The ASAS-SN Bright Supernova Catalog – II. 2015

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

Holoien, T. W. -S.; Brown, J. S.; Stanek, K. Z.

Here, this paper presents information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during 2015, its second full year of operations. The same information is presented for bright (mV ≤ 17), spectroscopically confirmed supernovae discovered by other sources in 2015. As with the first ASAS-SN bright supernova catalogue, we also present redshifts and near-ultraviolet through infrared magnitudes for all supernova host galaxies in both samples. Combined with our previous catalogue, this work comprises a complete catalogue of 455 supernovae from multiple professional and amateur sources, allowing for population studies that were previously impossible. This is themore » second of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.« less

X-ray studies of supernova remnants: A different view of supernova explosions

PubMed Central

Badenes, Carles

2010-01-01

The unprecedented spatial and spectral resolutions of Chandra have revolutionized our view of the X-ray emission from supernova remnants. The excellent datasets accumulated on young, ejecta-dominated objects like Cas A or Tycho present a unique opportunity to study at the same time the chemical and physical structure of the explosion debris and the characteristics of the circumstellar medium sculpted by the progenitor before the explosion. Supernova remnants can thus put strong constraints on fundamental aspects of both supernova explosion physics and stellar evolution scenarios for supernova progenitors. This view of the supernova phenomenon is completely independent of, and complementary to, the study of distant extragalactic supernovae at optical wavelengths. The calibration of these two techniques has recently become possible thanks to the detection and spectroscopic follow-up of supernova light echoes. In this paper, I review the most relevant results on supernova remnants obtained during the first decade of Chandra and the impact that these results have had on open issues in supernova research. PMID:20404206

Observational constraint on dynamical evolution of dark energy

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

Gong, Yungui; Cai, Rong-Gen; Chen, Yun

2010-01-01

We use the Constitution supernova, the baryon acoustic oscillation, the cosmic microwave background, and the Hubble parameter data to analyze the evolution property of dark energy. We obtain different results when we fit different baryon acoustic oscillation data combined with the Constitution supernova data to the Chevallier-Polarski-Linder model. We find that the difference stems from the different values of Ω{sub m0}. We also fit the observational data to the model independent piecewise constant parametrization. Four redshift bins with boundaries at z = 0.22, 0.53, 0.85 and 1.8 were chosen for the piecewise constant parametrization of the equation of state parametermore » w(z) of dark energy. We find no significant evidence for evolving w(z). With the addition of the Hubble parameter, the constraint on the equation of state parameter at high redshift is improved by 70%. The marginalization of the nuisance parameter connected to the supernova distance modulus is discussed.« less

NEW EQUATIONS OF STATE IN SIMULATIONS OF CORE-COLLAPSE SUPERNOVAE

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

Hempel, M.; Liebendoerfer, M.; Fischer, T.

2012-03-20

We discuss three new equations of state (EOS) in core-collapse supernova simulations. The new EOS are based on the nuclear statistical equilibrium model of Hempel and Schaffner-Bielich (HS), which includes excluded volume effects and relativistic mean-field (RMF) interactions. We consider the RMF parameterizations TM1, TMA, and FSUgold. These EOS are implemented into our spherically symmetric core-collapse supernova model, which is based on general relativistic radiation hydrodynamics and three-flavor Boltzmann neutrino transport. The results obtained for the new EOS are compared with the widely used EOS of H. Shen et al. and Lattimer and Swesty. The systematic comparison shows that themore » model description of inhomogeneous nuclear matter is as important as the parameterization of the nuclear interactions for the supernova dynamics and the neutrino signal. Furthermore, several new aspects of nuclear physics are investigated: the HS EOS contains distributions of nuclei, including nuclear shell effects. The appearance of light nuclei, e.g., deuterium and tritium, is also explored, which can become as abundant as alphas and free protons. In addition, we investigate the black hole formation in failed core-collapse supernovae, which is mainly determined by the high-density EOS. We find that temperature effects lead to a systematically faster collapse for the non-relativistic LS EOS in comparison with the RMF EOS. We deduce a new correlation for the time until black hole formation, which allows the determination of the maximum mass of proto-neutron stars, if the neutrino signal from such a failed supernova would be measured in the future. This would give a constraint for the nuclear EOS at finite entropy, complementary to observations of cold neutron stars.« less

Supernova neutrino physics with xenon dark matter detectors: A timely perspective

NASA Astrophysics Data System (ADS)

Lang, Rafael F.; McCabe, Christopher; Reichard, Shayne; Selvi, Marco; Tamborra, Irene

2016-11-01

Dark matter detectors that utilize liquid xenon have now achieved tonne-scale targets, giving them sensitivity to all flavors of supernova neutrinos via coherent elastic neutrino-nucleus scattering. Considering for the first time a realistic detector model, we simulate the expected supernova neutrino signal for different progenitor masses and nuclear equations of state in existing and upcoming dual-phase liquid xenon experiments. We show that the proportional scintillation signal (S2) of a dual-phase detector allows for a clear observation of the neutrino signal and guarantees a particularly low energy threshold, while the backgrounds are rendered negligible during the supernova burst. XENON1T (XENONnT and LZ; DARWIN) experiments will be sensitive to a supernova burst up to 25 (35; 65) kpc from Earth at a significance of more than 5 σ , observing approximately 35 (123; 704) events from a 27 M⊙ supernova progenitor at 10 kpc. Moreover, it will be possible to measure the average neutrino energy of all flavors, to constrain the total explosion energy, and to reconstruct the supernova neutrino light curve. Our results suggest that a large xenon detector such as DARWIN will be competitive with dedicated neutrino telescopes, while providing complementary information that is not otherwise accessible.

Measuring the supernova unknowns at the next-generation neutrino telescopes through the diffuse neutrino background

NASA Astrophysics Data System (ADS)

MØller, Klaes; Suliga, Anna M.; Tamborra, Irene; Denton, Peter B.

2018-05-01

The detection of the diffuse supernova neutrino background (DSNB) will preciously contribute to gauge the properties of the core-collapse supernova population. We estimate the DSNB event rate in the next-generation neutrino detectors, Hyper-Kamiokande enriched with Gadolinium, JUNO, and DUNE. The determination of the supernova unknowns through the DSNB will be heavily driven by Hyper-Kamiokande, given its higher expected event rate, and complemented by DUNE that will help in reducing the parameters uncertainties. Meanwhile, JUNO will be sensitive to the DSNB signal over the largest energy range. A joint statistical analysis of the expected rates in 20 years of data taking from the above detectors suggests that we will be sensitive to the local supernova rate at most at a 20‑33% level. A non-zero fraction of supernovae forming black holes will be confirmed at a 90% CL, if the true value of that fraction is gtrsim20%. On the other hand, the DSNB events show extremely poor statistical sensitivity to the nuclear equation of state and mass accretion rate of the progenitors forming black holes.

Equations of state for neutron stars and core-collapse supernovae

NASA Astrophysics Data System (ADS)

Oertel, Micaela; Providência, Constança

2018-04-01

Modelling compact stars is a complex task which depends on many ingredients, among others the properties of dense matter. In this contribution models for the equation of state (EoS) of dense matter will be discussed, relevant for the description of core-collapse supernovae, compact stars and compact star mergers. Such EoS models have to cover large ranges in baryon number density, temperature and isospin asymmetry. The characteristics of matter change dramatically within these ranges, from a mixture of nucleons, nuclei, and electrons to uniform, strongly interacting matter containing nucleons, and possibly other particles such as hyperons or quarks. Some implications for compact star astrophysics will be highlighted, too.

Preliminary constraints on variable w dark energy cosmologies from the SNLS

NASA Astrophysics Data System (ADS)

Carlberg, R. G.; Conley, A.; Howell, D. A.; Neill, J. D.; Perrett, K.; Pritchet, C. J.; Sullivan, M.

2005-12-01

The first 71 confirmed Ia supernovae from the Supernova Legacy Survey being conducted with CFHT imaging and Gemini, VLT and Keck spectroscopy set limits on variable dark energy cosmological models. For a generalized Chaplygin gas, in which the dark energy content is (1-Ω M)/ρ a, we find that a is statistically consistent with zero, with a best fit a=-0.2±-0.3 (68 systematic errors requires a further refinement of the photometric calibration and the potential model biases. A variable dark energy equation of state with w=w0+w_1 z shows the expected degeneracy between increasingly positive w0 and negative w1. The existing data rule out the parameters of the Weller & Linder (2002) Super-gravity inspired model cosmology (w0,w_1)=(-0.81,0.31). The full 700 Ia of the completed survey will provide a statistical error limit of w1 of about 0.2 and significant constraints on variable w models. The Canadian NSERC provided funding for the scientific analysis. These results are based on observations obtained at the CFHT, Gemini, VLT and Keck observatories.

An Updated Nuclear Equation of State for Neutron Stars and Supernova Simulations

NASA Astrophysics Data System (ADS)

Meixner, M. A.; Mathews, G. J.; Dalhed, H. E.; Lan, N. Q.

2011-10-01

We present an updated and improved Equation of State based upon the framework originally developed by Bowers & Wilson. The details of the EoS and improvements are described along with a description of how to access this EOS for numerical simulations. Among the improvements are an updated compressibility based upon recent measurements, the possibility of the formation of proton excess (Ye> 0.5) material and an improved treatment of the nuclear statistical equilibrium and the transition to pasta nuclei as the density approaches nuclear matter density. The possibility of a QCD chiral phase transition is also included at densities above nuclear matter density. We show comparisons of this EOS with the other two publicly available equations of state used in supernova collapse simulations. The advantages of the present EoS is that it is easily amenable to phenomenological parameterization to fit observed explosion properties and to accommodate new physical parameters.

Fast neutrino flavor conversions near the supernova core with realistic flavor-dependent angular distributions

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

Dasgupta, Basudeb; Sen, Manibrata; Mirizzi, Alessandro, E-mail: bdasgupta@theory.tifr.res.in, E-mail: alessandro.mirizzi@ba.infn.it, E-mail: manibrata.sen@gmail.com

2017-02-01

It has been recently pointed out that neutrino fluxes from a supernova can show substantial flavor conversions almost immediately above the core. Using linear stability analyses and numerical solutions of the fully nonlinear equations of motion, we perform a detailed study of these fast conversions , focussing on the region just above the supernova core. We carefully specify the instabilities for evolution in space or time, and find that neutrinos travelling towards the core make fast conversions more generic, i.e., possible for a wider range of flux ratios and angular asymmetries that produce a crossing between the zenith-angle spectra ofmore » ν {sub e} and ν-bar {sub e} . Using fluxes and angular distributions predicted by supernova simulations, we find that fast conversions can occur within tens of nanoseconds, only a few meters away from the putative neutrinospheres. If these fast flavor conversions indeed take place, they would have important implications for the supernova explosion mechanism and nucleosynthesis.« less

Progress of the equation of state table for supernova simulations and its influence

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

Sumiyoshi, Kohsuke

2012-11-12

We describe recent progress of the EOS tables for numerical simulations of core-collapse supernovae and related astrophysical phenomena. Based on the Shen EOS table, which has been widely used in supernova simulations, there is systematic progress by extending the degrees of freedom such as hyperons and quarks. These extended EOS tables have been used, for example, to study the neutrino bursts from the gravitational collapse of massive stars leading to the black hole formation. Observations of such neutrinos from galactic events in future will provide us with the information on the EOS. Recently, studies of the supernova EOS with themore » multi-composition of nuclei under the nuclear statistical equilibrium have been made beyond the single nucleus approximation as used in the Shen EOS. It has been found that light elements including deuterons are abundant in wide regions of the supernova cores. We discuss that neutrino-deuteron reactions may have a possible influence on the explosion mechanism through modifications of neutrino heating rates.« less

How Well Do We Know The Supernova Equation of State?

NASA Astrophysics Data System (ADS)

Hempel, Matthias; Oertel, Micaela; Typel, Stefan; Klähn, Thomas

We give an overview about equations of state (EOS) which are currently available for simulations of core-collapse supernovae and neutron star mergers. A few selected important aspects of the EOS, such as the symmetry energy, the maximum mass of neutron stars, and cluster formation, are confronted with constraints from experiments and astrophysical observations. There are just very few models which are compatible even with this very restricted set of constraints. These remaining models illustrate the uncertainty of the uniform nuclear matter EOS at high densities. In addition, at finite temperatures the medium modifications of nuclear clusters represent a conceptual challenge. In conclusion, there has been significant development in the recent years, but there is still need for further improved general purpose EOS tables.

The role of nuclear physics in supernovae and the evolution of neutron stars Neutrino Opacities, Equation of State, Transport Coefficients, and Dark Matter Production

NASA Astrophysics Data System (ADS)

Rrapaj, Ermal

A massive star, of at least eight solar masses, end their life cycle in a sudden, catastrophic collapse under its own gravity. In a thousandth of a second, it can shrink from thousands of kilometers across to a ball of ultra-condensed matter just a few kilometers across. Ultimately, it all ends in a cataclysmic explosion known as a supernova, and for a few short weeks it burns as brightly as several billion suns, briefly outshining the star's entire home galaxy. The visible light of a supernova, though, represents only about 1% of the released energy, the vast majority being in the form of ultraviolet light, x-rays, gamma rays and, especially neutrinos. In the first chapter of work, I study neutrino - nucleon interactions and their role in the nucleosynthesis of heavy elements. Another key ingredient is the equation of state, which relates the thermodynamic properties of these extreme environments to the micro physics of nuclear interactions, explored in the second chapter. As a supernova cools, a new neutron star is born. The thermal, electric properties and the shear viscosity of this object are analyzed in terms of a newly discovered interaction, among electrons and neutrons, in the third chapter. Given the enormous amount of energy released during the explosion, I study the possibility of producing light massive particles, candidates for what is commonly called dark matter, in the last chapter of this work. I find that supernovae are ideal environments where the interplay of all forces in nature can be observed, nuclear forces playing a paramount role.

Toward Microscopic Equations of State for Core-Collapse Supernovae from Chiral Effective Field Theory

NASA Astrophysics Data System (ADS)

Aboona, Bassam; Holt, Jeremy

2017-09-01

Chiral effective field theory provides a modern framework for understanding the structure and dynamics of nuclear many-body systems. Recent works have had much success in applying the theory to describe the ground- and excited-state properties of light and medium-mass atomic nuclei when combined with ab initio numerical techniques. Our aim is to extend the application of chiral effective field theory to describe the nuclear equation of state required for supercomputer simulations of core-collapse supernovae. Given the large range of densities, temperatures, and proton fractions probed during stellar core collapse, microscopic calculations of the equation of state require large computational resources on the order of one million CPU hours. We investigate the use of graphics processing units (GPUs) to significantly reduce the computational cost of these calculations, which will enable a more accurate and precise description of this important input to numerical astrophysical simulations. Cyclotron Institute at Texas A&M, NSF Grant: PHY 1659847, DOE Grant: DE-FG02-93ER40773.

Gamma-ray transfer and energy deposition in supernovae

NASA Technical Reports Server (NTRS)

Swartz, Douglas A.; Sutherland, Peter G.; Harkness, Robert P.

1995-01-01

Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the Ni-56 and Co-56 decay gamma-ray energy deposition in supernovae. The comparison shows that an effective, purely absorptive, gray opacity, kappa(sub gamma) approximately (0. 06 +/- 0.01)Y(sub e) sq cm/g, where Y is the total number of electrons per baryon, accurately describes the interaction of gamma-rays with the cool supernova gas and the local gamma-ray energy deposition within the gas. The nature of the gamma-ray interaction process (dominated by Compton scattering in the relativistic regime) creates a weak dependence of kappa(sub gamma) on the optical thickness of the (spherically symmetric) supernova atmosphere: The maximum value of kappa(sub gamma) applies during optically thick conditions when individual gamma-rays undergo multiple scattering encounters and the lower bound is reached at the phase characterized by a total Thomson optical depth to the center of the atmosphere tau(sub e) approximately less than 1. Gamma-ray deposition for Type Ia supernova models to within 10% for the epoch from maximum light to t = 1200 days. Our results quantitatively confirm that the quick and efficient solution to the gray transfer problem provides an accurate representation of gamma-ray energy deposition for a broad range of supernova conditions.

Supernova Ia Spectra and Spectrophotometric Time Series: Recognizing Twins and the Consequences for Cosmological Distance Measurements

NASA Astrophysics Data System (ADS)

Fakhouri, Hannah Kathleen

In Part I we introduce the method and results of the Twin Supernova analysis. This novel approach to Type Ia supernova standardization is currently only possible with spectrophotometric timeseries observations from the Nearby Supernova Factory. As Chapters 1 through 4 will explore, we select an ideal subset of supernovae, find pairs whose features match well in flux at all wavelengths and times, and test their dispersion in brightness. The analysis is completed in a blinded fashion, ensuring that we are not tuning our results. What we find is that twin supernovae do indeed have a small brightness dispersion. Part II shows two additional analyses related to the standardization of Type Ia supernovae. In Chapter 5 we present a check on the results of Bailey et al. [2009]. Literature supernovae with spectra near maximum light were tested to see how well their magnitudes could be standardized using the flux ratio method of Bailey et al [2009]. Chapter 6 shows a study with data from the Nearby Supernova Factory. Using only the spectrophotometric observations near maximum light, we calculate monochromatic Hubble Diagram residuals for each supernova. Those residuals are then corrected using a flux ratio, similar to Bailey et al. [2009] to test the standardization possibilities using only near-maximum observations.

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.

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

Untitled Document

Science.gov Websites

(Linear Redshift scale), with magnitude residuals from best fit cosmology. Postscript Figure 9: Age of the an equation of state w = p/rho. Postscript Figure 2: Hubble Diagram with 42 High- Redshift Supernovae

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

Fleury, Pierre, E-mail: fleury@iap.fr

In view of interpreting the cosmological observations precisely, especially when they involve narrow light beams, it is crucial to understand how light propagates in our statistically homogeneous, clumpy, Universe. Among the various approaches to tackle this issue, Swiss-cheese models propose an inhomogeneous spacetime geometry which is an exact solution of Einstein's equation, while the Dyer-Roeder approximation deals with inhomogeneity in an effective way. In this article, we demonstrate that the distance-redshift relation of a certain class of Swiss-cheese models is the same as the one predicted by the Dyer-Roeder approach, at a well-controlled level of approximation. Both methods are thereforemore » equivalent when applied to the interpretation of, e.g., supernova obervations. The proof relies on completely analytical arguments, and is illustrated by numerical results.« less

Hydrodynamic Simulations of Kepler's Supernova Remnant

NASA Astrophysics Data System (ADS)

Sullivan, Jessica; Blondin, John; Borkowski, Kazik; Reynolds, Stephen

2018-01-01

Kepler’s supernova remnant contains unusual features that strongly suggest an origin in a single-degenerate Type Ia explosion, including anisotropic circumstellar medium (CSM), a strong brightness gradient, and spatially varying expansion proper motions. We present 3Dhydrodynamic simulations to test a picture in which Kepler's progenitor binary emitted a strong asymmetric wind, densest in the orbital plane, while the system moved at high velocity through the ISM. We simulate the creation of the presupernova environment as well as the supernova blast wave, using the VH-1 grid-based hydrodynamics code. We first modeled an anisotropic wind to create an asymmetric bowshock around the progenitor, then the blast wave from thesupernova. The final simulation places both previous model pieces onto a single grid and allows the blast wave to expand into the bowshock. Models were completed on a Yin-Yang grids with matching angular resolutions. By manipulating parameters that control the asymmetry of the system, we attempted to find conditions that recreated the current state of Kepler. We analyzed these models by comparing images of Kepler from the Chandra X-ray Observatory to line-of-sight projections from the model results. We also present comparisons of simulated expansion velocities with recent observations of X-ray proper motions from Chandra images. We were able to produce models that contained similar features to those seen in Kepler. We find the greatest resemblance to Kepler images with a presupernova wind with an equator-to-pole density contrast of 3 and a moderately disk-like CSM at a 5° angle between equatorial plane and system motion.

Essential Ingredients in Core-collapse Supernovae

DOE PAGES

Hix, William Raphael; Lentz, E. J.; Endeve, Eirik; ...

2014-03-27

Marking the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae bring together physics at a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale) down to femtometer scale nuclear reactions. Carrying 10more » $$^{44}$$ joules of kinetic energy and a rich-mix of newly synthesized atomic nuclei, core-collapse supernovae are the preeminent foundries of the nuclear species which make up ourselves and our solar system. We will discuss our emerging understanding of the convectively unstable, neutrino-driven explosion mechanism, based on increasingly realistic neutrino-radiation hydrodynamic simulations that include progressively better nuclear and particle physics. Recent multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of how supernovae explode. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.« less

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 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.

Supernova Relic Neutrinos and the Supernova Rate Problem: Analysis of Uncertainties and Detectability of ONeMg and Failed Supernovae

NASA Astrophysics Data System (ADS)

Mathews, Grant J.; Hidaka, Jun; Kajino, Toshitaka; Suzuki, Jyutaro

2014-08-01

Direct measurements of the core collapse supernova rate (R SN) in the redshift range 0 <= z <= 1 appear to be about a factor of two smaller than the rate inferred from the measured cosmic massive star formation rate (SFR). This discrepancy would imply that about one-half of the massive stars that have been born in the local observed comoving volume did not explode as luminous supernovae. In this work, we explore the possibility that one could clarify the source of this "supernova rate problem" by detecting the energy spectrum of supernova relic neutrinos with a next generation 106 ton water Čerenkov detector like Hyper-Kamiokande. First, we re-examine the supernova rate problem. We make a conservative alternative compilation of the measured SFR data over the redshift range 0 <=z <= 7. We show that by only including published SFR data for which the dust obscuration has been directly determined, the ratio of the observed massive SFR to the observed supernova rate R SN has large uncertainties {\\sim }1.8^{+1.6}_{-0.6} and is statistically consistent with no supernova rate problem. If we further consider that a significant fraction of massive stars will end their lives as faint ONeMg SNe or as failed SNe leading to a black hole remnant, then the ratio reduces to {\\sim }1.1^{+1.0}_{-0.4} and the rate problem is essentially solved. We next examine the prospects for detecting this solution to the supernova rate problem. We first study the sources of uncertainty involved in the theoretical estimates of the neutrino detection rate and analyze whether the spectrum of relic neutrinos can be used to independently identify the existence of a supernova rate problem and its source. We consider an ensemble of published and unpublished core collapse supernova simulation models to estimate the uncertainties in the anticipated neutrino luminosities and temperatures. We illustrate how the spectrum of detector events might be used to establish the average neutrino temperature and constrain SN models. We also consider supernova ν-process nucleosynthesis to deduce constraints on the temperature of the various neutrino flavors. We study the effects of neutrino oscillations on the detected neutrino energy spectrum and also show that one might distinguish the equation of state (EoS) as well as the cause of the possible missing luminous supernovae from the detection of supernova relic neutrinos. We also analyze a possible enhanced contribution from failed supernovae leading to a black hole remnant as a solution to the supernova rate problem. We conclude that indeed it might be possible (though difficult) to measure the neutrino temperature, neutrino oscillations, and the EoS and confirm this source of missing luminous supernovae by the detection of the spectrum of relic neutrinos.

Supernova relic neutrinos and the supernova rate problem: Analysis of uncertainties and detectability of ONeMg and failed supernovae

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

Mathews, Grant J.; Hidaka, Jun; Kajino, Toshitaka

2014-08-01

Direct measurements of the core collapse supernova rate (R{sub SN}) in the redshift range 0 ≤ z ≤ 1 appear to be about a factor of two smaller than the rate inferred from the measured cosmic massive star formation rate (SFR). This discrepancy would imply that about one-half of the massive stars that have been born in the local observed comoving volume did not explode as luminous supernovae. In this work, we explore the possibility that one could clarify the source of this 'supernova rate problem' by detecting the energy spectrum of supernova relic neutrinos with a next generation 10{supmore » 6} ton water Čerenkov detector like Hyper-Kamiokande. First, we re-examine the supernova rate problem. We make a conservative alternative compilation of the measured SFR data over the redshift range 0 ≤z ≤ 7. We show that by only including published SFR data for which the dust obscuration has been directly determined, the ratio of the observed massive SFR to the observed supernova rate R{sub SN} has large uncertainties ∼1.8{sub −0.6}{sup +1.6} and is statistically consistent with no supernova rate problem. If we further consider that a significant fraction of massive stars will end their lives as faint ONeMg SNe or as failed SNe leading to a black hole remnant, then the ratio reduces to ∼1.1{sub −0.4}{sup +1.0} and the rate problem is essentially solved. We next examine the prospects for detecting this solution to the supernova rate problem. We first study the sources of uncertainty involved in the theoretical estimates of the neutrino detection rate and analyze whether the spectrum of relic neutrinos can be used to independently identify the existence of a supernova rate problem and its source. We consider an ensemble of published and unpublished core collapse supernova simulation models to estimate the uncertainties in the anticipated neutrino luminosities and temperatures. We illustrate how the spectrum of detector events might be used to establish the average neutrino temperature and constrain SN models. We also consider supernova ν-process nucleosynthesis to deduce constraints on the temperature of the various neutrino flavors. We study the effects of neutrino oscillations on the detected neutrino energy spectrum and also show that one might distinguish the equation of state (EoS) as well as the cause of the possible missing luminous supernovae from the detection of supernova relic neutrinos. We also analyze a possible enhanced contribution from failed supernovae leading to a black hole remnant as a solution to the supernova rate problem. We conclude that indeed it might be possible (though difficult) to measure the neutrino temperature, neutrino oscillations, and the EoS and confirm this source of missing luminous supernovae by the detection of the spectrum of relic neutrinos.« less

The Hubble diagram in V for supernovae of Type Ia and the value of H(0) therefrom

NASA Technical Reports Server (NTRS)

Sandage, Allan; Tammann, G. A.

1993-01-01

The Hubble diagram for Type I supernovae is derived in V and is summarized from the literature in B and in m(pg). The ridge line equation of the diagram in V and the calibration of the absolute magnitudes at maximum are presented. The intrinsic (B - V) color at B maximum light is 0.09 +/- 0.04 mag. The Virgo Cluster distance is derived and found to be 23.9 +/- 2.4 Mpc. This Virgo distance gives the cosmic value of the Hubble constant to be H(0) = 47 +/- 5 km/sec per Mpc.

Supernova neutrinos and explosive nucleosynthesis

NASA Astrophysics Data System (ADS)

Kajino, T.; Aoki, W.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Mathews, G. J.; Nakamura, K.; Shibagaki, S.; Suzuki, T.

2014-05-01

Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes 7Li, 11B, 92Nb, 138La and 180Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and θ13, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements 11B and 7Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ13, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

Swiss-cheese models and the Dyer-Roeder approximation

NASA Astrophysics Data System (ADS)

Fleury, Pierre

2014-06-01

In view of interpreting the cosmological observations precisely, especially when they involve narrow light beams, it is crucial to understand how light propagates in our statistically homogeneous, clumpy, Universe. Among the various approaches to tackle this issue, Swiss-cheese models propose an inhomogeneous spacetime geometry which is an exact solution of Einstein's equation, while the Dyer-Roeder approximation deals with inhomogeneity in an effective way. In this article, we demonstrate that the distance-redshift relation of a certain class of Swiss-cheese models is the same as the one predicted by the Dyer-Roeder approach, at a well-controlled level of approximation. Both methods are therefore equivalent when applied to the interpretation of, e.g., supernova obervations. The proof relies on completely analytical arguments, and is illustrated by numerical results.

Nuclear pasta phases within the quark-meson coupling model

NASA Astrophysics Data System (ADS)

Grams, Guilherme; Santos, Alexandre M.; Panda, Prafulla K.; Providência, Constança; Menezes, Débora P.

2017-05-01

In this work, the low-density regions of nuclear and neutron star matter are studied. The search for the existence of nuclear pasta phases in this region is performed within the context of the quark-meson coupling (QMC) model, which incorporates quark degrees of freedom. Fixed proton fractions are considered, as well as nuclear matter in β equilibrium at zero temperature. We discuss the recent attempts to better understand the surface energy in the coexistence phases regime and we present results that show the existence of the pasta phases subject to some choices of the surface energy coefficient. We also analyze the influence of the nuclear pasta on some neutron star properties. The equation of state containing the pasta phase will be part of a complete grid for future use in supernova simulations.

SN IA in the IR: RAISIN A progress report

NASA Astrophysics Data System (ADS)

Kirshner, Robert P.; The RAISIN TEAM

2014-01-01

SN Ia have proven to be a powerful tool for cosmology. Near-IR observations of SN Ia promise even better results because the supernovae are more nearly standard candles at those wavelengths and absorption by dust is diminished by a factor of 4 compared to rest-frame B-band observations. Near IR observations of cosmologically-distant SN Ia discovered with PanSTARRS are underway using the infrared camera on the Hubble Space Telescope (GO-13046). These targets are discovered in the difference images created in the CfA/JHU pipeline, confirmed spectroscopically at the MMT, Magellan, Gemini, or Keck, and inserted in a non-disruptive way into the HST observing schedule for WFC3-IR. We have observed over 20 SN Ia in the range 0.2 < z < 0.5 during Cycle 21 and this is a progress report on the analysis. The final results require a repeat observation after the supernova has faded. Those will be completed in 2014, but we have a sufficient sample of objects for which the supernova is well separated from the host galaxy to illustrate the power of this technique. Preliminary analysis shows HST data can reduce the uncertainty in the distance to each supernova by a factor or 2. Sufficiently large supernova samples have been gathered at all redshifts so that statistical errors in interesting parameters (like the dark energy equation-of-state index (1 +w)), have been driven down to the same level as the systematic errors (about 7%). Further progress is limited by our ability to master the systematic errors. These include the correction for luminosity based on the light curve shape and the correction based on intrinsic color and reddening by dust. Since SN IA behave better in the IR in both these ways, there is reason to expect that this approach will be effective in driving down the systematic errors over time. If we are diligent in building up the size of the sample that is observed in the rest-frame infrared, we can expect more certain knowledge of the properties of dark energy. Unsolved problems include constructing precise K-corrections and firming up the fundamental photometric system in y, J, H, and K, but this approach seems a promising one for the HST era now, JWST soon, and WFIRST in good time.

Quark Phase Transition in Compact Objects and Multimessenger Astronomy: Neutrino Signals, Supernovae and Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Sokolov, V. V.; Vlasyuk, V. V.; Petkov, V. B.

2016-06-01

The International Workshop on Quark Phase Transition in Compact Objects and Multimessenger Astronomy: Neutrino Signals, Supernovae and Gamma-Ray Bursts (October, 7-14, 2015) was dedicated to Quantum ChromoDynamics (QCD) Phase Transitions and observational signals of these transitions related to formation of compact astrophysical objects. The aim of this workshop was to bring together researchers working on the problems of behavior of matter under critical conditions achievable in such astrophysical objects as "strange" or "hybrid" stars and in laboratories at heavy-ion collisions to discuss fundamental issues and recent developments. Topics included both observations (radio, optical and X-ray astronomy, gamma ray bursts, gravitational waves, neutrino detection, heavy-ion collisions, etc.) and theory (supernova simulations, proto-neutron and neutron stars, equation of state of dense matter, neutron star cooling, unstable modes, nucleosynthesis, explosive transitions, quark-gluon plasma).

Supernova constraints on neutrino oscillation and EoS for proto-neutron star

NASA Astrophysics Data System (ADS)

Kajino, T.; Aoki, W.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Mathews, G. J.; Nakamura, K.; Shibagaki, S.; Suzuki, T.

2014-05-01

Core-collapse supernovae eject huge amount of flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like 7Li, 11B, 92Nb, 138La and Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We here discuss how to determine the neutrino temperatures and propose a method to determine still unknown neutrino oscillation parameters, mass hierarchy and θ13, simultaneously. Combining the recent experimental constraints on θ13 with isotopic ratios of the light elements discovered in presolar grains from the Murchison meteorite, we show that our method suggests at a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

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.

Are There Hidden Supernovae?

NASA Technical Reports Server (NTRS)

Bregman, Jesse; Harker, David; Dunham, E.; Rank, David; Temi, Pasquale

1997-01-01

Ames Research Center and UCSC have been working on the development of a Mid IR Camera for the KAO in order to search for extra galactic supernovae. The development of the camera and its associated data reduction software have been successfully completed. Spectral Imaging of the Orion Bar at 6.2 and 7.8 microns demonstrates the derotation and data reduction software which was developed.

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.

Supernova equations of state including full nuclear ensemble with in-medium effects

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

2017-01-01

We construct new equations of state for baryons at sub-nuclear densities for the use in core-collapse supernova simulations. The abundance of various nuclei is obtained together with thermodynamic quantities. The formulation is an extension of the previous model, in which we adopted the relativistic mean field theory with the TM1 parameter set for nucleons, the quantum approach for d, t, h and α as well as the liquid drop model for the other nuclei under the nuclear statistical equilibrium. We reformulate the model of the light nuclei other than d, t, h and α based on the quasi-particle description. Furthermore, we modify the model so that the temperature dependences of surface and shell energies of heavy nuclei could be taken into account. The pasta phases for heavy nuclei and the Pauli- and self-energy shifts for d, t, h and α are taken into account in the same way as in the previous model. We find that nuclear composition is considerably affected by the modifications in this work, whereas thermodynamical quantities are not changed much. In particular, the washout of shell effect has a great impact on the mass distribution above T ∼ 1 MeV. This improvement may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores.

Dark side of the Universe after Planck data

NASA Astrophysics Data System (ADS)

Cheng, Cheng; Huang, Qing-Guo

2014-02-01

Recently released Planck data imply a smaller Hubble constant H0 than that from the Hubble Space Telescope project (HST) and a larger percentage of the matter components Ωm compared to the Supernova Legacy Survey (SNLS) in the Λ cold dark matter (CDM) model. In this paper we found that even though the tension on H0 between Planck and HST can be relaxed if the dark radiation is introduced [ΔNeff=0.536-0.224+0.229 at 68% CL from the data sets of Planck+WMAP polarization (WP)+baryon acoustic oscillation (BAO)+the combination of supernova Union2.1 compilation of 580 Supernovae (Union2.1)+HST], Ωm from Planck is still not nicely compatible with that from SNLS. The tensions between Planck and other astrophysical data sets can be significantly relaxed in the wCDM model, and the combination of these data sets prefers a phantomlike dark energy at more than 95% CL: w =-1.15±0.07 and w=-1.16±0.06 at 68% CL from Planck+WP+BAO+Union2.1+HST and Planck+WP+BAO+SNLS+HST, respectively. From the statistical point of view, there is no evidence for a time-evolving equation of state (Δχ2=-0.3 compared to a constant equation of state for the combination of Planck+WP+BAO+SNLS+HST).

The Supernova Legacy Survey: Measurement of Omega_M, Omega_Lambda, and w from the First Year Data Set

DOE R&D Accomplishments Database

Astier, P.; Guy, J.; Regnault, N.; Pain, R.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Hook, I. M.; Howell, D. A.; Lafoux, H.; Neill, J. D.; Palanque-Delabrouille, N.; Perrett, K.; Pritchet, C. J.; Rich, J.; Sullivan, M.; Taillet, R.; Aldering, G.; Antilogus, P.; Arsenijevic, V.; Balland, C.; Baumont, S.; Bronder, J.; Courtois, H.; Ellis, R. S.; Filiol, M.; Goncalves, A. C.; Goobar, A.; Guide, D.; Hardin, D.; Lusset, V.; Lidman, C.; McMahon, R.; Mouchet, M.; Mourao, A.; Perlmutter, S.; Ripoche, P.; Tao, C.; Walton, N.

2005-10-14

We present distance measurements to 71 high redshift type Ia supernovae discovered during the first year of the 5-year Supernova Legacy Survey (SNLS). These events were detected and their multi-color light-curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in four bands. Follow-up spectroscopy was performed at the VLT, Gemini and Keck telescopes to confirm the nature of the supernovae and to measure their redshift. With this data set, we have built a Hubble diagram extending to z = 1, with all distance measurements involving at least two bands. Systematic uncertainties are evaluated making use of the multiband photometry obtained at CFHT. Cosmological fits to this first year SNLS Hubble diagram give the following results: {Omega}{sub M} = 0.263 {+-} 0.042 (stat) {+-} 0.032 (sys) for a flat {Lambda}CDM model; and w = -1.023 {+-} 0.090 (stat) {+-} 0.054 (sys) for a flat cosmology with constant equation of state w when combined with the constraint from the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations.

Cosmography by GRBs: Gamma Ray Bursts as possible distance indicators

NASA Astrophysics Data System (ADS)

Capozziello, S.; Izzo, L.

2009-10-01

A new method to constrain the cosmological equation of state is proposed by using combined samples of gammaray bursts (GRBs) and supernovae (SNeIa). The Chevallier-Polarski-Linder parameterization is adopted for the equation of state in order to find out a realistic approach to achieve the deceleration/acceleration transition phase of dark energy models. As results, we find that GRBs, calibrated by SNeIa, could be, at least, good distance indicators capable of discriminating cosmological models with respect to ΛCDM at high redshift.

Supernova constraints on neutrino oscillation and EoS for proto-neutron star

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

Kajino, T.; Aoki, W.; Cheoun, M.-K.

2014-05-02

Core-collapse supernovae eject huge amount of flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We here discuss how to determine the neutrino temperatures and propose a method to determine still unknown neutrino oscillation parameters, mass hierarchy and θ{sub 13}, simultaneously. Combining the recent experimental constraints on θ{sub 13} with isotopic ratios of the light elements discovered in presolar grains from the Murchison meteorite, we show that our methodmore » suggests at a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.« less

The Foundation Supernova Survey: motivation, design, implementation, and first data release

NASA Astrophysics Data System (ADS)

Foley, Ryan J.; Scolnic, Daniel; Rest, Armin; Jha, S. W.; Pan, Y.-C.; Riess, A. G.; Challis, P.; Chambers, K. C.; Coulter, D. A.; Dettman, K. G.; Foley, M. M.; Fox, O. D.; Huber, M. E.; Jones, D. O.; Kilpatrick, C. D.; Kirshner, R. P.; Schultz, A. S. B.; Siebert, M. R.; Flewelling, H. A.; Gibson, B.; Magnier, E. A.; Miller, J. A.; Primak, N.; Smartt, S. J.; Smith, K. W.; Wainscoat, R. J.; Waters, C.; Willman, M.

2018-03-01

The Foundation Supernova Survey aims to provide a large, high-fidelity, homogeneous, and precisely calibrated low-redshift Type Ia supernova (SN Ia) sample for cosmology. The calibration of the current low-redshift SN sample is the largest component of systematic uncertainties for SN cosmology, and new data are necessary to make progress. We present the motivation, survey design, observation strategy, implementation, and first results for the Foundation Supernova Survey. We are using the Pan-STARRS telescope to obtain photometry for up to 800 SNe Ia at z ≲ 0.1. This strategy has several unique advantages: (1) the Pan-STARRS system is a superbly calibrated telescopic system, (2) Pan-STARRS has observed 3/4 of the sky in grizyP1 making future template observations unnecessary, (3) we have a well-tested data-reduction pipeline, and (4) we have observed ˜3000 high-redshift SNe Ia on this system. Here, we present our initial sample of 225 SN Ia grizP1 light curves, of which 180 pass all criteria for inclusion in a cosmological sample. The Foundation Supernova Survey already contains more cosmologically useful SNe Ia than all other published low-redshift SN Ia samples combined. We expect that the systematic uncertainties for the Foundation Supernova Sample will be two to three times smaller than other low-redshift samples. We find that our cosmologically useful sample has an intrinsic scatter of 0.111 mag, smaller than other low-redshift samples. We perform detailed simulations showing that simply replacing the current low-redshift SN Ia sample with an equally sized Foundation sample will improve the precision on the dark energy equation-of-state parameter by 35 per cent, and the dark energy figure of merit by 72 per cent.

Figures of merit for present and future dark energy probes

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

Mortonson, Michael J.; Huterer, Dragan; Hu, Wayne

2010-09-15

We compare current and forecasted constraints on dynamical dark energy models from Type Ia supernovae and the cosmic microwave background using figures of merit based on the volume of the allowed dark energy parameter space. For a two-parameter dark energy equation of state that varies linearly with the scale factor, and assuming a flat universe, the area of the error ellipse can be reduced by a factor of {approx}10 relative to current constraints by future space-based supernova data and CMB measurements from the Planck satellite. If the dark energy equation of state is described by a more general basis ofmore » principal components, the expected improvement in volume-based figures of merit is much greater. While the forecasted precision for any single parameter is only a factor of 2-5 smaller than current uncertainties, the constraints on dark energy models bounded by -1{<=}w{<=}1 improve for approximately 6 independent dark energy parameters resulting in a reduction of the total allowed volume of principal component parameter space by a factor of {approx}100. Typical quintessence models can be adequately described by just 2-3 of these parameters even given the precision of future data, leading to a more modest but still significant improvement. In addition to advances in supernova and CMB data, percent-level measurement of absolute distance and/or the expansion rate is required to ensure that dark energy constraints remain robust to variations in spatial curvature.« less

Analysis of IUE Observations of Supernovae

NASA Technical Reports Server (NTRS)

Kirshner, Robert P.

1996-01-01

This program supported the analysis of IUE observations of supernovae. One aspect was a Target-of-Opportunity program to observe bright supernovae which was applied to SN 1993J in M81, and another was continuing analysis of the IUE data from SN 1987A. Because of its quick response time, the IUE satellite has continued to provide useful data on the ultraviolet spectra of supernovae. Even after the launch of the Hubble Space Telescope, which has much more powerful ultraviolet spectrometers, the IUE has enabled us to obtain early and frequent measurements of ultraviolet radiation: this information has been folded in with our HST data to create unique observations of supernova which can be interpreted to give powerful constraints on the physical properties of the exploding stars. Our chief result in the present grant period was the completion of a detailed reanalysis of the data on the circumstellar shell of SN 1987A. The presence of narrow high-temperature mission lines from nitrogen-rich gas close to SN 1987A has been the principal observational constraint on the evolution of the supernova's progenitor. Our new analysis shows that the onset of these lines, their rise to maximum, and their subsequent fading can be understood in the context of a model for the photoionization of circumstellar matter.

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.

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

New selection effect in statistical investigations of supernova remnants

NASA Astrophysics Data System (ADS)

Allakhverdiev, A. O.; Guseinov, O. Kh.; Kasumov, F. K.

1986-01-01

The influence of H II regions on the parameters of supernova remnants (SNR) is investigated. It has been shown that the projection of such regions on the SNRs leads to: a) local changes of morphological structure of young shell-type SNRs and b) considerable distortions of integral parameters of evolved shell-type SNRs (with D > 10 pc) and plerions, up to their complete undetectability on the background of classical and gigantic H II regions. A new selection effect, in fact, arises from these factors connected with additional limitations made by the real structure of the interstellar medium on the statistical investigations of SNRs. The influence of this effect on the statistical completeness of objects has been estimated.

Crossing statistic: reconstructing the expansion history of the universe

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

Shafieloo, Arman, E-mail: arman@ewha.ac.kr

2012-08-01

We present that by combining Crossing Statistic [1,2] and Smoothing method [3-5] one can reconstruct the expansion history of the universe with a very high precision without considering any prior on the cosmological quantities such as the equation of state of dark energy. We show that the presented method performs very well in reconstruction of the expansion history of the universe independent of the underlying models and it works well even for non-trivial dark energy models with fast or slow changes in the equation of state of dark energy. Accuracy of the reconstructed quantities along with independence of the methodmore » to any prior or assumption gives the proposed method advantages to the other non-parametric methods proposed before in the literature. Applying on the Union 2.1 supernovae combined with WiggleZ BAO data we present the reconstructed results and test the consistency of the two data sets in a model independent manner. Results show that latest available supernovae and BAO data are in good agreement with each other and spatially flat ΛCDM model is in concordance with the current data.« less

Detecting features in the dark energy equation of state: a wavelet approach

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

Hojjati, Alireza; Pogosian, Levon; Zhao, Gong-Bo, E-mail: alireza_hojjati@sfu.ca, E-mail: levon@sfu.ca, E-mail: gong-bo.zhao@port.ac.uk

2010-04-01

We study the utility of wavelets for detecting the redshift evolution of the dark energy equation of state w(z) from the combination of supernovae (SNe), CMB and BAO data. We show that local features in w, such as bumps, can be detected efficiently using wavelets. To demonstrate, we first generate a mock supernovae data sample for a SNAP-like survey with a bump feature in w(z) hidden in, then successfully discover it by performing a blind wavelet analysis. We also apply our method to analyze the recently released ''Constitution'' SNe data, combined with WMAP and BAO from SDSS, and find weakmore » hints of dark energy dynamics. Namely, we find that models with w(z) < −1 for 0.2 < z < 0.5, and w(z) > −1 for 0.5 < z < 1, are mildly favored at 95% confidence level. This is in good agreement with several recent studies using other methods, such as redshift binning with principal component analysis (PCA) (e.g. Zhao and Zhang, arXiv: 0908.1568)« less

Relativistic Kinetic Theory

NASA Astrophysics Data System (ADS)

Vereshchagin, Gregory V.; Aksenov, Alexey G.

2017-02-01

Preface; Acknowledgements; Acronyms and definitions; Introduction; Part I. Theoretical Foundations: 1. Basic concepts; 2. Kinetic equation; 3. Averaging; 4. Conservation laws and equilibrium; 5. Relativistic BBGKY hierarchy; 6. Basic parameters in gases and plasmas; Part II. Numerical Methods: 7. The basics of computational physics; 8. Direct integration of Boltzmann equations; 9. Multidimensional hydrodynamics; Part III. Applications: 10. Wave dispersion in relativistic plasma; 11. Thermalization in relativistic plasma; 12. Kinetics of particles in strong fields; 13. Compton scattering in astrophysics and cosmology; 14. Self-gravitating systems; 15. Neutrinos, gravitational collapse and supernovae; Appendices; Bibliography; Index.

