. The shock distribution function and the shocks power spectrum are studied for these environments dynamics. We find that shock waves on different environments undergo different formation and evolution processes, showing as well different characteristics. We identify three different phases of formation, evolution and dissipation of these shock waves, and an intricate migration between distinct environments and scales. Shock waves initially form at external, low density regions and are merged and amplified through the collapse of structures. Shock waves and cosmic structures follow a parallel evolution. Later on, shocks start to detach from them and dissipate. We also find that most of the power that shock waves dissipate is found at scales of k ˜0.5 Mpc^{-1}, with a secondary peak at k ˜8 Mpc^{-1}. The evolution of the shocks power spectrum confirms that shock waves evolution is coupled and conditioned by their environment.

Delayed Neutrino-Driven Supernova Explosions Aided by the Standing Accretion-Shock Instability

NASA Astrophysics Data System (ADS)

Marek, A.; Janka, H.-Th.

2009-03-01

We present two-dimensional hydrodynamic simulations of stellar core collapse and develop the framework for a detailed analysis of the energetic aspects of neutrino-powered supernova explosions. Our results confirm that the neutrino-heating mechanism remains a viable explanation of the explosion of a wider mass range of supernova progenitors with iron cores, but the explosion sets in later and develops differently than thought so far. The calculations were performed with an energy-dependent treatment of the neutrino transport based on the "ray-by-ray plus" approximation, in which the neutrino number, energy, and momentum equations are closed with a variable Eddington factor obtained by iteratively solving a model Boltzmann equation. We focus here on the evolution of a 15 M sun progenitor and provide evidence that shock revival and an explosion are initiated at about 600 ms after core bounce, powered by neutrino energy deposition. This is significantly later than previously found for an 11.2 M sun star, for which we also present a continuation of the explosion model published by Buras et al. The onset of the blast is fostered in both cases by the standing accretion-shock instability. This instability exhibits highest growth rates for the dipole and quadrupole modes, which lead to large-amplitude bipolar shock oscillations and push the shock to larger radii, thus increasing the time accreted matter is exposed to neutrino heating in the gain layer. As a consequence, also convective overturn behind the shock is strengthened, which otherwise is suppressed or damped because of the small shock stagnation radius. When the explosion sets in, the shock reveals a pronounced global deformation with a dominant dipolar component. In both the 11.2 M sun and 15 M sun explosions long-lasting equatorial downflows supply the gain layer with fresh gas, of which a sizable fraction is heated by neutrinos and leads to the build-up of the explosion energy of the ejecta over possibly hundreds of milliseconds. A "soft" nuclear equation of state that causes a rapid contraction, and a smaller radius of the forming neutron star and thus a fast release of gravitational binding energy, seems to be more favorable for the development of an explosion. Rotation has the opposite effect because in the long run it leads to a more extended and cooler neutron star and thus lower neutrino luminosities and mean energies and overall less neutrino heating. Neutron star g-mode oscillations, although we see their presence, and the acoustic mechanism play no important role in our simulations. While numerical tests show that our code is also well able to follow large-amplitude core g-modes if they are instigated; the amplitude of such oscillations remains small in our supernova runs and the acoustic energy flux injected by the ringing neutron star and by the deceleration of supersonic downflows near the neutron star surface is small compared to the neutrino energy deposition.

Interaction of rippled shock wave with flat fast-slow interface

NASA Astrophysics Data System (ADS)

Zhai, Zhigang; Liang, Yu; Liu, Lili; Ding, Juchun; Luo, Xisheng; Zou, Liyong

2018-04-01

The evolution of a flat air/sulfur-hexafluoride interface subjected to a rippled shock wave is investigated. Experimentally, the rippled shock wave is produced by diffracting a planar shock wave around solid cylinder(s), and the effects of the cylinder number and the spacing between cylinders on the interface evolution are considered. The flat interface is created by a soap film technique. The postshock flow and the evolution of the shocked interface are captured by a schlieren technique combined with a high-speed video camera. Numerical simulations are performed to provide more details of flows. The wave patterns of a planar shock wave diffracting around one cylinder or two cylinders are studied. The shock stability problem is analytically discussed, and the effects of the spacing between cylinders on shock stability are highlighted. The relationship between the amplitudes of the rippled shock wave and the shocked interface is determined in the single cylinder case. Subsequently, the interface morphologies and growth rates under different cases are obtained. The results show that the shock-shock interactions caused by multiple cylinders have significant influence on the interface evolution. Finally, a modified impulsive theory is proposed to predict the perturbation growth when multiple solid cylinders are present.

Shock Wave Technology and Application: An Update☆

PubMed Central

Rassweiler, Jens J.; Knoll, Thomas; Köhrmann, Kai-Uwe; McAteer, James A.; Lingeman, James E.; Cleveland, Robin O.; Bailey, Michael R.; Chaussy, Christian

2012-01-01

Context The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems. Objective To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies. Evidence acquisition We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy. Evidence synthesis Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60–80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures. Conclusions New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL. PMID:21354696

Increased Risk of New-Onset Hypertension After Shock Wave Lithotripsy in Urolithiasis: A Nationwide Cohort Study.

PubMed

Huang, Shi-Wei; Tsai, Chung-You; Wang, Jui; Pu, Yeong-Shiau; Chen, Pei-Chun; Huang, Chao-Yuan; Chien, Kuo-Liong

2017-10-01

Although shock wave lithotripsy is minimally invasive, earlier studies argued that it may increase patients' subsequent risk of hypertension and diabetes mellitus. This study evaluated the association between shock wave lithotripsy and new-onset hypertension or diabetes mellitus. The Taiwanese National Health Insurance Research Database was used to identify 20 219 patients aged 18 to 65 years who underwent the first stone surgical treatment (shock wave lithotripsy or ureterorenoscopic lithotripsy) between January 1999 and December 2011. A Cox proportional model was applied to evaluate associations. Time-varying Cox models were applied to evaluate the association between the number of shock wave lithotripsy sessions and the incidence of hypertension or diabetes mellitus. After a median follow-up of 74.9 and 82.6 months, 2028 and 688 patients developed hypertension in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups, respectively. Patients who underwent shock wave lithotripsy had a higher probability of developing hypertension than patients who underwent ureterorenoscopic lithotripsy, with a hazard ratio of 1.20 (95% confidence interval, 1.10-1.31) after adjusting for covariates. The risk increased as the number of shock wave lithotripsy sessions increased. However, the diabetes mellitus risk was similar in the shock wave lithotripsy and ureterorenoscopic lithotripsy groups. Furthermore, the hazard ratio did not increase as the number of shock wave lithotripsy sessions increased. Shock wave lithotripsy consistently increased the incidence of hypertension on long-term follow-up. Therefore, alternatives to urolithiasis treatment (eg, endoscopic surgery or medical expulsion therapy) could avoid the hypertension risk. Furthermore, avoiding multiple sessions of shock wave lithotripsy could also evade the hypertension risk. © 2017 American Heart Association, Inc.

Extracorporeal shock wave therapy in treatment of delayed bone-tendon healing.

PubMed

Wang, Lin; Qin, Ling; Lu, Hong-bin; Cheung, Wing-hoi; Yang, Hu; Wong, Wan-nar; Chan, Kai-ming; Leung, Kwok-sui

2008-02-01

Extracorporeal shock wave therapy is indicated for treatment of chronic injuries of soft tissues and delayed fracture healing and nonunion. No investigation has been conducted to study the effect of shock wave on delayed healing at the bone-tendon junction. Shock wave promotes osteogenesis, regeneration of fibrocartilage zone, and remodeling of healing tissue in delayed healing of bone-tendon junction surgical repair. Controlled laboratory study. Twenty-eight mature rabbits were used for establishing a delayed healing model at the patella-patellar tendon complex after partial patellectomy and then divided into control and shock wave groups. In the shock wave group, a single shock wave treatment was given at week 6 postoperatively to the patella-patellar tendon healing complex. Seven samples were harvested at week 8 and 7 samples at week 12 for radiologic, densitometric, histologic, and mechanical evaluations. Radiographic measurements showed 293.4% and 185.8% more new bone formation at the patella-patellar tendon healing junction in the shock wave group at weeks 8 and 12, respectively. Significantly better bone mineral status was found in the week 12 shock wave group. Histologically, the shock wave group showed more advanced remodeling in terms of better alignment of collagen fibers and thicker and more mature regenerated fibrocartilage zone at both weeks 8 and 12. Mechanical testing showed 167.7% and 145.1% higher tensile load and strength in the shock wave group at week 8 and week 12, respectively, compared with controls. Extracorporeal shock wave promotes osteogenesis, regeneration of fibrocartilage zone, and remodeling in the delayed bone-to-tendon healing junction in rabbits. These results provide a foundation for future clinical studies toward establishment of clinical indication for treatment of delayed bone-to-tendon junction healing.

An electromagnetic railgun accelerator: a generator of strong shock waves in channels

NASA Astrophysics Data System (ADS)

Bobashev, S. V.; Zhukov, B. G.; Kurakin, R. O.; Ponyaev, S. A.; Reznikov, B. I.

2014-11-01

Processes that accompany the generation of strong shock waves during the acceleration of a free plasma piston (PP) in the electromagnetic railgun channel have been experimentally studied. The formation of shock waves in the railgun channel and the motion of a shock-wave-compressed layer proceed (in contrast to the case of a classical shock tube) in a rather strong electric field (up to 300 V/cm). The experiments were performed at the initial gas pressures in the channel ranging from 25 to 500 Torr. At 25 Torr, the shock-wave Mach numbers reached 32 in argon and 16 in helium. At high concentrations of charged particles behind the shock wave, the electric field causes the passage of a part of the discharge current through the volume of the shock-wave-compressed layer, which induces intense glow comparable with that of the PP glow.

Theoretical and Observational Analysis of Particle Acceleration Mechanisms at Astrophysical Shocks

NASA Astrophysics Data System (ADS)

Lever, Edward Lawrence

We analytically and numerically investigate the viability of Shock Surfing as a pre-injection mechanism for Diffusive Shock Acceleration, believed to be responsible for the production of Cosmic Rays. We demonstrate mathematically and from computer simulations that four critical conditions must be satisfied for Shock Surfing to function; the shock ramp must be narrow, the shock front must be smooth, the magnetic field angle must be very nearly perpendicular and, finally, these conditions must persist without interruption over substantial time periods and spatial scales. We quantify these necessary conditions, exhibit predictive functions for velocity maxima and accelerated ion fluxes based on observable shock parameters, and show unequivocally from current observational evidence that all of these necessary conditions are violated at shocks within the heliosphere, at the heliospheric Termination Shock, and also at Supernovae.

HST-COS Observations of Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock

NASA Astrophysics Data System (ADS)

France, Kevin; McCray, Richard; Penton, Steven V.; Kirshner, Robert P.; Challis, Peter; Laming, J. Martin; Bouchet, Patrice; Chevalier, Roger; Garnavich, Peter M.; Fransson, Claes; Heng, Kevin; Larsson, Josefin; Lawrence, Stephen; Lundqvist, Peter; Panagia, Nino; Pun, Chun S. J.; Smith, Nathan; Sollerman, Jesper; Sonneborn, George; Sugerman, Ben; Wheeler, J. Craig

2011-12-01

We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Δv ~ 300 km s-1) emission lines from the circumstellar ring, broad (Δv ~ 10-20 × 103 km s-1) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Lyα emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at λ > 1350 Å can be explained by H I two-photon (2s 2 S 1/2-1s 2 S 1/2) emission from the same region. We confirm our earlier, tentative detection of N V λ1240 emission from the reverse shock and present the first detections of broad He II λ1640, C IV λ1550, and N IV] λ1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 ± 0.06. The N V/Hα line ratio requires partial ion-electron equilibration (Te /Tp ≈ 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expulsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expulsion of the circumstellar ring. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Gravitational radiation from magnetically funneled supernova fallback onto a magnetar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melatos, A.; Priymak, M., E-mail: amelatos@unimelb.edu.au, E-mail: m.priymak@pgrad.unimelb.edu.au

2014-10-20

Protomagnetars spun up to millisecond rotation periods by supernova fallback are predicted to radiate gravitational waves via hydrodynamic instabilities for ∼10{sup 2} s before possibly collapsing to form a black hole. It is shown that magnetic funneling of the accretion flow (1) creates a magnetically confined polar mountain, which boosts the gravitational wave signal, and (2) 'buries' the magnetic dipole moment, delaying the propeller phase and assisting black hole formation.

The Magellanic Cloud supernova remnants

NASA Astrophysics Data System (ADS)

Dopita, M. A.

1984-09-01

The first supernova remnant (SNR) in the Magellanic Clouds was discovered by Mathewson and Healey (1964). Surveys for SNR in the Magellanic Clouds are discussed, taking into account the selection procedure initially used, current optical selection criteria for SNR, the launching of the Einstein Observatory, and the information obtainable by a detailed study of the discovered SNR. Attention is also given to the oxygen-rich SNR, the nonradiative shock SNR, the evolved radiative SNR, and conclusions based on the obtained results.

Exploring the Diffuse X-ray Emission of Supernova Remnant Kesteven 69 with XMM-Newton

NASA Astrophysics Data System (ADS)

Seo, Kyoung-Ae; Hui, Chung Yue

2013-06-01

We have investigated the X-ray emission from the shock-heated plasma of the Galactic supernova remnant Kesteven 69 with XMM-Newton. Assuming the plasma is at collisional ionization equilibrium, a plasma temperature and a column absorption are found to be kT ~ 0.62 keV and NH ~ 2.85 ×10^22 cm-2 respectively by imaging spectroscopy. Together with the deduced emission measure, we place constraints on its Sedov parameters.

Observation of Dispersive Shock Waves, Solitons, and Their Interactions in Viscous Fluid Conduits.

PubMed

Maiden, Michelle D; Lowman, Nicholas K; Anderson, Dalton V; Schubert, Marika E; Hoefer, Mark A

2016-04-29

Dispersive shock waves and solitons are fundamental nonlinear excitations in dispersive media, but dispersive shock wave studies to date have been severely constrained. Here, we report on a novel dispersive hydrodynamic test bed: the effectively frictionless dynamics of interfacial waves between two high viscosity contrast, miscible, low Reynolds number Stokes fluids. This scenario is realized by injecting from below a lighter, viscous fluid into a column filled with high viscosity fluid. The injected fluid forms a deformable pipe whose diameter is proportional to the injection rate, enabling precise control over the generation of symmetric interfacial waves. Buoyancy drives nonlinear interfacial self-steepening, while normal stresses give rise to the dispersion of interfacial waves. Extremely slow mass diffusion and mass conservation imply that the interfacial waves are effectively dissipationless. This enables high fidelity observations of large amplitude dispersive shock waves in this spatially extended system, found to agree quantitatively with a nonlinear wave averaging theory. Furthermore, several highly coherent phenomena are investigated including dispersive shock wave backflow, the refraction or absorption of solitons by dispersive shock waves, and the multiphase merging of two dispersive shock waves. The complex, coherent, nonlinear mixing of dispersive shock waves and solitons observed here are universal features of dissipationless, dispersive hydrodynamic flows.