Constraining inverse-curvature gravity with supernovae.

PubMed

Mena, Olga; Santiago, José; Weller, Jochen

2006-02-03

We show that models of generalized modified gravity, with inverse powers of the curvature, can explain the current accelerated expansion of the Universe without resorting to dark energy and without conflicting with solar system experiments. We have solved the Friedmann equations for the full dynamical range of the evolution of the Universe and performed a detailed analysis of supernovae data in the context of such models that results in an excellent fit. If we further include constraints on the current expansion of the Universe and on its age, we obtain that the matter content of the Universe is 0.07

What We Know About Dark Energy From Supernovae

ScienceCinema

Filippenko, Alex

2018-01-24

The measured distances of type Ia (white dwarf) supernovae as a function of redshift (z) have shown that the expansion of the Universe is currently accelerating, probably due to the presence of dark energy (X) having a negative pressure. Combining all of the data with existing results from large-scale structure surveys, we find a best fit for Omega M and Omega X of 0.28 and 0.72 (respectively), in excellent agreement with the values derived independently from WMAP measurements of the cosmic microwave background radiation. Thus far, the best-fit value for the dark energy equation-of-state parameter is -1, and its first derivative is consistent with zero, suggesting that the dark energy may indeed be Einstein's cosmological constant.

Confined dense circumstellar material surrounding a regular type II supernova

NASA Astrophysics Data System (ADS)

Yaron, O.; Perley, D. A.; Gal-Yam, A.; Groh, J. H.; Horesh, A.; Ofek, E. O.; Kulkarni, S. R.; Sollerman, J.; Fransson, C.; Rubin, A.; Szabo, P.; Sapir, N.; Taddia, F.; Cenko, S. B.; Valenti, S.; Arcavi, I.; Howell, D. A.; Kasliwal, M. M.; Vreeswijk, P. M.; Khazov, D.; Fox, O. D.; Cao, Y.; Gnat, O.; Kelly, P. L.; Nugent, P. E.; Filippenko, A. V.; Laher, R. R.; Wozniak, P. R.; Lee, W. H.; Rebbapragada, U. D.; Maguire, K.; Sullivan, M.; Soumagnac, M. T.

2017-02-01

With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, which sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF 13dqy = SN 2013fs a mere ~3 h after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at ~6 h post-explosion) spectra, map the distribution of material in the immediate environment (<~1015 cm) of the exploding star and establish that it was surrounded by circumstellar material (CSM) that was ejected during the final ~1 yr prior to explosion at a high rate, around 10-3 solar masses per year. The complete disappearance of flash-ionized emission lines within the first several days requires that the dense CSM be confined to within <~1015 cm, consistent with radio non-detections at 70-100 days. The observations indicate that iPTF 13dqy was a regular type II supernova; thus, the finding that the probable red supergiant progenitor of this common explosion ejected material at a highly elevated rate just prior to its demise suggests that pre-supernova instabilities may be common among exploding massive stars.

A simple and general method for solving detailed chemical evolution with delayed production of iron and other chemical elements

NASA Astrophysics Data System (ADS)

Vincenzo, F.; Matteucci, F.; Spitoni, E.

2017-04-01

We present a theoretical method for solving the chemical evolution of galaxies by assuming an instantaneous recycling approximation for chemical elements restored by massive stars and the delay time distribution formalism for delayed chemical enrichment by Type Ia Supernovae. The galaxy gas mass assembly history, together with the assumed stellar yields and initial mass function, represents the starting point of this method. We derive a simple and general equation, which closely relates the Laplace transforms of the galaxy gas accretion history and star formation history, which can be used to simplify the problem of retrieving these quantities in the galaxy evolution models assuming a linear Schmidt-Kennicutt law. We find that - once the galaxy star formation history has been reconstructed from our assumptions - the differential equation for the evolution of the chemical element X can be suitably solved with classical methods. We apply our model to reproduce the [O/Fe] and [Si/Fe] versus [Fe/H] chemical abundance patterns as observed at the solar neighbourhood by assuming a decaying exponential infall rate of gas and different delay time distributions for Type Ia Supernovae; we also explore the effect of assuming a non-linear Schmidt-Kennicutt law, with the index of the power law being k = 1.4. Although approximate, we conclude that our model with the single-degenerate scenario for Type Ia Supernovae provides the best agreement with the observed set of data. Our method can be used by other complementary galaxy stellar population synthesis models to predict also the chemical evolution of galaxies.

New Equations of State Based on the Liquid Drop Model of Heavy Nuclei and Quantum Approach to Light Nuclei for Core-collapse Supernova Simulations

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

2013-08-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.

Supernova Cosmology in the Big Data Era

NASA Astrophysics Data System (ADS)

Kessler, Richard

Here we describe large "Big Data" Supernova (SN) Ia surveys, past and present, used to make precision measurements of cosmological parameters that describe the expansion history of the universe. In particular, we focus on surveys designed to measure the dark energy equation of state parameter w and its dependence on cosmic time. These large surveys have at least four photometric bands, and they use a rolling search strategy in which the same instrument is used for both discovery and photometric follow-up observations. These surveys include the Supernova Legacy Survey (SNLS), Sloan Digital Sky Survey II (SDSS-II), Pan-STARRS 1 (PS1), Dark Energy Survey (DES), and Large Synoptic Survey Telescope (LSST). We discuss the development of how systematic uncertainties are evaluated, and how methods to reduce them play a major role is designing new surveys. The key systematic effects that we discuss are (1) calibration, measuring the telescope efficiency in each filter band, (2) biases from a magnitude-limited survey and from the analysis, and (3) photometric SN classification for current surveys that don't have enough resources to spectroscopically confirm each SN candidate.

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.;

The XMM-Newton view of the non-thermal supernova remnant HESS J1731-347

NASA Astrophysics Data System (ADS)

Puehlhofer, G.; Doroshenko, V.; Acero, F.; Bamba, A.; Klochkov, D.; Tian, W.

2017-10-01

HESS J1731-347 belongs to a small group of supernova remnants that are characterized by a spatially-resolved shell-type TeV morphology and strong synchrotron X-ray emission. We report on XMM-Newton observations of the source that provide for the first time a complete X-ray view of the remnant. The data show an emissivity gradient across the source, which is not observed in the TeV gamma-ray and radio bands. While the broadband spectral analysis is compatible with a pure leptonic emission scenario up to TeV energies, the morphological analysis could be indicative of a blend of hadronic and leptonic TeV emission. We discuss the possibility of an interaction of the supernova remnant with nearby molecular clouds.

Core-collapse supernova simulations

NASA Astrophysics Data System (ADS)

Mueller, Bernhard

2017-01-01

Core-collapse supernovae, the deaths of massive stars, are among the most spectacular phenomena in astrophysics: Not only can supernovae outshine their host galaxy for weeks; they are also laboratories for the behavior of matter at supranuclear densities, and one of the few environments where collective neutrino effects can become important. Moreover, supernovae play a central role in the cosmic matter cycle, e.g., as the dominant producers of oxygen in the Universe. Yet the mechanism by which massive stars explode has eluded us for decades, partly because classical astronomical observations across the electromagnetic spectrum cannot directly probe the supernovae ``engine''. Numerical simulations are thus our primary tool for understanding the explosion mechanism(s) of massive stars. Rigorous modeling needs to take a host of important physical ingredients into account, such as the emission and partial reabsorption of neutrinos from the young proto-neutron star, multi-dimensional fluid motions, general relativistic gravity, the equation of state of nuclear matter, and magnetic fields. This is a challenging multi-physics problem that has not been fully solved yet. Nonetheless, as I shall argue in this talk, recent first-principle 3D simulations have gone a long way towards demonstrating the viability of the most popular explosion scenario, the ``neutrino-driven mechanism''. Focusing on successful explosion models of the MPA-QUB-Monash collaboration, I will discuss possible requirements for robust explosions across a wide range of progenitors, such as accurate neutrino opacities, stellar rotation, and seed asymmetries from convective shell burning. With the advent of successful explosion models, supernova theory can also be confronted with astronomical observations. I will show that recent 3D models come closer to matching observed explosion parameters (explosion energies, neutron star kicks) than older 2D models, although there are still discrepancies. This work has been supported by the ARC (grant DE150101145), NSF (PHY-1430152, JINA-CEE) and the supercomputing centers/initiatives NCI, Pawsey, and DiRAC.

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.

Improved models of stellar core collapse and still no explosions: what is missing?

PubMed

Buras, R; Rampp, M; Janka, H-Th; Kifonidis, K

2003-06-20

Two-dimensional hydrodynamic simulations of stellar core collapse are presented which for the first time were performed by solving the Boltzmann equation for the neutrino transport including a state-of-the-art description of neutrino interactions. Stellar rotation is also taken into account. Although convection develops below the neutrinosphere and in the neutrino-heated region behind the supernova shock, the models do not explode. This suggests missing physics, possibly with respect to the nuclear equation of state and weak interactions in the subnuclear regime. However, it might also indicate a fundamental problem with the neutrino-driven explosion mechanism.

The Cardassian expansion revisited: constraints from updated Hubble parameter measurements and type Ia supernova data

NASA Astrophysics Data System (ADS)

Magaña, Juan; Amante, Mario H.; Garcia-Aspeitia, Miguel A.; Motta, V.

2018-05-01

Motivated by an updated compilation of observational Hubble data (OHD) that consist of 51 points in the redshift range of 0.07 < z < 2.36, we study an interesting model known as Cardassian that drives the late cosmic acceleration without a dark energy component. Our compilation contains 31 data points measured with the differential age method by Jimenez & Loeb (2002), and 20 data points obtained from clustering of galaxies. We focus on two modified Friedmann equations: the original Cardassian (OC) expansion and the modified polytropic Cardassian (MPC). The dimensionless Hubble, E(z), and the deceleration parameter, q(z), are revisited in order to constrain the OC and MPC free parameters, first with the OHD and then contrasted with recent observations of type Ia supernova (SN Ia) using the compressed and full joint-light-analysis (JLA) samples (Betoule et al.). We also perform a joint analysis using the combination OHD plus compressed JLA. Our results show that the OC and MPC models are in agreement with the standard cosmology and naturally introduce a cosmological-constant-like extra term in the canonical Friedmann equation with the capability of accelerating the Universe without dark energy.

DEPENDENCE OF THE Sr-TO-Ba AND Sr-TO-Eu RATIO ON THE NUCLEAR EQUATION OF STATE IN METAL-POOR HALO STARS

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

Famiano, M. A.; Kajino, T.; Aoki, W.

A model is proposed in which the dependence on the equation of state (EOS) of the scatter of [Sr/Ba] in metal-poor stars is studied. Light r-process element enrichment in these stars has been explained via a truncated r-process, or “tr-process.” The truncation of the r-process from a generic core-collapse event followed by a collapse into an accretion-induced black hole is examined in the framework of a galactic chemical evolution model. The constraints on this model imposed by observations of extremely metal-poor stars are explained, and the upper limits in the [Sr/Ba] distributions are found to be related to the nuclearmore » EOS in a collapse scenario. The scatter in [Sr/Ba] and [Sr/Eu] as a function of metallicity has been found to be consistent with turbulent ejection in core-collapse supernovae. Adaptations of this model are evaluated to account for the scatter in isotopic observables. This is done by assuming mixing in ejecta in a supernova event. Stiff EOS are eliminated by this model.« less

A viable dark fluid model

NASA Astrophysics Data System (ADS)

Elkhateeb, Esraa

2018-01-01

We consider a cosmological model based on a generalization of the equation of state proposed by Nojiri and Odintsov (2004) and Štefančić (2005, 2006). We argue that this model works as a dark fluid model which can interpolate between dust equation of state and the dark energy equation of state. We show how the asymptotic behavior of the equation of state constrained the parameters of the model. The causality condition for the model is also studied to constrain the parameters and the fixed points are tested to determine different solution classes. Observations of Hubble diagram of SNe Ia supernovae are used to further constrain the model. We present an exact solution of the model and calculate the luminosity distance and the energy density evolution. We also calculate the deceleration parameter to test the state of the universe expansion.

Gas Removal in the Ursa Minor Galaxy: Linking Hydrodynamics and Chemical Evolution Models

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

Caproni, Anderson; Lanfranchi, Gustavo Amaral; Baio, Gabriel Henrique Campos

2017-04-01

We present results from a non-cosmological, three-dimensional hydrodynamical simulation of the gas in the dwarf spheroidal galaxy Ursa Minor. Assuming an initial baryonic-to-dark-matter ratio derived from the cosmic microwave background radiation, we evolved the galactic gas distribution over 3 Gyr, taking into account the effects of the types Ia and II supernovae. For the first time, we used in our simulation the instantaneous supernovae rates derived from a chemical evolution model applied to spectroscopic observational data of Ursa Minor. We show that the amount of gas that is lost in this process is variable with time and radius, being themore » highest rates observed during the initial 600 Myr in our simulation. Our results indicate that types Ia and II supernovae must be essential drivers of the gas loss in Ursa Minor galaxy (and probably in other similar dwarf galaxies), but it is ultimately the combination of galactic winds powered by these supernovae and environmental effects (e.g., ram-pressure stripping) that results in the complete removal of the gas content.« less

Radio emission of SN1993J: the complete picture. II. Simultaneous fit of expansion and radio light curves

NASA Astrophysics Data System (ADS)

Martí-Vidal, I.; Marcaide, J. M.; Alberdi, A.; Guirado, J. C.; Pérez-Torres, M. A.; Ros, E.

2011-02-01

We report on a simultaneous modelling of the expansion and radio light curves of the supernova SN1993J. We developed a simulation code capable of generating synthetic expansion and radio light curves of supernovae by taking into consideration the evolution of the expanding shock, magnetic fields, and relativistic electrons, as well as the finite sensitivity of the interferometric arrays used in the observations. Our software successfully fits all the available radio data of SN 1993J with a standard emission model for supernovae, which is extended with some physical considerations, such as an evolution in the opacity of the ejecta material, a radial decline in the magnetic fields within the radiating region, and a changing radial density profile for the circumstellar medium starting from day 3100 after the explosion.

NEW HYPERON EQUATIONS OF STATE FOR SUPERNOVAE AND NEUTRON STARS IN DENSITY-DEPENDENT HADRON FIELD THEORY

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

Banik, Sarmistha; Hempel, Matthias; Bandyopadhyay, Debades

2014-10-01

We develop new hyperon equation of state (EoS) tables for core-collapse supernova simulations and neutron stars. These EoS tables are based on a density-dependent relativistic hadron field theory where baryon-baryon interaction is mediated by mesons, using the parameter set DD2 for nucleons. Furthermore, light and heavy nuclei along with interacting nucleons are treated in the nuclear statistical equilibrium model of Hempel and Schaffner-Bielich which includes excluded volume effects. Of all possible hyperons, we consider only the contribution of Λs. We have developed two variants of hyperonic EoS tables: in the npΛφ case the repulsive hyperon-hyperon interaction mediated by the strangemore » φ meson is taken into account, and in the npΛ case it is not. The EoS tables for the two cases encompass a wide range of densities (10{sup –12} to ∼1 fm{sup –3}), temperatures (0.1 to 158.48 MeV), and proton fractions (0.01 to 0.60). The effects of Λ hyperons on thermodynamic quantities such as free energy per baryon, pressure, or entropy per baryon are investigated and found to be significant at higher densities. The cold, β-equilibrated EoS (with the crust included self-consistently) results in a 2.1 M {sub ☉} maximum mass neutron star for the npΛφ case, whereas that for the npΛ case is 1.95 M {sub ☉}. The npΛφ EoS represents the first supernova EoS table involving hyperons that is directly compatible with the recently measured 2 M {sub ☉} neutron stars.« 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.

A review of direct numerical simulations of astrophysical detonations and their implications

DOE PAGES

Parete-Koon, Suzanne T.; Smith, Christopher R.; Papatheodore, Thomas L.; ...

2013-04-11

Multi-dimensional direct numerical simulations (DNS) of astrophysical detonations in degenerate matter have revealed that the nuclear burning is typically characterized by cellular structure caused by transverse instabilities in the detonation front. Type Ia supernova modelers often use one- dimensional DNS of detonations as inputs or constraints for their whole star simulations. While these one-dimensional studies are useful tools, the true nature of the detonation is multi-dimensional. The multi-dimensional structure of the burning influences the speed, stability, and the composition of the detonation and its burning products, and therefore, could have an impact on the spectra of Type Ia supernovae. Considerablemore » effort has been expended modeling Type Ia supernovae at densities above 1x10 7 g∙cm -3 where the complexities of turbulent burning dominate the flame propagation. However, most full star models turn the nuclear burning schemes off when the density falls below 1x10 7 g∙cm -3 and distributed burning begins. The deflagration to detonation transition (DDT) is believed to occur at just these densities and consequently they are the densities important for studying the properties of the subsequent detonation. In conclusion, this work reviews the status of DNS studies of detonations and their possible implications for Type Ia supernova models. It will cover the development of Detonation theory from the first simple Chapman-Jouguet (CJ) detonation models to the current models based on the time-dependent, compressible, reactive flow Euler equations of fluid dynamics.« less

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.

Multi-azimuthal-angle effects in self-induced supernova neutrino flavor conversions without axial symmetry

NASA Astrophysics Data System (ADS)

Mirizzi, Alessandro

2013-10-01

The flavor evolution of neutrinos emitted by a supernova (SN) core is strongly affected by the refractive effects associated with the neutrino-neutrino interactions in the deepest stellar regions. Till now, all numerical studies have assumed the axial symmetry for the “multi-angle effects” associated with the neutrino-neutrino interactions. Recently, it has been pointed out in Raffelt, Sarikas, and Seixas [Phys. Rev. Lett. 111, 091101 (2013)] that if this assumption is removed, a new multi-azimuthal-angle (MAA) instability emerges in the flavor evolution of the dense SN neutrino gas, in addition to the one caused by multi-zenith-angle effects. Inspired by this result, for the first time we numerically solve the nonlinear neutrino propagation equations in SN, introducing the azimuthal angle as an angular variable in addition to the usual zenith angle. We consider simple energy spectra with an excess of νe over ν¯e. We find that even starting with a complete axial symmetric neutrino emission, the MAA effects would lead to significant flavor conversions in normal mass hierarchy, in cases otherwise stable under the only multi-zenith-angle effects. The final outcome of the flavor conversions, triggered by the MAA instability, depends on the initial asymmetry between νe and ν¯e spectra. If it is sufficiently large, final spectra would show an ordered behavior with spectral swaps and splits. Conversely, for small flavor asymmetries flavor decoherence among angular modes develops, also affecting the flavor evolution in the inverted mass hierarchy.

Topology and dark energy: testing gravity in voids.

PubMed

Spolyar, Douglas; Sahlén, Martin; Silk, Joe

2013-12-13

Modified gravity has garnered interest as a backstop against dark matter and dark energy (DE). As one possible modification, the graviton can become massive, which introduces a new scalar field--here with a Galileon-type symmetry. The field can lead to a nontrivial equation of state of DE which is density and scale dependent. Tension between type Ia supernovae and Planck could be reduced. In voids, the scalar field dramatically alters the equation of state of DE, induces a soon-observable gravitational slip between the two metric potentials, and develops a topological defect (domain wall) due to a nontrivial vacuum structure for the field.

Can we scan the supernova model space for collective oscillations?

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

Pehlivan, Y., E-mail: yamac.pehlivan@msgsu.edu.tr; National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo, 181-8588; Subaşı, A. L.

Collective neutrino oscillations in a core collapse supernova is a many-body phenomenon which can transform the neutrino energy spectra through emergent effects. One example of this behavior is the neutrino spectral swaps in which neutrinos of different flavors partially or completely exchange their spectra. In this talk, we address the question of how model dependent this behavior is. In particular, we demonstrate that these swaps may be independent of the mean field approximation that is typically employed in numerical treatments by showing an example of a spectral swap in the exact many-body picture.

Neutrino signal of electron-capture supernovae from core collapse to cooling.

PubMed

Hüdepohl, L; Müller, B; Janka, H-T; Marek, A; Raffelt, G G

2010-06-25

An 8.8M{⊙} electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time (∼9  s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities (∼200  ms), luminosity equipartition among all species becomes almost perfect and the spectra of ν{e} and ν{μ,τ} very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations.

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.

Nonstandard neutrino self-interactions in a supernova and fast flavor conversions

NASA Astrophysics Data System (ADS)

Dighe, Amol; Sen, Manibrata

2018-02-01

We study the effects of nonstandard self-interactions (NSSI) of neutrinos streaming out of a core-collapse supernova. We show that with NSSI, the standard linear stability analysis gives rise to linearly as well as exponentially growing solutions. For a two-box spectrum, we demonstrate analytically that flavor-preserving NSSI lead to a suppression of bipolar collective oscillations. In the intersecting four-beam model, we show that flavor-violating NSSI can lead to fast oscillations even when the angle between the neutrino and antineutrino beams is obtuse, which is forbidden in the standard model. This leads to the new possibility of fast oscillations in a two-beam system with opposing neutrino-antineutrino fluxes, even in the absence of any spatial inhomogeneities. Finally, we solve the full nonlinear equations of motion in the four-beam model numerically, and explore the interplay of fast and slow flavor conversions in the long-time behavior, in the presence of NSSI.

Neutrino Flavor Evolution in Turbulent Supernova Matter

NASA Astrophysics Data System (ADS)

Lund, Tina; Kneller, James P.

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 by including collective flavor effects, the evolution of the Mikheyev, Smirnov & Wolfenstein (MSW) matter conversions due to the shock wave passing through the star, and the impact of turbulence. The density profiles utilized in our calculations represent a 10.8 MG progenitor and comes from a 1D numerical simulation by Fischer et al.[1]. We find that small amplitude turbulence, up to 10% of the average potential, 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 are 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. 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 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. We illustrate how the progression of the shock wave is reflected in the changing survival probabilities over time, and we show preliminary results on how some of these collective and shock wave induced signatures appear in a detector signal.

Nuclear astrophysics of supernovae

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

Cooperstein, J.

1988-01-01

In this paper, I'll give a general introduction to Supernova Theory, beginning with the presupernova evolution and ending with the later stages of the explosion. This will be distilled from a colloquium type of talk. It is necessary to have the whole supernova picture in one's mind's eye when diving into some of its nooks and crannies, as it is quite a mess of contradictory ingredients. We will have some discussion of supernova 1987a, but will keep our discussion more general. Second, we'll look at the infall and bounce of the star, seeing why it goes unstable, what dynamics itmore » follows as it collapses, and how and why it bounces back. From there, we will go on to look at the equation of state (EOS) in more detail. We'll consider the cases T = 0 and T > 0. We'll focus on /rho/ < /rho//sub 0/, and then /rho/ > /rho//sub 0/ and the EOS of neutron stars, and whether or not they contain cores of strange matter. There are many things we could discuss here and not enough time. If I had more lectures, the remaining time would focus on two more questions of special interest to nuclear physicists: the electron capture reactions and neutrino transport. If time permitted, we'd have some discussion of the nucleosynthetic reactions in the explosion's debris as well. However, we cannot cover such material adequately, and I have chosen these topics because they are analytically tractable, pedagogically useful, and rather important. 23 refs., 14 figs., 3 tabs.« less

The Data Release of the Sloan Digital Sky Survey-II Supernova Survey

NASA Astrophysics Data System (ADS)

Sako, Masao; Bassett, Bruce; Becker, Andrew C.; Brown, Peter J.; Campbell, Heather; Wolf, Rachel; Cinabro, David; D’Andrea, Chris B.; Dawson, Kyle S.; DeJongh, Fritz; Depoy, Darren L.; Dilday, Ben; Doi, Mamoru; Filippenko, Alexei V.; Fischer, John A.; Foley, Ryan J.; Frieman, Joshua A.; Galbany, Lluis; Garnavich, Peter M.; Goobar, Ariel; Gupta, Ravi R.; Hill, Gary J.; Hayden, Brian T.; Hlozek, Renée; Holtzman, Jon A.; Hopp, Ulrich; Jha, Saurabh W.; Kessler, Richard; Kollatschny, Wolfram; Leloudas, Giorgos; Marriner, John; Marshall, Jennifer L.; Miquel, Ramon; Morokuma, Tomoki; Mosher, Jennifer; Nichol, Robert C.; Nordin, Jakob; Olmstead, Matthew D.; Östman, Linda; Prieto, Jose L.; Richmond, Michael; Romani, Roger W.; Sollerman, Jesper; Stritzinger, Max; Schneider, Donald P.; Smith, Mathew; Wheeler, J. Craig; Yasuda, Naoki; Zheng, Chen

2018-06-01

This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg2 area along the celestial equator. This data release is comprised of all transient sources brighter than r ≃ 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN Ia sample and assuming a flat ΛCDM cosmology, we determine Ω M = 0.315 ± 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7σ.

Cosmological and supernova neutrinos

NASA Astrophysics Data System (ADS)

Kajino, T.; Aoki, W.; Balantekin, A. B.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Kusakabe, M.; Mathews, G. J.; Nakamura, K.; Pehlivan, Y.; Shibagaki, S.; Suzuki, T.

2014-06-01

The Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies are the pillars of modern cosmology. It has recently been suggested that axion which is a dark matter candidate in the framework of the standard model could condensate in the early universe and induce photon cooling before the epoch of the photon last scattering. Although this may render a solution to the overproduction problem of primordial 7Li abundance, there arises another serious difficulty of overproducing D abundance. We propose a hybrid dark matter model with both axions and relic supersymmetric (SUSY) particles to solve both overproduction problems of the primordial D and 7Li abundances simultaneously. The BBN also serves to constrain the nature of neutrinos. Considering non-thermal photons produced in the decay of the heavy sterile neutrinos due to the magnetic moment, we explore the cosmological constraint on the strength of neutrino magnetic moment consistent with the observed light element abundances. Core-collapse supernovae eject huge flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like 7Li, 11B, 92Nb, 138La and 180Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. Combining the recent experimental constraints on θ13 with predicted and observed supernova-produced abundance ratio 11B/7Li encapsulated in the presolar grains from the Murchison meteorite, we show a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos (SRN) that may indicate the softness of the equation of state (EoS) of nuclear matter and adiabatic conditions of the neutrino oscillation.

Confined dense circumstellar material surrounding a regular type II supernova

DOE PAGES

Yaron, O.; Perley, D. A.; Gal-Yam, A.; ...

2017-02-13

With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, that sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF 13dqy = SN 2013fs a mere ~3 hr after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at ~6 hr post-explosion) spectra, map the distribution of material in the immediate environment (≲ 10 15 cm)more » of the exploding star and establish that it was surrounded by circumstellar material (CSM) that was ejected during the final ~1 yr prior to explosion at a high rate, around 10 -3 solar masses per year. The complete disappearance of flash-ionised emission lines within the first several days requires that the dense CSM be confined to within ≲10 15 cm, consistent with radio non-detections at 70–100 days. The observations indicate that iPTF 13dqy was a regular Type II SN; thus, the finding that the probable red supergiant (RSG) progenitor of this common explosion ejected material at a highly elevated rate just prior to its demise suggests that pre-supernova instabilities may be common among exploding massive stars.« less

Simulating Supernovae Driven Outflows in Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Rodriguez, Jaimee-Ian

2018-01-01

Galactic outflows, or winds, prove to be a necessary input for galactic simulations to produce results comparable to observation, for it solves issues caused by what previous literature dubbed the “angular momentum catastrophe.” While it is known that the nature of outflows depends on the nature of the Interstellar Medium (ISM), the mechanisms behind outflows are still not completely understood. We investigate the driving force behind galactic outflows and the factors that influence their behavior, hypothesizing that supernovae within the galaxy drive these winds. We study isolated, high-resolution, smooth particle hydrodynamic simulations, focusing specifically on dwarf galaxies due to their shallow potential wells, which allow for more significant outflows. We find that outflows follow star formation (and associated supernovae) suggesting the causal relationship between the two. Furthermore, simulations with higher diffusivity differ little in star formation rate, but show significantly lower outflow rates, suggesting that environmental factors that have little effect on regulating star formation can greatly influence outflows, and so efficient outflows can be driven by a constant rate of supernovae, depending on ISM behavior. We are currently analyzing disk morphology and ambient density in order to comprehend the effect of supernovae on the immediate interstellar gas. By attaining greater understanding of the origin of galactic outflows, we will be able to not only improve the accuracy of simulations, we will also be able to gain greater insight into galactic formation and evolution, as outflows and resultant inflows may be vital to the regulation of galaxies throughout their lifetimes.

Observational constraints on cosmological models with Chaplygin gas and quadratic equation of state

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

Sharov, G.S., E-mail: german.sharov@mail.ru

Observational manifestations of accelerated expansion of the universe, in particular, recent data for Type Ia supernovae, baryon acoustic oscillations, for the Hubble parameter H ( z ) and cosmic microwave background constraints are described with different cosmological models. We compare the ΛCDM, the models with generalized and modified Chaplygin gas and the model with quadratic equation of state. For these models we estimate optimal model parameters and their permissible errors with different approaches to calculation of sound horizon scale r {sub s} ( z {sub d} ). Among the considered models the best value of χ{sup 2} is achieved formore » the model with quadratic equation of state, but it has 2 additional parameters in comparison with the ΛCDM and therefore is not favored by the Akaike information criterion.« less

SHEDDING NEW LIGHT ON EXPLODING STARS: TERASCALE SIMULATIONS OF NEUTRINO-DRIVEN SUPERNOVAE AND THEIR NUCLEOSYNTHESIS

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

Haxton, Wick

2012-03-07

This project was focused on simulations of core-collapse supernovae on parallel platforms. The intent was to address a number of linked issues: the treatment of hydrodynamics and neutrino diffusion in two and three dimensions; the treatment of the underlying nuclear microphysics that governs neutrino transport and neutrino energy deposition; the understanding of the associated nucleosynthesis, including the r-process and neutrino process; the investigation of the consequences of new neutrino phenomena, such as oscillations; and the characterization of the neutrino signal that might be recorded in terrestrial detectors. This was a collaborative effort with Oak Ridge National Laboratory, State University ofmore » New York at Stony Brook, University of Illinois at Urbana-Champaign, University of California at San Diego, University of Tennessee at Knoxville, Florida Atlantic University, North Carolina State University, and Clemson. The collaborations tie together experts in hydrodynamics, nuclear physics, computer science, and neutrino physics. The University of Washington contributions to this effort include the further development of techniques to solve the Bloch-Horowitz equation for effective interactions and operators; collaborative efforts on developing a parallel Lanczos code; investigating the nuclear and neutrino physics governing the r-process and neutrino physics; and exploring the effects of new neutrino physics on the explosion mechanism, nucleosynthesis, and terrestrial supernova neutrino detection.« less

Apparent cosmic acceleration from Type Ia supernovae

NASA Astrophysics Data System (ADS)

Dam, Lawrence H.; Heinesen, Asta; Wiltshire, David L.

2017-11-01

Parameters that quantify the acceleration of cosmic expansion are conventionally determined within the standard Friedmann-Lemaître-Robertson-Walker (FLRW) model, which fixes spatial curvature to be homogeneous. Generic averages of Einstein's equations in inhomogeneous cosmology lead to models with non-rigidly evolving average spatial curvature, and different parametrizations of apparent cosmic acceleration. The timescape cosmology is a viable example of such a model without dark energy. Using the largest available supernova data set, the JLA catalogue, we find that the timescape model fits the luminosity distance-redshift data with a likelihood that is statistically indistinguishable from the standard spatially flat Λ cold dark matter cosmology by Bayesian comparison. In the timescape case cosmic acceleration is non-zero but has a marginal amplitude, with best-fitting apparent deceleration parameter, q_{0}=-0.043^{+0.004}_{-0.000}. Systematic issues regarding standardization of supernova light curves are analysed. Cuts of data at the statistical homogeneity scale affect light-curve parameter fits independent of cosmology. A cosmological model dependence of empirical changes to the mean colour parameter is also found. Irrespective of which model ultimately fits better, we argue that as a competitive model with a non-FLRW expansion history, the timescape model may prove a useful diagnostic tool for disentangling selection effects and astrophysical systematics from the underlying expansion history.

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.

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.

Transients in the Local Universe : Systematically Searching the Gap between Novae and Supernovae

NASA Astrophysics Data System (ADS)

Kasliwal, Mansi M.; Kulkarni, S.

2009-05-01

We present three systematic transient searches of the glaring luminosity gap between brightest novae (Mv = -10) and faintest supernovae (Mv = -16). The least explored regime in this gap, with several intriguing theoretical predictions, is short-duration transients (<10; days). Our searches are targeted and designed to be deeper and faster cadence (1-day) than traditional supernova searches and probe a larger volume compared to nova searches. We summarize discoveries from our search of the nearest, brightest galaxies (P60-FasTING, Fast Transients In Nearest Galaxies) and nearest galaxy clusters (CFHT-COVET, Coma and Virgo Exploration for Transients). We also highlight first results from the Palomar Transient Factory which targets local (<200 Mpc) luminosity concentrations. We suggest that building a complete inventory of transients in the local universe is timely. These transients are potential electromagnetic counterparts to next-generation instruments (e.g. Advanced LIGO, Auger, ICECUBE) which are also limited in sensitivity (due to intrumental or physical effects) to the local universe.

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

Fleury, Pierre; Uzan, Jean-Philippe; Larena, Julien, E-mail: fleury@iap.fr, E-mail: j.larena@ru.ac.za, E-mail: uzan@iap.fr

On the scale of the light beams subtended by small sources, e.g. supernovae, matter cannot be accurately described as a fluid, which questions the applicability of standard cosmic lensing to those cases. In this article, we propose a new formalism to deal with small-scale lensing as a diffusion process: the Sachs and Jacobi equations governing the propagation of narrow light beams are treated as Langevin equations. We derive the associated Fokker-Planck-Kolmogorov equations, and use them to deduce general analytical results on the mean and dispersion of the angular distance. This formalism is applied to random Einstein-Straus Swiss-cheese models, allowing usmore » to: (1) show an explicit example of the involved calculations; (2) check the validity of the method against both ray-tracing simulations and direct numerical integration of the Langevin equation. As a byproduct, we obtain a post-Kantowski-Dyer-Roeder approximation, accounting for the effect of tidal distortions on the angular distance, in excellent agreement with numerical results. Besides, the dispersion of the angular distance is correctly reproduced in some regimes.« less

The theory of stochastic cosmological lensing

NASA Astrophysics Data System (ADS)

Fleury, Pierre; Larena, Julien; Uzan, Jean-Philippe

2015-11-01

On the scale of the light beams subtended by small sources, e.g. supernovae, matter cannot be accurately described as a fluid, which questions the applicability of standard cosmic lensing to those cases. In this article, we propose a new formalism to deal with small-scale lensing as a diffusion process: the Sachs and Jacobi equations governing the propagation of narrow light beams are treated as Langevin equations. We derive the associated Fokker-Planck-Kolmogorov equations, and use them to deduce general analytical results on the mean and dispersion of the angular distance. This formalism is applied to random Einstein-Straus Swiss-cheese models, allowing us to: (1) show an explicit example of the involved calculations; (2) check the validity of the method against both ray-tracing simulations and direct numerical integration of the Langevin equation. As a byproduct, we obtain a post-Kantowski-Dyer-Roeder approximation, accounting for the effect of tidal distortions on the angular distance, in excellent agreement with numerical results. Besides, the dispersion of the angular distance is correctly reproduced in some regimes.

The CHilean Automatic Supernova sEarch (CHASE)

NASA Astrophysics Data System (ADS)

Pignata, G.; Maza, J.; Hamuy, M.; Antezana, R.; Gonzales, L.

2009-05-01

One of the most important challenges in modern cosmology will be to figure out the origin of the dark energy, to measure its equation of state and the time rate with which it changes (described by parameters w and w'). The measurement of these parameters will require high levels of accuracy in the Supernova (SN) Type Ia distances and various sources of systematic error such as reddening corrections and possible evolution in the SNcharacteristics which could couple with redshift and mimic the cosmological signal of interest. Fortunately, these concerns can be fully addressed through the comprehensive study of SNe in the local (z < 0.05) universe. Although Type II plateau SNe are not as luminous as SNe Ia, they afford two important, independent routes to cosmological distances using the Expanding Photosphere Method and the Standardized Candle Method. To assess the performance of these techniques a nearby sample of Type II SNe is necessary. With the purpose of addressing these issues the Millennium Center for Supernova Studies (MCSS) is teaming up with the Carnegie Supernova Project (CSP) to carry out an optical and near infrared (photometry, spectroscopy and polarimetry) follow up of nearby SNe. Unfortunately, the majority of the SNe observed by the MCSS and the CSP are discovered by searches carried out from the northern hemisphere. This entails a number of observational difficulties, in particular, it reduces the number of SNe for which the follow-up starts at very early epochs. The aim of the CHASE project is to remove this search bias by discovering young Southern SNe that will be extensively observed by the MCSS and the CSP. In the first nine-months of operation, CHASE has discovered two SNe: SN007oc (CBET 1114) and SN007pl (CBET 1130), thus demonstrating the feasibility of the survey.

THE CLUSTER LENSING AND SUPERNOVA SURVEY WITH HUBBLE: AN OVERVIEW

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

Postman, Marc; Coe, Dan; Bradley, Larry

2012-04-01

The Cluster Lensing And Supernova survey with Hubble (CLASH) is a 524-orbit Multi-Cycle Treasury Program to use the gravitational lensing properties of 25 galaxy clusters to accurately constrain their mass distributions. The survey, described in detail in this paper, will definitively establish the degree of concentration of dark matter in the cluster cores, a key prediction of structure formation models. The CLASH cluster sample is larger and less biased than current samples of space-based imaging studies of clusters to similar depth, as we have minimized lensing-based selection that favors systems with overly dense cores. Specifically, 20 CLASH clusters are solelymore » X-ray selected. The X-ray-selected clusters are massive (kT > 5 keV) and, in most cases, dynamically relaxed. Five additional clusters are included for their lensing strength ({theta}{sub Ein} > 35'' at z{sub s} = 2) to optimize the likelihood of finding highly magnified high-z (z > 7) galaxies. A total of 16 broadband filters, spanning the near-UV to near-IR, are employed for each 20-orbit campaign on each cluster. These data are used to measure precise ({sigma}{sub z} {approx} 0.02(1 + z)) photometric redshifts for newly discovered arcs. Observations of each cluster are spread over eight epochs to enable a search for Type Ia supernovae at z > 1 to improve constraints on the time dependence of the dark energy equation of state and the evolution of supernovae. We present newly re-derived X-ray luminosities, temperatures, and Fe abundances for the CLASH clusters as well as a representative source list for MACS1149.6+2223 (z 0.544).« less

Supernovae in Early-Type Galaxies: Directly Connecting Age and Metallicity with Type Ia Luminosity

NASA Astrophysics Data System (ADS)

Gallagher, Joseph S.; Garnavich, Peter M.; Caldwell, Nelson; Kirshner, Robert P.; Jha, Saurabh W.; Li, Weidong; Ganeshalingam, Mohan; Filippenko, Alexei V.

2008-10-01

We have obtained optical spectra of 29 early-type (E/S0) galaxies that hosted Type Ia supernovae (SNe Ia). We have measured absorption-line strengths and compared them to a grid of models to extract the relations between the supernova properties and the luminosity-weighted age/composition of the host galaxies. Such a direct measurement is a marked improvement over existing analyses that tend to rely on general correlations between the properties of stellar populations and morphology. We find a strong correlation suggesting that SNe Ia in galaxies whose populations have a characteristic age greater than 5 Gyr are ~1 mag fainter at Vmax than those found in galaxies with younger populations. We find that SN Ia distance residuals in the Hubble diagram are correlated with host-galaxy metal abundance with higher iron abundance galaxies hosting less-luminous supernovae. We thus conclude that the time since progenitor formation primarily determines the radioactive Ni production while progenitor metal abundance has a weaker influence on peak luminosity, but one not fully corrected by light-curve shape and color fitters. This result, particularly the secondary dependence on metallicity, has significant implications for the determination of the equation-of-state parameter, w = P/(ρ c2) , and could impact planning for future dark-energy missions such as JDEM. Assuming no selection effects in discovering SNe Ia in local early-type galaxies, we find a higher specific SN Ia rate in E/S0 galaxies with ages below 3 Gyr than in older hosts. The higher rate and brighter luminosities seen in the youngest E/S0 hosts may be a result of recent star formation and represents a tail of the "prompt" SN Ia progenitors.

Stability analysis in tachyonic potential chameleon cosmology

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

Farajollahi, H.; Salehi, A.; Tayebi, F.

2011-05-01

We study general properties of attractors for tachyonic potential chameleon scalar-field model which possess cosmological scaling solutions. An analytic formulation is given to obtain fixed points with a discussion on their stability. The model predicts a dynamical equation of state parameter with phantom crossing behavior for an accelerating universe. We constrain the parameters of the model by best fitting with the recent data-sets from supernovae and simulated data points for redshift drift experiment generated by Monte Carlo simulations.

Suppression of the multi-azimuthal-angle instability in dense neutrino gas during supernova accretion phase

NASA Astrophysics Data System (ADS)

Chakraborty, Sovan; Mirizzi, Alessandro; Saviano, Ninetta; Seixas, David de Sousa

2014-05-01

It has been recently pointed out that by removing the axial symmetry in the "multi-angle effects" associated with the neutrino-neutrino interactions for supernova (SN) neutrinos a new multi-azimuthal-angle (MAA) instability would arise. In particular, for a flux ordering Fνe>Fν ¯e>Fνx, as expected during the SN accretion phase, this instability occurs in the normal neutrino mass hierarchy. However, during this phase, the ordinary matter density can be larger than the neutrino one, suppressing the self-induced conversions. In this regard, we investigate the matter suppression of the MAA effects, performing a linearized stability analysis of the neutrino equations of motion, in the presence of realistic SN density profiles. We compare these results with the numerical solution of the SN neutrino nonlinear evolution equations. Assuming axially symmetric distributions of neutrino momenta, we find that the large matter term strongly inhibits the MAA effects. In particular, the hindrance becomes stronger including realistic forward-peaked neutrino angular distributions. As a result, in our model for a 10.8 M⊙ iron-core SNe, MAA instability does not trigger any flavor conversion during the accretion phase. Instead, for a 8.8 M⊙ O-Ne-Mg core SN model, with lower matter density profile and less forward-peaked angular distributions, flavor conversions are possible also at early times.

Black Hole Formation in Failing Core-Collapse Supernovae

NASA Astrophysics Data System (ADS)

O'Connor, Evan; Ott, Christian D.

2011-04-01

We present results of a systematic study of failing core-collapse supernovae and the formation of stellar-mass black holes (BHs). Using our open-source general-relativistic 1.5D code GR1D equipped with a three-species neutrino leakage/heating scheme and over 100 presupernova models, we study the effects of the choice of nuclear equation of state (EOS), zero-age main sequence (ZAMS) mass and metallicity, rotation, and mass-loss prescription on BH formation. We find that the outcome, for a given EOS, can be estimated, to first order, by a single parameter, the compactness of the stellar core at bounce. By comparing protoneutron star (PNS) structure at the onset of gravitational instability with solutions of the Tolman-Oppenheimer-Volkof equations, we find that thermal pressure support in the outer PNS core is responsible for raising the maximum PNS mass by up to 25% above the cold NS value. By artificially increasing neutrino heating, we find the critical neutrino heating efficiency required for exploding a given progenitor structure and connect these findings with ZAMS conditions, establishing, albeit approximately, for the first time based on actual collapse simulations, the mapping between ZAMS parameters and the outcome of core collapse. We also study the effect of progenitor rotation and find that the dimensionless spin of nascent BHs may be robustly limited below a* = Jc/GM 2 = 1 by the appearance of nonaxisymmetric rotational instabilities.

Conservative 3 + 1 general relativistic variable Eddington tensor radiation transport equations

DOE PAGES

Cardall, Christian Y.; Endeve, Eirik; Mezzacappa, Anthony

2013-05-07

We present conservative 3+1 general relativistic variable Eddington tensor radiation transport equations, including greater elaboration of the momentum space divergence (that is, the energy derivative term) than in previous work. These equations are intended for use in simulations involving numerical relativity, particularly in the absence of spherical symmetry. The independent variables are the lab frame coordinate basis spacetime position coordinates and the particle energy measured in the comoving frame. With an eye towards astrophysical applications—such as core-collapse supernovae and compact object mergers—in which the fluid includes nuclei and/or nuclear matter at finite temperature, and in which the transported particles aremore » neutrinos, we pay special attention to the consistency of four-momentum and lepton number exchange between neutrinos and the fluid, showing the term-by-term cancellations that must occur for this consistency to be achieved.« less

Mass loss due to gravitational waves with Λ > 0

NASA Astrophysics Data System (ADS)

Saw, Vee-Liem

2017-07-01

The theoretical basis for the energy carried away by gravitational waves that an isolated gravitating system emits was first formulated by Hermann Bondi during the ’60s. Recent findings from the observation of distant supernovae revealed that the rate of expansion of our universe is accelerating, which may be well explained by sticking a positive cosmological constant into the Einstein field equations for general relativity. By solving the Newman-Penrose equations (which are equivalent to the Einstein field equations), we generalize this notion of Bondi mass-energy and thereby provide a firm theoretical description of how an isolated gravitating system loses energy as it radiates gravitational waves, in a universe that expands at an accelerated rate. This is in line with the observational front of LIGO’s first announcement in February 2016 that gravitational waves from the merger of a binary black hole system have been detected.

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

Pereira, S.H.; Pinho, A.S.S.; Silva, J.M. Hoff da

In this work the exact Friedmann-Robertson-Walker equations for an Elko spinor field coupled to gravity in an Einstein-Cartan framework are presented. The torsion functions coupling the Elko field spin-connection to gravity can be exactly solved and the FRW equations for the system assume a relatively simple form. In the limit of a slowly varying Elko spinor field there is a relevant contribution to the field equations acting exactly as a time varying cosmological model Λ( t )=Λ{sub *}+3β H {sup 2}, where Λ{sub *} and β are constants. Observational data using distance luminosity from magnitudes of supernovae constraint the parametersmore » Ω {sub m} and β, which leads to a lower limit to the Elko mass. Such model mimics, then, the effects of a dark energy fluid, here sourced by the Elko spinor field. The density perturbations in the linear regime were also studied in the pseudo-Newtonian formalism.« less

The wave equation in Friedmann-Robertson-Walker space-times and asymptotics of the intensity and distance relationship of a localised source

NASA Astrophysics Data System (ADS)

Starko, Darij; Craig, Walter

2018-04-01

Variations in redshift measurements of Type 1a supernovae and intensity observations from large sky surveys are an indicator of a component of acceleration in the rate of expansion of space-time. A key factor in the measurements is the intensity-distance relation for Maxwell's equations in Friedmann-Robertson-Walker (FRW) space-times. In view of future measurements of the decay of other fields on astronomical time and spatial scales, we determine the asymptotic behavior of the intensity-distance relationship for the solution of the wave equation in space-times with an FRW metric. This builds on previous work done on initial value problems for the wave equation in FRW space-time [Abbasi, B. and Craig, W., Proc. R. Soc. London, Ser. A 470, 20140361 (2014)]. In this paper, we focus on the precise intensity decay rates of the special cases for curvature k = 0 and k = -1, as well as giving a general derivation of the wave solution for -∞ < k < 0. We choose a Cauchy surface {(t, x) : t = t0 > 0} where t0 represents the time of an initial emission source, relative to the Big Bang singularity at t = 0. The initial data [g(x), h(x)] are assumed to be compactly supported; supp(g, h) ⊆ BR(0) and terms in the expression for the fundamental solution for the wave equation with the slowest decay rate are retained. The intensities calculated for coordinate time {t : t > 0} contain correction terms proportional to the ratio of t0 and the time differences ρ = t - t0. For the case of general curvature k, these expressions for the intensity reduce by scaling to the same form as for k = -1, from which we deduce the general formula. We note that for typical astronomical events such as Type 1a supernovae, the first order correction term for all curvatures -∞ < k < 0 is on the order of 10-4 smaller than the zeroth order term. These correction terms are small but may be significant in applications to alternative observations of cosmological space-time expansion rates.

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.

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.

Investigating the Nature of Dark Energy using Type Ia Supernovae with WFIRST-AFTA Space Mission

NASA Astrophysics Data System (ADS)

Perlmutter, Saul

Scientifically, the WFIRST supernova program is unique: it makes possible a dark energy measurement that no other space mission or ground-based project is addressing, a measurement that will set the standard in determining the expansion history of the universe continuously from low to high redshifts (0.1 < z < 1.7). In the context of the WFIRST Science Definition Team several participants in this proposal have developed a first version of a supernova program, described in the WFIRST SDT Report. While this program was judged to be a robust one, and the estimates of the sensitivity to the cosmological parameters were felt to be reliable, due to limitations of time the analysis was clearly limited in depth on a number of issues. The objective of this proposal is to further develop this program. Technically this is the WFIRST measurement that arguably requires the most advanced project development, since it requires near-real-time analysis and follow-up with WFIRST, and since it is using the IFU spectrograph in the WFI package, the IFU being the WFIRST instrument that does not yet have a completely consistent set of specifications in the design iteration of the SDT report. In this proposal for the WFIRST Scientific Investigation Team, focused primarily on the supernova dark energy measurements, we address these crucial technical needs by bringing the larger supernova community's expertise on the science elements together with a smaller focused team that can produce the specific deliverables. Thus the objectives of this 5 year proposal are the following: 1. Development of scientific performance requirements for the study of Dark Energy using Type Ia supernovae 2. Design an observing strategy using the Wide Field Instrument (WFI) and the Integral Field Spectrometer Unit (IFU) 3. Development of science data analysis techniques and data analysis software 4. Development of ground and space calibration requirements and estimating realistic correlated errors, both statistical and systematic 5. Development of simulations and data challenges to validate the above 6. Development of complete plans in coordination with WFIRST project, for all aspects of science simulations, precursor observations, ground calibration, observational needs, data processing, anciliary data collection/incorporation, analysis, dissemination and documentation of the proposed science investigation. The 5 year program also intends to provide the following deliverables: 1. Documentation describing detailed scientific performance requirements 2. Documentation describing a design of an observing program 3. Documentation of science data analysis techniques 4. Simulations and data challenges to validate the above items 5. Algorithms used to perform processing of science data to serve as a basis for the WFIRST pipeline To achieve these objectives the plan is to set up a Supernova Project Office, seven Supernova Working Groups, and two Supernova Software Deliverables Teams. During the recent years of work with the Science Definition Team, it has been clear that the WFIRST Project Office requires a continuous series of scientific answers to the stream of design and requirements questions that arise in the development of the mission. One of the highest priorities of the Supernova Project Office will be to coordinate with the WFIRST Project Office and be the one-stop-shopping source of answers to such questions. The second topic of this proposal is Weak Lensing (WL). The intrinsic broad wavelength coverage and excellent flux calibration of the IFU spectra will provide an important training for the photometric redshift measurements, beyond what is possible from the ground, required for the WL survey. At this time the IFU design details are not fully developed, and our studies will ensure that the WL photo-z requirements are folded into a realistic final IFU design.

Spontaneous Symmetry Breaking in Supernova Neutrinos

NASA Astrophysics Data System (ADS)

Raffelt, Georg G.

2015-08-01

Some recent developments in supernova neutrino physics are introduced where spontaneous symmetry breaking is a common theme. The physics of self-induced flavor conversion has acquired a new complication in that a new class of instabilities breaks axial symmetry of a neutrino stream, the multi-azimuth angle (MAA) instability. A completely different new phenomenon, discovered in the first realistic three-dimensional (3D) simulations, is the Lepton-Emission Self-sustained Asymmetry (LESA) during the accretion phase. Here, a neutrino-hydrodynamical instability breaks global spherical symmetry in that the lepton-number flux (νe minus ν‾e) develops a stable dipole pattern such that the lepton flux is almost exclusively emitted in one hemisphere.

Evolution of an electron-positron plasma produced by induced gravitational collapse in binary-driven hypernovae

NASA Astrophysics Data System (ADS)

Melon Fuksman, J. D.; Becerra, L.; Bianco, C. L.; Karlica, M.; Kovacevic, M.; Moradi, R.; Muccino, M.; Pisani, G. B.; Primorac, D.; Rueda, J. A.; Ruffini, R.; Vereshchagin, G. V.; Wang, Y.

2018-01-01

The binary-driven hypernova (BdHN) model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs) with energies Eiso ≥ 1052 erg associated with type Ic supernovae. Such BdHNe have as progenitor a tight binary system composed of a carbon-oxigen (CO) core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN). This collapse produces an optically-thick e+e- plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs. In this work we follow the evolution of the e+e- plasma as it interacts with the SN ejecta, by solving the equations of relativistic hydrodynamics numerically. Our results are compatible with the Lorentz factors estimated for the sources that produce the flares, of typically Γ ≲ 4.

Neutron stars: A cosmic hadron physics laboratory

NASA Technical Reports Server (NTRS)

Pines, David

1989-01-01

A progress report is given on neutron stars as a cosmic hadron physics laboratory. Particular attention is paid to the crustal neutron superfluid, and to the information concerning its properties which may be deduced from observations of pulsar glitches and postglitch behavior. Current observational evidence concerning the softness or stiffness of the high density neutron matter equation of state is reviewed briefly, and the (revolutionary) implications of a confirmation of the existence of a 0.5 ms pulsar at the core of (Supernova) SN1987A are discussed.

Current problems in applied mathematics and mathematical physics

NASA Astrophysics Data System (ADS)

Samarskii, A. A.

Papers are presented on such topics as mathematical models in immunology, mathematical problems of medical computer tomography, classical orthogonal polynomials depending on a discrete variable, and boundary layer methods for singular perturbation problems in partial derivatives. Consideration is also given to the computer simulation of supernova explosion, nonstationary internal waves in a stratified fluid, the description of turbulent flows by unsteady solutions of the Navier-Stokes equations, and the reduced Galerkin method for external diffraction problems using the spline approximation of fields.

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

Yaron, O.; Perley, D. A.; Gal-Yam, A.

With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, that sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF 13dqy = SN 2013fs a mere ~3 hr after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at ~6 hr post-explosion) spectra, map the distribution of material in the immediate environment (≲ 10 15 cm)more » of the exploding star and establish that it was surrounded by circumstellar material (CSM) that was ejected during the final ~1 yr prior to explosion at a high rate, around 10 -3 solar masses per year. The complete disappearance of flash-ionised emission lines within the first several days requires that the dense CSM be confined to within ≲10 15 cm, consistent with radio non-detections at 70–100 days. The observations indicate that iPTF 13dqy was a regular Type II SN; thus, the finding that the probable red supergiant (RSG) progenitor of this common explosion ejected material at a highly elevated rate just prior to its demise suggests that pre-supernova instabilities may be common among exploding massive stars.« less

Gemini Spectroscopy of Supernovae from the Supernova Legacy Survey: Improving High-Redshift Supernova Selection and Classification

NASA Astrophysics Data System (ADS)

Howell, D. A.; Sullivan, M.; Perrett, K.; Bronder, T. J.; Hook, I. M.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Knop, R.; McMahon, R. G.; Perlmutter, S.; Walton, N. A.

2005-12-01

We present new techniques for improving the efficiency of supernova (SN) classification at high redshift using 64 candidates observed at Gemini North and South during the first year of the Supernova Legacy Survey (SNLS). The SNLS is an ongoing 5 year project with the goal of measuring the equation of state of dark energy by discovering and following over 700 high-redshift SNe Ia using data from the Canada-France-Hawaii Telescope Legacy Survey. We achieve an improvement in the SN Ia spectroscopic confirmation rate: at Gemini 71% of candidates are now confirmed as SNe Ia, compared to 54% using the methods of previous surveys. This is despite the comparatively high redshift of this sample, in which the median SN Ia redshift is z=0.81 (0.155<=z<=1.01). These improvements were realized because we use the unprecedented color coverage and light curve sampling of the SNLS to predict whether a candidate is a SN Ia and to estimate its redshift, before obtaining a spectrum, using a new technique called the ``SN photo-z.'' In addition, we have improved techniques for galaxy subtraction and SN template χ2 fitting, allowing us to identify candidates even when they are only 15% as bright as the host galaxy. The largest impediment to SN identification is found to be host galaxy contamination of the spectrum-when the SN was at least as bright as the underlying host galaxy the target was identified more than 90% of the time. However, even SNe in bright host galaxies can be easily identified in good seeing conditions. When the image quality was better than 0.55", the candidate was identified 88% of the time. Over the 5 year course of the survey, using the selection techniques presented here, we will be able to add ~170 more confirmed SNe Ia than would be possible using previous methods. APC, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France. DSM/DAPNIA, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France.

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.

Optical Emission Associated with the Galactic Supernova Remnant G179.0+2.6

NASA Astrophysics Data System (ADS)

How, Thomas G.; Fesen, Robert A.; Neustadt, Jack M. M.; Black, Christine S.; Outters, Nicolas

2018-04-01

Narrow passband optical images of the large Galactic supernova remnant G179.0+2.6 reveal a faint but nearly complete emission shell dominated by strong [O 3] 4959,5007 Å line emission. The remnant's optical emission, which consists of both diffuse and filamentary features, is brightest along its southern and northeastern limbs. Deep Hα images detect little coincidence emission indicating an unusually high [O 3]/Hα emission ratio for such a large and apparently old remnant. Low-dispersion optical spectra of several regions confirm large [O 3]/Hα line ratios with typical values around 10. The dominance of [O 3] emission for the majority of the remnant's optical filaments suggests shock velocities above 100 km s-1 are present throughout most of the remnant, likely reflecting a relatively low density ambient ISM. The remnant's unusually strong [O 3] emission adds to the remnant's interesting set of properties which include a thick radio emission shell, radial polarization of its radio emission like that typically seen in young supernova remnants, and an unusually slow-rotating gamma-ray pulsar with a characteristic spin-down age ≃ 50 kyr.

Collective three-flavor oscillations of supernova neutrinos

NASA Astrophysics Data System (ADS)

Dasgupta, Basudeb; Dighe, Amol

2008-06-01

Neutrinos and antineutrinos emitted from a core collapse supernova interact among themselves, giving rise to collective flavor conversion effects that are significant near the neutrinosphere. We develop a formalism to analyze these collective effects in the complete three-flavor framework. It naturally generalizes the spin-precession analogy to three flavors and is capable of analytically describing phenomena like vacuum/Mikheyev-Smirnov-Wolfenstein (MSW) oscillations, synchronized oscillations, bipolar oscillations, and spectral split. Using the formalism, we demonstrate that the flavor conversions may be “factorized” into two-flavor oscillations with hierarchical frequencies. We explicitly show how the three-flavor solution may be constructed by combining two-flavor solutions. For a typical supernova density profile, we identify an approximate separation of regions where distinctly different flavor conversion mechanisms operate, and demonstrate the interplay between collective and MSW effects. We pictorialize our results in terms of the “e3-e8 triangle” diagram, which is a tool that can be used to visualize three-neutrino flavor conversions in general, and offers insights into the analysis of the collective effects in particular.

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/

Possible Progenitor of Special Supernova Type Detected

NASA Astrophysics Data System (ADS)

2008-04-01

Using data from NASA's Chandra X-ray Observatory, scientists have reported the possible detection of a binary star system that was later destroyed in a supernova explosion. The new method they used provides great future promise for finding the detailed origin of these important cosmic events. In an article appearing in the February 14th issue of the journal Nature, Rasmus Voss of the Max Planck Institute for Extraterrestrial Physics in Germany and Gijs Nelemans of Radboud University in the Netherlands searched Chandra images for evidence of a much sought after, but as yet unobserved binary system - one that was about to go supernova. Near the position of a recently detected supernova, they discovered an object in Chandra images taken more than four years before the explosion. Optical image of SN 2007on Optical image of SN 2007on The supernova, known as SN 2007on, was identified as a Type Ia supernova. Astronomers generally agree that Type Ia supernovas are produced by the explosion of a white dwarf star in a binary star system. However, the exact configuration and trigger for the explosion is unclear. Is the explosion caused by a collision between two white dwarfs, or because a white dwarf became unstable by pulling too much material off a companion star? Answering such questions is a high priority because Type Ia supernovas are major sources of iron in the Universe. Also, because of their nearly uniform intrinsic brightness, Type Ia supernova are used as important tools by scientists to study the nature of dark energy and other cosmological issues. People Who Read This Also Read... Oldest Known Objects Are Surprisingly Immature Black Holes Have Simple Feeding Habits Discovery of Most Recent Supernova in Our Galaxy Geriatric Pulsar Still Kicking "Right now these supernovas are used as black boxes to measure distances and derive the rate of expansion of the universe," said Nelemans. "What we're trying to do is look inside the box." If the supernova explosion is caused by material being pulled off a companion star onto the white dwarf, fusion of this material on the surface of the star should heat the star and produce a strong source of X-radiation prior to the explosion. Once the supernova explosion occurs, the white dwarf is expected to be completely destroyed and then would be undetectable in X-rays. In the merger scenario, the intensity of X-ray emission prior to the explosion is expected to be much weaker. Based on the detection of a fairly strong X-ray source at approximately the position of SN 2007on 4 years before the explosion, Voss and Nelemans conclude that the data support the scenario where matter is pulled off a companion star. The small number of X-ray sources in the field implies that there is only a small chance of an unrelated source being so close by coincidence. Also, the X-ray source has similar properties to those expected for fusion on a white dwarf, unlike most X-ray sources in the sky. However, in follow-up studies, Voss, Nelemans and colleagues Gijs Roelofs (Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.) and Cees Bassa (McGill University, Canada) used higher-quality optical images to better determine the supernova's position. This work, which is not yet published, shows a small, but significant difference in the measured positions of the supernova and the X-ray source, suggesting the source may not be the progenitor. Follow-up Chandra observations hint that the X-ray object has disappeared, but further observations are needed to finally decide whether the source was the progenitor or not. The team is also applying this new method to other supernovas and has high hopes that they will eventually succeed in identifying the elusive cause of at least some of these explosions. "We're very excited about opening up a new way of studying supernovas, even though we're not sure that we've seen this particular stellar bomb before it exploded," said Gijs Roelofs. "We're very confident that we'll learn a lot more about these important supernovas in the future." Voss agrees that, even if the X-ray source is not found to be the progenitor of SN 2007on, the hunt is worth the effort. "Finding the progenitor to one of these Type Ia supernovas is a great chase in astronomy right now," he said. "These supernovas are great tools for studying dark energy, but if we knew more about how they form they might become even better tools." Rasmus Voss receives support from the Excellence Cluster Universe in Garching, Germany. NASA's Marshall Space Flight Center, 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

Astronomical Resources: Supernovae.

ERIC Educational Resources Information Center

Fraknoi, Andrew

1987-01-01

Contains a partially annotated, nontechnical bibliography of recent materials about supernovae, including some about the discovery of a supernova in the Large Magellanic Cloud. Includes citations of general books and articles about supernovae, articles about Supernova 1987A, and a few science fiction stories using supernovae. (TW)

Constraining smoothness parameter and the DD relation of Dyer-Roeder equation with supernovae

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

Yang, Xi; Yu, Hao-Ran; Zhang, Tong-Jie, E-mail: yangwds@mail.bnu.edu.cn, E-mail: yu@bnu.edu.cn, E-mail: tjzhang@bnu.edu.cn

2013-06-01

Our real universe is locally inhomogeneous. Dyer and Roeder introduced the smoothness parameter α to describe the influence of local inhomogeneity on angular diameter distance, and they obtained the angular diameter distance-redshift approximate relation (Dyer-Roeder equation) for locally inhomogeneous universe. Furthermore, the Distance-Duality (DD) relation, D{sub L}(z)(1+z){sup −2}/D{sub A}(z) = 1, should be valid for all cosmological models that are described by Riemannian geometry, where D{sub L} and D{sub A} are, respectively, the luminosity and angular distance distances. Therefore, it is necessary to test whether if the Dyer-Roeder approximate equation can satisfy the Distance-Duality relation. In this paper, we usemore » Union2.1 SNe Ia data to constrain the smoothness parameter α and test whether the Dyer-Roeder equation meet the DD relation. By using χ{sup 2} minimization, we get α = 0.92{sub −0.32}{sup +0.08} at 1σ and 0.92{sub −0.65}{sup +0.08} at 2σ, and our results show that the Dyer-Roeder equation is in good consistency with the DD relation at 1σ.« less

New limits on coupled dark energy model after Planck 2015

NASA Astrophysics Data System (ADS)

Li, Hang; Yang, Weiqiang; Wu, Yabo; Jiang, Ying

2018-06-01

We used the Planck 2015 cosmic microwave background anisotropy, baryon acoustic oscillation, type-Ia supernovae, redshift-space distortions, and weak gravitational lensing to test the model parameter space of coupled dark energy. We assumed the constant and time-varying equation of state parameter for dark energy, and treated dark matter and dark energy as the fluids whose energy transfer was proportional to the combined term of the energy densities and equation of state, such as Q = 3 Hξ(1 +wx) ρx and Q = 3 Hξ [ 1 +w0 +w1(1 - a) ] ρx, the full space of equation of state could be measured when we considered the term (1 +wx) in the energy exchange. According to the joint observational constraint, the results showed that wx = - 1.006-0.027+0.047 and ξ = 0.098-0.098>+0.026 for coupled dark energy with a constant equation of state, w0 = -1.076-0.076+0.085, w1 = - 0.069-0.319+0.361, and ξ = 0.210-0.210+0.048 for a variable equation of state. We did not get any clear evidence for the coupling in the dark fluids at 1 σ region.

Nuclear equation of state for core-collapse supernova simulations with realistic nuclear forces

NASA Astrophysics Data System (ADS)

Togashi, H.; Nakazato, K.; Takehara, Y.; Yamamuro, S.; Suzuki, H.; Takano, M.

2017-05-01

A new table of the nuclear equation of state (EOS) based on realistic nuclear potentials is constructed for core-collapse supernova numerical simulations. Adopting the EOS of uniform nuclear matter constructed by two of the present authors with the cluster variational method starting from the Argonne v18 and Urbana IX nuclear potentials, the Thomas-Fermi calculation is performed to obtain the minimized free energy of a Wigner-Seitz cell in non-uniform nuclear matter. As a preparation for the Thomas-Fermi calculation, the EOS of uniform nuclear matter is modified so as to remove the effects of deuteron cluster formation in uniform matter at low densities. Mixing of alpha particles is also taken into account following the procedure used by Shen et al. (1998, 2011). The critical densities with respect to the phase transition from non-uniform to uniform phase with the present EOS are slightly higher than those with the Shen EOS at small proton fractions. The critical temperature with respect to the liquid-gas phase transition decreases with the proton fraction in a more gradual manner than in the Shen EOS. Furthermore, the mass and proton numbers of nuclides appearing in non-uniform nuclear matter with small proton fractions are larger than those of the Shen EOS. These results are consequences of the fact that the density derivative coefficient of the symmetry energy of our EOS is smaller than that of the Shen EOS.

THE DEPENDENCE OF THE NEUTRINO MECHANISM OF CORE-COLLAPSE SUPERNOVAE ON THE EQUATION OF STATE

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

Couch, Sean M., E-mail: smc@flash.uchicago.edu

2013-03-01

We study the dependence of the delayed neutrino-heating mechanism for core-collapse supernovae on the equation of state (EOS). Using a simplified treatment of the neutrino physics with a parameterized neutrino luminosity, we explore the relationship between explosion time, mass accretion rate, and neutrino luminosity for a 15 M {sub Sun} progenitor in 1D and 2D. We test the EOS most commonly used in core-collapse simulations: the models of Lattimer and Swesty and the model of Shen et al. We find that for a given neutrino luminosity, 'stiffer' EOS, where stiffness is determined by a combination of nuclear matter properties notmore » just incompressibility, K, explode later than 'softer' EOS. The EOS of Shen et al., being the stiffest EOS, by virtue of larger incompressibility and symmetry energy slope, L, explodes later than any of the Lattimer and Swesty EOS models. Amongst the Lattimer and Swesty EOS that all share the same value of L, the explosion time increases with increasing nuclear incompressibility, K. We find that this holds in both 1D and 2D, while for all of the models, explosions are obtained more easily in 2D than in 1D. We argue that this EOS dependence is due in part to a greater amount of acoustic flux from denser proto-neutron star atmospheres that result from a softer EOS. We also discuss the relevance of approximate instability criteria to realistic simulations.« less

Test of the Chevallier-Polarski-Linder parametrization for rapid dark energy equation of state transitions

NASA Astrophysics Data System (ADS)

Linden, Sebastian; Virey, Jean-Marc

2008-07-01

We test the robustness and flexibility of the Chevallier-Polarski-Linder (CPL) parametrization of the dark energy equation of state w(z)=w0+wa(z)/(1+z) in recovering a four-parameter steplike fiducial model. We constrain the parameter space region of the underlying fiducial model where the CPL parametrization offers a reliable reconstruction. It turns out that non-negligible biases leak into the results for recent (z<2.5) rapid transitions, but that CPL yields a good reconstruction in all other cases. The presented analysis is performed with supernova Ia data as forecasted for a space mission like SNAP/JDEM, combined with future expectations for the cosmic microwave background shift parameter R and the baryonic acoustic oscillation parameter A.

Cartan symmetries and global dynamical systems analysis in a higher-order modified teleparallel theory

NASA Astrophysics Data System (ADS)

Karpathopoulos, L.; Basilakos, S.; Leon, G.; Paliathanasis, A.; Tsamparlis, M.

2018-07-01

In a higher-order modified teleparallel theory cosmological we present analytical cosmological solutions. In particular we determine forms of the unknown potential which drives the scalar field such that the field equations form a Liouville integrable system. For the determination of the conservation laws we apply the Cartan symmetries. Furthermore, inspired from our solutions, a toy model is studied and it is shown that it can describe the Supernova data, while at the same time introduces dark matter components in the Hubble function. When the extra matter source is a stiff fluid then we show how analytical solutions for Bianchi I universes can be constructed from our analysis. Finally, we perform a global dynamical analysis of the field equations by using variables different from that of the Hubble-normalization.

Photometric Supernova Classification with Machine Learning

NASA Astrophysics Data System (ADS)

Lochner, Michelle; McEwen, Jason D.; Peiris, Hiranya V.; Lahav, Ofer; Winter, Max K.

2016-08-01

Automated photometric supernova classification has become an active area of research in recent years in light of current and upcoming imaging surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given that spectroscopic confirmation of type for all supernovae discovered will be impossible. Here, we develop a multi-faceted classification pipeline, combining existing and new approaches. Our pipeline consists of two stages: extracting descriptive features from the light curves and classification using a machine learning algorithm. Our feature extraction methods vary from model-dependent techniques, namely SALT2 fits, to more independent techniques that fit parametric models to curves, to a completely model-independent wavelet approach. We cover a range of representative machine learning algorithms, including naive Bayes, k-nearest neighbors, support vector machines, artificial neural networks, and boosted decision trees (BDTs). We test the pipeline on simulated multi-band DES light curves from the Supernova Photometric Classification Challenge. Using the commonly used area under the curve (AUC) of the Receiver Operating Characteristic as a metric, we find that the SALT2 fits and the wavelet approach, with the BDTs algorithm, each achieve an AUC of 0.98, where 1 represents perfect classification. We find that a representative training set is essential for good classification, whatever the feature set or algorithm, with implications for spectroscopic follow-up. Importantly, we find that by using either the SALT2 or the wavelet feature sets with a BDT algorithm, accurate classification is possible purely from light curve data, without the need for any redshift information.

Modelling space-based integral-field spectrographs and their application to Type Ia supernova cosmology

NASA Astrophysics Data System (ADS)

Shukla, Hemant; Bonissent, Alain

2017-04-01

We present the parameterized simulation of an integral-field unit (IFU) slicer spectrograph and its applications in spectroscopic studies, namely, for probing dark energy with type Ia supernovae. The simulation suite is called the fast-slicer IFU simulator (FISim). The data flow of FISim realistically models the optics of the IFU along with the propagation effects, including cosmological, zodiacal, instrumentation and detector effects. FISim simulates the spectrum extraction by computing the error matrix on the extracted spectrum. The applications for Type Ia supernova spectroscopy are used to establish the efficacy of the simulator in exploring the wider parametric space, in order to optimize the science and mission requirements. The input spectral models utilize the observables such as the optical depth and velocity of the Si II absorption feature in the supernova spectrum as the measured parameters for various studies. Using FISim, we introduce a mechanism for preserving the complete state of a system, called the partial p/partial f matrix, which allows for compression, reconstruction and spectrum extraction, we introduce a novel and efficient method for spectrum extraction, called super-optimal spectrum extraction, and we conduct various studies such as the optimal point spread function, optimal resolution, parameter estimation, etc. We demonstrate that for space-based telescopes, the optimal resolution lies in the region near R ˜ 117 for read noise of 1 e- and 7 e- using a 400 km s-1 error threshold on the Si II velocity.

Finding Distances to Type Ia Supernovae

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-03-01

Type Ia supernovae are known as standard candles due to their consistency, allowing us to measure distances based on their brightness. But what if these explosions arent quite as consistent as we thought? Due scientific diligence requires careful checks, so a recent study investigates whether the metallicity of a supernovas environment affects the peak luminosity of the explosion.Metallicity Dependence?Type Ia supernovae are incredibly powerful tools for determining distances in our universe. Because these supernovae are formed by white dwarfs that explode when they reach a uniform accreted mass, the supernova peak luminosity is thought to be very consistent. This consistency allows these supernovae to be used as standard candles to measure distances to their host galaxies.But what if that peak luminosity is affected by a factor that we havent taken into account? Theorists have proposed that the luminosities of Type Ia supernovae might depend on the metallicity of their environments with high-metallicity environments suppressing supernova luminosities. If this is true, then we could be systematically mis-measuring cosmological distances using these supernovae.Testing AbundancesSupernova brightnesses vs. the metallicity of their environments. Low-metallicity supernovae (blue shading) and high-metallicity supernovae (red shading) have an average magnitude difference of ~0.14. [Adapted from Moreno-Raya et al. 2016]A team led by Manuel Moreno-Raya, of the Center for Energy, Environment and Technology (CIEMAT) in Spain, has observed 28 Type Ia supernovae in an effort to test for such a metallicity dependence. These supernovae each have independent distance measurements (e.g., from Cepheids or the Tully-Fisher relation).Moreno-Raya and collaborators used spectra from the 4.2-m William Herschel Telescope to estimate oxygen abundances in the region where each of these supernovae exploded. They then used these measurements to determine if metallicity of the local region affects the luminosity of the supernova.Determining DistancesThe authors find that there are indeed differences in peak supernova luminosity based on metallicity of the local environment. Their observations support a trend in which more metal-rich galaxies host less luminous supernovae, whereas lower-metallicity galaxies host supernovae with greater luminosities consistent with theoretical predictions.This observational confirmation suggests that the metallicity of the progenitor may well play a role in peak supernova luminosity and, as a result, the distances at which we estimate they exploded. This systematic effect can, however, be easily corrected for in the distance-estimate procedure.As the number of known supernovae is expected to drastically increase with the start of future large surveys such as the Large Synoptic Survey Telescope (LSST) or the Dark Energy Survey (DES), supernova distance measurements will soon be dominated by systematic errors rather than statistical ones. Correctly accounting for effects such as this apparent metallicity-dependence of supernovae continues to be important for accurately determining distances using Type Ia supernovae as indicators.CitationManuel E. Moreno-Raya et al 2016 ApJ 818 L19. doi:10.3847/2041-8205/818/1/L19

Muon Creation in Supernova Matter Facilitates Neutrino-Driven Explosions.

PubMed

Bollig, R; Janka, H-T; Lohs, A; Martínez-Pinedo, G; Horowitz, C J; Melson, T

2017-12-15

Muons can be created in nascent neutron stars (NSs) due to the high electron chemical potentials and the high temperatures. Because of their relatively lower abundance compared to electrons, their role has so far been ignored in numerical simulations of stellar core collapse and NS formation. However, the appearance of muons softens the NS equation of state, triggers faster NS contraction, and thus leads to higher luminosities and mean energies of the emitted neutrinos. This strengthens the postshock heating by neutrinos and can facilitate explosions by the neutrino-driven mechanism.

Supernova neutrino three-flavor evolution with dominant collective effects

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

Fogli, Gianluigi; Marrone, Antonio; Tamborra, Irene

2009-04-15

Neutrino and antineutrino fluxes from a core-collapse galactic supernova are studied, within a representative three-flavor scenario with inverted mass hierarchy and tiny 1-3 mixing. The initial flavor evolution is dominated by collective self-interaction effects, which are computed in a full three-family framework along an averaged radial trajectory. During the whole time span considered (t = 1-20 s), neutrino and antineutrino spectral splits emerge as dominant features in the energy domain for the final, observable fluxes. The main results can be useful for SN event rate simulations in specific detectors. Some minor or unobservable three-family features (e.g., related to the muonic-tauonicmore » flavor sector), as well as observable effects due to variations in the spectral input, are also discussed for completeness.« less

Are supernovae recorded in indigenous astronomical traditions?

NASA Astrophysics Data System (ADS)

Hamacher, Duane W.

2014-07-01

Novae and supernovae are rare astronomical events that would have had an influence on the skywatching peoples who witnessed them. Although several bright novae/supernovae have been visible during recorded human history, there are many proposed but no confirmed accounts of supernovae in indigenous oral traditions or material culture. Criteria are established for confirming novae/supernovae in oral traditions and material culture, and claims from around the world are discussed to determine if they meet these criteria. Aboriginal Australian traditions are explored for possible descriptions of novae/supernovae. Although representations of supernovae may exist in Aboriginal traditions, there are currently no confirmed accounts of supernovae in Indigenous Australian oral or material traditions.

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.

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.

Neutron stars in supernova remnants and beyond

NASA Astrophysics Data System (ADS)

Gvaramadze, V.

We propose a new approach for studying the neutron star/supernova remnant associations, based on the idea that the supernova remnants can be products of an off-centered supernova explosion in a preexisting bubble created by the wind of a moving massive star. A cavity supernova explosion of a moving star results in a considerable offset of the neutron star birth-place from the geometrical center of the supernova remnant. Therefore: a) the high transverse velocities inferred for a number of neutron stars through their association with supernova remnants can be reduced; b) the proper motion vector of a neutron star should not necessarily point away from the geometrical center of the associated supernova remnant. Taking into account these two facts allow us to enlarge the circle of possible neutron star/supernova remnant associations, and could significantly affect the results of previous studies of associations. The possibilities of our approach are illustrated with some examples. We also show that the concept of an off-centered cavity supernova explosion could be used to explain the peculiar structures of a number of supernova remnants and for searches for stellar remnants possibly associated with them.

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.

Multi-D Full Boltzmann Neutrino Hydrodynamic Simulations in Core Collapse Supernovae and their detailed comparison with Monte Carlo method

NASA Astrophysics Data System (ADS)

Nagakura, Hiroki; Richers, Sherwood; Ott, Christian; Iwakami, Wakana; Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi

2017-01-01

We have developed a multi-d radiation-hydrodynamic code which solves first-principles Boltzmann equation for neutrino transport. It is currently applicable specifically for core-collapse supernovae (CCSNe), but we will extend their applicability to further extreme phenomena such as black hole formation and coalescence of double neutron stars. In this meeting, I will discuss about two things; (1) detailed comparison with a Monte-Carlo neutrino transport (2) axisymmetric CCSNe simulations. The project (1) gives us confidence of our code. The Monte-Carlo code has been developed by Caltech group and it is specialized to obtain a steady state. Among CCSNe community, this is the first attempt to compare two different methods for multi-d neutrino transport. I will show the result of these comparison. For the project (2), I particularly focus on the property of neutrino distribution function in the semi-transparent region where only first-principle Boltzmann solver can appropriately handle the neutrino transport. In addition to these analyses, I will also discuss the ``explodability'' by neutrino heating mechanism.

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.

An optical supernova associated with the X-ray flash XRF 060218.

PubMed

Pian, E; Mazzali, P A; Masetti, N; Ferrero, P; Klose, S; Palazzi, E; Ramirez-Ruiz, E; Woosley, S E; Kouveliotou, C; Deng, J; Filippenko, A V; Foley, R J; Fynbo, J P U; Kann, D A; Li, W; Hjorth, J; Nomoto, K; Patat, F; Sauer, D N; Sollerman, J; Vreeswijk, P M; Guenther, E W; Levan, A; O'Brien, P; Tanvir, N R; Wijers, R A M J; Dumas, C; Hainaut, O; Wong, D S; Baade, D; Wang, L; Amati, L; Cappellaro, E; Castro-Tirado, A J; Ellison, S; Frontera, F; Fruchter, A S; Greiner, J; Kawabata, K; Ledoux, C; Maeda, K; Møller, P; Nicastro, L; Rol, E; Starling, R

2006-08-31

Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae that are more luminous than average and that eject material at very high velocities. Less-luminous supernovae were not hitherto known to be associated with GRBs, and therefore GRB-supernovae were thought to be rare events. Whether X-ray flashes--analogues of GRBs, but with lower luminosities and fewer gamma-rays--can also be associated with supernovae, and whether they are intrinsically 'weak' events or typical GRBs viewed off the axis of the burst, is unclear. Here we report the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. Supernova 2006aj is intrinsically less luminous than the GRB-supernovae, but more luminous than many supernovae not accompanied by a GRB. The ejecta velocities derived from our spectra are intermediate between these two groups, which is consistent with the weakness of both the GRB output and the supernova radio flux. Our data, combined with radio and X-ray observations, suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis. This extends the GRB-supernova connection to X-ray flashes and fainter supernovae, implying a common origin. Events such as XRF 060218 are probably more numerous than GRB-supernovae.

A Search for a Surviving White Dwarf Companion in SN 1006

NASA Astrophysics Data System (ADS)

Kerzendorf, W. E.; Strampelli, G.; Shen, K. J.; Schwab, J.; Pakmor, R.; Do, T.; Buchner, J.; Rest, A.

2018-05-01

Multiple channels have been proposed to produce Type Ia supernovae, with many scenarios suggesting that the exploding white dwarf accretes from a binary companion pre-explosion. In almost all cases, theory suggests that this companion will survive. However, no such companion has been unambiguously identified in ancient supernova remnants - possibly falsifying the accretion scenario. Existing surveys, however, have only looked for stars as faint as ≈0.1L⊙ and thus might have missed a surviving white dwarf companion. In this work, we present very deep DECAM imaging (u, g, r, z) of the Type Ia supernova remnant SN 1006 specifically to search for a potential surviving white dwarf companion. We find no object that is consistent with a relatively young cooling white dwarf within the inner half of the SN 1006 remnant. We find that if there is a companion white dwarf, it must be redder than the standard white dwarf cooling track, or it must have formed long ago and cooled undisturbed for >108 yr. We conclude that our findings are consistent with the complete destruction of the secondary (such as in a merger) or an anomalously red or very dim surviving companion white dwarf.

A Study of Quasar Selection in the Supernova Fields of the Dark Energy Survey

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

Tie, S. S.; Martini, P.; Mudd, D.

In this paper, we present a study of quasar selection using the supernova fields of the Dark Energy Survey (DES). We used a quasar catalog from an overlapping portion of the SDSS Stripe 82 region to quantify the completeness and efficiency of selection methods involving color, probabilistic modeling, variability, and combinations of color/probabilistic modeling with variability. In all cases, we considered only objects that appear as point sources in the DES images. We examine color selection methods based on the Wide-field Infrared Survey Explorer (WISE) mid-IR W1-W2 color, a mixture of WISE and DES colors (g - i and i-W1),more » and a mixture of Vista Hemisphere Survey and DES colors (g - i and i - K). For probabilistic quasar selection, we used XDQSO, an algorithm that employs an empirical multi-wavelength flux model of quasars to assign quasar probabilities. Our variability selection uses the multi-band χ 2-probability that sources are constant in the DES Year 1 griz-band light curves. The completeness and efficiency are calculated relative to an underlying sample of point sources that are detected in the required selection bands and pass our data quality and photometric error cuts. We conduct our analyses at two magnitude limits, i < 19.8 mag and i < 22 mag. For the subset of sources with W1 and W2 detections, the W1-W2 color or XDQSOz method combined with variability gives the highest completenesses of >85% for both i-band magnitude limits and efficiencies of >80% to the bright limit and >60% to the faint limit; however, the giW1 and giW1+variability methods give the highest quasar surface densities. The XDQSOz method and combinations of W1W2/giW1/XDQSOz with variability are among the better selection methods when both high completeness and high efficiency are desired. We also present the OzDES Quasar Catalog of 1263 spectroscopically confirmed quasars from three years of OzDES observation in the 30 deg 2 of the DES supernova fields. Finally, the catalog includes quasars with redshifts up to z ~ 4 and brighter than i = 22 mag, although the catalog is not complete up to this magnitude limit.« less

A Study of Quasar Selection in the Supernova Fields of the Dark Energy Survey

DOE PAGES

Tie, S. S.; Martini, P.; Mudd, D.; ...

2017-02-15

In this paper, we present a study of quasar selection using the supernova fields of the Dark Energy Survey (DES). We used a quasar catalog from an overlapping portion of the SDSS Stripe 82 region to quantify the completeness and efficiency of selection methods involving color, probabilistic modeling, variability, and combinations of color/probabilistic modeling with variability. In all cases, we considered only objects that appear as point sources in the DES images. We examine color selection methods based on the Wide-field Infrared Survey Explorer (WISE) mid-IR W1-W2 color, a mixture of WISE and DES colors (g - i and i-W1),more » and a mixture of Vista Hemisphere Survey and DES colors (g - i and i - K). For probabilistic quasar selection, we used XDQSO, an algorithm that employs an empirical multi-wavelength flux model of quasars to assign quasar probabilities. Our variability selection uses the multi-band χ 2-probability that sources are constant in the DES Year 1 griz-band light curves. The completeness and efficiency are calculated relative to an underlying sample of point sources that are detected in the required selection bands and pass our data quality and photometric error cuts. We conduct our analyses at two magnitude limits, i < 19.8 mag and i < 22 mag. For the subset of sources with W1 and W2 detections, the W1-W2 color or XDQSOz method combined with variability gives the highest completenesses of >85% for both i-band magnitude limits and efficiencies of >80% to the bright limit and >60% to the faint limit; however, the giW1 and giW1+variability methods give the highest quasar surface densities. The XDQSOz method and combinations of W1W2/giW1/XDQSOz with variability are among the better selection methods when both high completeness and high efficiency are desired. We also present the OzDES Quasar Catalog of 1263 spectroscopically confirmed quasars from three years of OzDES observation in the 30 deg 2 of the DES supernova fields. Finally, the catalog includes quasars with redshifts up to z ~ 4 and brighter than i = 22 mag, although the catalog is not complete up to this magnitude limit.« less

A solar-type star polluted by calcium-rich supernova ejecta inside the supernova remnant RCW 86

NASA Astrophysics Data System (ADS)

Gvaramadze, Vasilii V.; Langer, Norbert; Fossati, Luca; Bock, Douglas C.-J.; Castro, Norberto; Georgiev, Iskren Y.; Greiner, Jochen; Johnston, Simon; Rau, Arne; Tauris, Thomas M.

2017-06-01

When a massive star in a binary system explodes as a supernova, its companion star may be polluted with heavy elements from the supernova ejecta. Such pollution has been detected in a handful of post-supernova binaries 1 , but none of them is associated with a supernova remnant. We report the discovery of a binary G star strongly polluted with calcium and other elements at the position of the candidate neutron star [GV2003] N within the young galactic supernova remnant RCW 86. Our discovery suggests that the progenitor of the supernova that produced RCW 86 could have been a moving star, which exploded near the edge of its wind bubble and lost most of its initial mass because of common-envelope evolution shortly before core collapse, and that the supernova explosion might belong to the class of calcium-rich supernovae — faint and fast transients 2,3 , the origin of which is strongly debated 4-6 .

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.

A new equation of state Based on Nuclear Statistical Equilibrium for Core-Collapse Simulations

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

2012-09-01

We calculate a new equation of state for baryons at sub-nuclear densities for the use in core-collapse simulations of massive stars. The formulation is the nuclear statistical equilibrium description and the liquid drop approximation of nuclei. The model free energy to minimize is calculated by relativistic mean field theory for nucleons and the mass formula for nuclei with atomic number up to ~ 1000. We have also taken into account the pasta phase. We find that the free energy and other thermodynamical quantities are not very different from those given in the standard EOSs that adopt the single nucleus approximation. On the other hand, the average mass is systematically different, which may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores.

The ASAS-SN bright supernova catalogue - III. 2016

NASA Astrophysics Data System (ADS)

Holoien, T. W.-S.; Brown, J. S.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Prieto, J. L.; Dong, Subo; Brimacombe, J.; Bishop, D. W.; Bose, S.; Beacom, J. F.; Bersier, D.; Chen, Ping; Chomiuk, L.; Falco, E.; Godoy-Rivera, D.; Morrell, N.; Pojmanski, G.; Shields, J. V.; Strader, J.; Stritzinger, M. D.; Thompson, Todd A.; Woźniak, P. R.; Bock, G.; Cacella, P.; Conseil, E.; Cruz, I.; Fernandez, J. M.; Kiyota, S.; Koff, R. A.; Krannich, G.; Marples, P.; Masi, G.; Monard, L. A. G.; Nicholls, B.; Nicolas, J.; Post, R. S.; Stone, G.; Wiethoff, W. S.

2017-11-01

This catalogue summarizes information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) and all other bright (mpeak ≤ 17), spectroscopically confirmed supernovae discovered in 2016. We then gather the near-infrared through ultraviolet magnitudes of all host galaxies and the offsets of the supernovae from the centres of their hosts from public data bases. We illustrate the results using a sample that now totals 668 supernovae discovered since 2014 May 1, including the supernovae from our previous catalogues, with type distributions closely matching those of the ideal magnitude limited sample from Li et al. This is the third of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.

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.

A Type II Supernova Hubble Diagram from the CSP-I, SDSS-II, and SNLS Surveys

NASA Astrophysics Data System (ADS)

de Jaeger, T.; González-Gaitán, S.; Hamuy, M.; Galbany, L.; Anderson, J. P.; Phillips, M. M.; Stritzinger, M. D.; Carlberg, R. G.; Sullivan, M.; Gutiérrez, C. P.; Hook, I. M.; Howell, D. Andrew; Hsiao, E. Y.; Kuncarayakti, H.; Ruhlmann-Kleider, V.; Folatelli, G.; Pritchet, C.; Basa, S.