Whistler Waves Associated with Weak Interplanetary Shocks

NASA Technical Reports Server (NTRS)

Velez, J. C. Ramirez; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Russell, C. T.; Kajdic, P.; Jian,, L. K.; Luhmann, J. G.

2012-01-01

We analyze the properties of 98 weak interplanetary shocks measured by the dual STEREO spacecraft over approximately 3 years during the past solar minimum. We study the occurrence of whistler waves associated with these shocks, which on average are high beta shocks (0.2 < Beta < 10). We have compared the waves properties upstream and downstream of the shocks. In the upstream region the waves are mainly circularly polarized, and in most of the cases (approx. 75%) they propagate almost parallel to the ambient magnetic field (<30 deg.). In contrast, the propagation angle with respect to the shock normal varies in a broad range of values (20 deg. to 90 deg.), suggesting that they are not phase standing. We find that the whistler waves can extend up to 100,000 km in the upstream region but in most cases (88%) are contained in a distance within 30,000 km from the shock. This corresponds to a larger region with upstream whistlers associated with IP shocks than previously reported in the literature. The maximum amplitudes of the waves are observed next to the shock interface, and they decrease as the distance to the shock increases. In most cases the wave propagation direction becomes more aligned with the magnetic field as the distance to the shock increases. These two facts suggest that most of the waves in the upstream region are Landau damping as they move away from the shock. From the analysis we also conclude that it is likely that the generation mechanism of the upstream whistler waves is taking place at the shock interface. In the downstream region, the waves are irregularly polarized, and the fluctuations are very compressive; that is, the compressive component of the wave clearly dominates over the transverse one. The majority of waves in the downstream region (95%) propagate at oblique angles with respect to the ambient magnetic field (>60 deg.). The wave propagation with respect to the shock-normal direction has no preferred direction and varies similarly to the upstream case. It is possible that downstream fluctuations are generated by ion relaxation as suggested in previous hybrid simulation shocks.

Suspended liquid particle disturbance on laser-induced blast wave and low density distribution

NASA Astrophysics Data System (ADS)

Ukai, Takahiro; Zare-Behtash, Hossein; Kontis, Konstantinos

2017-12-01

The impurity effect of suspended liquid particles on the laser-induced gas breakdown was experimentally investigated in quiescent gas. The focus of this study is the investigation of the influence of the impurities on the shock wave structure as well as the low density distribution. A 532 nm Nd:YAG laser beam with an 188 mJ/pulse was focused on the chamber filled with suspended liquid particles 0.9 ± 0.63 μm in diameter. Several shock waves are generated by multiple gas breakdowns along the beam path in the breakdown with particles. Four types of shock wave structures can be observed: (1) the dual blast waves with a similar shock radius, (2) the dual blast waves with a large shock radius at the lower breakdown, (3) the dual blast waves with a large shock radius at the upper breakdown, and (4) the triple blast waves. The independent blast waves interact with each other and enhance the shock strength behind the shock front in the lateral direction. The triple blast waves lead to the strongest shock wave in all cases. The shock wave front that propagates toward the opposite laser focal spot impinges on one another, and thereafter a transmitted shock wave (TSW) appears. The TSW interacts with the low density core called a kernel; the kernel then longitudinally expands quickly due to a Richtmyer-Meshkov-like instability. The laser-particle interaction causes an increase in the kernel volume which is approximately five times as large as that in the gas breakdown without particles. In addition, the laser-particle interaction can improve the laser energy efficiency.

Investigating the Chemical Evolution of the Universe via Numerical Simulations: Supernova Dust Destruction and Non-Equilibrium Ionization Chemistry

NASA Astrophysics Data System (ADS)

Silvia, Devin W.

2013-12-01

The chemical evolution of the Universe is a complicated process with countless facets that define its properties over the course of time. In the early Universe, the metal-free first stars were responsible for originally introducing metals into the pristine gas left over from the Big Bang. Once these metals became prevalent, they forever altered the thermodynamics of the Universe. Understanding precisely where these metals originated, where they end up, and the conditions they experience along the way is of great interest in the astrophysical community. In this work, I have used numerical simulations as a means of understanding two separate phenomena related to the chemical evolution the Universe. The first topic focuses on the question as to whether or not core-collapse supernovae in the high-redshift universe are capable of being "dust factories" for the production of galactic dust. To achieve this, I carried out idealized simulations of supernova ejecta clouds being impacted by reverse-shock blast waves. By post-processing the results of these simulations, I was able to estimate the amount of dust destruction that would occur due to thermal sputtering. In the most extreme scenarios, simulated with high relative velocities between the shock and the ejecta cloud and high gas metallicities, I find complete destruction for some grains species and only 44% dust mass survival for even the most robust species. This raises the question as to whether or not high-redshift supernova can produce dust masses in sufficient excess of the ˜1 Msun per event required to match observations of high-z galaxies. The second investigation was driven by the desire to find an answer to the missing baryon problem and a curiosity as to the impact that including a full non-equilibrium treatment of ionization chemistry has on simulations of the intergalactic medium. To address these questions, I have helped to develop Dengo, a new software package for solving complex chemical networks. Once this new package was integrated into Enzo, I carried out a set of cosmological simulations that served as both a test of the new solver and a confirmation that non-equilibrium ionization chemistry produces results that are drastically different from those that assume collisional ionization equilibrium. Although my analysis of these simulations is in its early stages, I find that the observable properties of the intergalactic medium change considerably. Continued efforts to run state-of-the-art simulations of the intergalactic medium using Dengo are warranted.

Transonic Shock-Wave/Boundary-Layer Interactions on an Oscillating Airfoil

NASA Technical Reports Server (NTRS)

Davis, Sanford S.; Malcolm, Gerald N.

1980-01-01

Unsteady aerodynamic loads were measured on an oscillating NACA 64A010 airfoil In the NASA Ames 11 by 11 ft Transonic Wind Tunnel. Data are presented to show the effect of the unsteady shock-wave/boundary-layer interaction on the fundamental frequency lift, moment, and pressure distributions. The data show that weak shock waves induce an unsteady pressure distribution that can be predicted quite well, while stronger shock waves cause complex frequency-dependent distributions due to flow separation. An experimental test of the principles of linearity and superposition showed that they hold for weak shock waves while flows with stronger shock waves cannot be superimposed.

Optical distortion in the field of a lithotripter shock wave

NASA Astrophysics Data System (ADS)

Carnell, M. T.; Emmony, D. C.

1995-10-01

The schlieren observation of cavitation phenomena produced in the tail of a lithotripter shock wave has indicated the presence of some interesting features. The images produced appear to indicate that cavitation transients in the field of a shock wave propagate nonsymmetrically; this is not the case. The apparent lack of symmetry exhibited by the primary cavitation transients is due to a complex optical lensing effect, which is brought about by the change in refractive index associated with the pressure profile of the shock wave. Objects seen through or immersed in the shock-wave field of an electromagnetic acoustic transducer, such as cavitation, appear highly distorted because of the strong positive and negative lensing effects of the compression and rarefaction cycles of the shock wave. A modification of the schlieren technique called the scale method has been used to model the distortion introduced by the shock wave and consequently explain the cavitation distortion. The technique has also been used to quantitatively analyze and partially reconstruct the lithotripter shock wave. The combination of schlieren and scale imaging gives more information about the refractive index field and therefore the shock-wave structure itself.

Fading Supernova Creates Spectacular Light Show

NASA Technical Reports Server (NTRS)

2003-01-01

This image of SN 1987A, taken November 28, 2003 by the Advanced Camera for Surveys aboard NASA's Hubble Space Telescope (HST), shows many bright spots along a ring of gas, like pearls on a necklace. These cosmic pearls are being produced as superior shock waves unleashed during an explosion slam into the ring at more than a million miles per hour. The collision is heating the gas ring, causing its irnermost regions to glow. Astronomers detected the first of these hot spots in 1996, but now they see dozens of them all around the ring. With temperatures surging from a few thousand degrees to a million degrees, the flares are increasing in number. In the next few years, the entire ring will be ablaze as it absorbs the full force of the crash and is expected to become bright enough to illuminate the star's surroundings. Astronomers will then be able to obtain information on how the star ejected material before the explosion. The elongated and expanding object in the center of the ring is debris form the supernova blast which is being heated by radioactive elements, principally titanium 44, that were created in the explosion. This explosion was first observed by astronomers seventeen years ago in 1987, although the explosion took place about 160,000 years ago.

New method for enhanced efficiency in detection of gravitational waves from supernovae using coherent network of detectors

NASA Astrophysics Data System (ADS)

Mukherjee, S.; Salazar, L.; Mittelstaedt, J.; Valdez, O.

2017-11-01

Supernovae in our universe are potential sources of gravitational waves (GW) that could be detected in a network of GW detectors like LIGO and Virgo. Core-collapse supernovae are rare, but the associated gravitational radiation is likely to carry profuse information about the underlying processes driving the supernovae. Calculations based on analytic models predict GW energies within the detection range of the Advanced LIGO detectors, out to tens of Mpc for certain types of signals e.g. coalescing binary neutron stars. For supernovae however, the corresponding distances are much less. Thus, methods that can improve the sensitivity of searches for GW signals from supernovae are desirable, especially in the advanced detector era. Several methods have been proposed based on various likelihood-based regulators that work on data from a network of detectors to detect burst-like signals (as is the case for signals from supernovae) from potential GW sources. To address this problem, we have developed an analysis pipeline based on a method of noise reduction known as the harmonic regeneration noise reduction (HRNR) algorithm. To demonstrate the method, sixteen supernova waveforms from the Murphy et al. 2009 catalog have been used in presence of LIGO science data. A comparative analysis is presented to show detection statistics for a standard network analysis as commonly used in GW pipelines and the same by implementing the new method in conjunction with the network. The result shows significant improvement in detection statistics.

Numeric spectral radiation hydrodynamic calculations of supernova shock breakouts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sapir, Nir; Halbertal, Dorri

2014-12-01

We present here an efficient numerical scheme for solving the non-relativistic one-dimensional radiation-hydrodynamics equations including inelastic Compton scattering, which is not included in most codes and is crucial for solving problems such as shock breakout. The devised code is applied to the problems of a steady-state planar radiation mediated shock (RMS) and RMS breakout from a stellar envelope. The results are in agreement with those of a previous work on shock breakout, in which Compton equilibrium between matter and radiation was assumed and the 'effective photon' approximation was used to describe the radiation spectrum. In particular, we show that themore » luminosity and its temporal dependence, the peak temperature at breakout, and the universal shape of the spectral fluence derived in this earlier work are all accurate. Although there is a discrepancy between the spectral calculations and the effective photon approximation due to the inaccuracy of the effective photon approximation estimate of the effective photon production rate, which grows with lower densities and higher velocities, the difference in peak temperature reaches only 30% for the most discrepant cases of fast shocks in blue supergiants. The presented model is exemplified by calculations for supernova 1987A, showing the detailed evolution of the burst spectrum. The incompatibility of the stellar envelope shock breakout model results with observed properties of X-ray flashes (XRFs) and the discrepancy between the predicted and observed rates of XRFs remain unexplained.« less

The Progenitor Dependence of Core-collapse Supernovae from Three-dimensional Simulations with Progenitor Models of 12–40 M ⊙

NASA Astrophysics Data System (ADS)

Ott, Christian D.; Roberts, Luke F.; da Silva Schneider, André; Fedrow, Joseph M.; Haas, Roland; Schnetter, Erik

2018-03-01

We present a first study of the progenitor star dependence of the three-dimensional (3D) neutrino mechanism of core-collapse supernovae. We employ full 3D general-relativistic multi-group neutrino radiation-hydrodynamics and simulate the postbounce evolutions of progenitors with zero-age main sequence masses of 12, 15, 20, 27, and 40 M ⊙. All progenitors, with the exception of the 12 M ⊙ star, experience shock runaway by the end of their simulations. In most cases, a strongly asymmetric explosion will result. We find three qualitatively distinct evolutions that suggest a complex dependence of explosion dynamics on progenitor density structure, neutrino heating, and 3D flow. (1) Progenitors with massive cores, shallow density profiles, and high post-core-bounce accretion rates experience very strong neutrino heating and neutrino-driven turbulent convection, leading to early shock runaway. Accretion continues at a high rate, likely leading to black hole formation. (2) Intermediate progenitors experience neutrino-driven, turbulence-aided explosions triggered by the arrival of density discontinuities at the shock. These occur typically at the silicon/silicon–oxygen shell boundary. (3) Progenitors with small cores and density profiles without strong discontinuities experience shock recession and develop the 3D standing-accretion shock instability (SASI). Shock runaway ensues late, once declining accretion rate, SASI, and neutrino-driven convection create favorable conditions. These differences in explosion times and dynamics result in a non-monotonic relationship between progenitor and compact remnant mass.

Wave and particle evolution downstream of quasi-perpendicular shocks

NASA Technical Reports Server (NTRS)

Mckean, M. E.; Omidi, N.; Krauss-Varban, D.; Karimabadi, H.

1995-01-01

Distributions of ions heated in quasi-perpendicular bow shocks have large perpendicular temperature anisotropies that provide free energy for the growth of Alfven ion cyclotron (AIC) and mirror waves. These modes are often obsreved in the Earth's magnetosheath. Using two-dimensional hybrid simulations, we show that these waves are produced near the shock front and convected downstream rather than being produced locally downstream. The wave activity reduces the proton anisotropy to magnetosheath levels within a few tens of gyroradii of the shock but takes significantly longer to reduce the anisotropy of He(++) ions. The waves are primarily driven by proton anisotropy and the dynamics of the helium ions is controlled by the proton waves. Downstream of high Mach number shocks, mirror waves compete effectively with AIC waves. Downstream of low Mach number shocks, AIC waves dominate.