2017-02-01

The coming era of large photometric wide-field surveys will increase the detection rate of supernovae by orders of magnitude. Such numbers will restrict spectroscopic follow-up in the vast majority of cases, and hence new methods based solely on photometric data must be developed. Here, we construct a complete Hubble diagram of Type II supernovae (SNe II) combining data from three different samples: the Carnegie Supernova Project-I, the Sloan Digital Sky Survey II SN, and the Supernova Legacy Survey. Applying the Photometric Color Method (PCM) to 73 SNe II with a redshift range of 0.01-0.5 and with no spectral information, we derive an intrinsic dispersion of 0.35 mag. A comparison with the Standard Candle Method (SCM) using 61 SNe II is also performed and an intrinsic dispersion in the Hubble diagram of 0.27 mag, I.e., 13% in distance uncertainties, is derived. Due to the lack of good statistics at higher redshifts for both methods, only weak constraints on the cosmological parameters are obtained. However, assuming a flat universe and using the PCM, we derive the universe’s matter density: {{{Ω }}}m={0.32}-0.21+0.30 providing a new independent evidence for dark energy at the level of two sigma. This paper includes data gathered with the 6.5 m Magellan Telescopes, with the du Pont and Swope telescopes located at Las Campanas Observatory, Chile; and the Gemini Observatory, Cerro Pachon, Chile (Gemini Program N-2005A-Q-11, GN-2005B-Q-7, GN-2006A-Q-7, GS-2005A-Q-11, GS-2005B-Q-6, and GS-2008B-Q-56). Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (ESO Programmes 076.A-0156,078.D-0048, 080.A-0516, and 082.A-0526).

Massive Star Burps, Then Explodes

NASA Astrophysics Data System (ADS)

2007-04-01

Berkeley -- In a galaxy far, far away, a massive star suffered a nasty double whammy. On Oct. 20, 2004, Japanese amateur astronomer Koichi Itagaki saw the star let loose an outburst so bright that it was initially mistaken for a supernova. The star survived, but for only two years. On Oct. 11, 2006, professional and amateur astronomers witnessed the star actually blowing itself to smithereens as Supernova 2006jc. Swift UVOT Image Swift UVOT Image (Credit: NASA / Swift / S.Immler) "We have never observed a stellar outburst and then later seen the star explode," says University of California, Berkeley, astronomer Ryan Foley. His group studied the event with ground-based telescopes, including the 10-meter (32.8-foot) W. M. Keck telescopes in Hawaii. Narrow helium spectral lines showed that the supernova's blast wave ran into a slow-moving shell of material, presumably the progenitor's outer layers ejected just two years earlier. If the spectral lines had been caused by the supernova's fast-moving blast wave, the lines would have been much broader. artistic rendering This artistic rendering depicts two years in the life of a massive blue supergiant star, which burped and spewed a shell of gas, then, two years later, exploded. When the supernova slammed into the shell of gas, X-rays were produced. (Credit: NASA/Sonoma State Univ./A.Simonnet) Another group, led by Stefan Immler of NASA's Goddard Space Flight Center, Greenbelt, Md., monitored SN 2006jc with NASA's Swift satellite and Chandra X-ray Observatory. By observing how the supernova brightened in X-rays, a result of the blast wave slamming into the outburst ejecta, they could measure the amount of gas blown off in the 2004 outburst: about 0.01 solar mass, the equivalent of about 10 Jupiters. "The beautiful aspect of our SN 2006jc observations is that although they were obtained in different parts of the electromagnetic spectrum, in the optical and in X-rays, they lead to the same conclusions," says Immler. "This event was a complete surprise," added Alex Filippenko, leader of the UC Berkeley/Keck supernova group and a member of NASA'S Swift team. "It opens up a fascinating new window on how some kinds of stars die." All the observations suggest that the supernova's blast wave took only a few weeks to reach the shell of material ejected two years earlier, which did not have time to drift very far from the star. As the wave smashed into the ejecta, it heated the gas to millions of degrees, hot enough to emit copious X-rays. The Swift satellite saw the supernova continue to brighten in X-rays for 100 days, something that has never been seen before in a supernova. All supernovae previously observed in X-rays have started off bright and then quickly faded to invisibility. "You don't need a lot of mass in the ejecta to produce a lot of X-rays," notes Immler. Swift's ability to monitor the supernova's X-ray rise and decline over six months was crucial to his team's mass determination. But he adds that Chandra's sharp resolution enabled his group to resolve the supernova from a bright X-ray source that appears in the field of view of Swift's X-ray Telescope. "We could not have made this measurement without Chandra," says Immler, who will submit his team's paper next week to the Astrophysical Journal. "The synergy between Swift's fast response and its ability to observe a supernova every day for a long period, and Chandra's high spatial resolution, is leading to a lot of interesting results." Foley and his colleagues, whose paper appears in the March 10 Astrophysical Journal Letters, propose that the star recently transitioned from a Luminous Blue Variable (LBV) star to a Wolf-Rayet star. An LBV is a massive star in a brief but unstable phase of stellar evolution. Similar to the 2004 eruption, LBVs are prone to blow off large amounts of mass in outbursts so extreme that they are frequently mistaken for supernovae, events dubbed "supernova impostors." Wolf-Rayet stars are hot, highly evolved stars that have shed their outer envelopes. Swift XRT Image Swift XRT Image (Credit: NASA / GSFC / CXC /S.Immler) Most astronomers did not expect that a massive star would explode so soon after a major outburst, or that a Wolf-Rayet star would produce such a luminous eruption, so SN 2006jc represents a puzzle for theorists. "It challenges some aspects of our current model of stellar evolution," says Foley. "We really don't know what caused this star to have such a large eruption so soon before it went supernova." "SN 2006jc provides us with an important clue that LBV-style eruptions may be related to the deaths of massive stars, perhaps more closely than we used to think," adds coauthor and UC Berkeley astronomer Nathan Smith. "The fact that we have no well-established theory for what actually causes these outbursts is the elephant in the living room that nobody is talking about." SN 2006jc occurred in galaxy UGC 4904, located 77 million light years from Earth in the constellation Lynx. The supernova explosion, a peculiar variant of a Type Ib, was first sighted by Itagaki, American amateur astronomer Tim Puckett and Italian amateur astronomer Roberto Gorelli. See also NASA Goddard press release at: http://www.nasa.gov/centers/goddard/news/topstory/ 2007/supernova_imposter.html

Cosmic Explosions in Three Dimensions

NASA Astrophysics Data System (ADS)

Höflich, Peter; Kumar, Pawan; Wheeler, J. Craig

2011-08-01

Introduction: 3-D Explosions: a meditation on rotation (and magnetic fields) J. C. Wheeler; Part I. Supernovae: Observations Today: 1. Supernova explosions: lessons from spectropolarimetry L. Wang; 2. Spectropolarimetric observations of Supernovae A. Filippenko and D. C. Leonard; 3. Observed and physical properties of type II plateau supernovae M. Hamuy; 4. SN1997B and the different types of Type Ic Supernovae A. Clocchiatti, B. Leibundgut, J. Spyromilio, S. Benetti, E. Cappelaro, M. Turatto and M. Phillips; 5. Near-infrared spectroscopy of stripped-envelope Supernovae C. L. Gerardy, R. A. Fesen, G. H. Marion, P. Hoeflich and J. C. Wheeler; 6. Morphology of Supernovae remnants R. Fesen; 7. The evolution of Supernova remnants in the winds of massive stars V. Dwarkadas; 8. Types for the galactic Supernovae B. E. Schaefer; Part II. Theory of Thermonuclear Supernovae: 9. Semi-steady burning evolutionary sequences for CAL 83 and CAL 87: supersoft X-ray binaries are Supernovae Ia progenitors S. Starrfield, F. X. Timmes, W. R. Hix, E. M. Sion, W. M. Sparks and S. Dwyer; 10. Type Ia Supernovae progenitors: effects of the spin-up of the white dwarfs S.-C. Yoon and N. Langer; 11. Terrestrial combustion: feedback to the stars E. S. Oran; 12. Non-spherical delayed detonations E. Livne; 13. Numerical simulations of Type Ia Supernovae: deflagrations and detonations V. N. Gamezo, A. M. Khokhlov and E. S. Oran; 14. Type Ia Supernovae: spectroscopic surprises D. Branch; 15. Aspherity effects in Supernovae P. Hoeflich, C. Gerardy and R. Quimby; 16. Broad light curve SneIa: asphericity or something else? A. Howell and P. Nugent; 17. Synthetic spectrum methods for 3-D SN models R. Thomas; 18. A hole in Ia' spectroscopic and polarimetric signatures of SN Ia asymmetry due to a companion star D. Kasen; 19. Hunting for the signatures of 3-D explosions with 1-D synthetic spectra E. Lentz, E. Baron and P. H. Hauschildt; 20. On the variation of the peak luminosity of Type Ia J. W. Truran, E. X. Timmes and E. F. Brown; Part III. Theory of Core Collapse Supernovae: 21. Rotation of core collapse progenitors: single and binary stars N. Langer; 22. Large scale convection and the convective Supernova mechanism S. Colgate and M. E. Herant; 23. Topics in core-collapse Supernova A. Burrows, C. D. Ott and C. Meakin; 24. MHD Supernova jets: the missing link D. Meier and M. Nakamura; 25. Effects of super strong magnetic fields in core collapse Supernovae I. S. Akiyama; 26. Non radial instability of stalled accretion shocks advective-acoustic cycle T. Foglizzo and P. Galletti; 27. Asymmetry effects in Hypernovae K. Maeda, K. Nomoto, J. Deng and P.A. Mazzali; 28. Turbulent MHD jet collimation and thermal driving P. T. Williams; Part IV. Magnetars, N-Stars, Pulsars: 29. Supernova remnants and pulsar wind nebulae R. Chevalier; 30. X-Ray signatures of Supernovae D. Swartz; 31. Asymmetric Supernovae and Neutron Star Kicks D. Lai and D. Q. Lamb; 32. Triggers of magnetar outbursts R. Duncan; 33. Turbulent MHD Jet Collimation and Thermal Driving P. Williams; 34. The interplay between nuclear electron capture and fluid dynamics in core collapse Supernovae W. R. Hix, O. E. B. Messer and A. Mezzacappa; Part V. Gamma-Ray Bursts: 35. GRB 021004 and Gamma-ray burst distances B. E. Schaefer; 36. Gamma-ray bursts as a laboratory for the study of Type Ic Supernovae D. Q. Lamb, T. Q. Donaghy and C. Graziani; 37. The diversity of cosmic explosions: Gamma-ray bursts and Type Ib/c Supernovae E. Berger; 38. A GRB simulation using 3D relativistic hydrodynamics J. Cannizo, N. Gehrels and E. T. Vishniac; 39. The first direct link in the Supernova/GRB connection: GRB 030329 and SN 2003dh T. Matheson; Part VI. Summary: 40. Three-dimensional explosions C. Wheeler.

Supernova Cosmology Project

Science.gov Websites

Supernova The Supernova Cosmology Project The image above and the movie clips ( QuickTime, or MPEG), show Centaurus A galaxy. The image on the left shows how a supernova appears as it brightens and fades brightness is, from the image at left. The bottom right graph shows how the spectrum of the supernova changes

The ASAS-SN bright supernova catalogue – III. 2016

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

Holoien, T. W. -S.; Brown, J. S.; Stanek, K. Z.

In this catalogue we summarize information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) and all other bright (m peak ≤ 17), spectroscopically confirmed supernovae discovered in 2016. We then gather the near-infrared through ultraviolet magnitudes of all host galaxies and the offsets of the supernovae from the centres of their hosts from public data bases. We illustrate the results using a sample that now totals 668 supernovae discovered since 2014 May 1, including the supernovae from our previous catalogues, with type distributions closely matching those of the ideal magnitude limited sample from Li et al.more » This is then the third of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.« less

The ASAS-SN bright supernova catalogue – III. 2016

DOE PAGES

Holoien, T. W. -S.; Brown, J. S.; Stanek, K. Z.; ...

2017-08-18

In this catalogue we summarize information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) and all other bright (m peak ≤ 17), spectroscopically confirmed supernovae discovered in 2016. We then gather the near-infrared through ultraviolet magnitudes of all host galaxies and the offsets of the supernovae from the centres of their hosts from public data bases. We illustrate the results using a sample that now totals 668 supernovae discovered since 2014 May 1, including the supernovae from our previous catalogues, with type distributions closely matching those of the ideal magnitude limited sample from Li et al.more » This is then the third of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.« less

PHOTOMETRIC SUPERNOVA CLASSIFICATION WITH MACHINE LEARNING

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

Lochner, Michelle; Peiris, Hiranya V.; Lahav, Ofer

Automated photometric supernova classification has become an active area of research in recent years in light of current and upcoming imaging surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given that spectroscopic confirmation of type for all supernovae discovered will be impossible. Here, we develop a multi-faceted classification pipeline, combining existing and new approaches. Our pipeline consists of two stages: extracting descriptive features from the light curves and classification using a machine learning algorithm. Our feature extraction methods vary from model-dependent techniques, namely SALT2 fits, to more independent techniques that fit parametric models tomore » curves, to a completely model-independent wavelet approach. We cover a range of representative machine learning algorithms, including naive Bayes, k -nearest neighbors, support vector machines, artificial neural networks, and boosted decision trees (BDTs). We test the pipeline on simulated multi-band DES light curves from the Supernova Photometric Classification Challenge. Using the commonly used area under the curve (AUC) of the Receiver Operating Characteristic as a metric, we find that the SALT2 fits and the wavelet approach, with the BDTs algorithm, each achieve an AUC of 0.98, where 1 represents perfect classification. We find that a representative training set is essential for good classification, whatever the feature set or algorithm, with implications for spectroscopic follow-up. Importantly, we find that by using either the SALT2 or the wavelet feature sets with a BDT algorithm, accurate classification is possible purely from light curve data, without the need for any redshift information.« less

Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey

NASA Astrophysics Data System (ADS)

McCrum, M.; Smartt, S. J.; Rest, A.; Smith, K.; Kotak, R.; Rodney, S. A.; Young, D. R.; Chornock, R.; Berger, E.; Foley, R. J.; Fraser, M.; Wright, D.; Scolnic, D.; Tonry, J. L.; Urata, Y.; Huang, K.; Pastorello, A.; Botticella, M. T.; Valenti, S.; Mattila, S.; Kankare, E.; Farrow, D. J.; Huber, M. E.; Stubbs, C. W.; Kirshner, R. P.; Bresolin, F.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Jedicke, R.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Morgan, J. S.; Price, P. A.; Sweeney, W.; Wainscoat, R. J.; Waters, C.

2015-04-01

The Pan-STARRS1 (PS1) survey has obtained imaging in five bands (griz yP1) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of MAB ˜ 23.5, of which 76 were classified as Type Ia supernovae (SNe Ia). There were 57 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or type Ic SLSNe and 12 of these have had spectra taken. Of these 12 hostless, non-Type Ia SNe, 7 were SLSNe of type Ic at redshifts between 0.5 and 1.4. This illustrates that the discovery rate of type Ic SLSNe can be maximized by concentrating on hostless transients and removing normal SNe Ia. We present data for two possible SLSNe; PS1-10pm (z = 1.206) and PS1-10ahf (z = 1.1), and estimate the rate of type Ic SLSNe to be between 3^{+3}_{-2}× 10^{-5} and 8^{+2}_{-1}× 10^{-5} that of the CCSN rate within 0.3 ≤ z ≤ 1.4 by applying a Monte Carlo technique. The rate of slowly evolving, type Ic SLSNe (such as SN2007bi) is estimated as a factor of 10 lower than this range.

Neutrinos from type Ia supernovae: The deflagration-to-detonation transition scenario

DOE PAGES

Wright, Warren P.; Nagaraj, Gautam; Kneller, James P.; ...

2016-07-19

It has long been recognized that the neutrinos detected from the next core-collapse supernova in the Galaxy have the potential to reveal important information about the dynamics of the explosion and the nucleosynthesis conditions as well as allowing us to probe the properties of the neutrino itself. The neutrinos emitted from thermonuclear—type Ia—supernovae also possess the same potential, although these supernovae are dimmer neutrino sources. For the first time, we calculate the time, energy, line of sight, and neutrino-flavor-dependent features of the neutrino signal expected from a three-dimensional delayed-detonation explosion simulation, where a deflagration-to-detonation transition triggers the complete disruption ofmore » a near-Chandrasekhar mass carbon-oxygen white dwarf. We also calculate the neutrino flavor evolution along eight lines of sight through the simulation as a function of time and energy using an exact three-flavor transformation code. We identify a characteristic spectral peak at ˜10 MeV as a signature of electron captures on copper. This peak is a potentially distinguishing feature of explosion models since it reflects the nucleosynthesis conditions early in the explosion. We simulate the event rates in the Super-K, Hyper-K, JUNO, and DUNE neutrino detectors with the SNOwGLoBES event rate calculation software and also compute the IceCube signal. Hyper-K will be able to detect neutrinos from our model out to a distance of ˜10 kpc. Here, at 1 kpc, JUNO, Super-K, and DUNE would register a few events while IceCube and Hyper-K would register several tens of events.« less

Gamma ray constraints on the Galactic supernova rate

NASA Technical Reports Server (NTRS)

Hartmann, D.; The, L.-S.; Clayton, Donald D.; Leising, M.; Mathews, G.; Woosley, S. E.

1991-01-01

We perform Monte Carlo simulations of the expected gamma ray signatures of Galactic supernovae of all types to estimate the significance of the lack of a gamma ray signal due to supernovae occurring during the last millenium. Using recent estimates of the nuclear yields, we determine mean Galactic supernova rates consistent with the historic supernova record and the gamma ray limits. Another objective of these calculations of Galactic supernova histories is their application to surveys of diffuse Galactic gamma ray line emission.

Gamma ray constraints on the galactic supernova rate

NASA Technical Reports Server (NTRS)

Hartmann, D.; The, L.-S.; Clayton, D. D.; Leising, M.; Mathews, G.; Woosley, S. E.

1992-01-01

Monte Carlo simulations of the expected gamma-ray signatures of galactic supernovae of all types are performed in order to estimate the significance of the lack of a gamma-ray signal due to supernovae occurring during the last millenium. Using recent estimates of nuclear yields, we determine galactic supernova rates consistent with the historic supernova record and the gamma-ray limits. Another objective of these calculations of galactic supernova histories is their application to surveys of diffuse galactic gamma-ray line emission.

r-Process nucleosynthesis from three-dimensional jet-driven core-collapse supernovae with magnetic misalignments

NASA Astrophysics Data System (ADS)

Halevi, Goni; Mösta, Philipp

2018-06-01

We investigate r-process nucleosynthesis in three-dimensional general relativistic magnetohydrodynamic simulations of jet-driven supernovae resulting from rapidly rotating, strongly magnetized core-collapse. We explore the effect of misaligning the pre-collapse magnetic field with respect to the rotation axis by performing four simulations: one aligned model and models with 15°, 30°, and 45° misalignments. The simulations we present employ a microphysical finite-temperature equation of state and a leakage scheme that captures the overall energetics and lepton number exchange due to post-bounce neutrino emission and absorption. We track the thermodynamic properties of the ejected material with Lagrangian tracer particles and analyse its composition with the nuclear reaction network SKYNET. By using different neutrino luminosities in post-processing the tracer data with SKYNET, we constrain the impact of uncertainties in neutrino luminosities. We find that, for the aligned model considered here, the use of an approximate leakage scheme results in neutrino luminosity uncertainties corresponding to a factor of 100-1000 uncertainty in the abundance of third peak r-process elements. Our results show that for misalignments of 30° or less, r-process elements are robustly produced as long as neutrino luminosities are reasonably low (≲ 5 × 1052 erg s-1). For a more extreme misalignment of 45°, we find the production of r-process elements beyond the second peak significantly reduced. We conclude that robust r-process nucleosynthesis in magnetorotational supernovae requires a progenitor stellar core with a large poloidal magnetic field component that is at least moderately (within ˜30°) aligned with the rotation axis.

Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions

NASA Astrophysics Data System (ADS)

Paxton, Bill; Schwab, Josiah; Bauer, Evan B.; Bildsten, Lars; Blinnikov, Sergei; Duffell, Paul; Farmer, R.; Goldberg, Jared A.; Marchant, Pablo; Sorokina, Elena; Thoul, Anne; Townsend, Richard H. D.; Timmes, F. X.

2018-02-01

We update the capabilities of the software instrument Modules for Experiments in Stellar Astrophysics (MESA) and enhance its ease of use and availability. Our new approach to locating convective boundaries is consistent with the physics of convection, and yields reliable values of the convective-core mass during both hydrogen- and helium-burning phases. Stars with M< 8 M⊙ become white dwarfs and cool to the point where the electrons are degenerate and the ions are strongly coupled, a realm now available to study with MESA due to improved treatments of element diffusion, latent heat release, and blending of equations of state. Studies of the final fates of massive stars are extended in MESA by our addition of an approximate Riemann solver that captures shocks and conserves energy to high accuracy during dynamic epochs. We also introduce a 1D capability for modeling the effects of Rayleigh-Taylor instabilities that, in combination with the coupling to a public version of the STELLA radiation transfer instrument, creates new avenues for exploring Type II supernova properties. These capabilities are exhibited with exploratory models of pair-instability supernovae, pulsational pair-instability supernovae, and the formation of stellar-mass black holes. The applicability of MESA is now widened by the capability to import multidimensional hydrodynamic models into MESA. We close by introducing software modules for handling floating point exceptions and stellar model optimization, as well as four new software tools - MESA-Web, MESA-Docker, pyMESA, and mesastar.org - to enhance MESA's education and research impact.

Constraining a Possible Variation of G with Type Ia Supernovae

NASA Astrophysics Data System (ADS)

Mould, Jeremy; Uddin, Syed A.

2014-03-01

Astrophysical cosmology constrains the variation of Newton's Constant in a manner complementary to laboratory experiments, such as the celebrated lunar laser ranging campaign. Supernova cosmology is an example of the former and has attained campaign status, following planning by a Dark Energy Task Force in 2005. In this paper, we employ the full SNIa data set to the end of 2013 to set a limit on G variation. In our approach, we adopt the standard candle delineation of the redshift distance relation. We set an upper limit on its rate of change |dot{G}/G| of 0.1 parts per billion per year over 9 Gyrs. By contrast, lunar laser ranging tests variation of G over the last few decades. Conversely, one may adopt the laboratory result as a prior and constrain the effect of variable G in dark energy equation of state experiments to δw < 0.02. We also examine the parameterisation G 1 + z. Its short expansion age conflicts with the measured values of the expansion rate and the density in a flat Universe. In conclusion, supernova cosmology complements other experiments in limiting G variation. An important caveat is that it rests on the assumption that the same mass of 56Ni is burned to create the standard candle regardless of redshift. These two quantities, f and G, where f is the Chandrasekhar mass fraction burned, are degenerate. Constraining f variation alone requires more understanding of the SNIa mechanism.

zBEAMS: a unified solution for supernova cosmology with redshift uncertainties

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

Roberts, Ethan; Lochner, Michelle; Bassett, Bruce A.

Supernova cosmology without spectra will be an important component of future surveys such as LSST. This lack of supernova spectra results in uncertainty in the redshifts which, if ignored, leads to significantly biased estimates of cosmological parameters. Here we present a hierarchical Bayesian formalism— zBEAMS—that addresses this problem by marginalising over the unknown or uncertain supernova redshifts to produce unbiased cosmological estimates that are competitive with supernova data with spectroscopically confirmed redshifts. zBEAMS provides a unified treatment of both photometric redshifts and host galaxy misidentification (occurring due to chance galaxy alignments or faint hosts), effectively correcting the inevitable contamination inmore » the Hubble diagram. Like its predecessor BEAMS, our formalism also takes care of non-Ia supernova contamination by marginalising over the unknown supernova type. We illustrate this technique with simulations of supernovae with photometric redshifts and host galaxy misidentification. A novel feature of the photometric redshift case is the important role played by the redshift distribution of the supernovae.« less

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.

Dust in Supernovae and Supernova Remnants I: Formation Scenarios

NASA Astrophysics Data System (ADS)

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

2018-04-01

Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.

The supernova-gamma-ray burst-jet connection.

PubMed

Hjorth, Jens

2013-06-13

The observed association between supernovae and gamma-ray bursts represents a cornerstone in our understanding of the nature of gamma-ray bursts. The collapsar model provides a theoretical framework for this connection. A key element is the launch of a bipolar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star, whereas the (56)Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper, I summarize the observational status of the supernova-gamma-ray burst connection in the context of the 'engine' picture of jet-driven supernovae and highlight SN 2012bz/GRB 120422A--with its luminous supernova but intermediate high-energy luminosity--as a possible transition object between low-luminosity and jet gamma-ray bursts. The jet channel for supernova explosions may provide new insights into supernova explosions in general.

False-color images from observations by the Supernova Cosmology Project of one of the two most dista

NASA Technical Reports Server (NTRS)

2002-01-01

TFalse-color images from observations by the Supernova Cosmology Project of one of the two most distant spectroscopically confirmed supernova. From the left: the first two images, from the Cerro Tololo Interamerican Observatory 4-meter telescope, show a small region of sky just before and just after the the appearance of a type-Ia supernova that exploded when the universe was about half its present age. The third image shows the same supernova as observed with the Hubble Space Telescope. This much sharper picture allows a much better measurement of the apparent brightness and hence the distance of this supernova. Because their intrinsic brightness is predictable, such supernovae help to determine the deceleration, and so the eventual fate, of the universe. Credit: Perlmutter et al., The Supernova Cosmology Project

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.

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.

Investigating the Origin of the Supernova Remnant W49B

NASA Astrophysics Data System (ADS)

Crum, Ryan Matthew; Frank, Kari A.; Dwarkadas, Vikram; Burrows, David N.

2018-01-01

W49B is a Galactic supernova remnant whose origin is still debated. Is it the remains of an unusual asymmetric Type 1a supernova or of a jet-driven core collapse supernova? Using the X-ray analysis method, Smoothed Particle Inference (SPI), we dig deeper into understanding the complex properties of SNR W49B. We do this by characterizing the temperatures and abundance ratios throughout the remnant. We will compare the results with a wide variety of supernova nucleosynthesis models in order to constrain the mechanism behind this unusual supernova remnant.

Model-independent cosmological constraints from growth and expansion

NASA Astrophysics Data System (ADS)

L'Huillier, Benjamin; Shafieloo, Arman; Kim, Hyungjin

2018-05-01

Reconstructing the expansion history of the Universe from Type Ia supernovae data, we fit the growth rate measurements and put model-independent constraints on some key cosmological parameters, namely, Ωm, γ, and σ8. The constraints are consistent with those from the concordance model within the framework of general relativity, but the current quality of the data is not sufficient to rule out modified gravity models. Adding the condition that dark energy density should be positive at all redshifts, independently of its equation of state, further constrains the parameters and interestingly supports the concordance model.

Rise of planetary bodies.

NASA Astrophysics Data System (ADS)

Czechowski, Z.; Leliwa-Kopystyński, J.; Teisseyre, R.

Contents: 1. On the probability of the formation of planetary systems. 2. Condensation triggered by supernova explosion and tidal capture theory. 3. Foundations of accretion theory. 4. The structure and evolution of the protoplanetary disk. 5. Coagulation of orbiting bodies. 6. Collision phenomena related to planetology: accretion, fragmentation, cratering. 7. Dynamics of planetesimals: Introduction, Safronov's approach, elements of the kinetic theory of gases, Nakagawa's approach, approaches considering inelastic collisions and gravitational encounters of planetesimals, Hämeen-Anttila approach, planetesimals with different masses. 8. Growth of the planetary embryo: Basic equations, model of growth of planetary embryos. 9. Origin of the Moon and the satellites.

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.

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.

How high energy fluxes may affect Rayleigh–Taylor instability growth in young supernova remnants

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

Kuranz, Carolyn C.; Park, Hye -Sook; Huntington, Channing M.

Here, energy-transport effects can alter the structure that develops as a supernova evolves into a supernova remnant. The Rayleigh–Taylor instability is thought to produce structure at the interface between the stellar ejecta and the circumstellar matter, based on simple models and hydrodynamic simulations. Here we report experimental results from the National Ignition Facility to explore how large energy fluxes, which are present in supernovae, affect this structure. We observed a reduction in Rayleigh–Taylor growth. In analyzing the comparison with supernova SN1993J, a Type II supernova, we found that the energy fluxes produced by heat conduction appear to be larger thanmore » 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 supernova remnants and these dynamics should be noted in the understanding of young supernova remnants.« less

How high energy fluxes may affect Rayleigh–Taylor instability growth in young supernova remnants

DOE PAGES

Kuranz, Carolyn C.; Park, Hye -Sook; Huntington, Channing M.; ...

2018-04-19

Here, energy-transport effects can alter the structure that develops as a supernova evolves into a supernova remnant. The Rayleigh–Taylor instability is thought to produce structure at the interface between the stellar ejecta and the circumstellar matter, based on simple models and hydrodynamic simulations. Here we report experimental results from the National Ignition Facility to explore how large energy fluxes, which are present in supernovae, affect this structure. We observed a reduction in Rayleigh–Taylor growth. In analyzing the comparison with supernova SN1993J, a Type II supernova, we found that the energy fluxes produced by heat conduction appear to be larger thanmore » 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 supernova remnants and these dynamics should be noted in the understanding of young supernova remnants.« less

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.

Light-curve and spectral properties of ultra-stripped core-collapse supernovae

NASA Astrophysics Data System (ADS)

Moriya, Takashi J.

2017-11-01

We discuss light-curve and spectral properties of ultra-stripped core-collapse supernovae. Ultra-stripped supernovae are supernovae with ejecta masses of only ~0.1M ⊙ whose progenitors lose their envelopes due to binary interactions with their compact companion stars. We follow the evolution of an ultra-stripped supernova progenitor until core collapse and perform explosive nucleosynthesis calculations. We then synthesize light curves and spectra of ultra-stripped supernovae based on the nucleosynthesis results. We show that ultra-stripped supernovae synthesize ~0.01M ⊙ of the radioactive 56Ni, and their typical peak luminosity is around 1042 erg s-1 or -16 mag. Their typical rise time is 5 - 10 days. By comparing synthesized and observed spectra, we find that SN 2005ek and some of so-called calcium-rich gap transients like PTF10iuv may be related to ultra-stripped supernovae.

Dodging the dark matter degeneracy while determining the dynamics of dark energy

NASA Astrophysics Data System (ADS)

Busti, Vinicius C.; Clarkson, Chris

2016-05-01

One of the key issues in cosmology is to establish the nature of dark energy, and to determine whether the equation of state evolves with time. When estimating this from distance measurements there is a degeneracy with the matter density. We show that there exists a simple function of the dark energy equation of state and its first derivative which is independent of this degeneracy at all redshifts, and so is a much more robust determinant of the evolution of dark energy than just its derivative. We show that this function can be well determined at low redshift from supernovae using Gaussian Processes, and that this method is far superior to a variety of parameterisations which are also subject to priors on the matter density. This shows that parametrised models give very biased constraints on the evolution of dark energy.

White dwarf models for type 1 supernovae and quiet supernovae, and presupernova evolution

NASA Technical Reports Server (NTRS)

Nomoto, K.

1980-01-01

Supernova mechanisms in accreting white dwarfs are considered with emphasis on deflagration as a plausible mechanism for producing Type I supernovae and electron captures to form quiet supernovae leaving neutron stars. These outcomes depend on accretion rate of helium, initial mass and composition of the white dwarf. The various types of hydrogen shell burning in the presupernova stage are also discussed.

Matching Supernovae to Galaxies

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-12-01

One of the major challenges for modern supernova surveys is identifying the galaxy that hosted each explosion. Is there an accurate and efficient way to do this that avoids investing significant human resources?Why Identify Hosts?One problem in host galaxy identification. Here, the supernova lies between two galaxies but though the centroid of the galaxy on the right is closer in angular separation, this may be a distant background galaxy that is not actually near the supernova. [Gupta et al. 2016]Supernovae are a critical tool for making cosmological predictions that help us to understand our universe. But supernova cosmology relies on accurately identifying the properties of the supernovae including their redshifts. Since spectroscopic followup of supernova detections often isnt possible, we rely on observations of the supernova host galaxies to obtain redshifts.But how do we identify which galaxy hosted a supernova? This seems like a simple problem, but there are many complicating factors a seemingly nearby galaxy could be a distant background galaxy, for instance, or a supernovas host could be too faint to spot.The authors algorithm takes into account confusion, a measure of how likely the supernova is to be mismatched. In these illustrations of low (left) and high (right) confusion, the supernova is represented by a blue star, and the green circles represent possible host galaxies. [Gupta et al. 2016]Turning to AutomationBefore the era of large supernovae surveys, searching for host galaxies was done primarily by visual inspection. But current projects like the Dark Energy Surveys Supernova Program is finding supernovae by the thousands, and the upcoming Large Synoptic Survey Telescope will likely discover hundreds of thousands. Visual inspection will not be possible in the face of this volume of data so an accurate and efficient automated method is clearly needed!To this end, a team of scientists led by Ravi Gupta (Argonne National Laboratory) has recently developed a new automated algorithm for matching supernovae to their host galaxies. Their work builds on currently existing algorithms and makes use of information about the nearby galaxies, accounts for the uncertainty of the match, and even includes a machine learning component to improve the matching accuracy.Gupta and collaborators test their matching algorithm on catalogs of galaxies and simulated supernova events to quantify how well the algorithm is able to accurately recover the true hosts.Successful MatchingThe matching algorithms accuracy (purity) as a function of the true supernova-host separation, the supernova redshift, the true hosts brightness, and the true hosts size. [Gupta et al. 2016]The authors find that when the basic algorithm is run on catalog data, it matches supernovae to their hosts with 91% accuracy. Including the machine learning component, which is run after the initial matching algorithm, improves the accuracy of the matching to 97%.The encouraging results of this work which was intended as a proof of concept suggest that methods similar to this could prove very practical for tackling future survey data. And the method explored here has use beyond matching just supernovae to their host galaxies: it could also be applied to other extragalactic transients, such as gamma-ray bursts, tidal disruption events, or electromagnetic counterparts to gravitational-wave detections.CitationRavi R. Gupta et al 2016 AJ 152 154. doi:10.3847/0004-6256/152/6/154

Evolution of a proto-neutron star with a nuclear many-body equation of state: Neutrino luminosity and gravitational wave frequencies

DOE PAGES

Camelio, Giovanni; Lovato, Alessandro; Gualtieri, Leonardo; ...

2017-08-30

In a core-collapse supernova, a huge amount of energy is released in the Kelvin-Helmholtz phase subsequent to the explosion, when the proto-neutron star cools and deleptonizes as it loses neutrinos. Most of this energy is emitted through neutrinos, but a fraction of it can be released through gravitational waves. We model the evolution of a proto-neutron star in the Kelvin-Helmholtz phase using a general relativistic numerical code, and a recently proposed finite temperature, many-body equation of state; from this we consistently compute the diffusion coefficients driving the evolution. To include the many-body equation of state, we develop a new fittingmore » formula for the high density baryon free energy at finite temperature and intermediate proton fraction. Here, we estimate the emitted neutrino signal, assessing its detectability by present terrestrial detectors, and we determine the frequencies and damping times of the quasinormal modes which would characterize the gravitational wave signal emitted in this stage.« less

Evolution of a proto-neutron star with a nuclear many-body equation of state: Neutrino luminosity and gravitational wave frequencies

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

Camelio, Giovanni; Lovato, Alessandro; Gualtieri, Leonardo

In a core-collapse supernova, a huge amount of energy is released in the Kelvin-Helmholtz phase subsequent to the explosion, when the proto-neutron star cools and deleptonizes as it loses neutrinos. Most of this energy is emitted through neutrinos, but a fraction of it can be released through gravitational waves. We model the evolution of a proto-neutron star in the Kelvin-Helmholtz phase using a general relativistic numerical code, and a recently proposed finite temperature, many-body equation of state; from this we consistently compute the diffusion coefficients driving the evolution. To include the many-body equation of state, we develop a new fittingmore » formula for the high density baryon free energy at finite temperature and intermediate proton fraction. Here, we estimate the emitted neutrino signal, assessing its detectability by present terrestrial detectors, and we determine the frequencies and damping times of the quasinormal modes which would characterize the gravitational wave signal emitted in this stage.« less

De Sitter universe described by a binary mixture with a variable cosmological constant λ

NASA Astrophysics Data System (ADS)

Biswal, S. K.

2018-04-01

We have constructed a self-consistent system of Bianchi Type VI0 cosmology, and mingling of perfect fluid and dark energy in five dimensions. The usual equation of state p = γ ρ with γ \\in [0, 1] is chosen by the perfect fluid. The dark energy assumed to be chosen is taken into consideration to be either the quintessence or Chaplygin gas. The same solutions pertaining to the corresponding the field equations of Einstein are obtained as a quadrature. State parameter's equations for dark energy ω is found to be consistent enough with the recent observations of SNe Ia data (SNe Ia data with CMBR anisotropy) and galaxy clustering statistics. Here our models predict that the rate of expansion of Universe would increase with passage of time. The cosmological constant Λ is traced as a declining function of time and it gets nearer to a small positive value later on which is supported by the results from the current supernovae Ia observations. Also a detail discussion is made on the physical and geometrical aspects of the models.

Distribution of nuclei in equilibrium stellar matter from the free-energy density in a Wigner-Seitz cell

NASA Astrophysics Data System (ADS)

Grams, G.; Giraud, S.; Fantina, A. F.; Gulminelli, F.

2018-03-01

The aim of the present study is to calculate the nuclear distribution associated at finite temperature to any given equation of state of stellar matter based on the Wigner-Seitz approximation, for direct applications in core-collapse simulations. The Gibbs free energy of the different configurations is explicitly calculated, with special care devoted to the calculation of rearrangement terms, ensuring thermodynamic consistency. The formalism is illustrated with two different applications. First, we work out the nuclear statistical equilibrium cluster distribution for the Lattimer and Swesty equation of state, widely employed in supernova simulations. Secondly, we explore the effect of including shell structure, and consider realistic nuclear mass tables from the Brussels-Montreal Hartree-Fock-Bogoliubov model (specifically, HFB-24). We show that the whole collapse trajectory is dominated by magic nuclei, with extremely spread and even bimodal distributions of the cluster probability around magic numbers, demonstrating the importance of cluster distributions with realistic mass models in core-collapse simulations. Simple analytical expressions are given, allowing further applications of the method to any relativistic or nonrelativistic subsaturation equation of state.

Modeling the Evolution of Disk Galaxies. I. The Chemodynamical Method and the Galaxy Model

NASA Astrophysics Data System (ADS)

Samland, M.; Hensler, G.; Theis, Ch.

1997-02-01

Here we present our two-dimensional chemodynamical code CoDEx, which we developed for the purpose of modeling the evolution of galaxies in a self-consistent manner. The code solves the hydrodynamical and momentum equations for three stellar components and the multiphase interstellar medium (clouds and intercloud medium), including star formation, Type I and Type II supernovae, planetary nebulae, stellar winds, evaporation and condensation, drag, cloud collisions, heating and cooling, and stellar nucleosynthesis. These processes are treated simultaneously, coupling a large range in temporal and spatial scales, to account for feedback and self-regulation processes, which play an extraordinarily important role in the galactic evolution. The evolution of galaxies of different masses and angular momenta is followed through all stages from the initial protogalactic clouds until now. In this first paper we present a representative model of the Milky Way and compare it with observations. The capability of chemodynamical models is convincingly proved by the excellent agreement with various observations. In addition, well-known problems (the G-dwarf problem, the discrepancy between local effective yields, etc.), which so far could be only explained by artificial constraints, are also solved in the global scenario. Starting from a rotating protogalactic gas cloud in virial equilibrium, which collapses owing to dissipative cloud-cloud collisions, we can follow the galactic evolution in detail. Owing to the collapse, the gas density increases, stars are forming, and the first Type II supernovae explode. The collapse time is 1 order of magnitude longer than the dynamical free-fall time because of the energy release by Type II supernovae. The supernovae also drive hot metal-rich gas ejected from massive stars into the halo, and as a consequence, the clouds in the star-forming regions have lower metallicities than the clouds in the halo. The observed negative metallicity gradients do not form before t = 6 × 109 yr. These outward gas flows prevent any clear correlation between local star formation rate and enrichment and also prevent a unique age-metallicity relation. The situation, however, is even more complicated, because the mass return of intermediate-mass stars (Type I supernovae and planetary nebulae) is delayed depending on the type of precursor. Since our chemodynamical model includes all these processes, we can calculate, e.g., the [O/H] distribution of stars and find good agreement everywhere in bulge, disk, and halo. From the galactic oxygen to iron ratio, we can determine the supernovae ([II + Ib]/Ia) ratio for different types of Type Ia supernovae (such as carbon deflagration or sub-Chandrasekhar models) and find that the ratio should be in the range 1.0-3.8. The chemodynamical model also traces other chemical elements (e.g., N + C), density distributions, gas flows, velocity dispersions of the stars and clouds, star formation, planetary nebula rates, cloud collision, condensation and evaporation rates, and the cooling due to radiation. The chemodynamical treatment of galaxy evolution should be envisaged as a necessary development, which takes those processes into account that affect the dynamical, energetical, and chemical evolution.

An ASCA Study of the Composite Supernova Remnant G18.95-1.1

NASA Technical Reports Server (NTRS)

Harrus, Ilana

2000-01-01

This is the final report on the work done on Supernova Remnant (SNR) G18-95-1.1. The data were taken on April, 2. 1998 and delivered a couple of months later to the Principal Investigator (PI: Dr. Ilana Harrus). We received a CD-ROM containing the results of the standard processing pipeline and all the files needed for the analysis. We have analyzed the data and presented a poster on this object at the 194th American Astronomical Society Meeting in Chicago (June 1999). A copy of the poster is appended to this report. The poster presentation triggered several discussions and we are summarizing the analysis results and those discussions in a paper to be submitted soon to the Astrophysical Journal. We have appended the draft of the paper to this report. It must be noted that the paper is still in its early stages. In particular more work is needed in the physical implications of the results of the spectral analysis and in the comparison with theoretical models to understand the curious morphology of the remnant. The project should be completed within the next two months. Attachment: "ASCA study of the centrally-peaked thermal supernova remnant: G18.95-1.1".

ASTROPHYSICAL SHRAPNEL: DISCRIMINATING AMONG NEAR-EARTH STELLAR EXPLOSION SOURCES OF LIVE RADIOACTIVE ISOTOPES

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

Fry, Brian J.; Fields, Brian D.; Ellis, John R.

2015-02-10

We consider the production and deposition on Earth of isotopes with half-lives in the range 10{sup 5}-10{sup 8} yr that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include Electron-Capture Supernovae (ECSNe), Super-Asymptotic Giant Branch (SAGB) stars, Thermonuclear/Type Ia Supernovae (TNSNe), and Kilonovae/Neutron Star Mergers (KNe). We revisit previous estimates of the {sup 60}Fe and {sup 26}Al signatures, and extend these estimates to include {sup 244}Pu and {sup 53}Mn. We discuss interpretations of the {sup 60}Fe signals in terrestrial and lunar reservoirs in terms of a nearby stellar ejection ∼2.2 Myr ago, showingmore » that (1) the {sup 60}Fe yield rules out the TNSN and KN interpretations, (2) the {sup 60}Fe signals highly constrain SAGB interpretations but do not completely them rule out, (3) are consistent with a CCSN origin, and (4) are highly compatible with an ECSN interpretation. Future measurements could resolve the radioisotope deposition over time, and we use the Sedov blast wave solution to illustrate possible time-resolved profiles. Measuring such profiles would independently probe the blast properties including distance, and would provide additional constraints for the nature of the explosion.« less

Cosmological Results from High-z Supernovae

NASA Astrophysics Data System (ADS)

Tonry, John L.; Schmidt, Brian P.; Barris, Brian; Candia, Pablo; Challis, Peter; Clocchiatti, Alejandro; Coil, Alison L.; Filippenko, Alexei V.; Garnavich, Peter; Hogan, Craig; Holland, Stephen T.; Jha, Saurabh; Kirshner, Robert P.; Krisciunas, Kevin; Leibundgut, Bruno; Li, Weidong; Matheson, Thomas; Phillips, Mark M.; Riess, Adam G.; Schommer, Robert; Smith, R. Chris; Sollerman, Jesper; Spyromilio, Jason; Stubbs, Christopher W.; Suntzeff, Nicholas B.

2003-09-01

The High-z Supernova Search Team has discovered and observed eight new supernovae in the redshift interval z=0.3-1.2. These independent observations, analyzed by similar but distinct methods, confirm the results of Riess and Perlmutter and coworkers that supernova luminosity distances imply an accelerating universe. More importantly, they extend the redshift range of consistently observed Type Ia supernovae (SNe Ia) to z~1, where the signature of cosmological effects has the opposite sign of some plausible systematic effects. Consequently, these measurements not only provide another quantitative confirmation of the importance of dark energy, but also constitute a powerful qualitative test for the cosmological origin of cosmic acceleration. We find a rate for SN Ia of (1.4+/-0.5)×10-4h3Mpc-3yr-1 at a mean redshift of 0.5. We present distances and host extinctions for 230 SN Ia. These place the following constraints on cosmological quantities: if the equation of state parameter of the dark energy is w=-1, then H0t0=0.96+/-0.04, and ΩΛ-1.4ΩM=0.35+/-0.14. Including the constraint of a flat universe, we find ΩM=0.28+/-0.05, independent of any large-scale structure measurements. Adopting a prior based on the Two Degree Field (2dF) Redshift Survey constraint on ΩM and assuming a flat universe, we find that the equation of state parameter of the dark energy lies in the range -1.48-1, we obtain w<-0.73 at 95% confidence. These constraints are similar in precision and in value to recent results reported using the WMAP satellite, also in combination with the 2dF Redshift Survey. Based in part on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555. This research is primarily associated with proposal GO-8177, but also uses and reports results from proposals GO-7505, 7588, 8641, and 9118. Based in part on observations taken with the Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, le Centre National de la Recherche Scientifique de France, and the University of Hawaii. CTIO: Based in part on observations taken at the Cerro Tololo Inter-American Observatory. Keck: Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. UH: Based in part on observations with the University of Hawaii 2.2 m telescope at Mauna Kea Observatory, Institute for Astronomy, University of Hawaii. UKIRT: Based in part on observations with the United Kingdom Infrared Telescope (UKIRT) operated by the Joint Astronomy Centre on behalf of the UK. Particle Physics and Astronomy Research Council. VLT: Based in part on observations obtained at the European Southern Observatory, Paranal, Chile, under programs ESO 64.O-0391 and ESO 64.O-0404. WIYN: Based in part on observations taken at the WIYN Observatory, a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories.

Progress Report on the Berkeley/Anglo-Australian Observatory High-redshift Supernova Search

DOE R&D Accomplishments Database

Goldhaber, G.; Perlmutter, S.; Pennypacker, C.; Marvin, H.; Muller, R. A.; Couch, W.; Boyle, B.

1990-11-01

There are two main efforts related to supernovae in progress at Berkeley. The first is an automated supernova search for nearby supernovae, which was already discussed by Carl Pennypacker at this conference. The second is a search for distant supernovae, in the z = 0.3 to 0.5 region, aimed at measuring {Omega}. It is the latter that I want to discuss in this paper.

Detection of a Red Supergiant Progenitor Star of a Type II-Plateau Supernova

NASA Astrophysics Data System (ADS)

Smartt, Stephen J.; Maund, Justyn R.; Hendry, Margaret A.; Tout, Christopher A.; Gilmore, Gerard F.; Mattila, Seppo; Benn, Chris R.

2004-01-01

We present the discovery of a red supergiant star that exploded as supernova 2003gd in the nearby spiral galaxy M74. The Hubble Space Telescope (HST) and the Gemini Telescope imaged this galaxy 6 to 9 months before the supernova explosion, and subsequent HST images confirm the positional coincidence of the supernova with a single resolved star that is a red supergiant of 8+4-2 solar masses. This confirms both stellar evolution models and supernova theories predicting that cool red supergiants are the immediate progenitor stars of type II-plateau supernovae.

OGLE-2014-SN-073 as a fallback accretion powered supernova

NASA Astrophysics Data System (ADS)

Moriya, Takashi J.; Terreran, Giacomo; Blinnikov, Sergei I.

2018-03-01

We investigate the possibility that the energetic Type II supernova OGLE-2014-SN-073 is powered by a fallback accretion following the failed explosion of a massive star. Taking massive hydrogen-rich supernova progenitor models, we estimate the fallback accretion rate and calculate the light-curve evolution of supernovae powered by the fallback accretion. We find that such fallback accretion powered models can reproduce the overall observational properties of OGLE-2014-SN-073. It may imply that some failed explosions could be observed as energetic supernovae like OGLE-2014-SN-073 instead of faint supernovae as previously proposed.

The Carnegie Supernova Project: The Low-Redshift Survey

NASA Astrophysics Data System (ADS)

Hamuy, Mario; Folatelli, Gastón; Morrell, Nidia I.; Phillips, Mark M.; Suntzeff, Nicholas B.; Persson, S. E.; Roth, Miguel; Gonzalez, Sergio; Krzeminski, Wojtek; Contreras, Carlos; Freedman, Wendy L.; Murphy, D. C.; Madore, Barry F.; Wyatt, P.; Maza, José; Filippenko, Alexei V.; Li, Weidong; Pinto, P. A.

2006-01-01

Supernovae are essential to understanding the chemical evolution of the universe. Type Ia supernovae also provide the most powerful observational tool currently available for studying the expansion history of the universe and the nature of dark energy. Our basic knowledge of supernovae comes from the study of their photometric and spectroscopic properties. However, the presently available data sets of optical and near-infrared light curves of supernovae are rather small and/or heterogeneous, and employ photometric systems that are poorly characterized. Similarly, there are relatively few supernovae whose spectral evolution has been well sampled, both in wavelength and phase, with precise spectrophotometric observations. The low-redshift portion of the Carnegie Supernova Project (CSP) seeks to remedy this situation by providing photometry and spectrophotometry of a large sample of supernovae taken on telescope/filter/detector systems that are well understood and well characterized. During a 5 year program that began in 2004 September, we expect to obtain high-precision u'g'r'i'BVYJHKs light curves and optical spectrophotometry for about 250 supernovae of all types. In this paper we provide a detailed description of the CSP survey observing and data reduction methodology. In addition, we present preliminary photometry and spectra obtained for a few representative supernovae during the first observing campaign.

Explosions in Majestic Spiral Beauties

NASA Astrophysics Data System (ADS)

2004-12-01

Images of beautiful galaxies, and in particular of spiral brethren of our own Milky Way, leaves no-one unmoved. It is difficult indeed to resist the charm of these impressive grand structures. Astronomers at Paranal Observatory used the versatile VIMOS instrument on the Very Large Telescope to photograph two magnificent examples of such "island universes", both of which are seen in a southern constellation with an animal name. But more significantly, both galaxies harboured a particular type of supernova, the explosion of a massive star during a late and fatal evolutionary stage. The first image (PR Photo 33a/04) is of the impressive spiral galaxy NGC 6118 [1], located near the celestial equator, in the constellation Serpens (The Snake). It is a comparatively faint object of 13th magnitude with a rather low surface brightness, making it pretty hard to see in small telescopes. This shyness has prompted amateur astronomers to nickname NGC 6118 the "Blinking Galaxy" as it would appear to flick into existence when viewed through their telescopes in a certain orientation, and then suddenly disappear again as the eye position shifted. There is of course no such problem for the VLT's enormous light-collecting power and ability to produce sharp images, and this magnificent galaxy is here seen in unequalled detail. The colour photo is based on a series of exposures behind different optical filters, obtained with the VIMOS multi-mode instrument on the 8.2-m VLT Melipal telescope during several nights around August 21, 2004. About 80 million light-years away, NGC 6118 is a grand-design spiral seen at an angle, with a very small central bar and several rather tightly wound spiral arms (it is classified as of type "SA(s)cd" [2]) in which large numbers of bright bluish knots are visible. Most of them are active star-forming regions and in some, very luminous and young stars can be perceived. Of particular interest is the comparatively bright stellar-like object situated directly North of the galaxy's centre, near the periphery (see PR Photo 33b/04): it is Supernova 2004dk that was first reported on August 1, 2004. Observations a few days later showed this to be a supernova of Type Ib or Ic [3], caught a few days before maximum light. This particular kind of supernova is believed to result from the demise of a massive star that has somehow lost its entire hydrogen envelope, probably as a result of mass transfer in a binary system, before exploding. Also visible on the image is the trail left by a satellite, which passed by during one of the exposures taken in the B filter, hence its blue colour. This is an illustration that even in such a remote place as the Paranal Observatory in the Atacama desert, astronomers are not completely sheltered from light pollution. ESO PR Photo 33c/04 ESO PR Photo 33c/04 NGC 7424 - VIMOS+VLT Colour composite [Preview - JPEG: 400 x 514 pix - 110k] [Normal - JPEG: 800 x 1028 pix - 995k] [FullRes - JPEG: 1887 x 2424 pix - 5.4M] Caption: ESO PR Photo 33c/04 shows a composite colour-coded image of another magnificent spiral galaxy, NGC 7424, at a distance of 40 million light-years. It is based on images obtained with the multi-mode VIMOS instrument on the ESO Very Large Telescope (VLT) in three different wavelength bands (see Technical information below). The image covers 6.5 x 7.2 arcmin on the sky. North is up and East is to the right. The second galaxy imaged by the VLT (ESO PR Photo 33c/04) is another spiral, the beautiful multi-armed NGC 7424 that is seen almost directly face-on. Located at a distance of roughly 40 million light-years in the constellation Grus (the Crane), this galaxy was discovered by Sir John Herschel while observing at the Cape of Good Hope. This other example of a "grand design" galaxy is classified as "SAB(rs)cd" [2], meaning that it is intermediate between normal spirals (SA) and strongly barred galaxies (SB) and that it has rather open arms with a small central region. It also shows many ionised regions as well as clusters of young and massive stars. Ten young massive star clusters can be identified whose size span the range from 1 to 200 light-years. The galaxy itself is roughly 100,000 light-years across, that is, quite similar in size to our own Milky Way galaxy. Because of its low surface brightness, this galaxy also demands dark skies and a clear night to be observed in this impressive detail. When viewed in a small telescope, it appears as a large elliptical haze with no trace of the many beautiful filamentary arms with a multitude of branches revealed in this striking VLT image. Note also the very bright and prominent bar in the middle. ESO PR Photo 33d/04 ESO PR Photo 33d/04 NGC 7424 and SN2001ig (FORS 2 and VIMOS + VLT) [Preview - JPEG: 400 x 596 pix - 44k] [Normal - JPEG: 800 x 1192 pix - 637k] Caption: ESO PR Photo 33d/04 shows two composite colour-coded image of a part of NGC 7424. The left image was made from an exposure taken with the FORS 2 instrument on VLT Yepun on June 16, 2002. In this, the supernova - although considerably fainter than when it was discovered six months earlier - is still well visible in the middle right of the image. The right image is part of PR Photo 33d/04 on the same scale. Obtained in October 2004, the supernova is no more apparent. The image covers 3.8 x 3.2 arcmin. North is up and East is to the right. On the evening of 10 December 2001, Australian amateur astronomer Reverend Robert Evans, observing from his backyard in the Blue Mountains west of Sydney, discovered with his 30cm telescope his 39th supernova, Supernova 2001ig in the outskirts of NGC 7424. Of magnitude 14.5 (that is, 3000 times fainter than the faintest star that can be seen with the unaided eye), this supernova brightened quickly by a factor 8 to magnitude 12.3. A few months later, it had faded to an insignificant object below 17th magnitude. By comparison, the entire galaxy is of magnitude 11: at the time of its maximum, the supernova was thus only three times fainter than the whole galaxy. It must have been a splendid firework indeed! By digging into the vast Science Archive of the ESO Very Large Telescope, it was possible to find an image of NGC 7424 taken on June 16, 2002 by Massimo Turatto (Observatorio di Padova-INAF, Italy) with the FORS 2 instrument on Yepun (UT4). Although, the supernova was already much fainter than at its maximum 6 months earlier, it is still very well visible on this image (see PR Photo 33d/04). Spectra taken with ESO's 3.6-m telescope at La Silla over the months following the explosion showed the object to evolve to a Type Ib/c supernova. By October 2002, the transition to a Type Ib/c supernova was complete. It is now believed that this supernova arose from the explosion of a very massive star, a so-called Wolf-Rayet star, which together with a massive hot companion belonged to a very close binary system in which the two stars orbited each other once every 100 days or so (read the details in the paper by Ryder et al. here ). Future detailed observations may reveal the presence of the companion star that survived this explosion but which is now doomed to explode as another supernova in due time.

Discovery of the Most Distant Supernovae and the Quest for {Omega}

DOE R&D Accomplishments Database

Goldhaber, G.; Perlmutter, S.; Gabi, S.; Goobar, A.; Kim, A.; Kim, M.; Pain, R.; Pennypacker, C.; Small, I.; Boyle, B.

1994-05-01

A search for cosmological supernovae has discovered a number of a type Ia supernovae. In particular, one at z = 0.458 is the most distant supernovae yet observed. There is strong evidence from measurements of nearby type Ia supernovae that they can be considered as "standard candles". The authors plan to use these supernovae to measure the deceleration in the general expansion of the universe. The aim of their experiment is to try and observe and measure about 30 such distant supernovae in order to obtain a measurement of the deceleration parameter q{sub o} which is related to {Omega}. Here {Omega} is the ratio of the density of the universe to the critical density, and they expect a measurement with an accuracy of about 30%.

Coherent propagation of PeV neutrinos and the dip in the neutrino spectrum at IceCube

NASA Astrophysics Data System (ADS)

Kamada, Ayuki; Yu, Hai-Bo

2015-12-01

The energy spectrum of high-energy neutrinos reported by the IceCube Collaboration shows a dip between 400 TeV and 1 PeV. One intriguing explanation is that high-energy neutrinos scatter with the cosmic neutrino background through an ˜MeV mediator. Taking the density matrix approach, we develop a formalism to study the propagation of PeV neutrinos in the presence of the new neutrino interaction. If the interaction is flavored such as the gauged Lμ-Lτ model we consider, the resonant collision may not suppress the PeV neutrino flux completely. The new force mediator may also contribute to the number of effectively massless degrees of freedom in the early Universe and change the diffusion time of neutrinos from the supernova core. Astrophysical observations such as big bang nucleosynthesis and supernova cooling provide an interesting test for the explanation.

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.

The Search for Lensed Supernovae

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-01-01

Type Ia supernovae that have multiple images due to gravitational lensing can provide us with a wealth of information both about the supernovae themselves and about our surrounding universe. But how can we find these rare explosions?Clues from Multiple ImagesWhen light from a distant object passes by a massive foreground galaxy, the galaxys strong gravitational pull can bend the light, distorting our view of the backgroundobject. In severe cases, this process can cause multiple images of the distant object to appear in the foreground lensing galaxy.An illustration of gravitational lensing. Light from the distant supernova is bent as it passes through a giant elliptical galaxy in the foreground, causing multiple images of the supernova to appear to be hosted by the elliptical galaxy. [Adapted from image by NASA/ESA/A. Feild (STScI)]Observations of multiply-imaged Type Ia supernovae (explosions that occur when white dwarfs in binary systems exceed their maximum allowed mass) could answer a number of astronomical questions. Because Type Ia supernovae are standard candles, distant, lensed Type Ia supernovae can be used to extend the Hubble diagram to high redshifts. Furthermore, the lensing time delays from the multiply-imaged explosion can provide high-precision constraints on cosmological parameters.The catch? So far, weve only found one multiply-imaged Type Ia supernova: iPTF16geu, discovered late last year. Were going to need a lot more of them to develop a useful sample! So how do we identify themutiply-imaged Type Ias among the many billions of fleeting events discovered in current and future surveys of transients?Searching for AnomaliesAbsolute magnitudes for Type Ia supernovae in elliptical galaxies. None are expected to be above -20 in the B band, so if we calculate a magnitude for a Type Ia supernova thats larger than this, its probably not hosted by the galaxy we think it is! [Goldstein Nugent 2017]Two scientists from University of California, Berkeley and Lawrence Berkeley National Laboratory have a plan. In a recent publication, Daniel Goldstein and Peter Nugent propose the following clever procedure to apply to data from transient surveys:From the data, select only the supernova candidates that appear to be hosted by quiescent elliptical galaxies.Use the host galaxies photometric redshifts to calculate absolute magnitudes for the supernovae in this sample.Select from this only the supernovae above the maximum absolute magnitude expected for Type Ia supernovae.Supernovae selected in this way are likely tricking us: their apparent hosts are probably not their hosts at all! Instead, the supernova is likely behind the galaxy, and the galaxy is just lensing its light. Using this strategy therefore allows us to select supernova candidates that are most likely to be distant, gravitationally lensed Type Ia supernovae.Redshift distribution of the multiply-imaged Type Ia supernovae the authors estimate will be detectable by ZTF and LSST in their respective 3- and 10-year survey durations. [Goldstein Nugent 2017]A convenient aspect of Goldstein and Nugents technique is that we dont need to be able to resolve the lensed multiple images for discovery. This is useful, because ground-based optical surveys dont have the resolution to see the separate images yet theyll still be useful for discovering multiply-imaged supernovae.Future ProspectsHow useful? Goldstein and Nugent use Monte Carlo simulations to estimate how many multiply-imaged Type Ia supernovae will be discoverable with future survey projects. They find that theZwicky Transient Facility (ZTF), which will begin operating this year, should be able to find up to 10 using this technique in a 3-year search. The Large Synoptic Survey Telescope (LSST), which should start operating in 2022, will be able to find around 500 multiply-imaged Type Ia supernovae in a 10-year survey.CitationDaniel A. Goldstein and Peter E. Nugent 2017 ApJL 834 L5. doi:10.3847/2041-8213/834/1/L5

Imagery and spectroscopy of supernova remnants and H-2 regions

NASA Technical Reports Server (NTRS)

Dufour, R. J.

1984-01-01

Research activities relating to supernova remnants were summarized. The topics reviewed include: progenitor stars of supernova remnants, UV/optical/radio/X-ray imagery of selected regions in the Cygnus Loop, UV/optical spectroscopy of the Cygnus Loop spur, and extragalactic supernova remnant spectra.

Anisotropic emission of neutrino and gravitational-wave signals from rapidly rotating core-collapse supernovae

NASA Astrophysics Data System (ADS)

Takiwaki, Tomoya; Kotake, Kei

2018-03-01

We present analysis on neutrino and GW signals based on three-dimensional (3D) core-collapse supernova simulations of a rapidly rotating 27 M⊙ star. We find a new neutrino signature that is produced by a lighthouse effect where the spinning of strong neutrino emission regions around the rotational axis leads to quasi-periodic modulation in the neutrino signal. Depending on the observer's viewing angle, the time modulation will be clearly detectable in IceCube and the future Hyper-Kamiokande. The GW emission is also anisotropic where the GW signal is emitted, as previously identified, most strongly towards the equator at rotating core-collapse and bounce, and the non-axisymmetric instabilities in the postbounce phase lead to stronger GW emission towards the spin axis. We show that these GW signals can be a target of LIGO-class detectors for a Galactic event. The origin of the postbounce GW emission naturally explains why the peak GW frequency is about twice of the neutrino modulation frequency. We point out that the simultaneous detection of the rotation-induced neutrino and GW signatures could provide a smoking-gun signature of a rapidly rotating proto-neutron star at the birth.

Neutrino Astrophysics in Slowly Rotating Spacetimes Permeated by Nonlinear Electrodynamics Fields

NASA Astrophysics Data System (ADS)

Mosquera Cuesta, Herman J.

2017-02-01

Many theoretical and astrophysical arguments involve consideration of the effects of super strong electromagnetic fields and the rotation during the late stages of core-collapse supernovae. In what follows, we solve Einstein field equations that are minimally coupled to an arbitrary (current-free) Born-Infeld nonlinear Lagrangian L(F,G) of electrodynamics (NLED) in the slow rotation regime a ≪ r+ (outer horizon size), up to first order in a/r. We cross-check the physical properties of such NLED spacetime w.r.t. against the Maxwell one. A study case on both neutrino flavor ({ν }e\\to {ν }μ ,{ν }τ ) oscillations and flavor+helicity (spin) flip ({ν }e\\to {\\overline{ν }}μ ,τ ) gyroscopic precession proves that in the spacetime of a slowly rotating nonlinear charged black hole (RNCBH), the neutrino dynamics translates into a positive enhancement of the r-process (reduction of the electron fraction Ye < 0.5). Consequently, it guarantees successful hyperluminous core-collapse supernova explosions due to the enlargement of the number and amount of decaying nuclide species. This posits that, as far as the whole luminosity is concerned, hypernovae will be a proof of the formation of astrophysical RNCBH.

THE ABSOLUTE RATE OF LGRB FORMATION

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

Graham, J. F.; Schady, P.

2016-06-01

We estimate the long-duration gamma-ray burst (LGRB) progenitor rate using our recent work on the effects of environmental metallically on LGRB formation in concert with supernovae (SNe) statistics via an approach patterned loosely off the Drake equation. Beginning with the cosmic star formation history, we consider the expected number of broad-line Type Ic events (the SNe type associated with LGRBs) that are in low-metallicity host environments adjusted by the contribution of high-metallicity host environments at a much reduced rate. We then compare this estimate to the observed LGRB rate corrected for instrumental selection effects to provide a combined estimate ofmore » the efficiency fraction of these progenitors to produce LGRBs and the fraction of which are beamed in our direction. From this we estimate that an aligned LGRB occurs for approximately every 4000 ± 2000 low-metallically broad-lined SNe Ic. Therefore, if one assumes a semi-nominal beaming factor of 100, then only about one such supernova out of 40 produce an LGRB. Finally, we propose an off-axis LGRB search strategy of targeting only broad-line Type Ic events that occur in low-metallicity hosts for radio observation.« less

The Absolute Rate of LGRB Formation

NASA Astrophysics Data System (ADS)

Graham, J. F.; Schady, P.

2016-06-01

We estimate the long-duration gamma-ray burst (LGRB) progenitor rate using our recent work on the effects of environmental metallically on LGRB formation in concert with supernovae (SNe) statistics via an approach patterned loosely off the Drake equation. Beginning with the cosmic star formation history, we consider the expected number of broad-line Type Ic events (the SNe type associated with LGRBs) that are in low-metallicity host environments adjusted by the contribution of high-metallicity host environments at a much reduced rate. We then compare this estimate to the observed LGRB rate corrected for instrumental selection effects to provide a combined estimate of the efficiency fraction of these progenitors to produce LGRBs and the fraction of which are beamed in our direction. From this we estimate that an aligned LGRB occurs for approximately every 4000 ± 2000 low-metallically broad-lined SNe Ic. Therefore, if one assumes a semi-nominal beaming factor of 100, then only about one such supernova out of 40 produce an LGRB. Finally, we propose an off-axis LGRB search strategy of targeting only broad-line Type Ic events that occur in low-metallicity hosts for radio observation.

The Rate of Core Collapse Supernovae to Redshift 2.5 from the CANDELS and CLASH Supernova Surveys

NASA Astrophysics Data System (ADS)

Strolger, Louis-Gregory; Dahlen, Tomas; Rodney, Steven A.; Graur, Or; Riess, Adam G.; McCully, Curtis; Ravindranath, Swara; Mobasher, Bahram; Shahady, A. Kristin

2015-11-01

The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and Cluster Lensing And Supernova survey with Hubble multi-cycle treasury programs with the Hubble Space Telescope (HST) have provided new opportunities to probe the rate of core-collapse supernovae (CCSNe) at high redshift, now extending to z≈ 2.5. Here we use a sample of approximately 44 CCSNe to determine volumetric rates, RCC, in six redshift bins in the range 0.1\\lt z\\lt 2.5. Together with rates from our previous HST program, and rates from the literature, we trace a more complete history of {R}{CC}(z), with {R}{CC}=0.72+/- 0.06 yr-1 Mpc-3 10-4{h}703 at z\\lt 0.08, and increasing to {3.7}-1.6+3.1 yr-1 Mpc-3 10-4{h}703 to z≈ 2.0. The statistical precision in each bin is several factors better than than the systematic error, with significant contributions from host extinction, and average peak absolute magnitudes of the assumed luminosity functions for CCSN types. Assuming negligible time delays from stellar formation to explosion, we find these composite CCSN rates to be in excellent agreement with cosmic star formation rate density (SFRs) derived largely from dust-corrected rest-frame UV emission, with a scaling factor of k=0.0091+/- 0.0017 {M}⊙ -1, and inconsistent (to \\gt 95% confidence) with SFRs from IR luminous galaxies, or with SFR models that include simple evolution in the initial mass function over time. This scaling factor is expected if the fraction of the IMF contributing to CCSN progenitors is in the 8-50 M⊙ range. It is not supportive, however, of an upper mass limit for progenitors at \\lt 20 {M}⊙ .

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 faint type of supernova from a white dwarf with a helium-rich companion.

PubMed

Perets, H B; Gal-Yam, A; Mazzali, P A; Arnett, D; Kagan, D; Filippenko, A V; Li, W; Arcavi, I; Cenko, S B; Fox, D B; Leonard, D C; Moon, D-S; Sand, D J; Soderberg, A M; Anderson, J P; James, P A; Foley, R J; Ganeshalingam, M; Ofek, E O; Bildsten, L; Nelemans, G; Shen, K J; Weinberg, N N; Metzger, B D; Piro, A L; Quataert, E; Kiewe, M; Poznanski, D

2010-05-20

Supernovae are thought to arise from two different physical processes. The cores of massive, short-lived stars undergo gravitational core collapse and typically eject a few solar masses during their explosion. These are thought to appear as type Ib/c and type II supernovae, and are associated with young stellar populations. In contrast, the thermonuclear detonation of a carbon-oxygen white dwarf, whose mass approaches the Chandrasekhar limit, is thought to produce type Ia supernovae. Such supernovae are observed in both young and old stellar environments. Here we report a faint type Ib supernova, SN 2005E, in the halo of the nearby isolated galaxy, NGC 1032. The 'old' environment near the supernova location, and the very low derived ejected mass ( approximately 0.3 solar masses), argue strongly against a core-collapse origin. Spectroscopic observations and analysis reveal high ejecta velocities, dominated by helium-burning products, probably excluding this as a subluminous or a regular type Ia supernova. We conclude that it arises from a low-mass, old progenitor, likely to have been a helium-accreting white dwarf in a binary. The ejecta contain more calcium than observed in other types of supernovae and probably large amounts of radioactive (44)Ti.

Study of the influence of Type Ia supernovae environment on the Hubble diagram

NASA Astrophysics Data System (ADS)

Henne, Vincent

2016-06-01

The observational cosmology with distant Type Ia supernovae as standard candles claims that the Universe is in accelerated expansion, caused by a large fraction of dark energy. In this report we investigated SNe Ia environment, studying the impact of the nature of their host galaxies and their distance to the host galactic center on the Hubble diagram fitting. The supernovae used in the analysis were extracted from Joint-Light-curves-Analysis compilation of high-redshift and nearby supernovae. The analysis are based on the empirical fact that SN Ia luminosities depend on their light curve shapes and colors. No conclusive correlation between SN Ia light curve parameters and galocentric distance were identified. Concerning the host morphology, we showed that the stretch parameter of Type Ia supernovae is correlated with the host galaxy type. The supernovae with lower stretch mainly exploded in elliptical and lenticular galaxies. The studies show that into old star population and low dust environment, supernovae are fainter. We did not find any significant correlation between Type Ia supernovae color and host morphology. We confirm that supernova properties depend on their environment and propose to incorporate a host galaxy term into the Hubble diagram fit in the future cosmological analysis.

Low-z Type Ia Supernova Calibration

NASA Astrophysics Data System (ADS)

Hamuy, Mario

The discovery of acceleration and dark energy in 1998 arguably constitutes one of the most revolutionary discoveries in astrophysics in recent years. This paradigm shift was possible thanks to one of the most traditional cosmological tests: the redshift-distance relation between galaxies. This discovery was based on a differential measurement of the expansion rate of the universe: the current one provided by nearby (low-z) type Ia supernovae and the one in the past measured from distant (high-z) supernovae. This paper focuses on the first part of this journey: the calibration of the type Ia supernova luminosities and the local expansion rate of the universe, which was made possible thanks to the introduction of digital CCD (charge-coupled device) digital photometry. The new technology permitted us in the early 1990s to convert supernovae as precise tools to measure extragalactic distances through two key surveys: (1) the "Tololo Supernova Program" which made possible the critical discovery of the "peak luminosity-decline rate" relation for type Ia supernovae, the key underlying idea today behind precise cosmology from supernovae, and (2) the Calán/Tololo project which provided the low - z type Ia supernova sample for the discovery of acceleration.

Multi-azimuthal-angle instability for different supernova neutrino fluxes

NASA Astrophysics Data System (ADS)

Chakraborty, Sovan; Mirizzi, Alessandro

2014-08-01

It has been recently discovered that removing the axial symmetry in the "multiangle effects" associated with the neutrino-neutrino interactions for supernova (SN) neutrinos, a new multi-azimuthal-angle (MAA) instability will trigger flavor conversions in addition to the ones caused by the bimodal and multi-zenith-angle (MZA) instabilities. We investigate the dependence of the MAA instability on the original SN neutrino fluxes, performing a stability analysis of the linearized neutrino equations of motion. We compare these results with the numerical evolution of the SN neutrino nonlinear equations, looking at a local solution along a specific line of sight, under the assumption that the transverse variations of the global solution are small. We also assume that self-induced conversions are not suppressed by large matter effects. We show that the pattern of the spectral crossings (energies where Fνe=Fνx and Fν¯e=Fν¯x) is crucial in determining the impact of MAA effects on the flavor evolution. For neutrino spectra with a strong excess of νe over ν¯e, presenting only a single crossing, MAA instabilities will trigger new flavor conversions in normal mass hierarchy. In our simplified flavor evolution scheme, these will lead to spectral swaps and splits analogous to what is produced in inverted hierarchy by the bimodal instability. Conversely, in the presence of spectra with a moderate flavor hierarchy, having multiple crossing energies, MZA effects will produce a sizable delay in the onset of the flavor conversions, inhibiting the growth of the MAA instability. In this case, the splitting features for the oscillated spectra in both the mass hierarchies are the ones induced by the only bimodal and MZA effects.

Bianchi Type-I Anisotropic Dark Energy Model with Constant Deceleration Parameter

NASA Astrophysics Data System (ADS)

Pradhan, Anirudh; Amirhashchi, H.; Saha, Bijan

2011-09-01

A new dark energy model in anisotropic Bianchi type-I (B-I) space-time with time dependent equation of state (EoS) parameter and constant deceleration parameter has been investigated in the present paper. The Einstein's field equations have been solved by applying a variation law for generalized Hubble's parameter (Berman in Il Nuovo Cimento B 74:182, 1983) which generates two types of solutions, one is of power-law type and other is of the exponential form. The existing range of the dark energy EoS parameter ω for derived model is found to be in good agreement with the three recent observations (i) SNe Ia data (Knop et al. in Astrophys. J. 598:102, 2003), (ii) SNe Ia data collaborated with CMBR anisotropy and galaxy clustering statistics (Tegmark et al. in Astrophys. J. 606:702, 2004) and (iii) a combination of cosmological datasets coming from CMB anisotropies, luminosity distances of high redshift type Ia supernovae and galaxy clustering (Hinshaw et al. in Astrophys. J. Suppl. Ser. 180:225, 2009 and Komatsu et al. in Astrophys. J. Suppl. Ser. 180:330, 2009). The cosmological constant Λ is found to be a decreasing function of time and it approaches a small positive value at the present epoch which is corroborated by results from recent supernovae Ia observations. It has also been suggested that the dark energy that explains the observed accelerating universe may arise due to the contribution to the vacuum energy of the EoS in a time dependent background. Geometric and kinematic properties of the model and the behaviour of the anisotropy of the dark energy have been carried out.

supernovae: Photometric classification of supernovae

NASA Astrophysics Data System (ADS)

Charnock, Tom; Moss, Adam

2017-05-01

Supernovae classifies supernovae using their light curves directly as inputs to a deep recurrent neural network, which learns information from the sequence of observations. Observational time and filter fluxes are used as inputs; since the inputs are agnostic, additional data such as host galaxy information can also be included.

Gravitational lensing statistics of amplified supernovae

NASA Technical Reports Server (NTRS)

Linder, Eric V.; Wagoner, Robert V.; Schneider, P.

1988-01-01

Amplification statistics of gravitationally lensed supernovae can provide a valuable probe of the lensing matter in the universe. A general probability distribution for amplification by compact objects is derived which allows calculation of the lensed fraction of supernovae at or greater than an amplification A and at or less than an apparent magnitude. Comparison of the computed fractions with future results from ongoing supernova searches can lead to determination of the mass density of compact dark matter components with masses greater than about 0.001 solar mass, while the time-dependent amplification (and polarization) of the expanding supernovae constrain the individual masses. Type II supernovae are found to give the largest fraction for deep surveys, and the optimum flux-limited search is found to be at approximately 23d magnitude, if evolution of the supernova rate is neglected.

Supernovae neutrino pasta interaction

NASA Astrophysics Data System (ADS)

Lin, Zidu; Horowitz, Charles; Caplan, Matthew; Berry, Donald; Roberts, Luke

2017-01-01

In core-collapse supernovae, the neutron rich matter is believed to have complex structures, such as spherical, slablike, and rodlike shapes. They are collectively called ``nuclear pasta''. Supernovae neutrinos may scatter coherently on the ``nuclear pasta'' since the wavelength of the supernovae neutrinos are comparable to the nuclear pasta scale. Consequently, the neutrino pasta scattering is important to understand the neutrino opacity in the supernovae. In this work we simulated the ``nuclear pasta'' at different temperatures and densities using our semi-classical molecular dynamics and calculated the corresponding static structure factor that describes ν-pasta scattering. We found the neutrino opacities are greatly modified when the ``pasta'' exist and may have influence on the supernovae neutrino flux and average energy. Our neutrino-pasta scattering effect can finally be involved in the current supernovae simulations and we present preliminary proto neutron star cooling simulations including our pasta opacities.

Probing Late-Stage Stellar Evolution through Robotic Follow-Up of Nearby Supernovae

NASA Astrophysics Data System (ADS)

Hosseinzadeh, Griffin

2018-01-01

Many of the remaining uncertainties in stellar evolution can be addressed through immediate and long-term photometry and spectroscopy of supernovae. The early light curves of thermonuclear supernovae can contain information about the nature of the binary companion to the exploding white dwarf. Spectra of core-collapse supernovae can reveal material lost by massive stars in their final months to years. Thanks to a revolution in technology—robotic telescopes, high-speed internet, machine learning—we can now routinely discover supernovae within days of explosion and obtain well-sampled follow-up data for months and years. Here I present three major results from the Global Supernova Project at Las Cumbres Observatory that take advantage of these technological advances. (1) SN 2017cbv is a Type Ia supernova discovered within a day of explosion. Early photometry shows a bump in the U-band relative to previously observed Type Ia light curves, possibly indicating the presence of a nondegenerate binary companion. (2) SN 2016bkv is a low-luminosity Type IIP supernova also caught very young. Narrow emission lines in the earliest spectra indicate interaction between the ejecta and a dense shell of circumstellar material, previously observed only in the brightest Type IIP supernovae. (3) Type Ibn supernovae are a rare class that interact with hydrogen-free circumstellar material. An analysis of the largest-yet sample of this class has found that their light curves are much more homogeneous and faster-evolving than their hydrogen-rich counterparts, Type IIn supernovae, but that their maximum-light spectra are more diverse.

The effect of background galaxy contamination on the absolute magnitude and light curve speed class of type Ia supernovae

NASA Technical Reports Server (NTRS)

Boisseau, John R.; Wheeler, J. Craig

1991-01-01

Observational data are presented in support of the hypothesis that background galaxy contamination is present in the photometric data of Ia supernovae and that this effect can account for the observed dispersion in the light curve speeds of most of Ia supernovae. The implication is that the observed dispersion in beta is artificial and that most of Ia supernovae have nearly homogeneous light curves. The result supports the notion that Ia supernovae are good standard candles.

Search for core-collapse supernovae using the MiniBooNE neutrino detector

NASA Astrophysics Data System (ADS)

Aguilar-Arevalo, A. A.; Anderson, C. E.; Bazarko, A. O.; Brice, S. J.; Brown, B. C.; Bugel, L.; Cao, J.; Coney, L.; Conrad, J. M.; Cox, D. C.; Curioni, A.; Djurcic, Z.; Finley, D. A.; Fisher, M.; Fleming, B. T.; Ford, R.; Garcia, F. G.; Garvey, G. T.; Grange, J.; Green, C.; Green, J. A.; Hart, T. L.; Hawker, E.; Imlay, R.; Johnson, R. A.; Karagiorgi, G.; Kasper, P.; Katori, T.; Kobilarcik, T.; Kourbanis, I.; Koutsoliotas, S.; Laird, E. M.; Linden, S. K.; Link, J. M.; Liu, Y.; Liu, Y.; Louis, W. C.; Mahn, K. B. M.; Marsh, W.; Mauger, C.; McGary, V. T.; McGregor, G.; Metcalf, W.; Meyers, P. D.; Mills, F.; Mills, G. B.; Monroe, J.; Moore, C. D.; Mousseau, J.; Nelson, R. H.; Nienaber, P.; Nowak, J. A.; Osmanov, B.; Ouedraogo, S.; Patterson, R. B.; Pavlovic, Z.; Perevalov, D.; Polly, C. C.; Prebys, E.; Raaf, J. L.; Ray, H.; Roe, B. P.; Russell, A. D.; Sandberg, V.; Schirato, R.; Schmitz, D.; Shaevitz, M. H.; Shoemaker, F. C.; Smith, D.; Soderberg, M.; Sorel, M.; Spentzouris, P.; Spitz, J.; Stancu, I.; Stefanski, R. J.; Sung, M.; Tanaka, H. A.; Tayloe, R.; Tzanov, M.; van de Water, R. G.; Wascko, M. O.; White, D. H.; Wilking, M. J.; Yang, H. J.; Zeller, G. P.; Zimmerman, E. D.; MiniBooNE Collaboration

2010-02-01

We present a search for core-collapse supernovae in the Milky Way galaxy, using the MiniBooNE neutrino detector. No evidence is found for core-collapse supernovae occurring in our Galaxy in the period from December 14, 2004 to July 31, 2008, corresponding to 98% live time for collection. We set a limit on the core-collapse supernova rate out to a distance of 13.4 kpc to be less than 0.69 supernovae per year at 90% C.L.

Detecting the supernova breakout burst in terrestrial neutrino detectors

DOE PAGES

Wallace, Joshua; Burrows, Adam; Dolence, Joshua C.

2016-02-01

Here, we calculate the distance-dependent performance of a few representative terrestrial neutrino detectors in detecting and measuring the properties of the ν e breakout burst light curve in a Galactic core-collapse supernova. The breakout burst is a signature phenomenon of core collapse and offers a probe into the stellar core through collapse and bounce. We also examine cases of no neutrino oscillations and oscillations due to normal and inverted neutrino-mass hierarchies. For the normal hierarchy, other neutrino flavors emitted by the supernova overwhelm the νe signal, making a detection of the breakout burst difficult. Furthermore, for the inverted hierarchy (IH),more » some detectors at some distances should be able to see the ν e breakout burst peak and measure its properties. For the IH, the maximum luminosity of the breakout burst can be measured at 10 kpc to accuracies of ~30% for Hyper-Kamiokande (Hyper-K) and ~60% for the Deep Underground Neutrino Experiment (DUNE). Super-Kamiokande (Super-K) and Jiangmen Underground Neutrino Observatory (JUNO) lack the mass needed to make an accurate measurement. For the IH, the time of the maximum luminosity of the breakout burst can be measured in Hyper-K to an accuracy of ~3 ms at 7 kpc, in DUNE to ~2 ms at 4 kpc, and JUNO and Super-K can measure the time of maximum luminosity to an accuracy of ~2 ms at 1 kpc. Detector backgrounds in IceCube render a measurement of the νe breakout burst unlikely. For the IH, a measurement of the maximum luminosity of the breakout burst could be used to differentiate between nuclear equations of state.« less

Core-collapse supernovae as supercomputing science: A status report toward six-dimensional simulations with exact Boltzmann neutrino transport in full general relativity

NASA Astrophysics Data System (ADS)

Kotake, Kei; Sumiyoshi, Kohsuke; Yamada, Shoichi; Takiwaki, Tomoya; Kuroda, Takami; Suwa, Yudai; Nagakura, Hiroki

2012-08-01

This is a status report on our endeavor to reveal the mechanism of core-collapse supernovae (CCSNe) by large-scale numerical simulations. Multi-dimensionality of the supernova engine, general relativistic magnetohydrodynamics, energy and lepton number transport by neutrinos emitted from the forming neutron star, as well as nuclear interactions there, are all believed to play crucial roles in repelling infalling matter and producing energetic explosions. These ingredients are non-linearly coupled with one another in the dynamics of core collapse, bounce, and shock expansion. Serious quantitative studies of CCSNe hence make extensive numerical computations mandatory. Since neutrinos are neither in thermal nor in chemical equilibrium in general, their distributions in the phase space should be computed. This is a six-dimensional (6D) neutrino transport problem and quite a challenge, even for those with access to the most advanced numerical resources such as the "K computer". To tackle this problem, we have embarked on efforts on multiple fronts. In particular, we report in this paper our recent progresses in the treatment of multidimensional (multi-D) radiation hydrodynamics. We are currently proceeding on two different paths to the ultimate goal. In one approach, we employ an approximate but highly efficient scheme for neutrino transport and treat 3D hydrodynamics and/or general relativity rigorously; some neutrino-driven explosions will be presented and quantitative comparisons will be made between 2D and 3D models. In the second approach, on the other hand, exact, but so far Newtonian, Boltzmann equations are solved in two and three spatial dimensions; we will show some example test simulations. We will also address the perspectives of exascale computations on the next generation supercomputers.

Measuring the Properties of Dark Energy with Photometrically Classified Pan-STARRS Supernovae. I. Systematic Uncertainty from Core-collapse Supernova Contamination

NASA Astrophysics Data System (ADS)

Jones, D. O.; Scolnic, D. M.; Riess, A. G.; Kessler, R.; Rest, A.; Kirshner, R. P.; Berger, E.; Ortega, C. A.; Foley, R. J.; Chornock, R.; Challis, P. J.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Huber, M. E.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

2017-07-01

The Pan-STARRS (PS1) Medium Deep Survey discovered over 5000 likely supernovae (SNe) but obtained spectral classifications for just 10% of its SN candidates. We measured spectroscopic host galaxy redshifts for 3147 of these likely SNe and estimate that ˜1000 are Type Ia SNe (SNe Ia) with light-curve quality sufficient for a cosmological analysis. We use these data with simulations to determine the impact of core-collapse SN (CC SN) contamination on measurements of the dark energy equation of state parameter, w. Using the method of Bayesian Estimation Applied to Multiple Species (BEAMS), distances to SNe Ia and the contaminating CC SN distribution are simultaneously determined. We test light-curve-based SN classification priors for BEAMS as well as a new classification method that relies upon host galaxy spectra and the association of SN type with host type. By testing several SN classification methods and CC SN parameterizations on large SN simulations, we estimate that CC SN contamination gives a systematic error on w ({σ }w{CC}) of 0.014, 29% of the statistical uncertainty. Our best method gives {σ }w{CC}=0.004, just 8% of the statistical uncertainty, but could be affected by incomplete knowledge of the CC SN distribution. This method determines the SALT2 color and shape coefficients, α and β, with ˜3% bias. However, we find that some variants require α and β to be fixed to known values for BEAMS to yield accurate measurements of w. Finally, the inferred abundance of bright CC SNe in our sample is greater than expected based on measured CC SN rates and luminosity functions.

A hydrodynamical model of the circumstellar bubble created by two massive stars

NASA Astrophysics Data System (ADS)

van Marle, A. J.; Meliani, Z.; Marcowith, A.

2012-05-01

Context. Numerical models of the wind-blown bubble of massive stars usually only account for the wind of a single star. However, since massive stars are usually formed in clusters, it would be more realistic to follow the evolution of a bubble created by several stars. Aims: We develop a two-dimensional (2D) model of the circumstellar bubble created by two massive stars, a 40 M⊙ star and a 25 M⊙ star, and follow its evolution. The stars are separated by approximately 16 pc and surrounded by a cold medium with a density of 20 particles per cm3. Methods: We use the MPI-AMRVAC hydrodynamics code to solve the conservation equations of hydrodynamics on a 2D cylindrical grid using time-dependent models for the wind parameters of the two stars. At the end of the stellar evolution (4.5 and 7.0 million years for the 40 and 25 M⊙ stars, respectively), we simulate the supernova explosion of each star. Results: Each star initially creates its own bubble. However, as the bubbles expand they merge, creating a combined, aspherical bubble. The combined bubble evolves over time, influenced by the stellar winds and supernova explosions. Conclusions: The evolution of a wind-blown bubble created by two stars deviates from that of the bubbles around single stars. In particular, once one of the stars has exploded, the bubble is too large for the wind of the remaining star to maintain and the outer shell starts to disintegrate. The lack of thermal pressure inside the bubble also changes the behavior of circumstellar features close to the remaining star. The supernovae are contained inside the bubble, which reflects part of the energy back into the circumstellar medium. Movies are available in electronic form at http://www.aanda.org

Supernova-regulated ISM. V. Space and Time Correlations

NASA Astrophysics Data System (ADS)

Hollins, J. F.; Sarson, G. R.; Shukurov, A.; Fletcher, A.; Gent, F. A.

2017-11-01

We apply correlation analysis to random fields in numerical simulations of the supernova-driven interstellar medium (ISM) with the magnetic field produced by dynamo action. We solve the magnetohydrodynamic (MHD) equations in a shearing Cartesian box representing a local region of the ISM, subject to thermal and kinetic energy injection by supernova explosions, and parameterized, optically thin radiative cooling. We consider the cold, warm, and hot phases of the ISM separately; the analysis mostly considers the warm gas, which occupies the bulk of the domain. Various physical variables have different correlation lengths in the warm phase: 40,50, and 60 {pc} for the random magnetic field, density, and velocity, respectively, in the midplane. The correlation time of the random velocity is comparable to the eddy turnover time, about {10}7 {year}, although it may be shorter in regions with a higher star formation rate. The random magnetic field is anisotropic, with the standard deviations of its components {b}x/{b}y/{b}z having approximate ratios 0.5/0.6/0.6 in the midplane. The anisotropy is attributed to the global velocity shear from galactic differential rotation and locally inhomogeneous outflow to the galactic halo. The correlation length of Faraday depth along the z axis, 120 {pc}, is greater than for electron density, 60{--}90 {pc}, and the vertical magnetic field, 60 {pc}. Such comparisons may be sensitive to the orientation of the line of sight. Uncertainties of the structure functions of synchrotron intensity rapidly increase with the scale. This feature is hidden in a power spectrum analysis, which can undermine the usefulness of power spectra for detailed studies of interstellar turbulence.