The Impact of the Nuclear Equation of State in Core Collapse Supernovae

NASA Astrophysics Data System (ADS)

Baird, M. L.; Lentz, E. J.; Hix, W. R.; Mezzacappa, A.; Messer, O. E. B.; Liebendoerfer, M.; TeraScale Supernova Initiative Collaboration

2005-12-01

One of the key ingredients to the core collapse supernova mechanism is the physics of matter at or near nuclear density. Included in simulations as part of the Equation of State (EOS), nuclear repulsion experienced at high densities are responsible for the bounce shock, which initially causes the outer envelope of the supernova to expand, as well as determining the structure of the newly formed proto-neutron star. Recent years have seen renewed interest in this fundamental piece of supernova physics, resulting in several promising candidate EOS parameterizations. We will present the impact of these variations in the nuclear EOS using spherically symmetric, Newtonian and General Relativistic neutrino transport simulations of stellar core collapse and bounce. This work is supported in part by SciDAC grants to the TeraScale Supernovae Initiative from the DOE Office of Science High Energy, Nuclear, and Advanced Scientific Computing Research Programs. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for U.S. Department of Energy under contract DEAC05-00OR22725

Pulsational Pair-instability Model for Superluminous Supernova PTF12dam: Interaction and Radioactive Decay

NASA Astrophysics Data System (ADS)

Tolstov, Alexey; Nomoto, Ken'ichi; Blinnikov, Sergei; Sorokina, Elena; Quimby, Robert; Baklanov, Petr

2017-02-01

Being a superluminous supernova, PTF12dam can be explained by a 56Ni-powered model, a magnetar-powered model, or an interaction model. We propose that PTF12dam is a pulsational pair-instability supernova, where the outer envelope of a progenitor is ejected during the pulsations. Thus, it is powered by a double energy source: radioactive decay of 56Ni and a radiative shock in a dense circumstellar medium. To describe multicolor light curves and spectra, we use radiation-hydrodynamics calculations of the STELLA code. We found that light curves are well described in the model with 40 M⊙ ejecta and 20-40 M⊙ circumstellar medium. The ejected 56Ni mass is about 6 M⊙, which results from explosive nucleosynthesis with large explosion energy (2-3) × 1052 erg. In comparison with alternative scenarios of pair-instability supernova and magnetar-powered supernova, in the interaction model, all the observed main photometric characteristics are well reproduced: multicolor light curves, color temperatures, and photospheric velocities.

Numerical Simulations of Shock Wave Refraction at Inclined Gas Contact Discontinuity

ERIC Educational Resources Information Center

Bulat, Pavel V.; Volkov, Konstantin N.

2016-01-01

When a shock wave interacts with a contact discontinuity, there may appear a reflected rarefaction wave, a deflected contact discontinuity and a refracted supersonic shock. The numerical simulation of shock wave refraction at a plane contact discontinuity separating gases with different densities is performed. Euler equations describing inviscid…

Thermal and Nonthermal X-ray Emission from the Forward Shock in Tycho's Supernova Remnant

NASA Technical Reports Server (NTRS)

Hwang, Una; Decourchelle, Anne; Holt, Stephen S.; Petre, Robert; White, Nicholas E. (Technical Monitor)

2002-01-01

We present Chandra CCD images of Tycho's supernova remnant that delineate its outer shock, seen as a thin, smooth rim along the straight northeastern edge and most of the circular western half. The images also show that the Si and S ejecta are highly clumpy, and have reached the forward shock at numerous locations. Most of the X-ray spectra that we examine along the rim show line emission from Si and S, which in some cases must come from ejecta; the continuum is well represented by either thermal or nonthermal models. In the case that the continuum is assumed to be thermal, the temperatures at the rim are all similar at about 2 keV, and the ionization ages are very low because of the overall weakness of the line emission. Assuming shock velocities inferred from radio and X-ray expansion measurements, these temperatures are substantially below those expected for equilibration of the electron and ion temperatures; electron to mean temperature ratios of approximately less than 0.1 - 0.2 indicate at most modest collisionless heating of the electrons at the shock. The nonthermal contribution to these spectra may be important, however, and may account for as many as half of the counts in the 4-6 keV energy range, based on an extrapolation of the hard X-ray spectrum above 10 keV.

Supernova and Prompt Gravitational-wave Precursors to LIGO Gravitational-wave Sources and Short GRBs

NASA Astrophysics Data System (ADS)

Michaely, Erez; Perets, Hagai B.

2018-03-01

Binary black holes (BBHs) and binary neutron stars (BNSs) mergers have been recently detected through their gravitational-wave (GW) emission. A post-merger electromagnetic counterpart for the first BNS merger has been detected from seconds up to weeks after the merger. While such post-merger electromagnetic counterparts had been anticipated theoretically, far fewer electromagnetic precursors to GW sources have been proposed, and non have been observed. Here we show that a fraction of a few ×10‑3 (for a standard model) GW sources and short gamma-ray bursts (GRBs) observed by the Laser Interferometer Gravitational-wave Observatory (LIGO) could have been preceded by supernova (SN) explosions from years up to decades before the mergers. The GW sources are produced following the preceding binary evolution, the supernovae involved in the final formation of the GW source progenitors, and the natal kicks that likely accompany them. Together, these determine the orbits of surviving binaries, and hence the delay-time between the birth of the compact binary and its final merger through GW emission. We use data from binary evolution population-synthesis models to show that the delay-time distribution has a non-negligible tail of ultra-short delay-times between 1 and 100 years, thereby giving rise to potentially observable supernovae precursors to GW sources. Moreover, future LISA/DECIGO GW space-detectors will enable the detection of GW inspirals in the pre-merger stage weeks to decades before the final merger. These sources could therefore produce a unique type of promptly appearing LISA/DECIGO GW sources accompanied by coincident supernovae. The archival (and/or direct) detection of precursor (coincident) SNe with GW and/or short GRBs will provide unprecedented characterizations of the merging binaries, and their prior evolution through supernovae and natal kicks, otherwise inaccessible through other means.

Shock interaction with a two-gas interface in a novel dual-driver shock tube

NASA Astrophysics Data System (ADS)

Labenski, John R.

Fluid instabilities exist at the interface between two fluids having different densities if the flow velocity and density gradient are anti-parallel or if a shock wave crosses the boundary. The former case is called the Rayleigh-Taylor (R-T) instability and the latter, the Richtmyer-Meshkov (R-M) instability. Small initial perturbations on the interface destabilize and grow into larger amplitude structures leading to turbulent mixing. Instabilities of this type are seen in inertial confinement fusion (ICF) experiments, laser produced plasmas, supernova explosions, and detonations. A novel dual-driver shock tube was used to investigate the growth rate of the R-M instability. One driver is used to create an argon-refrigerant interface, and the other at the opposite end of the driven section generates a shock to force the interface with compressible flows behind the shock. The refrigerant gas in the first driver is seeded with sub-micron oil droplets for visualization of the interface. The interface travels down the driven section past the test section for a fixed amount of time. A stronger shock of Mach 1.1 to 1.3 drives the interface back past the test section where flow diagnostics are positioned. Two schlieren systems record the density fluctuations while light scattering detectors record the density of the refrigerant as a function of position over the interface. A pair of digital cameras take stereo images of the interface, as mapped out by the tracer particles under illumination by a Q-switched ruby laser. The amount of time that the interface is allowed to travel up the driven section determines the interaction time as a control. Comparisons made between the schlieren signals, light scattering detector outputs, and the images quantify the fingered characteristics of the interface and its growth due to shock forcing. The results show that the interface has a distribution of thickness and that the interaction with a shock further broadens the interface. The growth rate was found to exhibit a dependence on the shock strength.

ANTIMATTER PRODUCTION IN SUPERNOVA REMNANTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kachelriess, M.; Ostapchenko, S.; Tomas, R.

2011-06-01

We calculate the energy spectra of cosmic rays (CRs) and their secondaries produced in a supernova remnant (SNR) taking into account the time dependence of the SNR shock. We model the trajectories of charged particles as a random walk with a prescribed diffusion coefficient, accelerating the particles at each shock crossing. Secondary production by CRs colliding with gas is included as a Monte Carlo process. We find that SNRs produce less antimatter than suggested previously: the positron/electron ratio F{sub e}{sup +}/F{sub e}{sup +}{sub +e}{sup -} and the antiproton/proton ratio F{sub p-bar/}F{sub p-bar+p} are a few percent and few x 10{supmore » -5}, respectively. Moreover, the obtained positron/electron ratio decreases with energy, while the antiproton/proton ratio rises at most by a factor of two above 10 GeV.« less

Convection- and SASI-driven flows in parametrized models of core-collapse supernova explosions

DOE PAGES

Endeve, E.; Cardall, C. Y.; Budiardja, R. D.; ...

2016-01-21

We present initial results from three-dimensional simulations of parametrized core-collapse supernova (CCSN) explosions obtained with our astrophysical simulation code General Astrophysical Simulation System (GenASIS). We are interested in nonlinear flows resulting from neutrino-driven convection and the standing accretion shock instability (SASI) in the CCSN environment prior to and during the explosion. By varying parameters in our model that control neutrino heating and shock dissociation, our simulations result in convection-dominated and SASI-dominated evolution. We describe this initial set of simulation results in some detail. To characterize the turbulent flows in the simulations, we compute and compare velocity power spectra from convection-dominatedmore » and SASI-dominated (both non-exploding and exploding) models. When compared to SASI-dominated models, convection-dominated models exhibit significantly more power on small spatial scales.« less

Focusing of Shear Shock Waves

NASA Astrophysics Data System (ADS)

Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco

2018-01-01

Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.

Plasma wave phenomena at interplanetary shocks observed by the Ulysses URAP experiment. [Unified Radio and Plasma Waves

NASA Technical Reports Server (NTRS)

Lengyel-Frey, D.; Macdowall, R. J.; Stone, R. G.; Hoang, S.; Pantellini, F.; Harvey, C.; Mangeney, A.; Kellogg, P.; Thiessen, J.; Canu, P.

1992-01-01

We present Ulysses URAP observations of plasma waves at seven interplanetary shocks detected between approximately 1 and 3 AU. The URAP data allows ready correlation of wave phenomena from .1 Hz to 1 MHz. Wave phenomena observed in the shock vicinity include abrupt changes in the quasi-thermal noise continuum, Langmuir wave activity, ion acoustic noise, whistler waves and low frequency electrostatic waves. We focus on the forward/reverse shock pair of May 27, 1991 to demonstrate the characteristics of the URAP data.

Photoacoustic shock wave emission and cavitation from structured optical fiber tips

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammadzadeh, M.; Gonzalez-Avila, S. R.; Ohl, C. D., E-mail: cdohl@ntu.edu.sg

Photoacoustic waves generated at the tip of an optical fiber consist of a compressive shock wave followed by tensile diffraction waves. These tensile waves overlap along the fiber axis and form a cloud of cavitation bubbles. We demonstrate that shaping the fiber tip through micromachining alters the number and direction of the emitted waves and cavitation clouds. Shock wave emission and cavitation patterns from five distinctively shaped fiber tips have been studied experimentally and compared to a linear wave propagation model. In particular, multiple shock wave emission and generation of strong tension away from the fiber axis have been realizedmore » using modified fiber tips. These altered waveforms may be applied for novel microsurgery protocols, such as fiber-based histotripsy, by utilizing bubble-shock wave interaction.« less

Extracorporeal shock waves in the treatment of nonunions.

PubMed

Biedermann, Rainer; Martin, Arho; Handle, Gerhart; Auckenthaler, Thomas; Bach, Christian; Krismer, Martin

2003-05-01

Nonunion remains a major complication after skeletal trauma. In the last decade, extracorporeal shock wave therapy has become a common tool for the treatment of nonunions. To date, no prospective, randomized trial has been conducted to show the efficacy of this form of treatment. This study was performed to determine the value of extracorporeal shock wave therapy for nonunions. Previous published results in the literature and our own clinical results were analyzed and related to the natural history of bony union. No study has proven that extracorporeal shock wave therapy improves bone healing. Clinical studies reporting the acceleration of union after application of shock waves instead seem to misinterpret the natural history of bony union. No evidence supports the treatment of pseudarthroses with extracorporeal shock waves. A randomized, prospective, clinical trial with a control group has to be performed before a final decision can be made regarding this indication for extracorporeal shock wave therapy.

Turbulence in core-collapse supernovae

NASA Astrophysics Data System (ADS)

Radice, David; Abdikamalov, Ernazar; Ott, Christian D.; Mösta, Philipp; Couch, Sean M.; Roberts, Luke F.

2018-05-01

Multidimensional simulations show that non-radial, turbulent, fluid motion is a fundamental component of the core-collapse supernova explosion mechanism. Neutrino-driven convection, the standing accretion shock instability, and relic-perturbations from advanced nuclear burning stages can all impact the outcome of core collapse in a qualitative and quantitative way. Here, we review the current understanding of these phenomena and their role in the explosion of massive stars. We also discuss the role of protoneutron star convection and of magnetic fields in the context of the delayed neutrino mechanism.

Modeling multiscale evolution of numerous voids in shocked brittle material.

PubMed

Yu, Yin; Wang, Wenqiang; He, Hongliang; Lu, Tiecheng

2014-04-01

The influence of the evolution of numerous voids on macroscopic properties of materials is a multiscale problem that challenges computational research. A shock-wave compression model for brittle material, which can obtain both microscopic evolution and macroscopic shock properties, was developed using discrete element methods (lattice model). Using a model interaction-parameter-mapping procedure, qualitative features, as well as trends in the calculated shock-wave profiles, are shown to agree with experimental results. The shock wave splits into an elastic wave and a deformation wave in porous brittle materials, indicating significant shock plasticity. Void collapses in the deformation wave were the natural reason for volume shrinkage and deformation. However, media slippage and rotation deformations indicated by complex vortex patterns composed of relative velocity vectors were also confirmed as an important source of shock plasticity. With increasing pressure, the contribution from slippage deformation to the final plastic strain increased. Porosity was found to determine the amplitude of the elastic wave; porosity and shock stress together determine propagation speed of the deformation wave, as well as stress and strain on the final equilibrium state. Thus, shock behaviors of porous brittle material can be systematically designed for specific applications.

In vitro study of the mechanical effects of shock-wave lithotripsy.

PubMed

Howard, D; Sturtevant, B

1997-01-01

Impulsive stress in repeated shock waves administered during extracorporeal shock-wave lithotripsy (ESWL) causes injury to kidney tissue. In a study of the mechanical input of ESWL, the effects of focused shock waves on thin planar polymeric membranes immersed in a variety of tissue-mimicking fluids have been examined. A direct mechanism of failure by shock compression and an indirect mechanism by bubble collapse have been observed. Thin membranes are easily damaged by bubble collapse. After propagating through cavitation-free acoustically heterogeneous media (liquids mixed with hollow glass spheres, and tissue) shock waves cause membranes to fail in fatigue by a shearing mechanism. As is characteristic of dynamic fatigue, the failure stress increases with strain rate, determined by the amplitude and rise time of the attenuated shock wave. Shocks with large amplitude and short rise time (i.e., in uniform media) cause no damage. Thus the inhomogeneity of tissue is likely to contribute to injury in ESWL. A definition of dose is proposed which yields a criterion for damage based on measurable shock wave properties.

Myocardial effects of local shock wave therapy in a Langendorff model.

PubMed

Becker, M; Goetzenich, A; Roehl, A B; Huebel, C; de la Fuente, M; Dietz-Laursonn, K; Radermacher, K; Rossaint, R; Hein, M

2014-01-01

Applying shock waves to the heart has been reported to stimulate the heart and alter cardiac function. We hypothesized that shock waves could be used to diagnose regional viability. We used a Langendorff model to investigate the acute effects of shock waves at different energy levels and times related to systole, cycle duration and myocardial function. We found only a small time window to use shock waves. Myocardial fibrillation or extrasystolic beats will occur if the shock wave is placed more than 15 ms before or 30 ms after the onset of systole. Increased contractility and augmented relaxation were observed after the second beat, and these effects decreased after prolonging the shock wave delay from 15 ms before to 30 ms after the onset of systole. An energy dependency could be found only after short delays (-15 ms). The involved processes might include post-extrasystolic potentiation and simultaneous pacing. In summary, we found that low-energy shock waves can be a useful tool to stimulate the myocardium at a distance and influence function. Copyright © 2013 Elsevier B.V. All rights reserved.