TWO-DIMENSIONAL CORE-COLLAPSE SUPERNOVA SIMULATIONS WITH THE ISOTROPIC DIFFUSION SOURCE APPROXIMATION FOR NEUTRINO TRANSPORT

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

Pan, Kuo-Chuan; Liebendörfer, Matthias; Hempel, Matthias

2016-01-20

The neutrino mechanism of core-collapse supernova is investigated via non-relativistic, two-dimensional (2D), neutrino radiation–hydrodynamic simulations. For the transport of electron flavor neutrinos, we use the interaction rates defined by Bruenn and the isotropic diffusion source approximation (IDSA) scheme, which decomposes the transported particles into trapped-particle and streaming-particle components. Heavy neutrinos are described by a leakage scheme. Unlike the “ray-by-ray” approach in some other multidimensional supernova models, we use cylindrical coordinates and solve the trapped-particle component in multiple dimensions, improving the proto-neutron star resolution and the neutrino transport in angular and temporal directions. We provide an IDSA verification by performing one-dimensionalmore » (1D) and 2D simulations with 15 and 20 M{sub ⊙} progenitors from Woosley et al. and discuss the difference between our IDSA results and those existing in the literature. Additionally, we perform Newtonian 1D and 2D simulations from prebounce core collapse to several hundred milliseconds postbounce with 11, 15, 21, and 27 M{sub ⊙} progenitors from Woosley et al. with the HS(DD2) equation of state. General-relativistic effects are neglected. We obtain robust explosions with diagnostic energies E{sub dia} ≳ 0.1–0.5 B (1 B ≡ 10{sup 51} erg) for all considered 2D models within approximately 100–300 ms after bounce and find that explosions are mostly dominated by the neutrino-driven convection, although standing accretion shock instabilities are observed as well. We also find that the level of electron deleptonization during collapse dramatically affects the postbounce evolution, e.g., the neglect of neutrino–electron scattering during collapse will lead to a stronger explosion.« less

Supernovae - A new selection effect. [statistical distribution in and radial distance from center of parent galaxy

NASA Technical Reports Server (NTRS)

Shaw, R. L.

1979-01-01

A sample of 228 supernovae that occurred in galaxies with known redshifts is used to show that the mean projected linear supernova distance from the center of the parent galaxy increases with increasing redshift. This effect is interpreted as an observational bias: the discovery rate of supernovae is reduced in the inner parts of distant, poorly resolved galaxies. Even under the optimistic assumption that no selection effects work in galaxies closer than 33 Mpc, about 50% of all supernovae are lost in the inner regions of galaxies beyond 150 Mpc. This observational bias must be taken into account in the derivation of statistical properties of supernovae.

Towards Limits on Neutrino Mixing Parameters from Nucleosynthesis in the Big Bang and Supernovae

NASA Astrophysics Data System (ADS)

Cardall, Christian Young

1997-11-01

Astrophysical environments can often provide stricter limits on neutrino mass and mixing parameters than terrestrial experiments. However, before firm limits can be found, there must be confidence in the understanding of the astrophysical environment being used to make these limits. In this dissertation, progress towards limits on neutrino mixing parameters from big bang nucleosynthesis and supernova r-process nucleosynthesis is sought. By way of assessment of current knowledge of neutrino oscillation parameters, we examine the potential for a 'natural' three-neutrino mixing scheme (one without sterile neutrinos) to satisfy available data and astrophysical arguments. A small parameter space currently exists for a natural three-neutrino oscillation solution meeting known constraints. If such a solution is ruled out, and current hints about neutrino oscillations are confirmed, mixing between active and sterile neutrinos will probably be required. Because mixing between active and sterile neutrinos with parameters appropriate for the atmospheric or solar neutrino problems increases the primordial 4He abundance, big bang nucleosynthesis considerations can place limits on such mixing. In the present work the overall consistency of standard big bang nucleosynthesis is discussed in light of recent discordant determinations of the primordial deuterium abundance. Cosmological considerations favor a larger baryon density, which supports the lower reported value of D/H. Studies of limits on active-sterile neutrino mixing derived from big bang nucleosynthesis considerations are here extended to consider the dependance of these constraints on the primordial deuterium abundance. If the neutrino-heated ejecta in the post-core-bounce supernova environment is the site of r-process nucleosynthesis, limits can be placed on mixing between νe, and νsbμ, or νsbτ. Refined limits will require a better understanding of this r-process environment, since current supernova models do not show a completely successful r-process. In this work it is shown that general relativistic effects associated with a more compact supernova core can provide more suitable conditions for the r-process. As a step towards analyzing the effects of neutrino mixing in such a relativistic environment, neutrino oscillations in curved spacetime are studied.

Double-detonation Sub-Chandrasekhar Supernovae: Synthetic Observables for Minimum Helium Shell Mass Models

NASA Astrophysics Data System (ADS)

Kromer, M.; Sim, S. A.; Fink, M.; Röpke, F. K.; Seitenzahl, I. R.; Hillebrandt, W.

2010-08-01

In the double-detonation scenario for Type Ia supernovae, it is suggested that a detonation initiates in a shell of helium-rich material accreted from a companion star by a sub-Chandrasekhar-mass white dwarf. This shell detonation drives a shock front into the carbon-oxygen white dwarf that triggers a secondary detonation in the core. The core detonation results in a complete disruption of the white dwarf. Earlier studies concluded that this scenario has difficulties in accounting for the observed properties of Type Ia supernovae since the explosion ejecta are surrounded by the products of explosive helium burning in the shell. Recently, however, it was proposed that detonations might be possible for much less massive helium shells than previously assumed (Bildsten et al.). Moreover, it was shown that even detonations of these minimum helium shell masses robustly trigger detonations of the carbon-oxygen core (Fink et al.). Therefore, it is possible that the impact of the helium layer on observables is less than previously thought. Here, we present time-dependent multi-wavelength radiative transfer calculations for models with minimum helium shell mass and derive synthetic observables for both the optical and γ-ray spectral regions. These differ strongly from those found in earlier simulations of sub-Chandrasekhar-mass explosions in which more massive helium shells were considered. Our models predict light curves that cover both the range of brightnesses and the rise and decline times of observed Type Ia supernovae. However, their colors and spectra do not match the observations. In particular, their B - V colors are generally too red. We show that this discrepancy is mainly due to the composition of the burning products of the helium shell of the Fink et al. models which contain significant amounts of titanium and chromium. Using a toy model, we also show that the burning products of the helium shell depend crucially on its initial composition. This leads us to conclude that good agreement between sub-Chandrasekhar-mass explosions and observed Type Ia supernovae may still be feasible but further study of the shell properties is required.

The Origin of Stellar Species: constraining stellar evolution scenarios with Local Group galaxy surveys

NASA Astrophysics Data System (ADS)

Sarbadhicary, Sumit; Badenes, Carles; Chomiuk, Laura; Maldonado, Jessica; Caprioli, Damiano; Heger, Mairead; Huizenga, Daniel

2018-01-01

Our understanding of the progenitors of many stellar species, such as supernovae, massive and low-mass He-burning stars, is limited because of many poorly constrained aspects of stellar evolution theory. For my dissertation, I have focused on using Local Group galaxy surveys to constrain stellar evolution scenarios by measuring delay-time distributions (DTD). The DTD is the hypothetical occurrence rate of a stellar object per elapsed time after a brief burst of star formation. It is the measured distribution of timescales on which stars evolve, and therefore serves as a powerful observational constraint on theoretical progenitor models. The DTD can be measured from a survey of stellar objects and a set of star-formation histories of the host galaxy, and is particularly effective in the Local Group, where high-quality star-formation histories are available from resolved stellar populations. I am currently calculating a SN DTD with supernova remnants (SNRs) in order to provide the strongest constraints on the progenitors of thermonuclear and core-collapse supernovae. However, most SNRs do not have reliable age measurements and their evolution depends on the ambient environment. For this reason, I wrote a radio light curve model of an SNR population to extract the visibility times and rates of supernovae - crucial ingredients for the DTD - from an SNR survey. The model uses observational constraints on the local environments from multi-wavelength surveys, accounts for missing SNRs and employs the latest models of shock-driven particle acceleration. The final calculation of the SN DTD in the Local Group is awaiting completion of a systematic SNR catalog from deep radio-continuum images, now in preparation by a group led by Dr. Laura Chomiuk. I have also calculated DTDs for the LMC population of RR Lyrae and Cepheid variables, which serve as important distance calibrators and stellar population tracers. We find that Cepheids can have delay-times between 10 Myrs - 1 Gyr, while RR Lyrae can have delay-times < 10 Gyrs. These observations cannot be explained by models using mass and metallicity alone. In future projects, I will apply the DTD technique to constrain the supergiant and pre-supernova evolutionary models.

An asymptotic-giant-branch star in the progenitor system of a type Ia supernova.

PubMed

Hamuy, Mario; Phillips, M M; Suntzeff, Nicholas B; Maza, José; González, L E; Roth, Miguel; Krisciunas, Kevin; Morrell, Nidia; Green, E M; Persson, S E; McCarthy, P J

2003-08-07

Stars that explode as supernovae come in two main classes. A type Ia supernova is recognized by the absence of hydrogen and the presence of elements such as silicon and sulphur in its spectrum; this class of supernova is thought to produce the majority of iron-peak elements in the Universe. They are also used as precise 'standard candles' to measure the distances to galaxies. While there is general agreement that a type Ia supernova is produced by an exploding white dwarf star, no progenitor system has ever been directly observed. Significant effort has gone into searching for circumstellar material to help discriminate between the possible kinds of progenitor systems, but no such material has hitherto been found associated with a type Ia supernova. Here we report the presence of strong hydrogen emission associated with the type Ia supernova SN2002ic, indicating the presence of large amounts of circumstellar material. We infer from this that the progenitor system contained a massive asymptotic-giant-branch star that lost several solar masses of hydrogen-rich gas before the supernova explosion.

Probing r-Process Production of Nuclei Beyond 209Bi with Gamma Rays

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

Qian, Y.-Z.; Vogel, P.; Wasserburg, G. J.

We estimate gamma-ray fluxes due to the decay of nuclei beyond 209Bi from a supernova or a supernova remnant assuming that the r-process occurs in supernovae. We find that a detector with a sensitivity of {approx}10-7 {gamma} cm-2 s-1 at energies from {approx}40 keV to {approx}3 MeV may detect fluxes due to the decay of 226Ra, 229Th, 241Am, 243Am, 249Cf, and 251Cf in the newly discovered supernova remnant near Vela. In addition, such a detector may detect fluxes due to the decay of 227Ac and 228Ra produced in a future supernova at a distance of {approx}1 kpc. Because nuclei withmore » mass numbers A>209 are produced solely by the r-process, such detections are the best proof for a supernova r-process site. Further, they provide the most direct information on yields of progenitor nuclei with A>209 at r-process freeze-out. Finally, detection of fluxes due to the decay of r-process nuclei over a range of masses from a supernova or a supernova remnant provides the opportunity to compare yields in a single supernova event with the solar r-process abundance pattern. (c) (c) 1999. The American Astronomical Society.« less

A very luminous magnetar-powered supernova associated with an ultra-long γ-ray burst.

PubMed

Greiner, Jochen; Mazzali, Paolo A; Kann, D Alexander; Krühler, Thomas; Pian, Elena; Prentice, Simon; Olivares E, Felipe; Rossi, Andrea; Klose, Sylvio; Taubenberger, Stefan; Knust, Fabian; Afonso, Paulo M J; Ashall, Chris; Bolmer, Jan; Delvaux, Corentin; Diehl, Roland; Elliott, Jonathan; Filgas, Robert; Fynbo, Johan P U; Graham, John F; Guelbenzu, Ana Nicuesa; Kobayashi, Shiho; Leloudas, Giorgos; Savaglio, Sandra; Schady, Patricia; Schmidl, Sebastian; Schweyer, Tassilo; Sudilovsky, Vladimir; Tanga, Mohit; Updike, Adria C; van Eerten, Hendrik; Varela, Karla

2015-07-09

A new class of ultra-long-duration (more than 10,000 seconds) γ-ray bursts has recently been suggested. They may originate in the explosion of stars with much larger radii than those producing normal long-duration γ-ray bursts or in the tidal disruption of a star. No clear supernova has yet been associated with an ultra-long-duration γ-ray burst. Here we report that a supernova (SN 2011kl) was associated with the ultra-long-duration γ-ray burst GRB 111209A, at a redshift z of 0.677. This supernova is more than three times more luminous than type Ic supernovae associated with long-duration γ-ray bursts, and its spectrum is distinctly different. The slope of the continuum resembles those of super-luminous supernovae, but extends further down into the rest-frame ultraviolet implying a low metal content. The light curve evolves much more rapidly than those of super-luminous supernovae. This combination of high luminosity and low metal-line opacity cannot be reconciled with typical type Ic supernovae, but can be reproduced by a model where extra energy is injected by a strongly magnetized neutron star (a magnetar), which has also been proposed as the explanation for super-luminous supernovae.

The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star.

PubMed

Howell, D Andrew; Sullivan, Mark; Nugent, Peter E; Ellis, Richard S; Conley, Alexander J; Le Borgne, Damien; Carlberg, Raymond G; Guy, Julien; Balam, David; Basa, Stephane; Fouchez, Dominique; Hook, Isobel M; Hsiao, Eric Y; Neill, James D; Pain, Reynald; Perrett, Kathryn M; Pritchet, Christopher J

2006-09-21

The accelerating expansion of the Universe, and the need for dark energy, were inferred from observations of type Ia supernovae. There is a consensus that type Ia supernovae are thermonuclear explosions that destroy carbon-oxygen white dwarf stars that have accreted matter from a companion star, although the nature of this companion remains uncertain. These supernovae are thought to be reliable distance indicators because they have a standard amount of fuel and a uniform trigger: they are predicted to explode when the mass of the white dwarf nears the Chandrasekhar mass of 1.4 solar masses (M(o)). Here we show that the high-redshift supernova SNLS-03D3bb has an exceptionally high luminosity and low kinetic energy that both imply a super-Chandrasekhar-mass progenitor. Super-Chandrasekhar-mass supernovae should occur preferentially in a young stellar population, so this may provide an explanation for the observed trend that overluminous type Ia supernovae occur only in 'young' environments. As this supernova does not obey the relations that allow type Ia supernovae to be calibrated as standard candles, and as no counterparts have been found at low redshift, future cosmology studies will have to consider possible contamination from such events.

Shedding light on the Type Ia supernova extinction puzzle: dust location found

NASA Astrophysics Data System (ADS)

Bulla, M.; Goobar, A.; Dhawan, S.

2018-06-01

The colour evolution of reddened Type Ia supernovae can place strong constraints on the location of dust and help address the question of whether the observed extinction stems from the interstellar medium or from circumstellar material surrounding the progenitor. Here we analyse BV photometry of 48 reddened Type Ia supernovae from the literature and estimate the dust location from their B - V colour evolution. We find a time-variable colour excess E(B - V) for 15 supernovae in our sample and constrain dust to distances between 0.013 and 45 pc (4 × 1016 - 1020 cm). For the remaining supernovae, we obtain a constant E(B - V) evolution and place lower limits on the dust distance from the explosion. In all the 48 supernovae, the inferred dust location is compatible with an interstellar origin for the extinction. This is corroborated by the observation that supernovae with relatively nearby dust (≲ 1 pc) are located close to the center of their host galaxy, in high-density dusty regions where interactions between the supernova radiation and interstellar clouds close by are likely to occur. For supernovae showing time-variable E(B - V), we identify a potential preference for low RV values, unusually strong sodium absorption and blue-shifted and time-variable absorption features. Within the interstellar framework, this brings evidence to a proposed scenario where cloud-cloud collisions induced by the supernova radiation pressure can shift the grain size distribution to smaller values and enhance the abundance of sodium in the gaseous phase.

Neutrino signal from pair-instability supernovae

NASA Astrophysics Data System (ADS)

Wright, Warren P.; Gilmer, Matthew S.; Fröhlich, Carla; Kneller, James P.

2017-11-01

A very massive star with a carbon-oxygen core in the range of 64M ⊙

Interacting supernovae and supernova impostors

NASA Astrophysics Data System (ADS)

Tartaglia, Leonardo

2016-02-01

Massive stars are thought to end their lives with spectacular explosions triggered by the gravitational collapse of their cores. Interacting supernovae are generally attributed to supernova explosions occurring in dense circumstellar media, generated through mass-loss which characterisie the late phases of the life of their progenitors. In the last two decades, several observational evidences revealed that mass-loss in massive stars may be related to violent eruptions involving their outer layers, such as the luminous blue variables. Giant eruptions of extragalactic luminous blue variables, similar to that observed in Eta Car in the 19th century, are usually labelled 'SN impostors', since they mimic the behaviour of genuine SNe, but are not the final act of the life of the progenitor stars. The mechanisms producing these outbursts are still not understood, although the increasing number of observed cases triggered the efforts of the astronomical community to find possible theoretical interpretations. More recently, a number of observational evidences suggested that also lower-mass stars can experience pre-supernova outbursts, hence becoming supernova impostors. Even more interestingly, there is growing evidence of a connection among massive stars, their outbursts and interacting supernovae. All of this inspired this research, which has been focused in particular on the characterisation of supernova impostors and the observational criteria that may allow us to safely discriminate them from interacting supernovae. Moreover, the discovery of peculiar transients, motivated us to explore the lowest range of stellar masses that may experience violent outbursts. Finally, the quest for the link among massive stars, their giant eruptions and interacting supernovae, led us to study the interacting supernova LSQ13zm, which possibly exploded a very short time after an LBV-like major outburst.

A single low-energy, iron-poor supernova as the source of metals in the star SMSS J031300.36-670839.3.

PubMed

Keller, S C; Bessell, M S; Frebel, A; Casey, A R; Asplund, M; Jacobson, H R; Lind, K; Norris, J E; Yong, D; Heger, A; Magic, Z; Da Costa, G S; Schmidt, B P; Tisserand, P

2014-02-27

The element abundance ratios of four low-mass stars with extremely low metallicities (abundances of elements heavier than helium) indicate that the gas out of which the stars formed was enriched in each case by at most a few--and potentially only one--low-energy supernova. Such supernovae yield large quantities of light elements such as carbon but very little iron. The dominance of low-energy supernovae seems surprising, because it had been expected that the first stars were extremely massive, and that they disintegrated in pair-instability explosions that would rapidly enrich galaxies in iron. What has remained unclear is the yield of iron from the first supernovae, because hitherto no star has been unambiguously interpreted as encapsulating the yield of a single supernova. Here we report the optical spectrum of SMSS J031300.36-670839.3, which shows no evidence of iron (with an upper limit of 10(-7.1) times solar abundance). Based on a comparison of its abundance pattern with those of models, we conclude that the star was seeded with material from a single supernova with an original mass about 60 times that of the Sun (and that the supernova left behind a black hole). Taken together with the four previously mentioned low-metallicity stars, we conclude that low-energy supernovae were common in the early Universe, and that such supernovae yielded light-element enrichment with insignificant iron. Reduced stellar feedback both chemically and mechanically from low-energy supernovae would have enabled first-generation stars to form over an extended period. We speculate that such stars may perhaps have had an important role in the epoch of cosmic reionization and the chemical evolution of early galaxies.

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.

Was There a Decelerating Past for the Universe?

NASA Astrophysics Data System (ADS)

John, Moncy V.

2006-03-01

Some analyzes of the apparent magnitude-redshift data of type Ia supernovas indicate that the suspected dark energy in the universe cannot be regarded as a cosmological constant of general relativistic origin or as the vacuum energy encountered in quantum field theories. If this is the case, our knowledge of the physical world remains deficient since no tested theory involves such a dark energy. Under this circumstance, an equation of state of the form p = wρ is not well-motivated and one is unable to use the Einstein equation in this case as well. I argue that the very method of analysing the data by assuming exotic energy densities with strange equations of state itself is misleading and the reasonable remaining option is to make a model-independent analysis of SNe data, without reference to the energy densities. In this basically kinematic approach, we limit ourselves to the observationally justifiable assumptions of homogeneity and isotropy, i.e., to the assumption that the universe has a RW metric. This cosmographic approach is historically the original one in cosmology. The analysis was performed by expanding the scale factor into a fifth-order polynomial, an assumption that can be further generalized to any order. The values obtained for the present expansion rates h, q0, r0 etc. are relevant, since any cosmological solution would ultimately need to explain them. Using this method, we address an important question relevant to cosmology: Was there a decelerating past for the universe? To answer this, the Bayes's probability theory is employed, which is the most appropriate tool for quantifying our knowledge when it changes through the acquisition of new data. The cosmographic approach helps to sort out models which were always accelerating from those which decelerated for at least some time in the period of interest. Bayesian model comparison technique is used to discriminate these rival hypotheses with the aid of recent releases of supernova data. It is argued that the lessons learned using Bayesian theory are extremely valuable to avoid frequent U-turns in cosmology.

Elucidating dark energy with future 21 cm observations at the epoch of reionization

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

Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu

2017-02-01

We investigate how precisely we can determine the nature of dark energy such as the equation of state (EoS) and its time dependence by using future observations of 21 cm fluctuations at the epoch of reionization (06.8∼< z ∼<1) such as Square Kilometre Array (SKA) and Omniscope in combination with those from cosmic microwave background, baryon acoustic oscillation, type Ia supernovae and direct measurement of the Hubble constant. We consider several parametrizations for the EoS and find that future 21 cm observations will be powerful in constraining models of dark energy, especially when its EoS varies at high redshifts.

Well-balanced Schemes for Gravitationally Stratified Media

NASA Astrophysics Data System (ADS)

Käppeli, R.; Mishra, S.

2015-10-01

We present a well-balanced scheme for the Euler equations with gravitation. The scheme is capable of maintaining exactly (up to machine precision) a discrete hydrostatic equilibrium without any assumption on a thermodynamic variable such as specific entropy or temperature. The well-balanced scheme is based on a local hydrostatic pressure reconstruction. Moreover, it is computationally efficient and can be incorporated into any existing algorithm in a straightforward manner. The presented scheme improves over standard ones especially when flows close to a hydrostatic equilibrium have to be simulated. The performance of the well-balanced scheme is demonstrated on an astrophysically relevant application: a toy model for core-collapse supernovae.

Supernova Cosmology Project

Science.gov Websites

Supernova Survey: An Intensive HST Survey for z>1 Type Ia Supernovae by Targeting Galaxy Clusters Survey new survey strategy to discover and study high redshift Type Ia supernovae (SNe Ia) using the Hubble improvement in the efficiency of finding SNe compared to an HST field survey and a factor of three improvement

Supernova Cosmology Project

Science.gov Websites

Space Telescope Cluster Supernova Survey: II. The Type Ia Supernova Rate in High-Redshift Galaxy /abs/0809.1648 Constraining Dust and Color Variations of High-z SNe Using NICMOS on the Hubble Space /0804.4142 A New Determination of the High-Redshift Type Ia Supernova Rates with the Hubble Space Telescope

Type Ia Supernova Cosmology

NASA Astrophysics Data System (ADS)

Leibundgut, B.; Sullivan, M.

2018-03-01

The primary agent for Type Ia supernova cosmology is the uniformity of their appearance. We present the current status, achievements and uncertainties. The Hubble constant and the expansion history of the universe are key measurements provided by Type Ia supernovae. They were also instrumental in showing time dilation, which is a direct observational signature of expansion. Connections to explosion physics are made in the context of potential improvements of the quality of Type Ia supernovae as distance indicators. The coming years will see large efforts to use Type Ia supernovae to characterise dark energy.

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.

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.

Redshift drift in axially symmetric quasispherical Szekeres models

NASA Astrophysics Data System (ADS)

Mishra, Priti; Célérier, Marie-Noëlle; Singh, Tejinder P.

2012-10-01

Models of inhomogeneous universes constructed with exact solutions of Einstein’s general relativity have been proposed in the literature with the aim of reproducing the cosmological data without any need for a dark energy component. Besides large scale inhomogeneity models spherically symmetric around the observer, Swiss-cheese models have also been studied. Among them, Swiss cheeses where the inhomogeneous patches are modeled by different particular Szekeres solutions have been used for reproducing the apparent dimming of the type Ia supernovae. However, the problem of fitting such models to the type Ia supernovae data is completely degenerate and we need other constraints to fully characterize them. One of the tests which is known to be able to discriminate between different cosmological models is the redshift drift. This drift has already been calculated by different authors for Lemaître-Tolman-Bondi models. We compute it here for one particular axially symmetric quasispherical Szekeres Swiss cheese which has previously been shown to reproduce to a good accuracy the type Ia supernovae data, and we compare the results to the drift in the ΛCDM model and in some Lemaître-Tolman-Bondi models that can be found in the literature. We show that it is a good discriminator between them. Then, we discuss our model’s remaining degrees of freedom and propose a recipe to fully constrain them.

TYPE Ia SUPERNOVA DISTANCE MODULUS BIAS AND DISPERSION FROM K-CORRECTION ERRORS: A DIRECT MEASUREMENT USING LIGHT CURVE FITS TO OBSERVED SPECTRAL TIME SERIES

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

Saunders, C.; Aldering, G.; Aragon, C.

2015-02-10

We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a givenmore » supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion greater than ∼0.05 mag for measurements of photometry using the Sloan-like filters and a bias that corresponds to a 0.03 shift in w when applied to an outside data set. To test the result of a shift in supernova population or environment at higher redshifts, we repeat our calculations with the addition of a reweighting of the supernovae as a function of redshift and find that this strongly affects the results and would have repercussions for cosmology. We discuss possible methods to reduce the contribution of the K-correction bias and uncertainty.« less

An Open Catalog for Supernova Data

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

Guillochon, James; Parrent, Jerod; Kelley, Luke Zoltan

We present the Open Supernova Catalog , an online collection of observations and metadata for presently 36,000+ supernovae and related candidates. The catalog is freely available on the web (https://sne.space), with its main interface having been designed to be a user-friendly, rapidly searchable table accessible on desktop and mobile devices. In addition to the primary catalog table containing supernova metadata, an individual page is generated for each supernova, which displays its available metadata, light curves, and spectra spanning X-ray to radio frequencies. The data presented in the catalog is automatically rebuilt on a daily basis and is constructed by parsingmore » several dozen sources, including the data presented in the supernova literature and from secondary sources such as other web-based catalogs. Individual supernova data is stored in the hierarchical, human- and machine-readable JSON format, with the entirety of each supernova’s data being contained within a single JSON file bearing its name. The setup we present here, which is based on open-source software maintained via git repositories hosted on github, enables anyone to download the entirety of the supernova data set to their home computer in minutes, and to make contributions of their own data back to the catalog via git. As the supernova data set continues to grow, especially in the upcoming era of all-sky synoptic telescopes, which will increase the total number of events by orders of magnitude, we hope that the catalog we have designed will be a valuable tool for the community to analyze both historical and contemporary supernovae.« less

The Impact of Progenitor Mass Loss on the Dynamical and Spectral Evolution of Supernova Remnants

NASA Astrophysics Data System (ADS)

Patnaude, Daniel J.; Lee, Shiu-Hang; Slane, Patrick O.; Badenes, Carles; Nagataki, Shigehiro; Ellison, Donald C.; Milisavljevic, Dan

2017-11-01

There is now substantial evidence that the progenitors of some core-collapse supernovae undergo enhanced or extreme mass loss prior to explosion. The imprint of this mass loss is observed in the spectra and dynamics of the expanding blast wave on timescales of days to years after core collapse, and the effects on the spectral and dynamical evolution may linger long after the supernova has evolved into the remnant stage. In this paper, we present, for the first time, largely self-consistent end-to-end simulations for the evolution of a massive star from the pre-main sequence, up to and through core collapse, and into the remnant phase. We present three models and compare and contrast how the progenitor mass-loss history impacts the dynamics and spectral evolution of the supernovae and supernova remnants. We study a model that only includes steady mass loss, a model with enhanced mass loss over a period of ˜5000 yr prior to core collapse, and a model with extreme mass loss over a period of ˜500 yr prior to core collapse. The models are not meant to address any particular supernova or supernova remnant, but rather to highlight the important role that the progenitor evolution plays in the observable qualities of supernovae and supernova remnants. Through comparisons of these three different progenitor evolution scenarios, we find that the mass loss in late stages (during and after core carbon burning) can have a profound impact on the dynamics and spectral evolution of the supernova remnant centuries after core collapse.

An Open Catalog for Supernova Data

NASA Astrophysics Data System (ADS)

Guillochon, James; Parrent, Jerod; Kelley, Luke Zoltan; Margutti, Raffaella

2017-01-01

We present the Open Supernova Catalog, an online collection of observations and metadata for presently 36,000+ supernovae and related candidates. The catalog is freely available on the web (https://sne.space), with its main interface having been designed to be a user-friendly, rapidly searchable table accessible on desktop and mobile devices. In addition to the primary catalog table containing supernova metadata, an individual page is generated for each supernova, which displays its available metadata, light curves, and spectra spanning X-ray to radio frequencies. The data presented in the catalog is automatically rebuilt on a daily basis and is constructed by parsing several dozen sources, including the data presented in the supernova literature and from secondary sources such as other web-based catalogs. Individual supernova data is stored in the hierarchical, human- and machine-readable JSON format, with the entirety of each supernova’s data being contained within a single JSON file bearing its name. The setup we present here, which is based on open-source software maintained via git repositories hosted on github, enables anyone to download the entirety of the supernova data set to their home computer in minutes, and to make contributions of their own data back to the catalog via git. As the supernova data set continues to grow, especially in the upcoming era of all-sky synoptic telescopes, which will increase the total number of events by orders of magnitude, we hope that the catalog we have designed will be a valuable tool for the community to analyze both historical and contemporary supernovae.

Supernova Collisions with the Heliosphere

NASA Astrophysics Data System (ADS)

Fields, Brian D.; Athanassiadou, Themis; Johnson, Scott R.

2008-05-01

Nearby supernova explosions—within a few tens of pc of the solar system—have become a subject of intense scrutiny, due to the discovery of live undersea 60Fe from an event 2.8 Myr ago. A key open question concerns the delivery of supernova ejecta to the Earth, in particular penetration of the heliosphere by the supernova remnant (SNR). We present the first systematic numerical hydrodynamical study of the interaction between a supernova blast and the solar wind. Our simulations explore dynamic pressure regimes that are factors >=10 above those in other studies of the heliosphere under exotic conditions, for supernovae exploding at a range of distances through different interstellar environments, and interacting with solar winds of varying strengths. Our results are qualitatively consistent with the structure of the contemporary heliosphere modeled by previous work, but compressed to within the inner solar system. We demonstrate that key characteristics of the resulting heliospheric structure follow simple scaling laws that can be understood in terms of pressure-balance arguments, and which are in agreement with previous work. Our models show that a 10 pc supernova event, incident on a solar-wind outflow with the mean observed properties, compresses the heliopause to just beyond 1 AU. We also demonstrate scenarios where the supernova remnant compresses the heliopause to within 1 AU, in which cases supernova material will be directly deposited on Earth. Since 8 pc marks the nominal "kill radius" for severe biosphere damage, any extinction-level events should have left terrestrial deposits of supernova debris. We conclude with a brief discussion of the effect of our approximations and the impact of additional physics.

The Supernova Spectropolarimetry (SNSPOL) Project; Probing the Geometry of Supernova Explosions

NASA Astrophysics Data System (ADS)

Williams, George Grant; Leonard, Douglas; Smith, Nathan; Smith, Paul; Milne, Peter; Hoffman, Jennifer L.; Bilinski, Christopher

2018-01-01

In recent years, evidence has grown that most supernovae exhibit departures from spherical symmetry. These results, together with full three-dimensional modeling, are exposing the possibility that asymmetries are not simply an observable feature of some supernovae, but may, in fact, be a necessity of the explosion mechanism itself. However, with the exception of SN 1987A, a supernova photosphere cannot be resolved through direct imaging from ground or space. Only the powerful technique of polarimetry can directly probe asymmetries on those spatial scales. Spectropolarimetry enhances the power of this technique by revealing wavelength-dependent variations that may result from differences in the geometrical distributions of the various ionic species. Multi-epoch observations over several months can be used to follow the evolution of these asymmetries as a supernova evolves and its photosphere recedes through the ejecta. The Supernova Spectropolarimetry (SNSPOL) Project aims to study the predominance and characteristics of asymmetries in all types of supernovae by decoding their complex, time-dependent polarimetric behavior. This is accomplished through multi-epoch observations using the CCD Imaging/Spectropolarimeter (SPOL) on the 61” Kuiper, the 90” Bok, and the 6.5-m MMT telescopes. During the past six years, the SNSPOL Project has observed more than 95 supernovae, approximately 2/3 of which have been observed at multiple epochs. Here we present a summary of the project, its current status, and a few selected results.

Bridging the gap: from massive stars to supernovae.

PubMed

Maund, Justyn R; Crowther, Paul A; Janka, Hans-Thomas; Langer, Norbert

2017-10-28

Almost since the beginning, massive stars and their resultant supernovae have played a crucial role in the Universe. These objects produce tremendous amounts of energy and new, heavy elements that enrich galaxies, encourage new stars to form and sculpt the shapes of galaxies that we see today. The end of millions of years of massive star evolution and the beginning of hundreds or thousands of years of supernova evolution are separated by a matter of a few seconds, in which some of the most extreme physics found in the Universe causes the explosive and terminal disruption of the star. Key questions remain unanswered in both the studies of how massive stars evolve and the behaviour of supernovae, and it appears the solutions may not lie on just one side of the explosion or the other or in just the domain of the stellar evolution or the supernova astrophysics communities. The need to view massive star evolution and supernovae as continuous phases in a single narrative motivated the Theo Murphy international scientific meeting 'Bridging the gap: from massive stars to supernovae' at Chicheley Hall, UK, in June 2016, with the specific purpose of simultaneously addressing the scientific connections between theoretical and observational studies of massive stars and their supernovae, through engaging astronomers from both communities.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

VLA radio upper limit on Type IIn Supernova 2008S

NASA Astrophysics Data System (ADS)

Chandra, Poonam; Soderberg, Alicia

2008-02-01

Poonam Chandra and Alicia Soderberg report on behalf of a larger collaboration: We observed type IIn supernova SN 2008S (CBET 1234) with the Very Large Array (VLA) on 2008, February 10.62 UT. We do not detect any radio emission at the supernova position (CBET 1234). The flux density at the supernova position is -62 +/- 36 uJy.

ASASSN-18bt: Discovery of A Probable, Bright Supernova in a Kepler Supernova Field

NASA Astrophysics Data System (ADS)

Brown, Jon S.; Stanek, K. Z.; Vallely, P.; Kochanek, C. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Stritzinger, M.; Holmbo, S.; Brimacombe, J.

2018-02-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, in the galaxy UGC 04780, which is being monitored by Kepler between Dec 7 2017 and Feb 25, 2018.

Diagnostics of the Supernova Engine

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

Fryer, Chris L.; Ellinger, Carola; Young, Patrick A.

The standard engine behind core-collapse supernovae is continuously evolving with increasingly detailed models. At this time, most simulations focus on an engine invoking turbulence above the proto-neutron star, sometimes termed the “convection-enhanced” engine. Finally, we review this engine and why it has become the standard for normal supernovae, focusing on a wide set of observations that provide insight into the supernova engine.

Diagnostics of the Supernova Engine

DOE PAGES

Fryer, Chris L.; Ellinger, Carola; Young, Patrick A.; ...

2017-10-17

The standard engine behind core-collapse supernovae is continuously evolving with increasingly detailed models. At this time, most simulations focus on an engine invoking turbulence above the proto-neutron star, sometimes termed the “convection-enhanced” engine. Finally, we review this engine and why it has become the standard for normal supernovae, focusing on a wide set of observations that provide insight into the supernova engine.

A low-energy core-collapse supernova without a hydrogen envelope.

PubMed

Valenti, S; Pastorello, A; Cappellaro, E; Benetti, S; Mazzali, P A; Manteca, J; Taubenberger, S; Elias-Rosa, N; Ferrando, R; Harutyunyan, A; Hentunen, V P; Nissinen, M; Pian, E; Turatto, M; Zampieri, L; Smartt, S J

2009-06-04

The final fate of massive stars depends on many factors. Theory suggests that some with initial masses greater than 25 to 30 solar masses end up as Wolf-Rayet stars, which are deficient in hydrogen in their outer layers because of mass loss through strong stellar winds. The most massive of these stars have cores which may form a black hole and theory predicts that the resulting explosion of some of them produces ejecta of low kinetic energy, a faint optical luminosity and a small mass fraction of radioactive nickel. An alternative origin for low-energy supernovae is the collapse of the oxygen-neon core of a star of 7-9 solar masses. No weak, hydrogen-deficient, core-collapse supernovae have hitherto been seen. Here we report that SN 2008ha is a faint hydrogen-poor supernova. We propose that other similar events have been observed but have been misclassified as peculiar thermonuclear supernovae (sometimes labelled SN 2002cx-like events). This discovery could link these faint supernovae to some long-duration gamma-ray bursts, because extremely faint, hydrogen-stripped core-collapse supernovae have been proposed to produce such long gamma-ray bursts, the afterglows of which do not show evidence of associated supernovae.

A more direct measure of supernova rates in starburst galaxies

NASA Technical Reports Server (NTRS)

Van Buren, Dave; Greenhouse, Matthew A.

1994-01-01

We determine ages for young supernova remnants in the starburst galaxies M82 and NGC 253 by applying Chevalier's model for radio emission from supernova blast waves expanding into the ejecta of their precursor stars. Absolute ages are determined by calibrating the model with radio observations of Cas A. We derive supernova rates of 0.10 and 0.08/yr for M82 and NGC 253, respectively. Assuming L (sub FIR) to be proportional to the supernova rate, we find r(sub SN) approximately equal 2 x 10(exp -12) x L(sub FIR), solar yr(exp -1) for these archetypal starburst galaxies. This approach is unique in that the supernova rate is derived from direct observation of supernova remnants rather than from star formation rates and an assumed initial mass function (IMF). We suggest that the approach presented here can be used to derive star-formation rates that are more directly related to observable quantities than those derived by other methods. We find that the supernova rate, far infrared (FIR) luminosity, and dynamical mass of the M82 starburst place few constraints on the initial mass function (IMF) slope and mass limits.

A common explosion mechanism for type Ia supernovae.

PubMed

Mazzali, Paolo A; Röpke, Friedrich K; Benetti, Stefano; Hillebrandt, Wolfgang

2007-02-09

Type Ia supernovae, the thermonuclear explosions of white dwarf stars composed of carbon and oxygen, were instrumental as distance indicators in establishing the acceleration of the universe's expansion. However, the physics of the explosion are debated. Here we report a systematic spectral analysis of a large sample of well-observed type Ia supernovae. Mapping the velocity distribution of the main products of nuclear burning, we constrain theoretical scenarios. We find that all supernovae have low-velocity cores of stable iron-group elements. Outside this core, nickel-56 dominates the supernova ejecta. The outer extent of the iron-group material depends on the amount of nickel-56 and coincides with the inner extent of silicon, the principal product of incomplete burning. The outer extent of the bulk of silicon is similar in all supernovae, having an expansion velocity of approximately 11,000 kilometers per second and corresponding to a mass of slightly over one solar mass. This indicates that all the supernovae considered here burned similar masses and suggests that their progenitors had the same mass. Synthetic light-curve parameters and three-dimensional explosion simulations support this interpretation. A single explosion scenario, possibly a delayed detonation, may thus explain most type Ia supernovae.

Supernova Explosions Stay In Shape

NASA Astrophysics Data System (ADS)

2009-12-01

At a very early age, children learn how to classify objects according to their shape. Now, new research suggests studying the shape of the aftermath of supernovas may allow astronomers to do the same. A new study of images from NASA's Chandra X-ray Observatory on supernova remnants - the debris from exploded stars - shows that the symmetry of the remnants, or lack thereof, reveals how the star exploded. This is an important discovery because it shows that the remnants retain information about how the star exploded even though hundreds or thousands of years have passed. "It's almost like the supernova remnants have a 'memory' of the original explosion," said Laura Lopez of the University of California at Santa Cruz, who led the study. "This is the first time anyone has systematically compared the shape of these remnants in X-rays in this way." Astronomers sort supernovas into several categories, or "types", based on properties observed days after the explosion and which reflect very different physical mechanisms that cause stars to explode. But, since observed remnants of supernovas are leftover from explosions that occurred long ago, other methods are needed to accurately classify the original supernovas. Lopez and colleagues focused on the relatively young supernova remnants that exhibited strong X-ray emission from silicon ejected by the explosion so as to rule out the effects of interstellar matter surrounding the explosion. Their analysis showed that the X-ray images of the ejecta can be used to identify the way the star exploded. The team studied 17 supernova remnants both in the Milky Way galaxy and a neighboring galaxy, the Large Magellanic Cloud. For each of these remnants there is independent information about the type of supernova involved, based not on the shape of the remnant but, for example, on the elements observed in it. The researchers found that one type of supernova explosion - the so-called Type Ia - left behind relatively symmetric, circular remnants. This type of supernova is thought to be caused by a thermonuclear explosion of a white dwarf, and is often used by astronomers as "standard candles" for measuring cosmic distances. On the other hand, the remnants tied to the "core-collapse" supernova explosions were distinctly more asymmetric. This type of supernova occurs when a very massive, young star collapses onto itself and then explodes. "If we can link supernova remnants with the type of explosion", said co-author Enrico Ramirez-Ruiz, also of University of California, Santa Cruz, "then we can use that information in theoretical models to really help us nail down the details of how the supernovas went off." Models of core-collapse supernovas must include a way to reproduce the asymmetries measured in this work and models of Type Ia supernovas must produce the symmetric, circular remnants that have been observed. Out of the 17 supernova remnants sampled, ten were classified as the core-collapse variety, while the remaining seven of them were classified as Type Ia. One of these, a remnant known as SNR 0548-70.4, was a bit of an "oddball". This one was considered a Type Ia based on its chemical abundances, but Lopez finds it has the asymmetry of a core-collapse remnant. "We do have one mysterious object, but we think that is probably a Type Ia with an unusual orientation to our line of sight," said Lopez. "But we'll definitely be looking at that one again." While the supernova remnants in the Lopez sample were taken from the Milky Way and its close neighbor, it is possible this technique could be extended to remnants at even greater distances. For example, large, bright supernova remnants in the galaxy M33 could be included in future studies to determine the types of supernova that generated them. The paper describing these results appeared in the November 20 issue of The Astrophysical Journal Letters. 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.harvard.edu and http://chandra.nasa.gov

Neutrino flavor instabilities in a time-dependent supernova model

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

Abbar, Sajad; Duan, Huaiyu

2015-10-19

In this study, a dense neutrino medium such as that inside a core-collapse supernova can experience collective flavor conversion or oscillations because of the neutral-current weak interaction among the neutrinos. This phenomenon has been studied in a restricted, stationary supernova model which possesses the (spatial) spherical symmetry about the center of the supernova and the (directional) axial symmetry around the radial direction. Recently it has been shown that these spatial and directional symmetries can be broken spontaneously by collective neutrino oscillations. In this letter we analyze the neutrino flavor instabilities in a time-dependent supernova model. Our results show that collectivemore » neutrino oscillations start at approximately the same radius in both the stationary and time-dependent supernova models unless there exist very rapid variations in local physical conditions on timescales of a few microseconds or shorter. Our results also suggest that collective neutrino oscillations can vary rapidly with time in the regimes where they do occur which need to be studied in time-dependent supernova models.« less

Ozone Depletion from Nearby Supernovae

NASA Technical Reports Server (NTRS)

Gehrels, Neil; Laird, Claude M.; Jackman, Charles H.; Cannizzo, John K.; Mattson, Barbara J.; Chen, Wan; Bhartia, P. K. (Technical Monitor)

2002-01-01

Estimates made in the 1970's indicated that a supernova occurring within tens of parsecs of Earth could have significant effects on the ozone layer. Since that time improved tools for detailed modeling of atmospheric chemistry have been developed to calculate ozone depletion, and advances have been made also in theoretical modeling of supernovae and of the resultant gamma ray spectra. In addition, one now has better knowledge of the occurrence rate of supernovae in the galaxy, and of the spatial distribution of progenitors to core-collapse supernovae. We report here the results of two-dimensional atmospheric model calculations that take as input the spectral energy distribution of a supernova, adopting various distances from Earth and various latitude impact angles. In separate simulations we calculate the ozone depletion due to both gamma rays and cosmic rays. We find that for the combined ozone depletion from these effects roughly to double the 'biologically active' UV flux received at the surface of the Earth, the supernova must occur at approximately or less than 8 parsecs.

Supernova Cosmology Project

Science.gov Websites

, 2014 The Supernova Cosmology Project and High-Z Team share the 2015 Breakthrough Prize in Fundamental Perlmutter, leader of the international Supernova Cosmology Project, and principal investigator of the

On relative supernova rates and nucleosynthesis roles

NASA Technical Reports Server (NTRS)

Arnett, W. David; Schramm, David N.; Truran, James W.

1988-01-01

It is shown that the Ni-56-Fe-56 observed in SN 1987A argues that core collapse supernovae may be responsible for more that 50 percent of the iron in the galaxy. Furthermore it is argued that the time averaged rate of thermonuclear driven Type I supernovae may be at least an order of magnitude lower than the average rate of core collapse supernovae. The present low rate of Type II supernovae (below their time averaged rate of approx. 1/10 yr) is either because the past rate was much higher because many core collapse supernovae are dim like SN 1987A. However, even in this latter case they are only an order of magnitude dimmer that normal Type II's due to the contribution of Ni-56 decay to the light curve.

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.

Supernovae and cosmology with future European facilities.

PubMed

Hook, I M

2013-06-13

Prospects for future supernova surveys are discussed, focusing on the European Space Agency's Euclid mission and the European Extremely Large Telescope (E-ELT), both expected to be in operation around the turn of the decade. Euclid is a 1.2 m space survey telescope that will operate at visible and near-infrared wavelengths, and has the potential to find and obtain multi-band lightcurves for thousands of distant supernovae. The E-ELT is a planned, general-purpose ground-based, 40-m-class optical-infrared telescope with adaptive optics built in, which will be capable of obtaining spectra of type Ia supernovae to redshifts of at least four. The contribution to supernova cosmology with these facilities will be discussed in the context of other future supernova programmes such as those proposed for DES, JWST, LSST and WFIRST.

Late formation of silicon carbide in type II supernovae

PubMed Central

Liu, Nan; Nittler, Larry R.; Alexander, Conel M. O’D.; Wang, Jianhua

2018-01-01

We have found that individual presolar silicon carbide (SiC) dust grains from supernovae show a positive correlation between 49Ti and 28Si excesses, which is attributed to the radioactive decay of the short-lived (t½ = 330 days) 49V to 49Ti in the inner highly 28Si-rich Si/S zone. The 49V-49Ti chronometer shows that these supernova SiC dust grains formed at least 2 years after their parent stars exploded. This result supports recent dust condensation calculations that predict a delayed formation of carbonaceous and SiC grains in supernovae. The astronomical observation of continuous buildup of dust in supernovae over several years can, therefore, be interpreted as a growing addition of C-rich dust to the dust reservoir in supernovae. PMID:29376119

How supernovae became the basis of observational cosmology

NASA Astrophysics Data System (ADS)

Pruzhinskaya, Maria Victorovna; Lisakov, Sergey Mikhailovich

2016-12-01

This paper is dedicated to the discovery of one of the most important relationships in supernova cosmology - the relation between the peak luminosity of Type Ia supernovae and their luminosity decline rate after maximum light. The history of this relationship is quite long and interesting. The relationship was independently discovered by the American statistician and astronomer Bert Woodard Rust and the Soviet astronomer Yury Pavlovich Pskovskii in the 1970s. Using a limited sample of Type I supernovae they were able to show that the brighter the supernova is, the slower its luminosity declines after maximum. Only with the appearance of CCD cameras could Mark Phillips re-inspect this relationship on a new level of accuracy using a better sample of supernovae. His investigations confirmed the idea proposed earlier by Rust and Pskovskii.

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.

A well-balanced finite volume scheme for the Euler equations with gravitation. The exact preservation of hydrostatic equilibrium with arbitrary entropy stratification

NASA Astrophysics Data System (ADS)

Käppeli, R.; Mishra, S.

2016-03-01

Context. Many problems in astrophysics feature flows which are close to hydrostatic equilibrium. However, standard numerical schemes for compressible hydrodynamics may be deficient in approximating this stationary state, where the pressure gradient is nearly balanced by gravitational forces. Aims: We aim to develop a second-order well-balanced scheme for the Euler equations. The scheme is designed to mimic a discrete version of the hydrostatic balance. It therefore can resolve a discrete hydrostatic equilibrium exactly (up to machine precision) and propagate perturbations, on top of this equilibrium, very accurately. Methods: A local second-order hydrostatic equilibrium preserving pressure reconstruction is developed. Combined with a standard central gravitational source term discretization and numerical fluxes that resolve stationary contact discontinuities exactly, the well-balanced property is achieved. Results: The resulting well-balanced scheme is robust and simple enough to be very easily implemented within any existing computer code that solves time explicitly or implicitly the compressible hydrodynamics equations. We demonstrate the performance of the well-balanced scheme for several astrophysically relevant applications: wave propagation in stellar atmospheres, a toy model for core-collapse supernovae, convection in carbon shell burning, and a realistic proto-neutron star.

Neutron Stars in Supernova Remnants and Beyond

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

We discuss a concept of off-centred cavity supernova explosion as applied to neutron star/supernova remnant associations and show how this concept could be used to preclude the anti-humane decapitating the Duck (G5.4-1.2 + G5.27-0.9) and dismembering the Swan (Cygnus Loop), as well as to search for a stellar remnant associated with the supernova remnant RCW86.

Semi-supervised learning for photometric supernova classification

NASA Astrophysics Data System (ADS)

Richards, Joseph W.; Homrighausen, Darren; Freeman, Peter E.; Schafer, Chad M.; Poznanski, Dovi

2012-01-01

We present a semi-supervised method for photometric supernova typing. Our approach is to first use the non-linear dimension reduction technique diffusion map to detect structure in a data base of supernova light curves and subsequently employ random forest classification on a spectroscopically confirmed training set to learn a model that can predict the type of each newly observed supernova. We demonstrate that this is an effective method for supernova typing. As supernova numbers increase, our semi-supervised method efficiently utilizes this information to improve classification, a property not enjoyed by template-based methods. Applied to supernova data simulated by Kessler et al. to mimic those of the Dark Energy Survey, our methods achieve (cross-validated) 95 per cent Type Ia purity and 87 per cent Type Ia efficiency on the spectroscopic sample, but only 50 per cent Type Ia purity and 50 per cent efficiency on the photometric sample due to their spectroscopic follow-up strategy. To improve the performance on the photometric sample, we search for better spectroscopic follow-up procedures by studying the sensitivity of our machine-learned supernova classification on the specific strategy used to obtain training sets. With a fixed amount of spectroscopic follow-up time, we find that, despite collecting data on a smaller number of supernovae, deeper magnitude-limited spectroscopic surveys are better for producing training sets. For supernova Ia (II-P) typing, we obtain a 44 per cent (1 per cent) increase in purity to 72 per cent (87 per cent) and 30 per cent (162 per cent) increase in efficiency to 65 per cent (84 per cent) of the sample using a 25th (24.5th) magnitude-limited survey instead of the shallower spectroscopic sample used in the original simulations. When redshift information is available, we incorporate it into our analysis using a novel method of altering the diffusion map representation of the supernovae. Incorporating host redshifts leads to a 5 per cent improvement in Type Ia purity and 13 per cent improvement in Type Ia efficiency. A web service for the supernova classification method used in this paper can be found at .

Recent Hubble Space Telescope Imaging of the Light Echoes of Supernova 2014J in M 82 and Supernova 2016adj in Centaurus A

NASA Astrophysics Data System (ADS)

Lawrence, Stephen S.; Hyder, Ali; Sugerman, Ben; Crotts, Arlin P. S.

2017-06-01

We report on our ongoing use of Hubble Space Telescope (HST) imaging to monitor the scattered light echoes of recent heavily-extincted supernovae in two nearby, albeit unusual, galaxies.Supernova 2014J was a highly-reddened Type Ia supernova that erupted in the nearby irregular star-forming galaxy M 82 in 2014 January. It was discovered to have light echo by Crotts (2016) in early epoch HST imaging and has been further described by Yang, et al. (2017) based on HST imaging through late 2014. Our ongoing monitoring in the WFC3 F438W, F555W, and F814W filters shows that, consistent with Crotts (2106) and Yang, et al. (2017), throughout 2015 and 2016 the main light echo arc expanded through a dust complex located approximately 230 pc in the foreground of the supernova. This main light echo has, however, faded dramatically in our most recent HST imaging from 2017 March. The supernova itself has also faded to undetectable levels by 2017 March.Supernova 2016adj is a highly-reddened core-collapse supernova that erupted inside the unusual dust lane of the nearby giant elliptical galaxy Centaurus A (NGC 5128) in 2016 February. It was discovered to have a light echo by Sugerman & Lawrence (2016) in early epoch HST imaging in 2016 April. Our ongoing monitoring in the WFC3 F438W, F547M, and F814W filters shows a slightly elliptical series of light echo arc segments hosted by a tilted dust complex ranging approximately 150--225 pc in the foreground of the supernova. The supernova itself has also faded to undetectable levels by 2017 April.References: Crotts, A. P. S., ApJL, 804, L37 (2016); Yang et al., ApJ, 834, 60 (2017); Sugerman, B. and Lawrence, S., ATel #8890 (2016).

Walter Baade, Fritz Zwicky, and Rudolph Minkowski's Early Supernova Research, 1927 - 1973

NASA Astrophysics Data System (ADS)

Osterbrock, D. E.

1999-12-01

Long before he ``discovered" the two stellar populations, Walter Baade was a pioneer in research on supernovae and their remnants. In 1927, while still in Germany, Baade emphasized what he called ``Hauptnovae" (chief novae) as highly luminous, potential distance indicators. He joined the Mount Wilson staff in 1931, bringing the ``secret" of the Schmidt camera with him, and encouraged Fritz Zwicky to carry out a supernova search with one at Palomar. Baade and Zwicky used the term ``supernova" in their 1933 joint paper. Zwicky began a systematic search in 1936, and Baade followed up with the 100-in reflector to derive light curves. He confirmed that Tycho's ``nova" of 1572 and the Crab nebula had been supernovae in our Galaxy. Baade advised N. U. Mayall, at Lick, on his spectroscopic study of the Crab nebula. In 1933, after Hitler came to power, Rudolph Minkowski had to leave Germany. Baade managed to get him a Mount Wilson staff position. Minkowski then did the spectroscopic observations of supernovae, beginning in 1937. Within a few years he and Baade were able to distinguish type I and II supernovae. Baade's further work on supernovae included historical research in Latin, Italian, and German, as well as filter photography. He searched hard for a remnant of SN 1885 in M 31, but never succeeded in finding it. After World War II the Crab nebula was found to be a strong radio source, and Baade and Minkowski used the 200-in to identify other supernova remnants, beginning with Cas A. Baade collaborated closely with Jan Oort and his student, Lo Woltjer, in their studies of the Crab nebula. After Baade retired in 1958, Minkowski continued supernova research for more than a decade; one of his favorite objects was the expanding Cygnus Loop.

Supernova 1987A: The Supernova of a Lifetime

NASA Astrophysics Data System (ADS)

Kirshner, Robert

2017-01-01

Supernova 1987A, the brightest supernova since Kepler's in 1604, was detected 30 years ago at a distance of 160 000 light years in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. Visible with the naked eye and detected with the full range of technology constructed since Kepler's time, SN 1987A has continued to be a rich source of empirical information to help understand supernova explosions and their evolution into supernova remnants. While the light output has faded by a factor of 10 000 000 over those 30 years, instrumentation, like the Hubble Space Telescope, the Chandra X-ray Observatory, and the Atacama Large Millimeter Array has continued to improve so that this supernova continues to be visible in X-rays, ultraviolet light, visible light, infrared light and in radio emission. In this review, I will sketch what has been learned from these observations about the pre-supernova star and its final stages of evolution, the explosion physics, the energy sources for emission, and the shock physics as the expanding debris encounters the circumstellar ring that was created about 20 000 years before the explosion. Today, SN 1987A is making the transition to a supernova remnant- the energetics are no longer dominated by the radioactive elements produced in the explosion, but by the interaction of the expanding debris with the surrounding gas. While we are confident that the supernova explosion had its origin in gravitational collapse, careful searches for a compact object at the center of the remnant place upper limits of a few solar luminosities on that relic. Support for HST GO programs 13401 and 13405 was provided by NASA through grants from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

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.

Lensed Type Ia supernovae as probes of cluster mass models

Science.gov Websites

SAO/NASA ADS Astronomy Abstract Service Title: Lensed Type Ia supernovae as probes of cluster mass Origin: OUP Astronomy Keywords: gravitational lensing: strong, supernovae: general, galaxies: clusters

Supernova Remnant Kes 17: An Efficient Cosmic Ray Accelerator inside a Molecular Cloud

NASA Astrophysics Data System (ADS)

Gelfand, Joseph; Slane, Patrick; Hughes, John; Temim, Tea; Castro, Daniel; Rakowski, Cara

Supernova remnant are believed to be the dominant source of cosmic rays protons below the "knee" in the energy spectrum. However, relatively few supernova remnants have been identified as efficient producers of cosmic ray protons. In this talk, I will present evidence that the production of cosmic ray protons is required to explain the broadband non-thermal spectrum of supernova remnant Kes 17 (SNR G304.6+0.1). Evidence for efficient cosmic ray acceleration in Kes 17 supports recent theoretical work concluding that the strong magnetic field, turbulence, and clumpy nature of molecular clouds enhance cosmic ray production in supernova remnants. While additional observations are needed to confirm this interpretation, further study of Kes 17 and similar sources are important for understanding how cosmic rays are accelerated in supernova remnants.

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

The VLT Measures the Shape of a Type Ia Supernova

NASA Astrophysics Data System (ADS)

2003-08-01

First Polarimetric Detection of Explosion Asymmetry has Cosmological Implications Summary An international team of astronomers [2] has performed new and very detailed observations of a supernova in a distant galaxy with the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). They show for the first time that a particular type of supernova, caused by the explosion of a "white dwarf", a dense star with a mass around that of the Sun, is asymmetric during the initial phases of expansion . The significance of this observation is much larger than may seem at a first glance . This particular kind of supernova, designated "Type Ia", plays a very important role in the current attempts to map the Universe. It has for long been assumed that Type Ia supernovae all have the same intrinsic brightness , earning them a nickname as "standard candles". If so, differences in the observed brightness between individual supernovae of this type simply reflect their different distances. This, and the fact that the peak brightness of these supernovae rivals that of their parent galaxy, has allowed to measure distances of even very remote galaxies . Some apparent discrepancies that were recently found have led to the discovery of cosmic acceleration . However, this first clearcut observation of explosion asymmetry in a Type Ia supernova means that the exact brightness of such an object will depend on the angle from which it is seen. Since this angle is unknown for any particular supernova, this obviously introduces an amount of uncertainty into this kind of basic distance measurements in the Universe which must be taken into account in the future. Fortunately, the VLT data also show that if you wait a little - which in observational terms makes it possible to look deeper into the expanding fireball - then it becomes more spherical. Distance determinations of supernovae that are performed at this later stage will therefore be more accurate. PR Photo 24a/03 : Spiral galaxy NGC 1448 and SN 2001el (DSS and NTT/EMMI). PR Photo 24b/03 : Optical spectrum of SN 2001el and fractional polarisation (VLT/FORS) Supernova explosions and cosmic distances During Type Ia supernova events, remnants of stars with an initial mass of up to a few times that of the Sun (so-called "white dwarf stars") explode, leaving nothing behind but a rapidly expanding cloud of "stardust". Type Ia supernovae are apparently quite similar to one another. This provides them a very useful role as "standard candles" that can be used to measure cosmic distances. Their peak brightness rivals that of their parent galaxy, hence qualifying them as prime cosmic yardsticks. Astronomers have exploited this fortunate circumstance to study the expansion history of our Universe. They recently arrived at the fundamental conclusion that the Universe is expanding at an accelerating rate, cf. ESO PR 21/98, December 1998 (see also the Supernova Acceleration Probe web page). The explosion of a white dwarf star In the most widely accepted models of Type Ia supernovae the pre-explosion white dwarf star orbits a solar-like companion star, completing a revolution every few hours. Due to the close interaction, the companion star continuously loses mass, part of which is picked up (in astronomical terminology: "accreted") by the white dwarf. A white dwarf represents the penultimate stage of a solar-type star. The nuclear reactor in its core has run out of fuel a long time ago and is now inactive. However, at some point the mounting weight of the accumulating material will have increased the pressure inside the white dwarf so much that the nuclear ashes in there will ignite and start burning into even heavier elements. This process very quickly becomes uncontrolled and the entire star is blown to pieces in a dramatic event. An extremely hot fireball is seen that often outshines the host galaxy. The shape of the explosion Although all supernovae of Type Ia have quite similar properties, it has never been clear until now how similar such an event would appear to observers who view it from different directions. All eggs look similar and indistinguishable from each other when viewed from the same angle, but the side view (oval) is obviously different from the end view (round). And indeed, if Type Ia supernova explosions were asymmetric, they would shine with different brightness in different directions. Observations of different supernovae - seen under different angles - could therefore not be directly compared. Not knowing these angles, however, the astronomers would then infer incorrect distances and the precision of this fundamental method for gauging the structure of the Universe would be in question. Polarimetry to the rescue A simple calculation shows that even to the eagle eyes of the VLT Interferometer (VLTI), all supernovae at cosmological distances will appear as unresolved points of light; they are simply too far. But there is another way to determine the angle at which a particular supernova is viewed: polarimetry is the name of the trick! Polarimetry works as follows: light is composed of electromagnetic waves (or photons) which oscillate in certain directions (planes). Reflection or scattering of light favours certain orientations of the electric and magnetic fields over others. This is why polarising sunglasses can filter out the glint of sunlight reflecting off a pond. When light scatters through the expanding debris of a supernova, it retains information about the orientation of the scattering layers. If the supernova is spherically symmetric, all orientations will be present equally and will average out, so there will be no net polarisation . If, however, the gas shell is not round, a slight net polarisation will be imprinted on the light. " Even for quite noticable asymmetries, however, the polarisation is very small and barely exceeds the level of one percent ", says Dietrich Baade, ESO astronomer and a member of the team that performed the observations. " Measuring them requires an instrument that is very sensitive and very stable . " The VLT observation of SN 2001el in NGC 1448 ESO PR Photo 24a/03 ESO PR Photo 24a/03 [Preview - JPEG: 620 x 400 pix - 156k [Normal - JPEG: 1240 x 800 pix - 396k] ESO PR Photo 24b/03 ESO PR Photo 24b/03 [Preview - JPEG: 400 x 524 pix - 104k [Normal - JPEG: 800 x 1047 pix - 240k] Captions : PR Photo 24a/03 shows the spiral galaxy NGC 1448, as seen in an archive image from the Digital Sky Survey (Courtesy of STScI) and as seen close to the brightness maximum of the supernova using EMMI on the NTT. SN 2001el is marked by the arrow. The field measures 4.5 x 4.5 arcmin 2 ; North is up and east is right. PR Photo 24b/03 illustrates the optical spectrum of SN 2001el in NGC 1448 (upper panel). The middle and lower panels show the corresponding fractional polarisations. They measure the different numbers of photons oscillating in perpendicular directions; they are directly related to the geometry of the supernova. The shaded area indicates the spectral signatures of high-velocity matter in the expanding envelope. The measurement in faint and distant light sources of differences at a level of less than one percent is a considerable observational challenge. "However, the ESO Very Large Telescope (VLT) offers the precision, the light collecting power, as well as the specialized instrumentation required for such a demanding polarimetric observation" , explains Dietrich Baade . "But this project would not have been possible without the VLT being operated in service mode. It is indeed impossible to predict when a supernova will explode and we need to be ready all the time. Only service mode allows observations at short notice. Some years ago, it was a farsighted and courageous decision by ESO's directorate to put so much emphasis on Service Mode. And it was the team of competent and devoted ESO astronomers on Paranal who made this concept a practical success" , he adds. The astronomers [1] used the VLT multi-mode FORS1 instrument to observe SN 2001el , a Type Ia supernova that was discovered in September 2001 in the galaxy NGC 1448, cf. PR Photo 24a/03 at a distance of 60 million light-years. Observations obtained about a week before this supernova reached maximum brightness around October 2 revealed polarisation at levels of 0.2-0.3% ( PR Photo 24b/03 ). Near maximum light and up to two weeks thereafter, the polarisation was still measurable. Six weeks after maximum, the polarisation had dropped below detectability. This is the first time ever that a normal Type Ia supernova has been found to exhibit such clear-cut evidence of asymmetry . Looking deeper into the supernova Immediately following the supernova explosion, most of the expelled matter moves at velocities around 10,000 km/sec. During this expansion, the outermost layers become progressively more transparent. With time one can thus look deeper and deeper into the supernova. The polarisation measured in SN 2001el therefore provides evidence that the outermost parts of the supernova (which are first seen) are significantly asymmetric . Later, when the VLT observations "penetrate" deeper towards the heart of the supernova, the explosion geometry is increasingly more symmetric. If modeled in terms of a flattened spheroidal shape, the measured polarisation in SN 2001el implies a minor-to-major axis ratio of around 0.9 before maximum brightness is reached and a spherically symmetric geometry from about one week after this maximum and onward. Cosmological implications One of the key parameters on which Type Ia distance estimates are based is the optical brightness at maximum. The measured asphericity at this moment would introduce an absolute brightness uncertainty (dispersion) of about 10% if no correction were made for the viewing angle (which is not known). While Type Ia supernovae are by far the best standard candles for measuring cosmological distances, and hence for investigating the so-called dark energy, a small measurement uncertainty persists. " The asymmetry we have measured in SN 2001el is large enough to explain a large part of this intrinsic uncertainty ", says Lifan Wang, the leader of the team. " If all Type Ia supernovae are like this, it would account for a lot of the dispersion in brightness measurements. They may be even more uniform than we thought ." Reducing the dispersion in brightness measurements could of course also be attained by increasing significantly the number of supernovae we observe, but given that these measurements demand the largest and most expensive telescopes in the world, like the VLT, this is not the most efficient method. Thus, if the brightness measured a week or two after maximum was used instead, the sphericity would then have been restored and there would be no systematic errors from the unknown viewing angle. By this slight change in observational procedure, Type Ia supernovae could become even more reliable cosmic yardsticks. Theoretical implications The present detection of polarised spectral features strongly suggests that, to understand the underlying physics, the theoretical modelling of Type Ia supernovae events will have to be done in all three dimensions with more accuracy than is presently done. In fact, the available, highly complex hydrodynamic calculations have so far not been able to reproduce the structures exposed by SN 2001el. More information The results presented in this press release have been been described in a research paper in "Astrophysical Journal" ("Spectropolarimetry of SN 2001el in NGC 1448: Asphericity of a Normal Type Ia Supernova" by Lifan Wang and co-authors, Volume 591, p. 1110).

A Classical and a Relativistic Law of Motion for Spherical Supernovae

NASA Astrophysics Data System (ADS)

Zaninetti, Lorenzo

2014-11-01

In this paper we derive some first order differential equations which model the classical and the relativistic thin layer approximations. The circumstellar medium is assumed to follow a density profile of the Plummer type, the Lane-Emden (n = 5) type, or a power law. The first order differential equations are solved analytically, numerically, by a series expansion, or by recursion. The initial conditions are chosen in order to model the temporal evolution of SN 1993J over 10 yr and a smaller chi-squared is obtained for the Plummer case with η = 6. The stellar mass ejected by the SN progenitor prior to the explosion, expressed in solar mass, is identified with the total mass associated with the selected density profile and varies from 0.217 to 0.402 when the central number density is 107 particles per cubic centimeter. The FWHM of the three density profiles, which can be identified with the size of the pre-SN 1993J envelope, varies from 0.0071 pc to 0.0092 pc.

Kadomtsev-Petviashvili solitons propagation in a plasma system with superthermal and weakly relativistic effects

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

Hafeez-Ur-Rehman; Mahmood, S.; Department of Physics and Applied Mathematics, PIEAS, Nilore, 44000 Islamabad

2011-12-15

Two dimensional (2D) solitons are studied in a plasma system comprising of relativistically streaming ions, kappa distributed electrons, and positrons. Kadomtsev-Petviashvili (KP) equation is derived through the reductive perturbation technique. Analytical solution of the KP equation has been studied numerically and graphically. It is noticed that kappa parameters of electrons and positrons as well as the ions relativistic streaming factor have an emphatic influence on the structural as well as propagation characteristics of two dimensional solitons in the considered plasma system. Our results may be helpful in the understanding of soliton propagation in astrophysical and laboratory plasmas, specifically the interactionmore » of pulsar relativistic wind with supernova ejecta and the transfer of energy to plasma by intense electric field of laser beams producing highly energetic superthermal and relativistic particles [L. Arons, Astrophys. Space Sci. Lib. 357, 373 (2009); P. Blasi and E. Amato, Astrophys. Space Sci. Proc. 2011, 623; and A. Shah and R. Saeed, Plasma Phys. Controlled Fusion 53, 095006 (2011)].« less

Planck satellite constraints on pseudo-Nambu-Goldstone boson quintessence

NASA Astrophysics Data System (ADS)

Smer-Barreto, Vanessa; Liddle, Andrew R.

2017-01-01

The pseudo-Nambu-Goldstone Boson (PNGB) potential, defined through the amplitude M4 and width f of its characteristic potential V(phi) = M4[1 + cos(phi/f)], is one of the best-suited models for the study of thawing quintessence. We analyse its present observational constraints by direct numerical solution of the scalar field equation of motion. Observational bounds are obtained using Supernovae data, cosmic microwave background temperature, polarization and lensing data from Planck, direct Hubble constant constraints, and baryon acoustic oscillations data. We find the parameter ranges for which PNGB quintessence gives a viable theory for dark energy. This exact approach is contrasted with the use of an approximate equation-of-state parametrization for thawing theories. We also discuss other possible parameterization choices, as well as commenting on the accuracy of the constraints imposed by Planck alone. Overall our analysis highlights a significant prior dependence to the outcome coming from the choice of modelling methodology, which current data are not sufficient to override.

Planck satellite constraints on pseudo-Nambu-Goldstone boson quintessence

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

Smer-Barreto, Vanessa; Liddle, Andrew R., E-mail: vsm@roe.ac.uk, E-mail: arl@roe.ac.uk

2017-01-01

The pseudo-Nambu-Goldstone Boson (PNGB) potential, defined through the amplitude M {sup 4} and width f of its characteristic potential V (φ) = M {sup 4}[1 + cos(φ/ f )], is one of the best-suited models for the study of thawing quintessence. We analyse its present observational constraints by direct numerical solution of the scalar field equation of motion. Observational bounds are obtained using Supernovae data, cosmic microwave background temperature, polarization and lensing data from Planck , direct Hubble constant constraints, and baryon acoustic oscillations data. We find the parameter ranges for which PNGB quintessence gives a viable theory for darkmore » energy. This exact approach is contrasted with the use of an approximate equation-of-state parametrization for thawing theories. We also discuss other possible parameterization choices, as well as commenting on the accuracy of the constraints imposed by Planck alone. Overall our analysis highlights a significant prior dependence to the outcome coming from the choice of modelling methodology, which current data are not sufficient to override.« less

The ASAS-SN bright supernova catalogue – I. 2013–2014

DOE PAGES

Holoien, T. W. -S.; Stanek, K. Z.; Kochanek, C. S.; ...

2016-09-12

We present basic statistics for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during its first year-and-a-half of operations, spanning 2013 and 2014. We also present the same information for all other bright (m V ≤ 17), spectroscopically confirmed supernovae discovered from 2014 May 1 through the end of 2014, providing a comparison to the ASAS-SN sample starting from the point where ASAS-SN became operational in both hemispheres. In addition, we present collected redshifts and near-UV through IR magnitudes, where available, for all host galaxies of the bright supernovae in both samples. This work represents a comprehensivemore » catalogue of bright supernovae and their hosts from multiple professional and amateur sources, allowing for population studies that were not previously possible because the all-sky emphasis of ASAS-SN redresses many previously existing biases. In particular, ASAS-SN systematically finds bright supernovae closer to the centres of host galaxies than either other professional surveys or amateurs, a remarkable result given ASAS-SN's poorer angular resolution. In conclusion, this is the first of a series of yearly papers on bright supernovae and their hosts that will be released by the ASAS-SN team.« less

Detectability of galactic supernova neutrinos coherently scattered on xenon nuclei in XMASS

NASA Astrophysics Data System (ADS)

Abe, K.; Hiraide, K.; Ichimura, K.; Kishimoto, Y.; Kobayashi, K.; Kobayashi, M.; Moriyama, S.; Nakagawa, K.; Nakahata, M.; Norita, T.; Ogawa, H.; Sekiya, H.; Takachio, O.; Takeda, A.; Yamashita, M.; Yang, B. S.; Kim, N. Y.; Kim, Y. D.; Tasaka, S.; Liu, J.; Martens, K.; Suzuki, Y.; Fujita, R.; Hosokawa, K.; Miuchi, K.; Oka, N.; Onishi, Y.; Takeuchi, Y.; Kim, Y. H.; Lee, J. S.; Lee, K. B.; Lee, M. K.; Fukuda, Y.; Itow, Y.; Kegasa, R.; Kobayashi, K.; Masuda, K.; Takiya, H.; Uchida, H.; Nishijima, K.; Fujii, K.; Murayama, I.; Nakamura, S.; Xmass Collaboration

2017-03-01

The coherent elastic neutrino-nucleus scattering (CEvNS) plays a crucial role at the final evolution of stars. The detection of it would be of importance in astroparticle physics. Among all available neutrino sources, galactic supernovae give the highest neutrino flux in the MeV range. Among all liquid xenon dark matter experiments, XMASS has the largest sensitive volume and light yield. The possibility to detect galactic supernova via the CEvNS-process on xenon nuclei in the current XMASS detector was investigated. The total number of events integrated in about 18 s after the explosion of a supernova 10 kpc away from the Earth was expected to be from 3.5 to 21.1, depending on the supernova model used to predict the neutrino flux, while the number of background events in the same time window was measured to be negligible. All lead to very high possibility to detect CEvNS experimentally for the first time utilizing the combination of galactic supernovae and the XMASS detector. In case of a supernova explosion as close as Betelgeuse, the total observable events can be more than ∼ 104, making it possible to distinguish different supernova models by examining the evolution of neutrino event rate in XMASS.

Atomic and molecular supernovae

NASA Technical Reports Server (NTRS)

Liu, Weihong

1997-01-01

Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the oxygen-rich clumps where the efficient molecular cooling makes the nucleation of dust grains possible. For Type Ia supernovae, the analyses of their nebular spectra lead to strong constraints on the supernova explosion models.

The double-degenerate, super-Chandrasekhar nucleus of the planetary nebula Henize 2-428.

PubMed

Santander-García, M; Rodríguez-Gil, P; Corradi, R L M; Jones, D; Miszalski, B; Boffin, H M J; Rubio-Díez, M M; Kotze, M M

2015-03-05

The planetary nebula stage is the ultimate fate of stars with masses one to eight times that of the Sun (M(⊙)). The origin of their complex morphologies is poorly understood, although several mechanisms involving binary interaction have been proposed. In close binary systems, the orbital separation is short enough for the primary star to overfill its Roche lobe as the star expands during the asymptotic giant branch phase. The excess gas eventually forms a common envelope surrounding both stars. Drag forces then result in the envelope being ejected into a bipolar planetary nebula whose equator is coincident with the orbital plane of the system. Systems in which both stars have ejected their envelopes and are evolving towards the white dwarf stage are said to be double degenerate. Here we report that Henize 2-428 has a double-degenerate core with a combined mass of ∼1.76M(⊙), which is above the Chandrasekhar limit (the maximum mass of a stable white dwarf) of 1.4M(⊙). This, together with its short orbital period (4.2 hours), suggests that the system should merge in 700 million years, triggering a type Ia supernova event. This supports the hypothesis of the double-degenerate, super-Chandrasekhar evolutionary pathway for the formation of type Ia supernovae.

A massive hypergiant star as the progenitor of the supernova SN 2005gl.

PubMed

Gal-Yam, A; Leonard, D C

2009-04-16

Our understanding of the evolution of massive stars before their final explosions as supernovae is incomplete, from both an observational and a theoretical standpoint. A key missing piece in the supernova puzzle is the difficulty of identifying and studying progenitor stars. In only a single case-that of supernova SN 1987A in the Large Magellanic Cloud-has a star been detected at the supernova location before the explosion, and been subsequently shown to have vanished after the supernova event. The progenitor of SN 1987A was a blue supergiant, which required a rethink of stellar evolution models. The progenitor of supernova SN 2005gl was proposed to be an extremely luminous object, but the association was not robustly established (it was not even clear that the putative progenitor was a single luminous star). Here we report that the previously proposed object was indeed the progenitor star of SN 2005gl. This very massive star was likely a luminous blue variable that standard stellar evolution predicts should not have exploded in that state.

Supernova Cosmology Inference with Probabilistic Photometric Redshifts (SCIPPR)

NASA Astrophysics Data System (ADS)

Peters, Christina; Malz, Alex; Hlozek, Renée

2018-01-01

The Bayesian Estimation Applied to Multiple Species (BEAMS) framework employs probabilistic supernova type classifications to do photometric SN cosmology. This work extends BEAMS to replace high-confidence spectroscopic redshifts with photometric redshift probability density functions, a capability that will be essential in the era the Large Synoptic Survey Telescope and other next-generation photometric surveys where it will not be possible to perform spectroscopic follow up on every SN. We present the Supernova Cosmology Inference with Probabilistic Photometric Redshifts (SCIPPR) Bayesian hierarchical model for constraining the cosmological parameters from photometric lightcurves and host galaxy photometry, which includes selection effects and is extensible to uncertainty in the redshift-dependent supernova type proportions. We create a pair of realistic mock catalogs of joint posteriors over supernova type, redshift, and distance modulus informed by photometric supernova lightcurves and over redshift from simulated host galaxy photometry. We perform inference under our model to obtain a joint posterior probability distribution over the cosmological parameters and compare our results with other methods, namely: a spectroscopic subset, a subset of high probability photometrically classified supernovae, and reducing the photometric redshift probability to a single measurement and error bar.

The Distant Type Ia Supernova Rate

DOE R&D Accomplishments Database

Pain, R.; Fabbro, S.; Sullivan, M.; Ellis, R. S.; Aldering, G.; Astier, P.; Deustua, S. E.; Fruchter, A. S.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hardin, D.; Hook, I. M.; Howell, D. A.; Irwin, M. J.; Kim, A. G.; Kim, M. Y.; Knop, R. A.; Lee, J. C.; Perlmutter, S.; Ruiz-Lapuente, P.; Schahmaneche, K.; Schaefer, B.; Walton, N. A.

2002-05-28

We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample, which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean red shift z {approx_equal} 0.55 of 1.53 {sub -0.25}{sub -0.31}{sup 0.28}{sup 0.32} x 10{sup -4} h{sup 3} Mpc{sup -3} yr{sup -1} or 0.58{sub -0.09}{sub -0.09}{sup +0.10}{sup +0.10} h{sup 2} SNu(1 SNu = 1 supernova per century per 10{sup 10} L{sub B}sun), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models.

Gauging the cosmic acceleration with recent type Ia supernovae data sets

NASA Astrophysics Data System (ADS)

Velten, Hermano; Gomes, Syrios; Busti, Vinicius C.

2018-04-01

We revisit a model-independent estimator for cosmic acceleration based on type Ia supernovae distance measurements. This approach does not rely on any specific theory for gravity, energy content, nor parametrization for the scale factor or deceleration parameter and is based on falsifying the null hypothesis that the Universe never expanded in an accelerated way. By generating mock catalogs of known cosmologies, we test the robustness of this estimator, establishing its limits of applicability. We detail the pros and cons of such an approach. For example, we find that there are specific counterexamples in which the estimator wrongly provides evidence against acceleration in accelerating cosmologies. The dependence of the estimator on the H0 value is also discussed. Finally, we update the evidence for acceleration using the recent UNION2.1 and Joint Light-Curve Analysis samples. Contrary to recent claims, available data strongly favor an accelerated expansion of the Universe in complete agreement with the standard Λ CDM model.

Ground-Level Ozone Following Astrophysical Ionizing Radiation Events: An Additional Biological Hazard?

PubMed

Thomas, Brian C; Goracke, Byron D

2016-01-01

Astrophysical ionizing radiation events such as supernovae, gamma-ray bursts, and solar proton events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in solar UV radiation at Earth's surface and in the upper levels of the ocean. Other work has also considered the potential impact of nitric acid rainout, concluding that no significant threat is likely. Not yet studied to date is the potential impact of ozone produced in the lower atmosphere following an ionizing radiation event. Ozone is a known irritant to organisms on land and in water and therefore may be a significant additional hazard. Using previously completed atmospheric chemistry modeling, we examined the amount of ozone produced in the lower atmosphere for the case of a gamma-ray burst and found that the values are too small to pose a significant additional threat to the biosphere. These results may be extended to other ionizing radiation events, including supernovae and extreme solar proton events.

XMM-Newton observations of the non-thermal supernova remnant HESS J1731-347 (G353.6-0.7)

NASA Astrophysics Data System (ADS)

Doroshenko, V.; Pühlhofer, G.; Bamba, A.; Acero, F.; Tian, W. W.; Klochkov, D.; Santangelo, A.

2017-12-01

We report on the analysis of XMM-Newton observations of the non-thermal shell-type supernova remnant HESS J1731-347 (G353.6-0.7). For the first time the complete remnant shell has been covered in X-rays, which allowed direct comparison with radio and TeV observations. We carried out a spatially resolved spectral analysis of XMM-Newton data and confirmed the previously reported non-thermal power-law X-ray spectrum of the source with negligible variations of spectral index across the shell. On the other hand, the X-ray absorption column is strongly variable and correlates with the CO emission thus confirming that the absorbing material must be in the foreground and reinforcing the previously suggested lower limit on distance. Finally, we find that the X-ray emission of the remnant is suppressed towards the Galactic plane, which points to lower shock velocities in this region, likely due to the interaction of the shock with the nearby molecular cloud.

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

Siverd, Robert J.; Stassun, Keivan G.; Pepper, Joshua

We report observations of the bright M82 supernova 2014J serendipitously obtained with the Kilodegree Extremely Little Telescope (KELT). The supernova (SN) was observed at high cadence for over 100 days, from pre-explosion, to early rise and peak times, through the secondary bump. The high cadence KELT data with high signal-to-noise ratio is completely unique for SN 2014J and for any other SNIa, with the exception of the (yet) unpublished Kepler data. Here, we report determinations of the SN explosion time and peak time. We also report measures of the ''smoothness'' of the light curve on timescales of minutes/hours never before probed,more » and we use this to place limits on energy produced from short-lived isotopes or inhomogeneities in the explosion or the circumstellar medium. From the non-observation of significant perturbations of the light curves, we derive a 3σ upper limit corresponding to 8.7 × 10{sup 36} erg  s{sup –1} for any such extra sources of luminosity at optical wavelengths.« less

Ultra-Bright Optical Transients Are Linked With Type Ic Supernovae

DTIC Science & Technology

2010-11-20

Station, Flagstaff, AZ 86001, USA Received 2010 August 16; accepted 2010 September 9; published 2010 October 25 ABSTRACT Recent searches by unbiased...wide-field surveys have uncovered a group of extremely luminous optical transients. The initial discoveries of SN 2005ap by the Texas Supernova Search ...supernova searches (e.g., the Texas Supernova Search ) or all-sky surveys, such as the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS), the

Diffuse neutrino supernova background as a cosmological test

NASA Astrophysics Data System (ADS)

Barranco, J.; Bernal, A.; Delepine, D.

2018-05-01

The future detection and measurement of the diffuse neutrino supernova background will provide us with information about supernova neutrino emission and the cosmic core-collapse supernova rate. Little has been said about the information that this measurement could give us about the expansion history of the Universe. The purpose of this article is to study the change of the predicted diffuse supernova neutrino background as a function of the cosmological model. In particular, we study three different models: the Λ–Cold Dark Matter model, the Logotropic universe and a bulk viscous matter-dominated universe. By fitting the free parameters of each model with the supernova Ia probe, we calculate the predicted number of events in these three models. We found that the spectra and number of events for the Λ–Cold dark matter model and the Logotropic model are almost indistinguishable, while a bulk viscous matter-dominated cosmological model predicts more events.

An enigmatic long-lasting gamma-ray burst not accompanied by a bright supernova.

PubMed

Della Valle, M; Chincarini, G; Panagia, N; Tagliaferri, G; Malesani, D; Testa, V; Fugazza, D; Campana, S; Covino, S; Mangano, V; Antonelli, L A; D'Avanzo, P; Hurley, K; Mirabel, I F; Pellizza, L J; Piranomonte, S; Stella, L

2006-12-21

Gamma-ray bursts (GRBs) are short, intense flashes of soft gamma-rays coming from the distant Universe. Long-duration GRBs (those lasting more than approximately 2 s) are believed to originate from the deaths of massive stars, mainly on the basis of a handful of solid associations between GRBs and supernovae. GRB 060614, one of the closest GRBs discovered, consisted of a 5-s hard spike followed by softer, brighter emission that lasted for approximately 100 s (refs 8, 9). Here we report deep optical observations of GRB 060614 showing no emerging supernova with absolute visual magnitude brighter than M(V) = -13.7. Any supernova associated with GRB 060614 was therefore at least 100 times fainter, at optical wavelengths, than the other supernovae associated with GRBs. This demonstrates that some long-lasting GRBs can either be associated with a very faint supernova or produced by different phenomena.

Type Ia supernova rate studies from the SDSS-II Supernova Study

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

Dilday, Benjamin

2008-08-01

The author presents new measurements of the type Ia SN rate from the SDSS-II Supernova Survey. The SDSS-II Supernova Survey was carried out during the Fall months (Sept.-Nov.) of 2005-2007 and discovered ~ 500 spectroscopically confirmed SNe Ia with densely sampled (once every ~ 4 days), multi-color light curves. Additionally, the SDSS-II Supernova Survey has discovered several hundred SNe Ia candidates with well-measured light curves, but without spectroscopic confirmation of type. This total, achieved in 9 months of observing, represents ~ 15-20% of the total SNe Ia discovered worldwide since 1885. The author describes some technical details of the SNmore » Survey observations and SN search algorithms that contributed to the extremely high-yield of discovered SNe and that are important as context for the SDSS-II Supernova Survey SN Ia rate measurements.« less

Astrophysics. Multiple images of a highly magnified supernova formed by an early-type cluster galaxy lens.

PubMed

Kelly, Patrick L; Rodney, Steven A; Treu, Tommaso; Foley, Ryan J; Brammer, Gabriel; Schmidt, Kasper B; Zitrin, Adi; Sonnenfeld, Alessandro; Strolger, Louis-Gregory; Graur, Or; Filippenko, Alexei V; Jha, Saurabh W; Riess, Adam G; Bradac, Marusa; Weiner, Benjamin J; Scolnic, Daniel; Malkan, Matthew A; von der Linden, Anja; Trenti, Michele; Hjorth, Jens; Gavazzi, Raphael; Fontana, Adriano; Merten, Julian C; McCully, Curtis; Jones, Tucker; Postman, Marc; Dressler, Alan; Patel, Brandon; Cenko, S Bradley; Graham, Melissa L; Tucker, Bradley E

2015-03-06

In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z = 0.54 elliptical galaxy in the MACS J1149.6+2223 cluster. The cluster's gravitational potential also creates multiple images of the z = 1.49 spiral supernova host galaxy, and a future appearance of the supernova elsewhere in the cluster field is expected. The magnifications and staggered arrivals of the supernova images probe the cosmic expansion rate, as well as the distribution of matter in the galaxy and cluster lenses. Copyright © 2015, American Association for the Advancement of Science.

Kepler Beyond Planets: Finding Exploding Stars (Type Ia Supernova from a White Dwarf Stealing Matter)

NASA Image and Video Library

2018-03-26

This frame from an animation shows a gigantic star exploding in a "core collapse" supernova. As atoms fuse inside the star, eventually the star can't support its own weight anymore. Gravity makes the star collapse on itself. Core collapse supernovae are called type Ib, Ic, or II depending on the chemical elements present. Stellar explosions forge and distribute materials that make up the world in which we live, and also hold clues to how fast the universe is expanding. By understanding supernovae, scientists can unlock mysteries that are key to what we are made of and the fate of our universe. But to get the full picture, scientists must observe supernovae from a variety of perspectives, especially in the first moments of the explosion. That's really difficult -- there's no telling when or where a supernova might happen next. An animation is available at https://photojournal.jpl.nasa.gov/catalog/PIA22352

UBVRIz LIGHT CURVES OF 51 TYPE II SUPERNOVAE

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

Galbany, Lluis; Hamuy, Mario; Jaeger, Thomas de

We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986–2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C and T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) frommore » maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.« less

UBVRIz Light Curves of 51 Type II Supernovae

NASA Astrophysics Data System (ADS)

Galbany, Lluís; Hamuy, Mario; Phillips, Mark M.; Suntzeff, Nicholas B.; Maza, José; de Jaeger, Thomas; Moraga, Tania; González-Gaitán, Santiago; Krisciunas, Kevin; Morrell, Nidia I.; Thomas-Osip, Joanna; Krzeminski, Wojtek; González, Luis; Antezana, Roberto; Wishnjewski, Marina; McCarthy, Patrick; Anderson, Joseph P.; Gutiérrez, Claudia P.; Stritzinger, Maximilian; Folatelli, Gastón; Anguita, Claudio; Galaz, Gaspar; Green, Elisabeth M.; Impey, Chris; Kim, Yong-Cheol; Kirhakos, Sofia; Malkan, Mathew A.; Mulchaey, John S.; Phillips, Andrew C.; Pizzella, Alessandro; Prosser, Charles F.; Schmidt, Brian P.; Schommer, Robert A.; Sherry, William; Strolger, Louis-Gregory; Wells, Lisa A.; Williger, Gerard M.

2016-02-01

We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986-2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.

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.

Design, characterization, and sensitivity of the supernova trigger system at Daya Bay

NASA Astrophysics Data System (ADS)

Wei, Hanyu; Lebanowski, Logan; Li, Fei; Wang, Zhe; Chen, Shaomin

2016-02-01

Providing an early warning of galactic supernova explosions from neutrino signals is important in studying supernova dynamics and neutrino physics. A dedicated supernova trigger system has been designed and installed in the data acquisition system at Daya Bay and integrated into the worldwide Supernova Early Warning System (SNEWS). Daya Bay's unique feature of eight identically-designed detectors deployed in three separate experimental halls makes the trigger system naturally robust against cosmogenic backgrounds, enabling a prompt analysis of online triggers and a tight control of the false-alert rate. The trigger system is estimated to be fully sensitive to 1987A-type supernova bursts throughout most of the Milky Way. The significant gain in sensitivity of the eight-detector configuration over a mass-equivalent single detector is also estimated. The experience of this online trigger system is applicable to future projects with spatially distributed detectors.