STOCHASTICITY AND EFFICIENCY IN SIMPLIFIED MODELS OF CORE-COLLAPSE SUPERNOVA EXPLOSIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardall, Christian Y.; Budiardja, Reuben D., E-mail: cardallcy@ornl.gov, E-mail: reubendb@utk.edu

2015-11-01

We present an initial report on 160 simulations of a highly simplified model of the post-bounce core-collapse supernova environment in three spatial dimensions (3D). We set different values of a parameter characterizing the impact of nuclear dissociation at the stalled shock in order to regulate the post-shock fluid velocity, thereby determining the relative importance of convection and the stationary accretion shock instability (SASI). While our convection-dominated runs comport with the paradigmatic notion of a “critical neutrino luminosity” for explosion at a given mass accretion rate (albeit with a nontrivial spread in explosion times just above threshold), the outcomes of ourmore » SASI-dominated runs are much more stochastic: a sharp threshold critical luminosity is “smeared out” into a rising probability of explosion over a ∼20% range of luminosity. We also find that the SASI-dominated models are able to explode with 3–4 times less efficient neutrino heating, indicating that progenitor properties, and fluid and neutrino microphysics, conducive to the SASI would make the neutrino-driven explosion mechanism more robust.« less

Stochasticity and efficiency of convection-dominated vs. SASI-dominated supernova explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardall, Christian Y.; Budiardja, Reuben D.

2015-10-22

We present an initial report on 160 simulations of a highly simplified model of the post-bounce supernova environment in three position space dimensions (3D). We set different values of a parameter characterizing the impact of nuclear dissociation at the stalled shock in order to regulate the post-shock fluid velocity, thereby determining the relative importance of convection and the stationary accretion shock instability (SASI). While our convection-dominated runs comport with the paradigmatic notion of a `critical neutrino luminosity' for explosion at a given mass accretion rate (albeit with a nontrivial spread in explosion times just above threshold), the outcomes of our SASI-dominated runs are more stochastic: a sharp threshold critical luminosity is `smeared out' into a rising probability of explosion over amore » $$\\sim 20\\%$$ range of luminosity. We also find that the SASI-dominated models are able to explode with 3 to 4 times less efficient neutrino heating, indicating that progenitor properties, and fluid and neutrino microphysics, conducive to the SASI would make the neutrino-driven explosion mechanism more robust.« less

Shock Wave-Induced Damage and Poration in Eukaryotic Cell Membranes.

PubMed

López-Marín, Luz M; Millán-Chiu, Blanca E; Castaño-González, Karen; Aceves, Carmen; Fernández, Francisco; Varela-Echavarría, Alfredo; Loske, Achim M

2017-02-01

Shock waves are known to permeabilize eukaryotic cell membranes, which may be a powerful tool for a variety of drug delivery applications. However, the mechanisms involved in shock wave-mediated membrane permeabilization are still poorly understood. In this study, the effects on both the permeability and the ultrastructural features of two human cell lineages were investigated after the application of underwater shock waves in vitro. Scanning Electron Microscopy of cells derived from a human embryo kidney (HEK)-293 and Michigan Cancer Foundation (MCF)-7 cells, an immortalized culture derived from human breast adenocarcinoma, showed a small amount of microvilli (as compared to control cells), the presence of hole-like structures, and a decrease in cell size after shock wave exposure. Interestingly, these effects were accompanied by the permeabilization of acid and macromolecular dyes and gene transfection. Trypan blue exclusion assays indicated that cell membranes were porated during shock wave treatment but resealed after a few seconds. Deformations of the cell membrane lasted for at least 5 min, allowing their observation in fixed cells. For each cell line, different shock wave parameters were needed to achieve cell membrane poration. This difference was correlated to successful gene transfection by shock waves. Our results demonstrate, for the first time, that shock waves induce transient micro- and submicrosized deformations at the cell membrane, leading to cell transfection and cell survival. They also indicate that ultrastructural analyses of cell surfaces may constitute a useful way to match the use of shock waves to different cells and settings.

Cytoplasmic molecular delivery with shock waves: importance of impulse.

PubMed Central

Kodama, T; Hamblin, M R; Doukas, A G

2000-01-01

Cell permeabilization using shock waves may be a way of introducing macromolecules and small polar molecules into the cytoplasm, and may have applications in gene therapy and anticancer drug delivery. The pressure profile of a shock wave indicates its energy content, and shock-wave propagation in tissue is associated with cellular displacement, leading to the development of cell deformation. In the present study, three different shock-wave sources were investigated; argon fluoride excimer laser, ruby laser, and shock tube. The duration of the pressure pulse of the shock tube was 100 times longer than the lasers. The uptake of two fluorophores, calcein (molecular weight: 622) and fluorescein isothiocyanate-dextran (molecular weight: 71,600), into HL-60 human promyelocytic leukemia cells was investigated. The intracellular fluorescence was measured by a spectrofluorometer, and the cells were examined by confocal fluorescence microscopy. A single shock wave generated by the shock tube delivered both fluorophores into approximately 50% of the cells (p < 0.01), whereas shock waves from the lasers did not. The cell survival fraction was >0.95. Confocal microscopy showed that, in the case of calcein, there was a uniform fluorescence throughout the cell, whereas, in the case of FITC-dextran, the fluorescence was sometimes in the nucleus and at other times not. We conclude that the impulse of the shock wave (i.e., the pressure integrated over time), rather than the peak pressure, was a dominant factor for causing fluorophore uptake into living cells, and that shock waves might have changed the permeability of the nuclear membrane and transferred molecules directly into the nucleus. PMID:11023888

Effect of Shock Waves on Dielectric Properties of KDP Crystal

NASA Astrophysics Data System (ADS)

Sivakumar, A.; Suresh, S.; Pradeep, J. Anto; Balachandar, S.; Martin Britto Dhas, S. A.

2018-05-01

An alternative non-destructive approach is proposed and demonstrated for modifying electrical properties of crystal using shock-waves. The method alters dielectric properties of a potassium dihydrogen phosphate (KDP) crystal by loading shock-waves generated by a table-top shock tube. The experiment involves launching the shock-waves perpendicular to the (100) plane of the crystal using a pressure driven table-top shock tube with Mach number 1.9. Electrical properties of dielectric constant, dielectric loss, permittivity, impedance, AC conductivity, DC conductivity and capacitance as a function of spectrum of frequency from 1 Hz to 1 MHz are reported for both pre- and post-shock wave loaded conditions of the KDP crystal. The experimental results reveal that dielectric constant of KDP crystal is sensitive to the shock waves such that the value decreases for the shock-loaded KDP sample from 158 to 147. The advantage of the proposed approach is that it is an alternative to the conventional doping process for tailoring dielectric properties of this type of crystal.

Possible explanation of the correlations between events recorded by underground detectors during the Supernova 1987A explosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexeyev, E. N., E-mail: alexeyev@ms2.inr.ac.r

A possible explanation of the time correlations between the data from underground detectors (Baksan telescope, LSD, IMB, Kamiokande II) and from the Rome and Maryland gravitational-wave antennas obtained during the Supernova 1987A explosion is proposed. It is shown that the synchronization of the events recorded by various underground facilities could be produced by gravitational radiation from the Supernova.

A Model of the Vela Supernova Remnant

NASA Astrophysics Data System (ADS)

Gvaramadze, Vasilii

2000-10-01

A model of the Vela supernova remnant (SNR) based on a cavity explosion of a supernova (SN) star is proposed. It is suggested that the general structure of the remnant is determined by the interaction of the SN blast wave with a massive shell created by the SN progenitor (15-20 M_solar) star. A possible origin of the nebula of hard X-ray emission detected around the Vela pulsar is discussed.

ON THE IMPORTANCE OF THE EQUATION OF STATE FOR THE NEUTRINO-DRIVEN SUPERNOVA EXPLOSION MECHANISM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suwa, Yudai; Takiwaki, Tomoya; Kotake, Kei

2013-02-10

By implementing the widely used equations of state (EOS) from Lattimer and Swesty (LS) and H. Shen et al. (SHEN) in core-collapse supernova simulations, we explore possible impacts of these EOS on the post-bounce dynamics prior to the onset of neutrino-driven explosions. Our spherically symmetric (1D) and axially symmetric (2D) models are based on neutrino radiation hydrodynamics including spectral transport, which is solved by the isotropic diffusion source approximation. We confirm that in 1D simulations neutrino-driven explosions cannot be obtained for any of the employed EOS. Impacts of the EOS on the post-bounce hydrodynamics are more clearly visible in 2Dmore » simulations. In 2D models of a 15 M {sub Sun} progenitor using the LS EOS, the stalled bounce shock expands to increasingly larger radii, which is not the case when using the SHEN EOS. Keeping in mind that the omission of the energy drain by heavy-lepton neutrinos in the present scheme could facilitate explosions, we find that 2D models of an 11.2 M {sub Sun} progenitor produce neutrino-driven explosions for all the EOS under investigation. Models using the LS EOS are slightly more energetic compared with those with the SHEN EOS. The more efficient neutrino heating in the LS models coincides with a higher electron antineutrino luminosity and a larger mass that is enclosed within the gain region. The models based on the LS EOS also show a more vigorous and aspherical downflow of accreting matter to the surface of the protoneutron star (PNS). The accretion pattern is essential for the production and strength of outgoing pressure waves, which can push in turn the shock to larger radii and provide more favorable conditions for the explosion. Based on our models, we investigate several diagnostic indicators of the explosion that have been suggested in the literature, e.g., the amplitude of the standing accretion shock instability mode, the mass-weighted average entropy in the gain region, the PNS radius, the antesonic condition, the ratio of advection and heating timescales, the neutrino heating efficiency, and the growth parameter of convection.« less

High-Energy Cosmic Rays from Supernovae

NASA Astrophysics Data System (ADS)

Morlino, Giovanni

Cosmic rays are charged relativistic particles that reach the Earth with extremely high energies, providing striking evidence of the existence of effective accelerators in the Universe. Below an energy around ˜ 1017 eV, cosmic rays are believed to be produced in the Milky Way, while above that energy, their origin is probably extragalactic. In the early 1930s, supernovae were already identified as possible sources for the galactic component of cosmic rays. After the 1970s this idea has gained more and more credibility, thanks to the development of the diffusive shock acceleration theory, which provides a robust theoretical framework for particle energization in astrophysical environments. Afterward, mostly in recent years, much observational evidence has been gathered in support of this framework, converting a speculative idea in a real paradigm. In this chapter the basic pillars of this paradigm will be illustrated. This includes the acceleration mechanism, the nonlinear effects produced by accelerated particles onto the shock dynamics needed to reach the highest energies, the escape process from the sources, and the transportation of cosmic rays through the Galaxy. The theoretical picture will be corroborated by discussing several observations which support the idea that supernova remnants are effective cosmic ray factories.

Interaction of strong converging shock wave with SF6 gas bubble

NASA Astrophysics Data System (ADS)

Liang, Yu; Zhai, ZhiGang; Luo, XiSheng

2018-06-01

Interaction of a strong converging shock wave with an SF6 gas bubble is studied, focusing on the effects of shock intensity and shock shape on interface evolution. Experimentally, the converging shock wave is generated by shock dynamics theory and the gas bubble is created by soap film technique. The post-shock flow field is captured by a schlieren photography combined with a high-speed video camera. Besides, a three-dimensional program is adopted to provide more details of flow field. After the strong converging shock wave impact, a wide and pronged outward jet, which differs from that in planar shock or weak converging shock condition, is derived from the downstream interface pole. This specific phenomenon is considered to be closely associated with shock intensity and shock curvature. Disturbed by the gas bubble, the converging shocks approaching the convergence center have polygonal shapes, and the relationship between shock intensity and shock radius verifies the applicability of polygonal converging shock theory. Subsequently, the motion of upstream point is discussed, and a modified nonlinear theory considering rarefaction wave and high amplitude effects is proposed. In addition, the effects of shock shape on interface morphology and interface scales are elucidated. These results indicate that the shape as well as shock strength plays an important role in interface evolution.

Observations of TeV Gamma Rays from Supernova Remnants

NASA Astrophysics Data System (ADS)

Buckley, James H.

1994-12-01

Measurements of the gamma ray flux from a number of supernova remnants (SNRs) at energies above 250 GeV have been made with the Whipple Imaging air \\v Cerenkov detector. Observation of the gamma ray emission of SNRs at energies above 1 GeV should provide a sensitive test of shock acceleration models of particle acceleration in SNRs. Gamma-ray luminosities of supernova remnants are well constrained by the observed supernova rate and the cosmic ray flux if supernovae are indeed the source of cosmic rays. Drury et al. (Astron. Astrophys. 287, 959 (1994)) predict that the luminosity of nearby Sedov-phase SNRs should be observable by the Whipple telescope. In this model, diffusive shock acceleration produces energetic charged particles which interact with the ambient medium forming gamma rays. There is an indication that a number of unidentified EGRET sources may correspond to supernova remnants (G. Kanbach, private communication), although at these energies (>100 MeV) the diffuse background is somewhat uncertain. Measurements of the gamma-ray flux with the Whipple instrument have a similar sensitivity to the EGRET detector for a source spectral index of 2.15, and less sensitivity to diffuse background. A number of observations of SNRs including: Tycho, W66, IC443, and others have been made. Currently for Tycho an upper limit of 9times 10(-12) cm(-2) sec(-1) is obtained. The status of these observations will be presented, and it will be shown that these measurements combined with the EGRET observations are beginning to provide a useful constraint on models of cosmic ray origin. Gamma-ray observations may also be used to constrain models of particle acceleration in SNRs exhibiting pulser-powered synchrotron nebula (plerions). The status of observations of this class of objects, including the Crab nebula, will also be presented. Supported in part by the U.S. Dept. of Energy.

A numerical study of shock wave reflections on low density foam

NASA Astrophysics Data System (ADS)

Baer, M. R.

1992-06-01

A continuum mixture theory is used to describe shock wave reflections on low density open-cell polyurethane foam. Numerical simulations are compared to the shock tube experiments of Skews (1991) and detailed wave fields are shown of a shock wave interacting with a layer of foam adjacent to a rigid wall boundary. These comparisons demonstrate that a continuum mixture theory describes well the shock interactions with low density foam.

Shock Waves in a Bose-Einstein Condensate

NASA Technical Reports Server (NTRS)

Kulikov, Igor; Zak, Michail

2005-01-01

A paper presents a theoretical study of shock waves in a trapped Bose-Einstein condensate (BEC). The mathematical model of the BEC in this study is a nonlinear Schroedinger equation (NLSE) in which (1) the role of the wave function of a single particle in the traditional Schroedinger equation is played by a space- and time-dependent complex order parameter (x,t) proportional to the square root of the density of atoms and (2) the atoms engage in a repulsive interaction characterized by a potential proportional to | (x,t)|2. Equations that describe macroscopic perturbations of the BEC at zero temperature are derived from the NLSE and simplifying assumptions are made, leading to equations for the propagation of sound waves and the transformation of sound waves into shock waves. Equations for the speeds of shock waves and the relationships between jumps of velocity and density across shock fronts are derived. Similarities and differences between this theory and the classical theory of sound waves and shocks in ordinary gases are noted. The present theory is illustrated by solving the equations for the example of a shock wave propagating in a cigar-shaped BEC.

The Observable Signatures of GRB Cocoons

NASA Astrophysics Data System (ADS)

Nakar, Ehud; Piran, Tsvi

2017-01-01

As a long gamma-ray burst (GRB) jet propagates within the stellar atmosphere it creates a cocoon composed of an outer Newtonian shocked stellar material and an inner (possibly relativistic) shocked jet. The jet deposits {10}51{--}{10}52 erg into this cocoon. This is comparable to the energies of the GRB and of the accompanying supernova, yet the cocoon’s signature has been largely ignored. The cocoon radiates a fraction of this energy as it expands, following the breakout from the star, and later as it interacts with the surrounding matter. We explore the possible signatures of this emission and outline a framework to calculate them from the conditions of the cocoon at the time of the jet breakout. The cocoon signature depends strongly on the, currently unknown, mixing between the shocked jet and shocked stellar material. With no mixing the γ-ray emission from the cocoon is so bright that it should have been already detected. The lack of such detections indicates that some mixing must take place. For partial and full mixing the expected signals are weaker than regular GRB afterglows. However, the latter are highly beamed while the former are wider. Future optical, UV, and X-ray transient searches, like LSST, ZTF, ULTRASAT, ISS-Lobster, and others, will most likely detect such signals, providing a wealth of information on the progenitors and jets of GRBs. While we focus on long GRBs, analogous (but weaker) cocoons may arise in short GRBs. Their signatures might be the most promising electromagnetic counterparts for gravitational wave signals from compact binary mergers.

Seismic excitation by the space shuttle Columbia

USGS Publications Warehouse

Kanamori, H.; Mori, J.; Anderson, D.L.; Heaton, T.H.

1991-01-01

SEISMIC stations in southern California recorded the atmospheric shock waves generated by the space shuttle Columbia on its return to the Edwards Air Force base on 13 August 1989 (Fig. 1). In addition to the shock wave, the broad-band IRIS-TERRAscope station at Pasadena recorded a distinct pulse with a period of ???2-3 seconds, which arrived 12.5 seconds before the shock wave (Fig. 2). This pulse was also recorded at the University of Southern California, near downtown Los Angeles, where it arrived 3 seconds after the shock wave. The origin of this pulse could not be readily identified. We show here that it was a seismic P wave excited by the motion of high-rise buildings in downtown Los Angeles, which were hit by the shock wave. The proximity of the natural period of the high-rise buildings to that of the Los Angeles basin enabled efficient energy transfer from shock wave to seismic wave.

Shock wave interaction with L-shaped structures

NASA Astrophysics Data System (ADS)

Miller, Richard C.

1993-12-01

This study investigated the interaction of shock waves with L-shaped structures using the CTH hydrodynamics code developed by Sandia National Laboratories. Computer models of shock waves traveling through air were developed using techniques similar to shock tube experiments. Models of L-shaped buildings were used to determine overpressures achieved by the reflecting shock versus angle of incidence of the shock front. An L-shaped building model rotated 45 degrees to the planar shock front produced the highest reflected overpressure of 9.73 atmospheres in the corner joining the two wings, a value 9.5 times the incident overpressure of 1.02 atmospheres. The same L-shaped building was modeled with the two wings separated by 4.24 meters to simulate an open courtyard. This open area provided a relief path for the incident shock wave, creating a peak overpressure of only 4.86 atmospheres on the building's wall surfaces from the same 1.02 atmosphere overpressure incident shock wave.

Bifurcation parameters of a reflected shock wave in cylindrical channels of different roughnesses

NASA Astrophysics Data System (ADS)

Penyazkov, O.; Skilandz, A.

2018-03-01

To investigate the effect of bifurcation on the induction time in cylindrical shock tubes used for chemical kinetic experiments, one should know the parameters of the bifurcation structure of a reflected shock wave. The dynamics and parameters of the shock wave bifurcation, which are caused by reflected shock wave-boundary layer interactions, are studied experimentally in argon, in air, and in a hydrogen-nitrogen mixture for Mach numbers M = 1.3-3.5 in a 76-mm-diameter shock tube without any ramp. Measurements were taken at a constant gas density behind the reflected shock wave. Over a wide range of experimental conditions, we studied the axial projection of the oblique shock wave and the pressure distribution in the vicinity of the triple Mach configuration at 50, 150, and 250 mm from the endwall, using side-wall schlieren and pressure measurements. Experiments on a polished shock tube and a shock tube with a surface roughness of 20 {μ }m Ra were carried out. The surface roughness was used for initiating small-scale turbulence in the boundary layer behind the incident shock wave. The effect of small-scale turbulence on the homogenization of the transition zone from the laminar to turbulent boundary layer along the shock tube perimeter was assessed, assuming its influence on a subsequent stabilization of the bifurcation structure size versus incident shock wave Mach number, as well as local flow parameters behind the reflected shock wave. The influence of surface roughness on the bifurcation development and pressure fluctuations near the wall, as well as on the Mach number, at which the bifurcation first develops, was analyzed. It was found that even small additional surface roughness can lead to an overshoot in pressure growth by a factor of two, but it can stabilize the bifurcation structure along the shock tube perimeter.

Circular Polarizations of Gravitational Waves from Core-Collapse Supernovae: A Clear Indication of Rapid Rotation.

PubMed

Hayama, Kazuhiro; Kuroda, Takami; Nakamura, Ko; Yamada, Shoichi

2016-04-15

We propose to employ the circular polarization of gravitational waves emitted by core-collapse supernovae as an unequivocal indication of rapid rotation deep in their cores just prior to collapse. It has been demonstrated by three dimensional simulations that nonaxisymmetric accretion flows may develop spontaneously via hydrodynamical instabilities in the postbounce cores. It is not surprising, then, that the gravitational waves emitted by such fluid motions are circularly polarized. We show, in this Letter, that a network of the second generation detectors of gravitational waves worldwide may be able to detect such polarizations up to the opposite side of the Galaxy as long as the rotation period of the core is shorter than a few seconds prior to collapse.

Critical Resolution and Physical Dependenices of Supernovae: Stars in Heat and Under Pressure

NASA Astrophysics Data System (ADS)

Vartanyan, David; Burrows, Adam Seth

2017-01-01

For over five decades, the mechanism of explosion in core-collapse supernova continues to remain one of the last untoppled bastions in astrophysics, presenting both a technical and physical problem.Motivated by advances in computation and nuclear physics and the resilience of the core-collapse problem, collaborators Adam Burrows (Princeton), Joshua Dolence (LANL), and Aaron Skinner (LNL) have developed FORNAX - a highly parallelizable multidimensional supernova simulation code featuring an explicit hydrodynamic and radiation-transfer solver.We present the results (Vartanyan et. al 2016, Burrows et. al 2016, both in preparation) of a sequence of two-dimensional axisymmetric simulations of core-collapse supernovae using FORNAX, probing both progenitor mass dependence and the effect of physical inputs in explosiveness in our study on the revival of the stalled shock via the neutrino heating mechanism. We also performed a resolution study, testing spatial and energy group resolutions as well as compilation flags. We illustrate that, when the protoneutron star bounded by a stalled shock is close to the critical explosion condition (Burrows & Goshy 1993), small changes of order 10% in neutrino energies and luminosities can result in explosion, and that these effects couple nonlinearly.We show that many-body medium effects due to neutrino-nucleon scattering as well as inelastic neutrino-nucleon and neutrino-electron scattering are strongly favorable to earlier and more vigorous explosions by depositing energy in the gain region. Additionally, we probe the effects of a ray-by-ray+ transport solver (which does not include transverse velocity terms) employed by many groups and confirm that it artificially accelerates explosion (see also Skinner et. al 2016).In the coming year, we are gearing up for the first set of 3D simulations yet performed in the context of core-collapse supernovae employing 20 energy groups, and one of the most complete nuclear physics modules in the field with the ambitious goal of simulating supernova remants like Cas A. The current environment for core-collapse supernova provides for invigorating optimism that a robust explosion mechanism is within reach on graduate student lifetimes.

Second sound shock waves and critical velocities in liquid helium 2. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Turner, T. N.

1979-01-01

Large amplitude second-sound shock waves were generated and the experimental results compared to the theory of nonlinear second-sound. The structure and thickness of second-sound shock fronts are calculated and compared to experimental data. Theoretically it is shown that at T = 1.88 K, where the nonlinear wave steepening vanishes, the thickness of a very weak shock must diverge. In a region near this temperature, a finite-amplitude shock pulse evolves into an unusual double-shock configuration consisting of a front steepened, temperature raising shock followed by a temperature lowering shock. Double-shocks are experimentally verified. It is experimentally shown that very large second-sound shock waves initiate a breakdown in the superfluidity of helium 2, which is dramatically displayed as a limit to the maximum attainable shock strength. The value of the maximum shock-induced relative velocity represents a significant lower bound to the intrinsic critical velocity of helium 2.

Multipoint study of interplanetary shocks

NASA Astrophysics Data System (ADS)

Blanco-Cano, Xochitl; Kajdic, Primoz; Russell, Christopher T.; Aguilar-Rodriguez, Ernesto; Jian, Lan K.; Luhmann, Janet G.

2016-04-01

Interplanetary (IP) shocks are driven in the heliosphere by Interplanetary Coronal Mass Ejections (ICMEs) and Stream Interaction Regions (SIRs). These shocks perturb the solar wind plasma, and play an active role in the acceleration of ions to suprathermal energies. Shock fronts evolve as they move from the Sun. Their surfaces can be far from uniform and be modulated by changes in the ambient solar wind (magnetic field orientation, flow velocity), shocks rippling, and perturbations upstream and downstream from the shocks, i.e., electromagnetic waves. In this work we use multipoint observations from STEREO, WIND, and MESSENGER missions to study shock characteristics at different helio-longitudes and determine the properties of the waves near them. We also determine shock longitudinal extensions and foreshock sizes. The variations of geometry along the shock surface can result in different extensions of the wave and ion foreshocks ahead of the shocks, and in different wave modes upstream and downtream of the shocks. We find that the ion foreshock can extend up to 0.2 AU ahead of the shock, and that the upstream region with modified solar wind/waves can be very asymmetric.

Detonation onset following shock wave focusing

NASA Astrophysics Data System (ADS)

Smirnov, N. N.; Penyazkov, O. G.; Sevrouk, K. L.; Nikitin, V. F.; Stamov, L. I.; Tyurenkova, V. V.

2017-06-01

The aim of the present paper is to study detonation initiation due to focusing of a shock wave reflected inside a cone. Both numerical and experimental investigations were conducted. Comparison of results made it possible to validate the developed 3-d transient mathematical model of chemically reacting gas mixture flows incorporating hydrogen - air mixtures. The results of theoretical and numerical experiments made it possible improving kinetic schemes and turbulence models. Several different flow scenarios were detected in reflection of shock waves all being dependent on incident shock wave intensity: reflecting of shock wave with lagging behind combustion zone, formation of detonation wave in reflection and focusing, and intermediate transient regimes.

3D Simulations of Supernova Remnants from Type Ia Supernova Models

NASA Astrophysics Data System (ADS)

Johnson, Heather; Reynolds, S. P.; Frohlich, C.; Blondin, J. M.

2014-01-01

Type Ia supernovae (SNe) originate from thermonuclear explosions of white dwarfs. A great deal is still unknown about the explosion mechanisms, particularly the degree of asymmetry. However, Type Ia supernova remnants (SNRs) can bear the imprint of asymmetry long after the explosion. A SNR of interest is G1.9+0.3, the youngest Galactic SNR, which demonstrates an unusual spatial distribution of elements in the ejecta. While its X-ray spectrum is dominated by synchrotron emission, spectral lines of highly ionized Si, S, and Fe are seen in a few locations, with Fe near the edge of the remnant and with strongly varying Fe/Si ratios. An asymmetric explosion within the white dwarf progenitor may be necessary to explain these unusual features of G1.9+0.3, in particular the shocked Fe at large radii. We use the VH-1 hydrodynamics code to evolve initial Type Ia explosion models in 1, 2, and 3 dimensions at an age of 100 seconds provided by other researchers to study asymmetry, the ignition properties, and the nucleosynthesis resulting from these explosions. We follow the evolution of these models interacting with a uniform external medium to a few hundred years in age. We find the abundance and location of ejecta elements from our models to be inconsistent with the observations of G1.9+0.3; while our models show asymmetric element distributions, we find no tendency for iron-group elements to be found beyond intermediate-mass elements, or for significant iron to be reverse-shocked at all at the age of G1.9+0.3. We compare the amounts of shocked iron-group and intermediate-mass elements as a function of time in the different models. Some new kind of explosion asymmetry may be required to explain G1.9+0.3. This work was performed as part of NC State University's Undergraduate Research in Computational Astrophysics (URCA) program, an REU program supported by the National Science Foundation through award AST-1032736.

Shock wave attenuation in a micro-channel

NASA Astrophysics Data System (ADS)

Giordano, J.; Perrier, P.; Meister, L.; Brouillette, M.

2018-05-01

This work presents optical measurements of shock wave attenuation in a glass micro-channel. This transparent facility, with a cross section ranging from 1 mm× 150 μm to 1 mm× 500 μm, allowed for the use of high-speed schlieren videography to visualize the propagation of a shock wave within the entire micro-channel and to quantify velocity attenuation of the wave due to wall effects. In this paper, we present the experimental technique and the relevant data treatment we have used to increase the sensitivity of shock wave detection. Then, we compared our experimental results for different channel widths, lengths, and shock wave velocities with the analytical model for shock attenuation proposed by Russell (J Fluid Mech 27(2):305-314, 1967), which assumes laminar flow, and by Mirels (Attenuation in a shock tube due to unsteady-boundary-layer action, NACA Report 1333, 1957) for turbulent flow. We found that these models are inadequate to predict the observed data, owing to the presence of fully developed flow which violates the basic assumption of these models. The data are also compared with the empirical shock attenuation models proposed by Zeitoun (Phys Fluids 27(1):011701, 2015) and Deshpande and Puranik (Shock Waves 26(4):465-475, 2016), where better agreement is observed. Finally, we presented experimental data for the flow field behind the shock wave from measurements of the Mach wave angle which shows globally decreasing flow Mach numbers due to viscous wall effects.

Wave and ion evolution downstream of quasi-perpendicular bow shocks

NASA Technical Reports Server (NTRS)

Mckean, M. E.; Omidi, N.; Krauss-Varban, D.

1995-01-01

Distribution functions of ions heated in quasi-perpendicular bow shocks have a large perpendicular temperature anisotropy that provides free energy for the growth of Alfven ion cyclotron (AIC) waves and mirror waves. Both types of waves have been observed in the Earth's magnetosheath downstream of quasi-perpendicular shocks. We use a two-dimensional hybrid simulations to give a self-consistent description of the evolution of the wave spectra downstream of quasi-perpendicular shocks. Both mirror and AIC waves are identified in the simulated magnetosheath. They are generated at or near the shock front and convected away from it by the sheath plasma. Near the shock, the waves have a broad spectrum, but downstream of the shock, shorter-wavelength modes are heavily damped and only longer-wavelength modes persist. The characteristics of these surviving modes can be predicted with reasonable accuracy by linear kinetic theory appropriate for downstream conditions. We also follow the evolution of the ion distribution function. The shocked ions that provide the free energy for wave growth have a two-component distribution function. The halo is initially gyrophase-bunched and extremely anisotropic. Within a relatively short distance downstream of the shock (of the order of 10 ion inertial lengths), wave-particle interactions remove these features from the halo and reduce the anisotropy of the distribution to near-threshold levels for the mirror and AIC instabilities. A similar evolution has been observed for ions at the Earth's bow shock.

A new shock wave assisted sandalwood oil extraction technique

NASA Astrophysics Data System (ADS)

Arunkumar, A. N.; Srinivasa, Y. B.; Ravikumar, G.; Shankaranarayana, K. H.; Rao, K. S.; Jagadeesh, G.

A new shock wave assisted oil extraction technique from sandalwood has been developed in the Shock Waves Lab, IISc, Bangalore. The fragrant oil extracted from sandalwood finds variety of applications in medicine and perfumery industries. In the present method sandal wood specimens (2.5mm diameter and 25mm in length)are subjected to shock wave loading (over pressure 15 bar)in a constant area shock tube, before extracting the sandal oil using non-destructive oil extraction technique. The results from the study indicates that both the rate of extraction as well as the quantity of oil obtained from sandal wood samples exposed to shock waves are higher (15-40 percent) compared to non-destructive oil extraction technique. The compressive squeezing of the interior oil pockets in the sandalwood specimen due to shock wave loading appears to be the main reason for enhancement in the oil extraction rate. This is confirmed by the presence of warty structures in the cross-section and micro-fissures in the radial direction of the wood samples exposed to shock waves in the scanning electron microscopic investigation. In addition the gas chromatographic studies do not show any change in the q uality of sandal oil extracted from samples exposed to shock waves.

Shock waves and shock tubes; Proceedings of the Fifteenth International Symposium, Berkeley, CA, July 28-August 2, 1985

NASA Technical Reports Server (NTRS)

Bershader, D. (Editor); Hanson, R. (Editor)

1986-01-01

A detailed survey is presented of shock tube experiments, theoretical developments, and applications being carried out worldwide. The discussions explore shock tube physics and the related chemical, physical and biological science and technology. Extensive attention is devoted to shock wave phenomena in dusty gases and other multiphase and heterogeneous systems, including chemically reactive mixtures. Consideration is given to techniques for measuring, visualizing and theoretically modeling flowfield, shock wave and rarefaction wave characteristics. Numerical modeling is explored in terms of the application of computational fluid dynamics techniques to describing flowfields in shock tubes. Shock interactions and propagation, in both solids, fluids, gases and mixed media are investigated, along with the behavior of shocks in condensed matter. Finally, chemical reactions that are initiated as the result of passage of a shock wave are discussed, together with methods of controlling the evolution of laminar separated flows at concave corners on advanced reentry vehicles.

Shock waves and shock tubes; Proceedings of the Fifteenth International Symposium, Berkeley, CA, July 28-August 2, 1985

NASA Astrophysics Data System (ADS)

Bershader, D.; Hanson, R.

A detailed survey is presented of shock tube experiments, theoretical developments, and applications being carried out worldwide. The discussions explore shock tube physics and the related chemical, physical and biological science and technology. Extensive attention is devoted to shock wave phenomena in dusty gases and other multiphase and heterogeneous systems, including chemically reactive mixtures. Consideration is given to techniques for measuring, visualizing and theoretically modeling flowfield, shock wave and rarefaction wave characteristics. Numerical modeling is explored in terms of the application of computational fluid dynamics techniques to describing flowfields in shock tubes. Shock interactions and propagation, in both solids, fluids, gases and mixed media are investigated, along with the behavior of shocks in condensed matter. Finally, chemical reactions that are initiated as the result of passage of a shock wave are discussed, together with methods of controlling the evolution of laminar separated flows at concave corners on advanced reentry vehicles.

Intense plasma waves at and near the solar wind termination shock.

PubMed

Gurnett, D A; Kurth, W S

2008-07-03

Plasma waves are a characteristic feature of shocks in plasmas, and are produced by non-thermal particle distributions that develop in the shock transition layer. The electric fields of these waves have a key role in dissipating energy in the shock and driving the particle distributions back towards thermal equilibrium. Here we report the detection of intense plasma-wave electric fields at the solar wind termination shock. The observations were obtained from the plasma-wave instrument on the Voyager 2 spacecraft. The first evidence of the approach to the shock was the detection of upstream electron plasma oscillations on 1 August 2007 at a heliocentric radial distance of 83.4 au (1 au is the Earth-Sun distance). These narrowband oscillations continued intermittently for about a month until, starting on 31 August 2007 and ending on 1 September 2007, a series of intense bursts of broadband electrostatic waves signalled a series of crossings of the termination shock at a heliocentric radial distance of 83.7 au. The spectrum of these waves is quantitatively similar to those observed at bow shocks upstream of Jupiter, Saturn, Uranus and Neptune.

Application of the wavenumber jump condition to the normal and oblique interaction of a plane acoustic wave and a plane shock

NASA Technical Reports Server (NTRS)

Kleinstein, G. G.; Gunzburger, M. D.

1977-01-01

The kinematics of normal and oblique interactions between a plane acoustic wave and a plane shock wave are investigated separately using an approach whereby the shock is considered as a sharp discontinuity surface separating two half-spaces, so that the dispersion relation on either side of the shock and the wavenumber jump condition across a discontinuity surface completely specify the kinematics of the problem in the whole space independently of the acoustic-field dynamics. The normal interaction is analyzed for a stationary shock, and the spectral change of the incident wave is investigated. The normal interaction is then examined for the case of a shock wave traveling into an ambient region where an acoustic disturbance is propagating in the opposite direction. Detailed attention is given to the consequences of the existence of a critical shock speed above which the frequency of the transmitted wave becomes negative. Finally, the oblique interaction with a fixed shock is considered, and the existence and nature of the transmitted wave is investigated, particularly as a function of the angle of incidence.

The Observational Consequences of Proton-Generated Waves at Shocks

NASA Technical Reports Server (NTRS)

Reames, Donald V.

2000-01-01

In the largest solar energetic particle (SEP) events, acceleration takes place at shock waves driven out from the Sun by fast coronal mass ejections. Protons streaming away from strong shocks generate Alfven waves that trap particles in the acceleration region, limiting outflowing intensities but increasing the efficiency of acceleration to higher energies. Early in the events, with the shock still near the Sun, intensities at 1 AU are bounded and spectra are flattened at low energies. Elements with different charge-to-mass ratios, Q/A, differentially probe the wave spectra near shocks, producing abundance ratios that vary in space and time. An initial rise in He/H, while Fe/O declines, is a typical symptom of the non-Kolmogorov wave spectra in the largest events. Strong wave generation can cause cross-field scattering near the shock and unusually rapid reduction in anisotropies even far from the shock. At the highest energies, shock spectra steepen to form a "knee." For protons, this spectral knee can vary from approx. 10 MeV to approx. 1 GeV depending on shock conditions for wave growth. In one case, the location of the knee scales approximately as Q/A in the energy/nucleon spectra of other species.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Measurements of laser-induced shock waves in aluminium

NASA Astrophysics Data System (ADS)

Werdiger, M.; Arad, B.; Moshe, E.; Eliezer, S.

1995-02-01

A simple optical method for measurements of high-irradiance (3×1013 W cm-2) laser-induced shock waves is described. The shock wave velocity (~13 km s-1) was measured with an error not exceeding 5%. The laser-induced one-to-two-dimensional (1D-to-2D) shock wave transition was studied.

Extracorporeal shock wave therapy in orthopedics, basic research, and clinical implications

NASA Astrophysics Data System (ADS)

Hausdorf, Joerg; Jansson, Volkmar; Maier, Markus; Delius, Michael

2005-04-01

The molecular events following shock wave treatment of bone are widely unknown. Nevertheless patients with osteonecrosis and non unions are already treated partly successful with shock waves. Concerning the first indication, the question of the permeation of the shock wave into the bone was addressed. Therefore shockwaves were applied to porcine femoral heads and the intraosseous pressure was measured. A linear correlation of the pressure to the intraosseous distance was found. Approximately 50% of the pressure are still measurable 10 mm inside the femoral head. These findings should encourage continued shock wave research on this indication. Concerning the second indication (non union), osteoblasts were subjected to 250 or 500 shock waves at 25 kV. After 24, 48, and 72 h the levels of the bone and vascular growth factors bFGF, TGFbeta1, and VEGF were examined. After 24 h there was a significant increase in bFGF levels (p<0.05) with significant correlation (p<0.05) to the number of impulses. TGFbeta1, and VEGF showed no significant changes. This may be one piece in the cascade of new bone formation following shock wave treatment and may lead to a more specific application of shock waves in orthopedic surgery.

Overview of shock waves in medicine

NASA Astrophysics Data System (ADS)

Cleveland, Robin O.

2003-10-01

A brief overview of three applications of shock waves is presented. Shock wave lithotripsy (SWL) has been in clinical use for more than 20 years. In the United States it is used to treat more than 80% of kidney stone cases and has wide acceptance with patients because it is a noninvasive procedure. Despite SWLs enormous success there is no agreement on how shock waves comminute stones. There is also a general acceptance that shock waves lead to trauma to the soft tissue of the kidney. Yet there has been little forward progress in developing lithotripters which provide comminution with less side-effects, indeed the original machine is still considered the gold standard. The last decade has seen the advent of new shock wave devices for treating principally musculoskeletal indications, such as plantar fasciitis, tennis elbow, and bone fractures that do not heal. This is referred to as shock wave therapy (SWT). The mechanisms by which SWT works are even less well understood than SWL and the consequences of bioeffects have also not been studied in detail. Shock waves have also been shown to be effective at enhancing drug delivery into cells and assisting with gene transfection. [Work partially supported by NIH.

Shock wave and flame front induced detonation in a rapid compression machine

NASA Astrophysics Data System (ADS)

Wang, Y.; Qi, Y.; Xiang, S.; Mével, R.; Wang, Z.

2018-05-01

The present study focuses on one mode of detonation initiation observed in a rapid compression machine (RCM). This mode is referred to as shock wave and flame front-induced detonation (SWFID). Experimental high-speed imaging and two-dimensional numerical simulations with skeletal chemistry are combined to unravel the dominant steps of detonation initiation under SWFID conditions. It is shown that the interaction between the shock wave generated by the end-gas auto-ignition and the spherical flame creates a region of high pressure and temperature which enables the acceleration of the flame front and the detonation onset. The experimental observation lacks adequate spatial and temporal resolution despite good reproducibility of the detonation onset. Based on the numerical results, phenomenological interpretation of the event within the framework of shock wave refraction indicates that the formation of a free-precursor shock wave at the transition between regular and irregular refraction may be responsible for detonation onset. The present results along with previous findings on shock wave reflection-induced detonation in the RCM indicate that super-knock occurs after the interaction of the shock wave generated by end-gas auto-ignition with the RCM walls, preignition flame, or another shock wave.

Focusing of noncircular self-similar shock waves.

PubMed

Betelu, S I; Aronson, D G

2001-08-13

We study the focusing of noncircular shock waves in a perfect gas. We construct an explicit self-similar solution by combining three convergent plane waves with regular shock reflections between them. We then show, with a numerical Riemann solver, that there are initial conditions with smooth shocks whose intermediate asymptotic stage is described by the exact solution. Unlike the focusing of circular shocks, our self-similar shocks have bounded energy density.

DETECTION OF EXTREMELY BROAD WATER EMISSION FROM THE MOLECULAR CLOUD INTERACTING SUPERNOVA REMNANT G349.7+0.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rho, J.; Hewitt, J. W.; Boogert, A.

2015-10-10

We performed Herschel HIFI, PACS, and SPIRE observations toward the molecular cloud interacting supernova remnant G349.7+0.2. An extremely broad emission line was detected at 557 GHz from the ground state transition 1{sub 10}-1{sub 01} of ortho-water. This water line can be separated into three velocity components with widths of 144, 27, and 4 km s{sup −1}. The 144 km s{sup −1} component is the broadest water line detected to date in the literature. This extremely broad line width shows the importance of probing shock dynamics. PACS observations revealed three additional ortho-water lines, as well as numerous high-J carbon monoxide (CO)more » lines. No para-water lines were detected. The extremely broad water line is indicative of a high velocity shock, which is supported by the observed CO rotational diagram that was reproduced with a J-shock model with a density of 10{sup 4} cm{sup −3} and a shock velocity of 80 km s{sup −1}. Two far-infrared fine-structure lines, [O i] at 145 μm and [C ii] line at 157 μm, are also consistent with the high velocity J-shock model. The extremely broad water line could be simply from short-lived molecules that have not been destroyed in high velocity J-shocks; however, it may be from more complicated geometry such as high-velocity water bullets or a shell expanding in high velocity. We estimate the CO and H{sub 2}O densities, column densities, and temperatures by comparison with RADEX and detailed shock models.« less

Left Behind: A Bound Remnant from a White Dwarf Supernova?

NASA Astrophysics Data System (ADS)

Jha, Saurabh

2017-08-01

Type Ia supernovae (SN Ia) have enormous importance to cosmology and astrophysics, but their progenitors and explosion mechanisms are not understood in detail. Recently, observations and theoretical models have suggested that not all thermonuclear white-dwarf supernova explosions are normal SN Ia. In particular, type Iax supernovae (peculiar cousins to SN Ia), are thought to be exploding white dwarfs that are not completely disrupted, leaving behind a bound remnant. In deep and serendipitous HST pre-explosion data, we have discovered a luminous, blue progenitor system for the type Iax SN 2012Z in NGC 1309, which we interpret as a helium-star donor to the exploding white dwarf. HST observations of SN 2012Z in 2016, when the supernova light was expected to have faded away, still show a source at the location, as expected in our model where the pre-explosion flux was coming from the companion. However, the 2016 data also show a surprise: an excess flux compared to the progenitor system. Our proposed observations here will help unravel the mystery of that excess flux: is it from the bound ex-white dwarf remnant? Or is it from the shocked companion star that has been bombarded by supernova ejecta? Either of these possibilities would provide key new evidence as to the nature of these white dwarf supernovae.

Oscillations of a standing shock wave generated by the Richtmyer-Meshkov instability

NASA Astrophysics Data System (ADS)

Mikaelian, Karnig O.

2016-07-01

In a typical Richtmyer-Meshkov experiment a fast moving flat shock strikes a stationary perturbed interface between fluids A and B creating a transmitted and a reflected shock, both of which are perturbed. We propose shock tube experiments in which the reflected shock is stationary in the laboratory. Such a standing perturbed shock undergoes well-known damped oscillations. We present the conditions required for producing such a standing shock wave, which greatly facilitates the measurement of the oscillations and their rate of damping. We define a critical density ratio Rcritical, in terms of the adiabatic indices of the two fluids, and a critical Mach number Mscritical of the incident shock wave, which produces a standing reflected wave. If the initial density ratio R of the two fluids is less than Rcritical then a standing shock wave is possible at Ms=Mscritical . Otherwise a standing shock is not possible and the reflected wave always moves in the direction opposite the incident shock. Examples are given for present-day operating shock tubes with sinusoidal or inclined interfaces. We consider the effect of viscosity, which affects the damping rate of the oscillations. We point out that nonlinear bubble and spike amplitudes depend relatively weakly on the viscosity of the fluids and that the interface area is a better diagnostic.

Supernova ejecta with a relativistic wind from a central compact object: a unified picture for extraordinary supernovae

NASA Astrophysics Data System (ADS)

Suzuki, Akihiro; Maeda, Keiichi

2017-04-01

The hydrodynamical interaction between freely expanding supernova ejecta and a relativistic wind injected from the central region is studied in analytic and numerical ways. As a result of the collision between the ejecta and the wind, a geometrically thin shell surrounding a hot bubble forms and expands in the ejecta. We use a self-similar solution to describe the early dynamical evolution of the shell and carry out a two-dimensional special relativistic hydrodynamic simulation to follow further evolution. The Rayleigh-Taylor instability inevitably develops at the contact surface separating the shocked wind and ejecta, leading to the complete destruction of the shell and the leakage of hot gas from the hot bubble. The leaking hot materials immediately catch up with the outermost layer of the supernova ejecta and thus different layers of the ejecta are mixed. We present the spatial profiles of hydrodynamical variables and the kinetic energy distributions of the ejecta. We stop the energy injection when a total energy of 1052 erg, which is 10 times larger than the initial kinetic energy of the supernova ejecta, is deposited into the ejecta and follow the subsequent evolution. From the results of our simulations, we consider expected emission from supernova ejecta powered by the energy injection at the centre and discuss the possibility that superluminous supernovae and broad-lined Ic supernovae could be produced by similar mechanisms.

NEAR-EXTREMAL BLACK HOLES AS INITIAL CONDITIONS OF LONG GRB SUPERNOVAE AND PROBES OF THEIR GRAVITATIONAL WAVE EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Putten, Maurice H. P. M.

2015-09-01

Long gamma-ray bursts (GRBs) associated with supernovae and short GRBs with extended emission (SGRBEE) from mergers are probably powered by black holes as a common inner engine, as their prompt GRB emission satisfies the same Amati correlation in the E{sub p,i}–E{sub iso} plane. We introduce modified Bardeen equations to identify hyper-accretion driving newly formed black holes in core-collapse supernovae to near-extremal spin as a precursor to prompt GRB emission. Subsequent spin-down is observed in the BATSE catalog of long GRBs. Spin-down provides a natural unification of long durations associated with the lifetime of black hole spin for normal long GRBsmore » and SGRBEEs, given the absence of major fallback matter in mergers. The results point to major emissions unseen in high frequency gravitational waves. A novel matched filtering method is described for LIGO–Virgo and KAGRA broadband probes of nearby core-collapse supernovae at essentially maximal sensitivity.« less

The variety of MHD shock waves interactions in the solar wind flow

NASA Technical Reports Server (NTRS)

Grib, S. A.

1995-01-01

Different types of nonlinear shock wave interactions in some regions of the solar wind flow are considered. It is shown, that the solar flare or nonflare CME fast shock wave may disappear as the result of the collision with the rotational discontinuity. By the way the appearance of the slow shock waves as the consequence of the collision with other directional discontinuity namely tangential is indicated. Thus the nonlinear oblique and normal MHD shock waves interactions with different solar wind discontinuities (tangential, rotational, contact, shock and plasmoidal) both in the free flow and close to the gradient regions like the terrestrial magnetopause and the heliopause are described. The change of the plasma pressure across the solar wind fast shock waves is also evaluated. The sketch of the classification of the MHD discontinuities interactions, connected with the solar wind evolution is given.

Dry and wet granular shock waves.

PubMed

Zaburdaev, V Yu; Herminghaus, S

2007-03-01

The formation of a shock wave in one-dimensional granular gases is considered, for both the dry and the wet cases, and the results are compared with the analytical shock wave solution in a sticky gas. Numerical simulations show that the behavior of the shock wave in both cases tends asymptotically to the sticky limit. In the inelastic gas (dry case) there is a very close correspondence to the sticky gas, with one big cluster growing in the center of the shock wave, and a step-like stationary velocity profile. In the wet case, the shock wave has a nonzero width which is marked by two symmetric heavy clusters performing breathing oscillations with slowly increasing amplitude. All three models have the same asymptotic energy dissipation law, which is important in the context of the free cooling scenario. For the early stage of the shock formation and asymptotic oscillations we provide analytical results as well.

Endoscopically-controlled electrohydraulic intracorporeal shock wave lithotripsy (EISL) of salivary stones.

PubMed

Königsberger, R; Feyh, J; Goetz, A; Kastenbauer, E

1993-02-01

Twenty-nine patients with salivary stones were treated with the endoscopically-controlled electrohydraulic shock wave lithotripsy (EISL). This new minimally invasive treatment of sialolithiasis is performed under local anesthesia on an outpatient basis with little inconvenience to the patient. For endoscopy, a flexible fibroscope with an additional probe to generate shock waves is placed into the submandibular duct and advanced until the stone is identified. For shock wave-induced stone disintegration, the probe electrode must be placed 1 mm in front of the concrement. The shock waves are generated by a sparkover at the tip of the probe. By means of the endoscopically-controlled shock wave lithotripsy it was possible to achieve complete stone fragmentation in 20 out of 29 patients without serious side effects. In three patients, only partial stone fragmentation could be achieved due to the stone quality. Endoscopically-controlled electrohydraulic intracorporeal shock wave lithotripsy represents a novel minimally invasive therapy for endoscopically accessible salivary gland stones. The advantage in comparison to the endoscopically-controlled laser lithotripsy will be discussed.

Accuracy Study of the Space-Time CE/SE Method for Computational Aeroacoustics Problems Involving Shock Waves

NASA Technical Reports Server (NTRS)

Wang, Xiao Yen; Chang, Sin-Chung; Jorgenson, Philip C. E.

1999-01-01

The space-time conservation element and solution element(CE/SE) method is used to study the sound-shock interaction problem. The order of accuracy of numerical schemes is investigated. The linear model problem.govemed by the 1-D scalar convection equation, sound-shock interaction problem governed by the 1-D Euler equations, and the 1-D shock-tube problem which involves moving shock waves and contact surfaces are solved to investigate the order of accuracy of numerical schemes. It is concluded that the accuracy of the CE/SE numerical scheme with designed 2nd-order accuracy becomes 1st order when a moving shock wave exists. However, the absolute error in the CE/SE solution downstream of the shock wave is on the same order as that obtained using a fourth-order accurate essentially nonoscillatory (ENO) scheme. No special techniques are used for either high-frequency low-amplitude waves or shock waves.

Infrared spectroscopy of interstellar shocks

NASA Technical Reports Server (NTRS)

Mckee, C. F.; Chernoff, D. F.; Hollenbach, D. J.

1984-01-01

Infrared emission lines from interstellar shocks provide valuable diagnostics for violent events in the interstellar medium, such as supernova remnants and mass outflow from young stellar objects. There are two types of interstellar shocks: in J shocks, gas properties 'jump' from their preshock to their postshock values in a shock front with a thickness equal to or less than one mean free path; radiation is emitted behind the shock front, primarily in the visible and ultraviolet, but with a few strong infrared lines, such as OI(63 microns). Such shocks occur in ionized or neutral atomic gas, or at high velocities (equal to or greater than 50 km/s) in molecular gas. In C shocks, gas is accelerated and heated by collisions between charged particles, which have a low concentration and are coupled to the magnetic field, and neutral particles; radiation is generated throughout the shock and is emitted almost entirely in infrared emission lines. Such shocks occur in weakly ionized molecular gas for shock velocities below about 50 km/s.

The Role of Shocks in the Appearance and Aftermath of Stellar Mergers and Type IIn Supernovae

NASA Astrophysics Data System (ADS)

Metzger, Brian

2017-08-01

HST has played a crucial role in elucidating the environments, progenitors, explosions, and late-time behavior of Type IIn supernovae (SNe) and binary star mergers (also known as common envelope events). Although shock interaction plays a dominant role in the dynamics and appearance of these events, the details of this process and the nature of the mass loss leading up to the core collapse or dynamical stage of the merger, remain poorly understood. Mounting evidence suggests that the pre-explosion mass loss geometry is a disk or equatorially-concentrated outflow. We will perform the first multi-dimensional radiation hydrodynamical simulations of the shock interaction between the fast ejecta from the SN explosion/dynamical merger and a slower equatorially-focused outflow representing the earlier phase of mass loss. Our calculations will quantify the geometry of the ejecta and make detailed predictions for the shock-powered emission. In combination with an analytic model to be developed in parallel, we will translate the light curves and spectral information on a large sample of IIn SNe and stellar mergers into probes of their mass loss history. We will address whether the combination of hydrogen recombination and shock-powered emission can explain the common double-peaked nature of the light curves of stellar mergers. By accounting self-consistently for the role of radiative shock compression on the ejecta density structure, and thus on the global geometry and microphysical properties of dust grains formed, we will also address the late-time appearance of IIn SNe and stellar mergers observed by HST and JWST.

Spherical shock waves in general relativity

NASA Astrophysics Data System (ADS)

Nutku, Y.

1991-11-01

We present the metric appropriate to a spherical shock wave in the framework of general relativity. This is a Petrov type-N vacuum solution of the Einstein field equations where the metric is continuous across the shock and the Riemann tensor suffers a step-function discontinuity. Spherical gravitational waves are described by type-N Robinson-Trautman metrics. However, for shock waves the Robinson-Trautman solutions are unacceptable because the metric becomes discontinuous in the Robinson-Trautman coordinate system. Other coordinate systems that have so far been introduced for describing Robinson-Trautman solutions also suffer from the same defect. We shall present the C0-form of the metric appropriate to spherical shock waves using Penrose's approach of identification with warp. Further extensions of Penrose's method yield accelerating, as well as coupled electromagnetic-gravitational shock-wave solutions.

Observation of dust acoustic shock wave in a strongly coupled dusty plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Sumita K., E-mail: sumita-sharma82@yahoo.com; Boruah, A.; Nakamura, Y.

2016-05-15

Dust acoustic shock wave is observed in a strongly coupled laboratory dusty plasma. A supersonic flow of charged microparticles is allowed to perturb a stationary dust fluid to excite dust acoustic shock wave. The evolution process beginning with steepening of initial wave front and then formation of a stable shock structure is similar to the numerical results of the Korteweg-de Vries-Burgers equation. The measured Mach number of the observed shock wave agrees with the theoretical results. Reduction of shock amplitude at large distances is also observed due to the dust neutral collision and viscosity effects. The dispersion relation and themore » spatial damping of a linear dust acoustic wave are also measured and compared with the relevant theory.« less

Various continuum approaches for studying shock wave structure in carbon dioxide

NASA Astrophysics Data System (ADS)

Alekseev, I. V.; Kosareva, A. A.; Kustova, E. V.; Nagnibeda, E. A.

2018-05-01

Shock wave structure in carbon dioxide is studied using different continuum models within the framework of one-temperature thermal equilibrium flow description. Navier-Stokes and Euler equations as well as commonly used Rankine-Hugoniot equations with different specific heat ratios are used to find the gas-dynamic parameters behind the shock wave. The accuracy of the Rankine-Hugoniot relations in polyatomic gases is assessed, and it is shown that they give a considerable error in the predicted values of fluid-dynamic variables. The effect of bulk viscosity on the shock wave structure in CO2 is evaluated. Taking into account bulk viscosity yields a significant increase in the shock wave width; for the complete model, the shock wave thickness varies non-monotonically with the Mach number.

Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, I.; Quevedo, H. J.; Feldman, S.

2013-12-15

Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental datamore » characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.« less

44Ti Nucleosynthesis Lines and Hard X-ray Continuum in Young SNRs: from INTEGRAL to Simbol-X

NASA Astrophysics Data System (ADS)

Renaud, M.; Terrier, R.; Trap, G.; Lebrun, F.; Decourchelle, A.; Vink, J.

2009-05-01

Supemovae and their remnants are the main Galactic nucleosynthesis sites and the privileged sources of Galactic cosmic rays. The youngest of such remnants can be studied through two distinct observational features: 44Ti γ-ray lines and the hard X-ray nonthermal continuum emission. The former gives unique information on the nucleosynthesis conditions occuring during the first stages of the explosion, while the latter provides clues on acceleration processes at supernova remnant shocks. In this contribution, we present new INTEGRAL results on Tycho, the remnant of a historical supernova, and on G1.9+0.3, which has been recently unveiled as the youngest Galactic supernova remnant. Expectations with Simbol-X are also addressed.

Approximate supernova remnant dynamics with cosmic ray production

NASA Technical Reports Server (NTRS)

Voelk, H. J.; Drury, L. O.; Dorfi, E. A.

1985-01-01

Supernova explosions are the most violent and energetic events in the galaxy and have long been considered probably sources of Cosmic Rays. Recent shock acceleration models treating the Cosmic Rays (CR's) as test particles nb a prescribed Supernova Remnant (SNR) evolution, indeed indicate an approximate power law momentum distribution f sub source (p) approximation p(-a) for the particles ultimately injected into the Interstellar Medium (ISM). This spectrum extends almost to the momentum p = 1 million GeV/c, where the break in the observed spectrum occurs. The calculated power law index approximately less than 4.2 agrees with that inferred for the galactic CR sources. The absolute CR intensity can however not be well determined in such a test particle approximation.

The History of the APS Topical Group on Shock Compression of Condensed Matter

NASA Astrophysics Data System (ADS)

Forbes, Jerry W.

2002-07-01

In order to provide broader scientific recognition and to advance the science of shock compressed condensed matter, a group of American Physical Society (APS) members worked within the Society to make this field an active part of the APS. Individual papers were presented at APS meetings starting in the 1940's and shock wave sessions were organized starting with the 1967 Pasadena meeting. Shock wave topical conferences began in 1979 in Pullman, WA. Signatures were obtained on a petition in 1984 from a balanced cross-section of the shock wave community to form an APS Topical Group (TG). The APS Council officially accepted the formation of the Shock Compression of Condensed Matter (SCCM) TG at its October 1984 meeting. This action firmly aligned the shock wave field with a major physical science organization. Most early topical conferences were sanctioned by the APS while those held after 1992 were official APS meetings. The topical group organizes a shock wave topical conference in odd numbered years while participating in shock wave/high pressure sessions at APS general meetings in even numbered years.

Upstream waves and particles /Tutorial Lecture/. [from shocks in interplanetary space

NASA Technical Reports Server (NTRS)

Russell, C. T.; Hoppe, M. M.

1983-01-01

The plasma waves, MHD waves, energetic electrons and ions associated with the proximity of the region upstream from terrestrial, planetary and interplanetary shocks are discussed in view of observations and current theories concerning their origin. These waves cannot be separated from the study of shock structure. Since the shocks are supersonic, they continually overtake any ULF waves created in the plasma in front of the shock. The upstream particles and waves are also of intrinsic interest because they provide a plasma laboratory for the study of wave-particle interactions in a plasma which, at least at the earth, is accessible to sophisticated probing. Insight may be gained into interstellar medium cosmic ray acceleration through the study of these phenomena.

High Energy Astronomy Observatory (HEAO)

NASA Image and Video Library

1980-01-01

This x-ray photograph of the Supernova remnant Cassiopeia A, taken with the High Energy Astronomy Observatory (HEAO) 2/Einstein Observatory, shows that the regions with fast moving knots of material in the expanding shell are bright and clear. A faint x-ray halo, just outside the bright shell, is interpreted as a shock wave moving ahead of the expanding debris. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO-2, designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center, was launched aboard an Atlas/Centaur launch vehicle on November 13, 1978.

Exploring transient X-ray sky with Einstein Probe

NASA Astrophysics Data System (ADS)

Yuan, W.; Zhang, C.; Ling, Z.; Zhao, D.; Chen, Y.; Lu, F.; Zhang, S.

2017-10-01

The Einstein Probe is a small satellite in time-domain astronomy to monitor the soft X-ray sky. It is a small mission in the space science programme of the Chinese Academy of Sciences. It will carry out systematic survey and characterisation of high-energy transients at unprecedented sensitivity, spatial resolution, Grasp and monitoring cadence. Its wide-field imaging capability is achieved by using established technology of micro-pore lobster-eye X-ray focusing optics. Complementary to this is X-ray follow-up capability enabled by a narrow-field X-ray telescope. It is capable of on-board triggering and real time downlink of transient alerts, in order to trigger fast follow-up observations at multi-wavelengths. Its scientific goals are concerned with discovering and characterising diverse types of X-ray transients, including tidal disruption events, supernova shock breakouts, high-redshift GRBs, and of particular interest, X-ray counterparts of gravitational wave events.

Discovery of powerful gamma-ray flares from the Crab Nebula.

PubMed

Tavani, M; Bulgarelli, A; Vittorini, V; Pellizzoni, A; Striani, E; Caraveo, P; Weisskopf, M C; Tennant, A; Pucella, G; Trois, A; Costa, E; Evangelista, Y; Pittori, C; Verrecchia, F; Del Monte, E; Campana, R; Pilia, M; De Luca, A; Donnarumma, I; Horns, D; Ferrigno, C; Heinke, C O; Trifoglio, M; Gianotti, F; Vercellone, S; Argan, A; Barbiellini, G; Cattaneo, P W; Chen, A W; Contessi, T; D'Ammando, F; DePris, G; Di Cocco, G; Di Persio, G; Feroci, M; Ferrari, A; Galli, M; Giuliani, A; Giusti, M; Labanti, C; Lapshov, I; Lazzarotto, F; Lipari, P; Longo, F; Fuschino, F; Marisaldi, M; Mereghetti, S; Morelli, E; Moretti, E; Morselli, A; Pacciani, L; Perotti, F; Piano, G; Picozza, P; Prest, M; Rapisarda, M; Rappoldi, A; Rubini, A; Sabatini, S; Soffitta, P; Vallazza, E; Zambra, A; Zanello, D; Lucarelli, F; Santolamazza, P; Giommi, P; Salotti, L; Bignami, G F

2011-02-11

The well-known Crab Nebula is at the center of the SN1054 supernova remnant. It consists of a rotationally powered pulsar interacting with a surrounding nebula through a relativistic particle wind. The emissions originating from the pulsar and nebula have been considered to be essentially stable. Here, we report the detection of strong gamma-ray (100 mega-electron volts to 10 giga-electron volts) flares observed by the AGILE satellite in September 2010 and October 2007. In both cases, the total gamma-ray flux increased by a factor of three compared with the non-flaring flux. The flare luminosity and short time scale favor an origin near the pulsar, and we discuss Chandra Observatory x-ray and Hubble Space Telescope optical follow-up observations of the nebula. Our observations challenge standard models of nebular emission and require power-law acceleration by shock-driven plasma wave turbulence within an approximately 1-day time scale.

Spatially-resolved Spectroscopy of the IC443 Pulsar Wind Nebula and Environs

NASA Astrophysics Data System (ADS)

Swartz, Douglas A.; Weisskopf, M. C.; Zavlin, V.; Bucciantini, N.; Clarke, T. E.; Karovska, M.; Pavlov, G. G.; van der Horst, A.; Yukita, M.

2013-04-01

Deep Chandra ACIS observations of the region around the putative pulsar, CXO J061705.3+222127, in the supernova remnant IC443 confirm that (1) the spectrum and flux of the central object are consistent with a rotation-powered pulsar interpretation, (2) the non-thermal surrounding nebula is likely powered by a pulsar wind, and (3) the thermal-dominated spectrum at greater distances is consistent with emission from the supernova remnant. The observations further reveal, for the first time, a ring-like morphology surrounding the pulsar and a jet-like structure oriented roughly north-south across the ring and through the pulsar location. The cometary shape of the nebula, suggesting motion towards the southwest, appears to be subsonic; there is no evidence for a strong bow shock and the ring, presumably formed at a wind termination shock, is not distorted by motion through the ambient medium.

Symmetry of spherically converging shock waves through reflection, relating to the shock ignition fusion energy scheme.

PubMed

Davie, C J; Evans, R G

2013-05-03

We examine the properties of perturbed spherically imploding shock waves in an ideal fluid through the collapse, bounce, and development into an outgoing shock wave. We find broad conservation of the size and shape of ingoing and outgoing perturbations when viewed at the same radius. The outgoing shock recovers the velocity of the unperturbed shock outside the strongly distorted core. The results are presented in the context of the robustness of the shock ignition approach to inertial fusion energy.

Turbulence Evolution and Shock Acceleration of Solar Energetic Particles

NASA Technical Reports Server (NTRS)

Chee, Ng K.

2007-01-01

We model the effects of self-excitation/damping and shock transmission of Alfven waves on solar-energetic-particle (SEP) acceleration at a coronal-mass-ejection (CME) driven parallel shock. SEP-excited outward upstream waves speedily bootstrap acceleration. Shock transmission further raises the SEP-excited wave intensities at high wavenumbers but lowers them at low wavenumbers through wavenumber shift. Downstream, SEP excitation of inward waves and damping of outward waves tend to slow acceleration. Nevertheless, > 2000 km/s parallel shocks at approx. 3.5 solar radii can accelerate SEPs to 100 MeV in < 5 minutes.

Hot Dust in Ultraluminous Infrared Galaxies

NASA Astrophysics Data System (ADS)

Shchekinov, Yu. A.; Vasiliev, E. O.

2017-12-01

Ultraluminous infrared galaxies with total luminosities an order of magnitude greater than that of our galaxy over wavelengths of λλ = 10-800 μm are characterized by a high mass concentration of dust. Because of this, the optical thickness of the interstellar gas is extremely high, especially in the central regions of the galaxies, ranging from 1 at millimeter wavelengths to 104 in the visible. The average temperature of the dust in them is about Td=30 K, but the variations from one galaxy to another are large, with Td=20-70 K. The main source of dust in these galaxies seems to be type II supernova bursts and the main heating source is stars. In addition, given that shock waves from supernovae are an effective mechanism for destruction of interstellar dust in our galaxy and the high optical thickness of the gas with respect to the heating radiation from the stars, this conclusion merits detailed analysis. This paper provides estimates of the dust mass balance and details of its heating in these galaxies based on the example of the ultraluminous galaxy closest to us, Arp 220. It is shown that when supernovae are dominant in the production and destruction of dust in the interstellar gas, the resultant dust mass fraction is close to the observed value for Arp 220. It is also found that the observed stellar population of this galaxy can support a high ( Td ≃ 67 K ) temperature if the dust in its central region is concentrated in small, dense (n 105 cm-3) clouds with radii of 0.003 ≲ pc. Mechanisms capable of maintaining an interstellar gas structure in this state are discussed.

Cosmochemical evidence for astrophysical processes during the formation of our solar system.

PubMed

MacPherson, Glenn J; Boss, Alan

2011-11-29

Through the laboratory study of ancient solar system materials such as meteorites and comet dust, we can recognize evidence for the same star-formation processes in our own solar system as those that we can observe now through telescopes in nearby star-forming regions. High temperature grains formed in the innermost region of the solar system ended up much farther out in the solar system, not only the asteroid belt but even in the comet accretion region, suggesting a huge and efficient process of mass transport. Bi-polar outflows, turbulent diffusion, and marginal gravitational instability are the likely mechanisms for this transport. The presence of short-lived radionuclides in the early solar system, especially (60)Fe, (26)Al, and (41)Ca, requires a nearby supernova shortly before our solar system was formed, suggesting that the Sun was formed in a massive star-forming region similar to Orion or Carina. Solar system formation may have been "triggered" by ionizing radiation originating from massive O and B stars at the center of an expanding HII bubble, one of which may have later provided the supernova source for the short-lived radionuclides. Alternatively, a supernova shock wave may have simultaneously triggered the collapse and injected the short-lived radionuclides. Because the Sun formed in a region where many other stars were forming more or less contemporaneously, the bi-polar outflows from all such stars enriched the local region in interstellar silicate and oxide dust. This may explain several observed anomalies in the meteorite record: a near absence of detectable (no extreme isotopic properties) presolar silicate grains and a dichotomy in the isotope record between (26)Al and nucleosynthetic (nonradiogenic) anomalies.

Cosmochemical evidence for astrophysical processes during the formation of our solar system

PubMed Central

MacPherson, Glenn J.; Boss, Alan

2011-01-01

Through the laboratory study of ancient solar system materials such as meteorites and comet dust, we can recognize evidence for the same star-formation processes in our own solar system as those that we can observe now through telescopes in nearby star-forming regions. High temperature grains formed in the innermost region of the solar system ended up much farther out in the solar system, not only the asteroid belt but even in the comet accretion region, suggesting a huge and efficient process of mass transport. Bi-polar outflows, turbulent diffusion, and marginal gravitational instability are the likely mechanisms for this transport. The presence of short-lived radionuclides in the early solar system, especially 60Fe, 26Al, and 41Ca, requires a nearby supernova shortly before our solar system was formed, suggesting that the Sun was formed in a massive star-forming region similar to Orion or Carina. Solar system formation may have been “triggered” by ionizing radiation originating from massive O and B stars at the center of an expanding HII bubble, one of which may have later provided the supernova source for the short-lived radionuclides. Alternatively, a supernova shock wave may have simultaneously triggered the collapse and injected the short-lived radionuclides. Because the Sun formed in a region where many other stars were forming more or less contemporaneously, the bi-polar outflows from all such stars enriched the local region in interstellar silicate and oxide dust. This may explain several observed anomalies in the meteorite record: a near absence of detectable (no extreme isotopic properties) presolar silicate grains and a dichotomy in the isotope record between 26Al and nucleosynthetic (nonradiogenic) anomalies. PMID:22106251

Shock tube and shock wave research; Proceedings of the Eleventh International Symposium, University of Washington, Seattle, Wash., July 11-14, 1977

NASA Technical Reports Server (NTRS)

Ahlborn, B. (Editor); Hertzberg, A.; Russell, D.

1978-01-01

Papers are presented on the applications of shock-wave technology to the study of hydrodynamics, the use of the pressure-wave machine for charging diesel engines, and measurements of the heat-transfer rate in gas-turbine components. Consideration is given to shock propagation along 90-degree bends, the explosive dissemination of liquids, and rotational and vibrational relaxation behind weak shock waves in water vapor. Shock phenomena associated with expansion flows are described and stratospheric-related research using the shock tube is outlined. Attention is given to shock-wave ignition of magnesium powders, Mach reflection and boundary layers, and transition in the shock-induced unsteady boundary layer on a flat plate. Shock-tube measurements of induction and post-induction rates for low-Btu gas mixtures are presented and shock-initiated ignition in COS-N2O-Ar mixtures is described. Cluster growth rates in supersaturated lead vapor are presented and a study of laser-induced plasma motion in a solenoidal magnetic field is reviewed.

Experimental investigation on aero-optical aberration of shock wave/boundary layer interactions

NASA Astrophysics Data System (ADS)

Ding, Haolin; Yi, Shihe; Fu, Jia; He, Lin

2016-10-01

After streaming through the flow field which including the expansion, shock wave, boundary, etc., the optical wave would be distorted by fluctuations in the density field. Interactions between laminar/turbulent boundary layer and shock wave contain large number complex flow structures, which offer a condition for studying the influences that different flow structures of the complex flow field have on the aero-optical aberrations. Interactions between laminar/turbulent boundary layer and shock wave are investigated in a Mach 3.0 supersonic wind tunnel, based on nanoparticle-tracer planar laser scattering (NPLS) system. Boundary layer separation/attachment, induced suppression waves, induced shock wave, expansion fan and boundary layer are presented by NPLS images. Its spatial resolution is 44.15 μm/pixel. Time resolution is 6ns. Based on the NPLS images, the density fields with high spatial-temporal resolution are obtained by the flow image calibration, and then the optical path difference (OPD) fluctuations of the original 532nm planar wavefront are calculated using Ray-tracing theory. According to the different flow structures in the flow field, four parts are selected, (1) Y=692 600pixel; (2) Y=600 400pixel; (3) Y=400 268pixel; (4) Y=268 0pixel. The aerooptical effects of different flow structures are quantitatively analyzed, the results indicate that: the compressive waves such as incident shock wave, induced shock wave, etc. rise the density, and then uplift the OPD curve, but this kind of shock are fixed in space position and intensity, the aero-optics induced by it can be regarded as constant; The induced shock waves are induced by the coherent structure of large size vortex in the interaction between turbulent boundary layer, its unsteady characteristic decides the induced waves unsteady characteristic; The space position and intensity of the induced shock wave are fixed in the interaction between turbulent boundary layer; The boundary layer aero-optics are induced by the coherent structure of large size vortex, which result in the fluctuation of OPD.