Rotational properties of hypermassive neutron stars from binary mergers

NASA Astrophysics Data System (ADS)

Hanauske, Matthias; Takami, Kentaro; Bovard, Luke; Rezzolla, Luciano; Font, José A.; Galeazzi, Filippo; Stöcker, Horst

2017-08-01

Determining the differential-rotation law of compact stellar objects produced in binary neutron stars mergers or core-collapse supernovae is an old problem in relativistic astrophysics. Addressing this problem is important because it impacts directly on the maximum mass these objects can attain and, hence, on the threshold to black-hole formation under realistic conditions. Using the results from a large number of numerical simulations in full general relativity of binary neutron star mergers described with various equations of state and masses, we study the rotational properties of the resulting hypermassive neutron stars. We find that the angular-velocity distribution shows only a modest dependence on the equation of state, thus exhibiting the traits of "quasiuniversality" found in other aspects of compact stars, both isolated and in binary systems. The distributions are characterized by an almost uniformly rotating core and a "disk." Such a configuration is significantly different from the j -constant differential-rotation law that is commonly adopted in equilibrium models of differentially rotating stars. Furthermore, the rest-mass contained in such a disk can be quite large, ranging from ≃0.03 M⊙ in the case of high-mass binaries with stiff equations of state, up to ≃0.2 M⊙ for low-mass binaries with soft equations of state. We comment on the astrophysical implications of our findings and on the long-term evolutionary scenarios that can be conjectured on the basis of our simulations.

Three Great Eyes on Kepler's Supernova Remnant

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site] Composite

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Chandra X-Ray Data (blue) Chandra X-Ray Data (green)Hubble Telescope (visible-light)Spitzer Telescope (infrared)

NASA's three Great Observatories -- the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory -- joined forces to probe the expanding remains of a supernova, called Kepler's supernova remnant, first seen 400 years ago by sky watchers, including astronomer Johannes Kepler.

The combined image unveils a bubble-shaped shroud of gas and dust that is 14 light-years wide and is expanding at 4 million miles per hour (2,000 kilometers per second). Observations from each telescope highlight distinct features of the supernova remnant, a fast-moving shell of iron-rich material from the exploded star, surrounded by an expanding shock wave that is sweeping up interstellar gas and dust.

Each color in this image represents a different region of the electromagnetic spectrum, from X-rays to infrared light. These diverse colors are shown in the panel of photographs below the composite image. The X-ray and infrared data cannot be seen with the human eye. By color-coding those data and combining them with Hubble's visible-light view, astronomers are presenting a more complete picture of the supernova remnant.

Visible-light images from the Hubble telescope (colored yellow) reveal where the supernova shock wave is slamming into the densest regions of surrounding gas. The bright glowing knots are dense clumps from instabilities that form behind the shock wave. The Hubble data also show thin filaments of gas that look like rippled sheets seen edge-on. These filaments reveal where the shock wave is encountering lower-density, more uniform interstellar material.

The Spitzer telescope shows microscopic dust particles (colored red) that have been heated by the supernova shock wave. The dust re-radiates the shock wave's energy as infrared light. The Spitzer data are brightest in the regions surrounding those seen in detail by the Hubble telescope.

The Chandra X-ray data show regions of very hot gas, and extremely high-energy particles. The hottest gas (higher-energy X-rays, colored blue) is located primarily in the regions directly behind the shock front. These regions also show up in the Hubble observations, and also align with the faint rim of glowing material seen in the Spitzer data. The X-rays from the region on the lower left (colored blue) may be dominated by extremely high-energy electrons that were produced by the shock wave and are radiating at radio through X-ray wavelengths as they spiral in the intensified magnetic field behind the shock front. Cooler X-ray gas (lower-energy X-rays, colored green) resides in a thick interior shell and marks the location of heated material expelled from the exploded star.

Kepler's supernova, the last such object seen to explode in our Milky Way galaxy, resides about 13,000 light-years away in the constellation Ophiuchus.

The Chandra observations were taken in June 2000, the Hubble in August 2003; and the Spitzer in August 2004.

Discovery of a Supernova Explosion at Half the Age of the Universe and its Cosmological Implications

DOE R&D Accomplishments Database

Perlmutter, S.; Aldering, G.; Della Valle, M.; Deustua, S.; Ellis, R. S.; Fabbro, S.; Fruchter, A.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hook, I. M.; Kim, A. G.; Kim, M. Y.; Knop, R. A.; Lidman, C.; McMahon, R. G.; Nugent, P.; Pain, R.; Panagia, N.; Pennypacker, C. R.; Ruiz-Lapuente, P.; Schaefer, B.; Walton, N.

1997-12-16

The ultimate fate of the universe, infinite expansion or a big crunch, can be determined by measuring the redshifts, apparent brightnesses, and intrinsic luminosities of very distant supernovae. Recent developments have provided tools that make such a program practicable: (1) Studies of relatively nearby Type la supernovae (SNe la) have shown that their intrinsic luminosities can be accurately determined; (2) New research techniques have made it possible to schedule the discovery and follow-up observations of distant supernovae, producing well over 50 very distant (z = 0.3-0.7) SNe Ia to date. These distant supernovae provide a record of changes in the expansion rate over the past several billion years. By making precise measurements of supernovae at still greater distances, and thus extending this expansion history back far enough in time, we can even distinguish the slowing caused by the gravitational attraction of the universe's mass density {Omega}{sub M} from the effect of a possibly inflationary pressure caused by a cosmological constant {Lambda}. We report here the first such measurements, with our discovery of a Type Ia supernova (SN 1997ap) at z = 0.83. Measurements at the Keck II 10-m telescope make this the most distant spectroscopically confirmed supernova. Over two months of photometry of SN 1997ap with the Hubble Space Telescope and ground-based telescopes, when combined with previous measurements of nearer SNe la, suggests that we may live in a low mass-density universe. Further supernovae at comparable distances are currently scheduled for ground and space-based observations.

The past, present and future supernova threat to Earth's biosphere

NASA Astrophysics Data System (ADS)

Beech, Martin

2011-12-01

A brief review of the threat posed to Earth's biosphere via near-by supernova detonations is presented. The expected radiation dosage, cosmic ray flux and expanding blast wave collision effects are considered, and it is argued that a typical supernova must be closer than ˜10-pc before any appreciable and potentially harmful atmosphere/biosphere effects are likely to occur. In contrast, the critical distance for Gamma-ray bursts is of order 1-kpc. In spite of the high energy effects potentially involved, the geological record provides no clear-cut evidence for any historic supernova induced mass extinctions and/or strong climate change episodes. This, however, is mostly a reflection of their being numerous possible (terrestrial and astronomical) forcing mechanisms acting upon the biosphere and the difficulty of distinguishing between competing scenarios. Key to resolving this situation, it is suggested, is the development of supernova specific extinction and climate change linked ecological models. Moving to the future, we estimate that over the remaining lifetime of the biosphere (˜2 Gyr) the Earth might experience 1 GRB and 20 supernova detonations within their respective harmful threat ranges. There are currently at least 12 potential pre-supernova systems within 1-kpc of the Sun. Of these systems IK Pegasi is the closest Type Ia pre-supernova candidate and Betelgeuse is the closest potential Type II supernova candidate. We review in some detail the past, present and future behavior of these two systems. Developing a detailed evolutionary model we find that IK Pegasi will likely not detonate until some 1.9 billion years hence, and that it affords absolutely no threat to Earth's biosphere. Betelgeuse is the closest, reasonably well understood, pre-supernova candidate to the Sun at the present epoch, and may undergo detonation any time within the next several million years. The stand-off distance of Betelgeuse at the time of its detonation is estimated to fall between 150 and 300-pc—again, affording no possible threat to Earth's biosphere. Temporally, the next most likely, close, potential Type Ic supernova to the Sun is the Wolf-Rayet star within the γ 2 Velorum binary system located at least 260-pc away. It is suggested that evidence relating to large-scale astroengineering projects might fruitfully be looked for in those regions located within 10 to 30-pc of any pre-supernova candidate system.

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

Bailey, S.; Aldering, G.; Antilogus, P.

The use of Type Ia supernovae as distance indicators led to the discovery of the accelerating expansion of the universe a decade ago. Now that large second generation surveys have significantly increased the size and quality of the high-redshift sample, the cosmological constraints are limited by the currently available sample of ~50 cosmologically useful nearby supernovae. The Nearby Supernova Factory addresses this problem by discovering nearby supernovae and observing their spectrophotometric time development. Our data sample includes over 2400 spectra from spectral timeseries of 185 supernovae. This talk presents results from a portion of this sample including a Hubble diagrammore » (relative distance vs. redshift) and a description of some analyses using this rich dataset.« less

Revealing the supernova-gamma-ray burst connection with TeV neutrinos.

PubMed

Ando, Shin'ichiro; Beacom, John F

2005-08-05

Gamma-ray bursts (GRBs) are rare, powerful explosions displaying highly relativistic jets. It has been suggested that a significant fraction of the much more frequent core-collapse supernovae are accompanied by comparably energetic but mildly relativistic jets, which would indicate an underlying supernova-GRB connection. We calculate the neutrino spectra from the decays of pions and kaons produced in jets in supernovae, and show that the kaon contribution is dominant and provides a sharp break near 20 TeV, which is a sensitive probe of the conditions inside the jet. For a supernova at 10 Mpc, 30 events above 100 GeV are expected in a 10 s burst in the IceCube detector.

Preparatory studies for the WFIRST supernova cosmology measurements

NASA Astrophysics Data System (ADS)

Perlmutter, Saul

In the context of the WFIRST-AFTA Science Definition Team we developed a first version of a supernova program, described in the WFIRST-AFTA SDT report. This program uses the imager to discover supernova candidates and an Integral Field Spectrograph (IFS) to obtain spectrophotometric light curves and higher signal to noise spectra of the supernovae near peak to better characterize the supernovae and thus minimize systematic errors. While this program was judged a robust one, and the estimates of the sensitivity to the cosmological parameters were felt to be reliable, due to limitation of time the analysis was clearly limited in depth on a number of issues. The goal of this proposal is to further develop this program and refine the estimates of the sensitivities to the cosmological parameters using more sophisticated systematic uncertainty models and covariance error matrices that fold in more realistic data concerning observed populations of SNe Ia as well as more realistic instrument models. We propose to develop analysis algorithms and approaches that are needed to build, optimize, and refine the WFIRST instrument and program requirements to accomplish the best supernova cosmology measurements possible. We plan to address the following: a) Use realistic Supernova populations, subclasses and population drift. One bothersome uncertainty with the supernova technique is the possibility of population drift with redshift. We are in a unique position to characterize and mitigate such effects using the spectrophotometric time series of real Type Ia supernovae from the Nearby Supernova Factory (SNfactory). Each supernova in this sample has global galaxy measurements as well as additional local environment information derived from the IFS spectroscopy. We plan to develop methods of coping with this issue, e.g., by selecting similar subsamples of supernovae and allowing additional model flexibility, in order to reduce systematic uncertainties. These studies will allow us to tune details, like the wavelength coverage and S/N requirements, of the WFIRST IFS to capitalize on these systematic error reduction methods. b) Supernova extraction and host galaxy subtractions. The underlying light of the host galaxy must be subtracted from the supernova images making up the lightcurves. Using the IFS to provide the lightcurve points via spectrophotometry requires the subtraction of a reference spectrum of the galaxy taken after the supernova light has faded to a negligible level. We plan to apply the expertise obtained from the SNfactory to develop galaxy background procedures that minimize the systematic errors introduced by this step in the analysis. c) Instrument calibration and ground to space cross calibration. Calibrating the entire supernova sample will be a challenge as no standard stars exist that span the range of magnitudes and wavelengths relevant to the WFIRST survey. Linking the supernova measurements to the relatively brighter standards will require several links. WFIRST will produce the high redshift sample, but the nearby supernova to anchor the Hubble diagram will have to come from ground based observations. Developing algorithms to carry out the cross calibration of these two samples to the required one percent level will be an important goal of our proposal. An integral part of this calibration will be to remove all instrumental signatures and to develop unbiased measurement techniques starting at the pixel level. We then plan to pull the above studies together in a synthesis to produce a correlated error matrix. We plan to develop a Fisher Matrix based model to evaluate the correlated error matrix due to the various systematic errors discussed above. A realistic error model will allow us to carry out a more reliable estimates of the eventual errors on the measurement of the cosmological parameters, as well as serve as a means of optimizing and fine tuning the requirements for the instruments and survey strategies.

LIGO - The Laser Interferometer Gravitational-Wave Observatory

NASA Technical Reports Server (NTRS)

Abramovici, Alex; Althouse, William E.; Drever, Ronald W. P.; Gursel, Yekta; Kawamura, Seiji; Raab, Frederick J.; Shoemaker, David; Sievers, Lisa; Spero, Robert E.; Thorne, Kip S.

1992-01-01

The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics for gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses, birth rates, collisions, and distributions of black holes and neutron stars in the universe and probe the cores of supernovae and the very early universe. The technology for LIGO has been developed during the past 20 years. Construction will begin in 1992, and under the present schedule, LIGO's gravitational-wave searches will begin in 1998.

Detection of Broad Hα Emission Lines in the Late-time Spectra of a Hydrogen-poor Superluminous Supernova

NASA Astrophysics Data System (ADS)

Yan, Lin; Quimby, R.; Ofek, E.; Gal-Yam, A.; Mazzali, P.; Perley, D.; Vreeswijk, P. M.; Leloudas, G.; De Cia, A.; Masci, F.; Cenko, S. B.; Cao, Y.; Kulkarni, S. R.; Nugent, P. E.; Rebbapragada, Umaa D.; Woźniak, P. R.; Yaron, O.

2015-12-01

iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83-148 days to reach a peak bolometric luminosity of ˜1.3 × 1044 erg s-1, then decays slowly at 0.015 mag day-1. The measured ejecta velocity is ˜ 13,000 km s-1. The inferred explosion characteristics, such as the ejecta mass (70-220 M⊙), and the total radiative and kinetic energy (Erad ˜ 1051 erg, Ekin ˜ 2 × 1053 erg), are typical of slow-evolving H-poor SLSN events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer Hα emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ˜4500 km s-1 and a ˜300 km s-1 blueward shift relative to the narrow component. We interpret this broad Hα emission with a luminosity of ˜2 × 1041 erg s-1 as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ˜4 × 1016 cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ≤1, thus setting upper limits on the shell mass ≤30 M⊙. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 M⊙ H-shell, ejected from a progenitor star with an initial mass of (95-150) M⊙ about 40 years ago. We estimate that at least ˜15% of all SLSNe-I may have late-time Balmer emission lines.

Amplification and polarization of supernovae by gravitational lensing

NASA Technical Reports Server (NTRS)

Schneider, P.; Wagoner, Robert V.

1987-01-01

The gravitational lensing of supernovae by individual masses which could comprise the dark matter is analyzed. Detailed predictions of the amplification and polarization are presented, including effects of a galactic environment. Their time dependence is produced by the expansion of the supernovae beam within the lens. The fraction of supernovae which might thus be identified as being lensed in surveys at proposed limiting magnitudes is estimated. These two effects could provide the only known unique signature of microlensing.

Nebular phase observations of the Type-Ib supernova iPTF13bvn favour a binary progenitor

NASA Astrophysics Data System (ADS)

Kuncarayakti, H.; Maeda, K.; Bersten, M. C.; Folatelli, G.; Morrell, N.; Hsiao, E. Y.; González-Gaitán, S.; Anderson, J. P.; Hamuy, M.; de Jaeger, T.; Gutiérrez, C. P.; Kawabata, K. S.

2015-07-01

Aims: We present and analyse late-time observations of the Type-Ib supernova with possible pre-supernova progenitor detection, iPTF13bvn, which were done ~300 days after the explosion. We discuss them in the context of constraints on the supernova's progenitor. Previous studies have proposed two possible natures for the progenitor of the supernova, i.e. a massive Wolf-Rayet star or a lower-mass star in a close binary system. Methods: Our observations show that the supernova has entered the nebular phase, with the spectrum dominated by Mg I]λλ4571, [O I]λλ6300, 6364, and [Ca II]λλ7291, 7324 emission lines. We measured the emission line fluxes to estimate the core oxygen mass and compared the [O I]/[Ca II] line ratio with other supernovae. Results.The core oxygen mass of the supernova progenitor was estimated to be ≲0.7 M⊙, which implies initial progenitor mass that does not exceed ~15-17 M⊙.Since the derived mass is too low for a single star to become a Wolf-Rayet star, this result lends more support to the binary nature of the progenitor star of iPTF13bvn. The comparison of [O I]/[Ca II] line ratio with other supernovae also shows that iPTF13bvn appears to be in close association with the lower mass progenitors of stripped-envelope and Type-II supernovae. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the US National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU); Chilean Telescope Time Allocation Committee proposal CN2014A-91.

Direct Measurement of the Supernova Rate in Starburst Galaxies

NASA Technical Reports Server (NTRS)

Bregman, Jesse D.; Temi, Pasquale; Rank, David; DeVincenzi, Donald L. (Technical Monitor)

1999-01-01

Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short times. Many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extintion is especially severe. Thus, determining the supernova rate in the active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micron emission line was the strongest line in the infrared spectrum for a period of a year and a half after the explosion. Since dust extintion is much less at 6.63 pm than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the NiII line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micron using ISOCAM to search for the NiII emission line characteristic of recent supernovae. We did not detect any NiII line emission brighter than a 5sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled to the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a NiII with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a NiII line luminosity greater than the line in SN1987A.

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.

The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the Fourier space wedges of the final sample

NASA Astrophysics Data System (ADS)

Grieb, Jan Niklas; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Scoccimarro, Román; Crocce, Martín; Dalla Vecchia, Claudio; Montesano, Francesco; Gil-Marín, Héctor; Ross, Ashley J.; Beutler, Florian; Rodríguez-Torres, Sergio; Chuang, Chia-Hsun; Prada, Francisco; Kitaura, Francisco-Shu; Cuesta, Antonio J.; Eisenstein, Daniel J.; Percival, Will J.; Vargas-Magaña, Mariana; Tinker, Jeremy L.; Tojeiro, Rita; Brownstein, Joel R.; Maraston, Claudia; Nichol, Robert C.; Olmstead, Matthew D.; Samushia, Lado; Seo, Hee-Jong; Streblyanska, Alina; Zhao, Gong-bo

2017-05-01

We extract cosmological information from the anisotropic power-spectrum measurements from the recently completed Baryon Oscillation Spectroscopic Survey (BOSS), extending the concept of clustering wedges to Fourier space. Making use of new fast-Fourier-transform-based estimators, we measure the power-spectrum clustering wedges of the BOSS sample by filtering out the information of Legendre multipoles ℓ > 4. Our modelling of these measurements is based on novel approaches to describe non-linear evolution, bias and redshift-space distortions, which we test using synthetic catalogues based on large-volume N-body simulations. We are able to include smaller scales than in previous analyses, resulting in tighter cosmological constraints. Using three overlapping redshift bins, we measure the angular-diameter distance, the Hubble parameter and the cosmic growth rate, and explore the cosmological implications of our full-shape clustering measurements in combination with cosmic microwave background and Type Ia supernova data. Assuming a Λ cold dark matter (ΛCDM) cosmology, we constrain the matter density to Ω M= 0.311_{-0.010}^{+0.009} and the Hubble parameter to H_0 = 67.6_{-0.6}^{+0.7} km s^{-1 Mpc^{-1}}, at a confidence level of 68 per cent. We also allow for non-standard dark energy models and modifications of the growth rate, finding good agreement with the ΛCDM paradigm. For example, we constrain the equation-of-state parameter to w = -1.019_{-0.039}^{+0.048}. This paper is part of a set that analyses the final galaxy-clustering data set from BOSS. The measurements and likelihoods presented here are combined with others in Alam et al. to produce the final cosmological constraints from BOSS.

The distant type Ia supernova rate

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

Pain, R.; Fabbro, S.; Sullivan, M.

2002-05-20

We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample,which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean red shift z {approx_equal} 0.55 of 1.53 {sub -0.25}{sub -0.31}{sup 0.28}{sup 0.32} x 10{sup -4} h{sup 3} Mpc{sup -3} yr{sup -1} or 0.58{sub -0.09}{sub -0.09}{sup +0.10}{sup +0.10} h{sup 2} SNu(1 SNu = 1more » supernova per century per 10{sup 10} L{sub B}sun), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models.« less

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.

HD271791: dynamical versus binary-supernova ejection scenario

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

2009-05-01

The atmosphere of the extremely high-velocity (530-920kms-1) early B-type star HD271791 is enriched in α-process elements, which suggests that this star is a former secondary component of a massive tight binary system and that its surface was polluted by the nucleosynthetic products after the primary star exploded in a supernova. It was proposed that the (asymmetric) supernova explosion unbind the system and that the secondary star (HD271791) was released at its orbital velocity in the direction of Galactic rotation. In this Letter, we show that to explain the Galactic rest-frame velocity of HD271791 within the framework of the binary-supernova scenario, the stellar remnant of the supernova explosion (a <~10Msolar black hole) should receive an unrealistically large kick velocity of >=750-1200kms-1. We therefore consider the binary-supernova scenario as highly unlikely and instead propose that HD271791 attained its peculiar velocity in the course of a strong dynamical three- or four-body encounter in the dense core of the parent star cluster. Our proposal implies that by the moment of encounter HD271791 was a member of a massive post-supernova binary.

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.;

Statistical Study of High-Velocity Compact Clouds Based on the Complete CO Imagings of the Central Molecular Zone

NASA Astrophysics Data System (ADS)

Tokuyama, Sekito; Oka, Tomoharu; Takekawa, Shunya; Yamada, Masaya; Iwata, Yuhei; Tsujimoto, Shiho

2017-01-01

High-velocity compact clouds (HVCCs) is one of the populations of peculiar clouds detected in the Central Molecular Zone (CMZ) of our Galaxy. They have compact appearances (< 5 pc) and large velocity widths (> 50 km s-1). Several explanations for the origin of HVCC were proposed; e.g., a series of supernovae (SN) explosions (Oka et al. 1999) or a gravitational kick by a point-like gravitational source (Oka et al. 2016). To investigate the statistical property of HVCCs, a complete list of them is acutely necessary. However, the previous list is not complete since the identification procedure included automated processes and manual selection (Nagai 2008). Here we developed an automated procedure to identify HVCCs in a spectral line data.

How Bright Can Supernovae Get?

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-04-01

Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms and a magnetic field of 2*1013 Gauss deposits energy into ~12 solar masses of ejecta. Click for a closerlook! [Adapted from SukhboldWoosley 2016]The authors find that the maximum luminosity that can be produced by these different supernova models ranges between 5*1043 and 2*1046 erg/s, with total radiated energies of 3*1050 to 4*1052 erg. This places the upper limit on the brightness of a supernova at about 5 trillion times the luminosity of the Sun.The calculations performed by Sukhbold and Woosley confirm that, of the options they explore, the least luminous events are produced by prompt explosions. The brightest events possible are powered by the rotational energy of a newly born magnetar at the heart of the explosion.The energies of observed ultra-luminous supernovae are (just barely) containedwithin the bounds of the mechanisms explored here. This is even true of the extreme ASASSN-15lh which, based on the authors calculations, was almost certainly powered by an embedded magnetar. If we were to observe a supernova more than twice as bright as ASASSN-15lh, however, it would be nearly impossible to explain with current models.CitationTuguldur Sukhbold and S. E. Woosley 2016 ApJ 820 L38. doi:10.3847/2041-8205/820/2/L38

The detectability of supernovae against elliptical galactic disks.

NASA Astrophysics Data System (ADS)

Pearce, E. C.

A 75 cm telescope has been automated with a Prime 300 mini-computer to search approximately 250 galaxies per hour for young supernovae. The high-speed star-location and comparison algorithms used in the Digitized Astronomy Supernova Search (DASS) system is described.

VLA radio upper limit on Type IIn Supernova 2007rt

NASA Astrophysics Data System (ADS)

Chandra, Poonam; Soderberg, Alicia

2008-01-01

Poonam Chandra and Alicia Soderberg report on behalf of a larger collaboration: We observed a Type IIn supernova SN 2007rt (CBET 1148) with the Very Large Array (VLA) in the 8.46 GHz band on 2008, January 12.55 UT. The observations were taken for total duration of one hour in the VLA B-configuration. We do not detect any radio emission at the supernova position (CBET 1148). The flux density at the supernova position is 9 ± 27 uJy.

A local recent supernova - Evidence from X-rays, Al-26 radioactivity and cosmic rays

NASA Technical Reports Server (NTRS)

Clayton, Donald D.; Cox, Donald P.; Michel, Curtis F.

1986-01-01

Possible ways in which cosmic rays could have been contaminated by a local recent supernova are discussed, and ways in which this contamination may be affecting interpretation of Al-26 gamma radiation and locally observed cosmic rays as samples of the average Galactic distribution are considered. Mass spectra of cosmic rays are examined to see whether there is enrichment by a population arising from supernova preacceleration. The reinterpretation of the anomalous component in terms of a local supernova model is addressed.

A high-resolution radio image of a young supernova

NASA Technical Reports Server (NTRS)

Bartel, N.; Rupen, M. P.; Shapiro, I. I.; Preston, R. A.; Rius, A.

1991-01-01

A VLBI radio images of the bright supernova 1986J, which occurred in the galaxy NGC891 at a distance of about 12 Mpc, is presented. No detailed image of any supernova or remnant has been obtained before so soon after the explosion. The image shows a shell of emission with jetlike protrusions. Analysis of the images should advance understanding of the dynamics of the expanding debris, the dissipation of energy into the surrounding circumstellar medium, and the evolution of the supernova into the remnant.

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.

The Perth Automated Supernova Search

NASA Astrophysics Data System (ADS)

Williams, A. J.

1997-12-01

An automated search for supernovae in late spiral galaxies has been established at Perth Observatory, Western Australia. This automated search uses three low-cost PC-clone computers, a liquid nitrogen cooled CCD camera built locally, and a 61-cm telescope automated for the search. The images are all analysed automatically in real-time by routines in Perth Vista, the image processing system ported to the PC architecture for the search system. The telescope control software written for the project, Teljoy, maintains open-loop position accuracy better than 30" of arc after hundreds of jumps over an entire night. Total capital cost to establish and run this supernova search over the seven years of development and operation was around US$30,000. To date, the system has discovered a total of 6 confirmed supernovae, made an independent detection of a seventh, and detected one unconfirmed event assumed to be a supernova. The various software and hardware components of the search system are described in detail, the analysis of the first three years of data is discussed, and results presented. We find a Type Ib/c rate of 0.43 +/- 0.43 SNu, and a Type IIP rate of 0.86 +/- 0.49 SNu, where SNu are 'supernova units', expressed in supernovae per 10^10 solar blue luminosity galaxy per century. These values are for a Hubble constant of 75 km/s per Mpc, and scale as (H0/75)^2. The small number of discoveries has left large statistical uncertainties, but our strategy of frequent observations has reduced systematic errors - altering detection threshold or peak supernova luminosity by +/- 0.5 mag changes estimated rates by only around 20%. Similarly, adoption of different light curve templates for Type Ia and Type IIP supernovae has a minimal effect on the final statistics (2% and 4% change, respectively).

Delay-time distribution of core-collapse supernovae with late events resulting from binary interaction

NASA Astrophysics Data System (ADS)

Zapartas, E.; de Mink, S. E.; Izzard, R. G.; Yoon, S.-C.; Badenes, C.; Götberg, Y.; de Koter, A.; Neijssel, C. J.; Renzo, M.; Schootemeijer, A.; Shrotriya, T. S.

2017-05-01

Most massive stars, the progenitors of core-collapse supernovae, are in close binary systems and may interact with their companion through mass transfer or merging. We undertake a population synthesis study to compute the delay-time distribution of core-collapse supernovae, that is, the supernova rate versus time following a starburst, taking into account binary interactions. We test the systematic robustness of our results by running various simulations to account for the uncertainties in our standard assumptions. We find that a significant fraction, %, of core-collapse supernovae are "late", that is, they occur 50-200 Myr after birth, when all massive single stars have already exploded. These late events originate predominantly from binary systems with at least one, or, in most cases, with both stars initially being of intermediate mass (4-8 M⊙). The main evolutionary channels that contribute often involve either the merging of the initially more massive primary star with its companion or the engulfment of the remaining core of the primary by the expanding secondary that has accreted mass at an earlier evolutionary stage. Also, the total number of core-collapse supernovae increases by % because of binarity for the same initial stellar mass. The high rate implies that we should have already observed such late core-collapse supernovae, but have not recognized them as such. We argue that φ Persei is a likely progenitor and that eccentric neutron star - white dwarf systems are likely descendants. Late events can help explain the discrepancy in the delay-time distributions derived from supernova remnants in the Magellanic Clouds and extragalactic type Ia events, lowering the contribution of prompt Ia events. We discuss ways to test these predictions and speculate on the implications for supernova feedback in simulations of galaxy evolution.

Eta Carinae: An Astrophysical Laboratory to Study Conditions During the Transition Between a Pseudo-Supernova and a Supernova

NASA Astrophysics Data System (ADS)

McKinnon, Darren; Gull, T. R.; Madura, T.

2014-01-01

A major puzzle in the studies of supernovae is the pseudo-supernova, or the near-supernovae state. It has been found to precede, in timespans ranging from months to years, a number of recently-detected distant supernovae. One explanation of these systems is that a member of a massive binary underwent a near-supernova event shortly before the actual supernova phenomenon. Luckily, we have a nearby massive binary, Eta Carinae, that provides an astrophysical laboratory of a near-analog. The massive, highly-eccentric, colliding-wind binary star system survived a non-terminal stellar explosion in the 1800's, leaving behind the incredible bipolar, 10"x20" Homunculus nebula. Today, the interaction of the binary stellar winds 1") is resolvable by the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). Using HST/STIS, several three-dimensional (3D) data cubes (2D spatial, 1D velocity) have been obtained at selected phases during Eta Carinae's 5.54-year orbital cycle. The data cubes were collected by mapping the central 1-2" at 0.05" intervals with a 52"x0.1" aperture. Selected forbidden lines, that form in the colliding wind regions, provide information on electron density of the shocked regions, the ionization by the hot secondary companion of the primary wind and how these regions change with orbital phase. By applying various analysis techniques to these data cubes, we can compare and measure temporal changes due to the interactions between the two massive winds. The observations, when compared to current 3D hydrodynamic models, provide insight on Eta Carinae's recent mass-loss history, important for determining the current and future states of this likely nearby supernova progenitor.

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.

A black hole-white dwarf compact binary model for long gamma-ray bursts without supernova association

NASA Astrophysics Data System (ADS)

Dong, Yi-Ze; Gu, Wei-Min; Liu, Tong; Wang, Junfeng

2018-03-01

Gamma-ray bursts (GRBs) are luminous and violent phenomena in the Universe. Traditionally, long GRBs are expected to be produced by the collapse of massive stars and associated with supernovae. However, some low-redshift long GRBs have no detection of supernova association, such as GRBs 060505, 060614, and 111005A. It is hard to classify these events convincingly according to usual classifications, and the lack of the supernova implies a non-massive star origin. We propose a new path to produce long GRBs without supernova association, the unstable and extremely violent accretion in a contact binary system consisting of a stellar-mass black hole and a white dwarf, which fills an important gap in compact binary evolution.

Hardy Star Survives Supernova Blast

NASA Image and Video Library

2014-03-20

This composite image contains data from Chandra (purple) that provides evidence for the survival of a companion star from the blast of a supernova explosion. Chandra's X-rays reveal a point-like source in the supernova remnant at the location of a massive star. The data suggest that mass is being pulled away from the massive star towards a neutron star or a black hole companion. If confirmed, this would be only the third binary system containing both a massive star and a neutron star or black hole ever found in the aftermath of a supernova. This supernova remnant is found embedded in clouds of ionized hydrogen, which are shown in optical light (yellow and cyan) from the MCELS survey, along with additional optical data from the DSS (white).

Supernovae, supernebulae, and nucleosynthesis

NASA Astrophysics Data System (ADS)

Wheeler, J. Craig; Harkness, Robert P.; Barkat, Zalman; Swartz, Douglas

1986-10-01

Supernova atmosphere calculations continue to show that variants of previously calculated carbon-deflagration models provide a good representation of the maximum light spectra of classical type Ia supernovae including the ultraviolet deficit. Careful consideration of the conditions leading to central thermonuclear runaway of degenerate carbon shows that runaway can, however, lead to detonation and direct conflict with observations. As witnessed by the spectra of type Ib supernovae, massive stars are expected to be the primary source of oxygen. Estimates of the absolute production of oxygen in massive stars suggest that if all stars more massive than ≡12 M_sun; explode as supernovae, oxygen would be overproduced in the solar neighborhood, an effect exacerbated by the recent increase in the reaction rate for 12C(α, γ)16O.

On the Origin of Hard X-ray Structures in the VELA Supernova Remnant

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

1998-12-01

We propose an alternative explanation for the origin of two hard X-ray structures recently discovered in the central part of the Vela supernova remnant (SNR) by Willmore et al. (1992, MNRAS, 254, 139) and Markwardt & Ogelman (1995, Nature, 375, 40; 1997, ApJ, 480, L13), and interpreted as a plerion and a pulsar jet respectively. We suggest that the first structure is a dense material shed by the supernova progenitor star during the red supergiant stage, and reheated after the supernova exploded, while the "jet" is simply a dense filament in the Vela SNR's general shell, whose origin is connected with the Rayleigh-Taylor instability in the (main-sequence) wind-driven shell reaccelerated by the supernova blast wave.

Alteration of TiC in Supernovae Outflows: Transmission Electron Microscopy Study of TiC Subgrains in Supernovae Graphite

NASA Astrophysics Data System (ADS)

Daulton, T. L.; Bernatowicz, T. J.; Croat, T. K.

2009-03-01

TiC and metal subgrains within supernovae graphites often exhibit rims suggesting alteration prior to encapsulation in the graphite. Detailed TEM microcharacterizations of the rimmed grains are performed to determine the mechanism of rim formation.

The All-Sky Automated Survey for Supernovae

NASA Astrophysics Data System (ADS)

Bersier, D.

2016-12-01

This is an overview of the All-Sky Automated Survey for SuperNovae - ASAS-SN. We briefly present the hardware and capabilities of the survey and describe the most recent science results, in particular tidal disruption events and supernovae, including the brightest SN ever found.

Simulating the detection and classification of high-redshift supernovae with HARMONI on the ELT

NASA Astrophysics Data System (ADS)

Bounissou, S.; Thatte, N.; Zieleniewski, S.; Houghton, R. C. W.; Tecza, M.; Hook, I.; Neichel, B.; Fusco, T.

2018-02-01

We present detailed simulations of integral field spectroscopic observations of a supernova in a host galaxy at z ˜ 3, as observed by the HARMONI spectrograph on the Extremely Large Telescope, asssisted by laser tomographic adaptive optics. The goal of the simulations, using the HSIM simulation tool, is to determine whether HARMONI can discern the supernova Type from spectral features in the supernova spectrum. We find that in a 3 hour observation, covering the near-infrared H and K bands, at a spectral resolving power of ˜3000, and using the 20×20 mas spaxel scale, we can classify supernova Type Ia and their redshift robustly up to 80 days past maximum light (20 days in the supernova rest frame). We show that HARMONI will provide spectra at z ˜ 3 that are of comparable (or better) quality to the best spectra we can currently obtain at z ˜ 1, thus allowing studies of cosmic expansion rates to be pushed to substantially higher redshifts.

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

Fermi Large Area Telescope Detection of Gamma-Ray Emission from the Direction of Supernova iPTF14hls

NASA Astrophysics Data System (ADS)

Yuan, Qiang; Liao, Neng-Hui; Xin, Yu-Liang; Li, Ye; Fan, Yi-Zhong; Zhang, Bing; Hu, Hong-Bo; Bi, Xiao-Jun

2018-02-01

The remnant of a supernova explosion is widely believed to be the acceleration site of high-energy cosmic-ray particles. The acceleration timescale is, however, typically very long. Here, we report the detection of a variable γ-ray source with the Fermi Large Area Telescope, which is positionally and temporally consistent with a peculiar supernova, iPTF14hls. A quasi-stellar object SDSS J092054.04+504251.5, which is probably a blazar candidate according to the infrared data, is found in the error circle of the γ-ray source. More data about the γ-ray source and SDSS J092054.04+504251.5 are needed to confirm their association. On the other hand, if the association between the γ-ray source and the supernova is confirmed, this would be the first time detecting high-energy γ-ray emission from a supernova, suggesting very fast particle acceleration by supernova explosions.

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

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.

The UV behaviour of GRB 161219B/SN2016jca

NASA Astrophysics Data System (ADS)

Levan, Andrew

2016-10-01

The connection between long duration gamma-ray bursts and the stripped-envelope supernova is now secure, however, central questions remain about the nature of the supernovae and the power sources that drive them. Progress in these areas can be made through in-depth observations of nearby GRBs, in which the supernova light is sufficiently bright for detailed studies. However, such events are extremely rare, with only a handful of classical long-duration GRBs being found at z<0.2. Here we request observations of the recent GRB 161219B, and its supernova SN 2016jca. Utilising the unique ultraviolet capabilities of HST we will map the UV spectrum and its evolution with time. At a minimum, this will provide a route to tracking the afterglow and decomposing afterglow and supernova and host contributions - diagnostics that ground-based observations alone struggle to achieve. However, our sensitive UV observations will also probe the UV properties of a GRB-SN for the first time, providing insight into the metal content of the progenitor, and crucially into the nature of the central engine, which may power the prompt emission of the burst, and continue to provide energy to event at much later times. Recent observations suggest that in extremum these engines may drive supernovae to exceptional luminosities (the so-called superluminous supernovae) and provide a link between the most powerful explosions in the Universe. Our observations may offer the route to identifying such an engine at work in a lower luminosity supernova, solidifying this link.

Interacting supernovae and supernova impostors. LSQ13zm: an outburst heralds the death of a massive star

DOE PAGES

Tartaglia, L.; Pastorello, A.; Sullivan, M.; ...

2016-03-23

Here we report photometric and spectroscopic observations of the optical transient LSQ13zm. Historical data reveal the presence of an eruptive episode (that we label as ‘2013a’) followed by a much brighter outburst (‘2013b’) three weeks later, that we argue to be the genuine supernova explosion. This sequence of events closely resemble those observed for SN 2010mc and (in 2012) SN 2009ip. Furthermore, the absolute magnitude reached by LSQ13zm during 2013a (MR = -14.87 ± 0.25 mag) is comparable with those of supernova impostors, while that of the 2013b event (M R = -18.46 ± 0.21 mag) is consistent with thosemore » of interacting supernovae. Our spectra reveal the presence of a dense and structured circumstellar medium, probably produced through numerous pre-supernova mass-loss events. In addition, we find evidence for high-velocity ejecta, with a fraction of gas expelled at more than 20 000 km s -1. The spectra of LSQ13zm show remarkable similarity with those of well-studied core-collapse supernovae. From the analysis of the available photometric and spectroscopic data, we conclude that we first observed the last event of an eruptive sequence from a massive star, likely a Luminous Blue Variable, which a short time later exploded as a core-collapse supernova. Our detailed analysis of archival images suggests that the host galaxy is a star-forming Blue Dwarf Compact Galaxy.« less

Interacting supernovae and supernova impostors. LSQ13zm: an outburst heralds the death of a massive star

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

Tartaglia, L.; Pastorello, A.; Sullivan, M.

Here we report photometric and spectroscopic observations of the optical transient LSQ13zm. Historical data reveal the presence of an eruptive episode (that we label as ‘2013a’) followed by a much brighter outburst (‘2013b’) three weeks later, that we argue to be the genuine supernova explosion. This sequence of events closely resemble those observed for SN 2010mc and (in 2012) SN 2009ip. Furthermore, the absolute magnitude reached by LSQ13zm during 2013a (MR = -14.87 ± 0.25 mag) is comparable with those of supernova impostors, while that of the 2013b event (M R = -18.46 ± 0.21 mag) is consistent with thosemore » of interacting supernovae. Our spectra reveal the presence of a dense and structured circumstellar medium, probably produced through numerous pre-supernova mass-loss events. In addition, we find evidence for high-velocity ejecta, with a fraction of gas expelled at more than 20 000 km s -1. The spectra of LSQ13zm show remarkable similarity with those of well-studied core-collapse supernovae. From the analysis of the available photometric and spectroscopic data, we conclude that we first observed the last event of an eruptive sequence from a massive star, likely a Luminous Blue Variable, which a short time later exploded as a core-collapse supernova. Our detailed analysis of archival images suggests that the host galaxy is a star-forming Blue Dwarf Compact Galaxy.« less

Models of Interacting Supernovae: Understanding the Physics and Probing the Circumstellar Environment

NASA Astrophysics Data System (ADS)

Baron, Edward

"Interacting supernovae" are poorly understood astronomical events with great potential for expanding our understanding of how stars evolve and die, and could provide important clues about the early formation of large-scale structures such as galaxies in the universe. Interacting supernovae occur when a star explodes within a dense cloud of material shed from the star in the course of its evolution. The resulting violent interaction between the expanding supernova explosion and the cloud of circumstellar material can lead to an enormously bright visual display --- indeed, many of the brightest supernovae ever recorded are thought to arise from circumstellar interaction. In order to understand the properties of the progenitor star and the details of the circumstellar interaction, there is a need for theoretical models of interacting supernovae. These simulated computer spectra can be directly compared to the spectra observed by telescopes. These models allow us to probe the physical circumstances that underlie the observations. The spectra of interacting supernovae are dominated by strong, narrow emission lines of light elements such as hydrogen and helium. These narrow lines give Type IIn supernovae their designation. Similarly, objects of Type Ian, Ibn, Icn, and IIn are somewhat distinct, but are all defined by the narrow emission lines that result from the interaction of their expanding envelopes with their surroundings. The photosphere in these supernovae is formed in the material accreted during the coasting phase, and most of the luminosity has its origin from the conversion of kinetic explosion energy into luminosity. Both thermonuclear (Type Ia) and core-collapse (Types Ib/Ic and II) supernovae may be the inner engine. In fact, several Type IIn supernovae at early times have later been classified as Type Ia, Type Ib/c, or Type II as their spectra reveal more details about the nature of the central explosion. As a result of the dominance of the interaction, models of interacting supernovae must take into account descriptions of the hydrodynamical, ionization, and light fronts: a full radiation-hydrodynamical problem. The low densities imply strong departures from thermodynamic equilibrium and, thus, demand a non-LTE treatment in the radiative transfer calculation. We propose a collaboration between the University of Oklahoma (OU) and Florida State University (FSU) to calculate hydrodynamical models, light curves, and NLTE spectra of circumstellar interacting supernovae. We will parameterize the explosion of a massive star, study the hydrodynamical impact onto a circumstellar medium and calculate light curves and spectra. Direct comparison with observed supernovae with give us detailed information on the progenitor star, its mass loss history, and the nature of binary stellar evolution. We will calculate explosion models for some of the stellar structures and the ongoing interaction with the circumstellar material using our radiation hydro code HYDRA and NLTE generalized model atmospheres code PHOENIX. We intend to focus on the physics of interacting supernovae, going beyond the regime where self-similar solutions and phenomenological approaches are valid. This will limit the parameter space that needs to be examined, while still allowing for direct comparison with observations. Since many interacting supernovae are extremely bright, they can be seen at the highest redshifts and are good probes of the darkages. These supernovae will be well observed by upcoming NASA mission JWST as well as ground based surveys such as LSST. The tools for this work are in place: FSU PI Peter Hoeflich has been developing and using the hydrodynamic code HYDRA for over two decades and PI Eddie Baron (OU) has been developing the generalized stellar atmosphere code PHOENIX over the same time period. Baron and Hoeflich have a good working relationship and have cross-compared our codes.

A Unified Approach to Teaching Quadratic and Cubic Equations.

ERIC Educational Resources Information Center

Ward, A. J. B.

2003-01-01

Presents a simple method for teaching the algebraic solution of cubic equations via completion of the cube. Shows that this method is readily accepted by students already familiar with completion of the square as a method for quadratic equations. (Author/KHR)

Kepler Supernova Remnant: A View from Hubble Space Telescope

NASA Image and Video Library

2004-10-06

This image represents a view of NASA Kepler supernova remnant taken in X-rays, visible light, and infrared radiation, indicating that the bubble of gas that makes up the supernova remnant appears different in various types of light. http://photojournal.jpl.nasa.gov/catalog/PIA06909

Theoretical models of highly magnetic white dwarf stars that violate the Chandrasekhar Limit

NASA Astrophysics Data System (ADS)

Shah, Hridaya

2017-08-01

Until recently, white dwarf (WD) stars were believed to be no more massive than 1.44 solar masses (M ⊙ ). This belief has been changed now with the observations of over-luminous or 'peculiar' Type la supernovae that have lead researchers to hypothesize the existence of WDs in the mass range 2.4 - 2.8 M ⊙ . This discovery also raises some doubt over the reliability of the Type Ia supernova as a standard candle. It is thought that these super-massive WDs are their most likely progenitors and that they probably have a very strong magnetic field inside them. A degenerate electron gas in a magnetic field, such as that present inside this star, will be Landau quantized. Magnetic field changes the momentum space of electrons which in turn changes their density of states (DOS) and that in turn changes the equation of state (EoS) of matter inside the star, as opposed to that without a field. When this change in the DOS is taken into account and a link between the DOS and the EoS is established, as is done in this work, I find a physical reason behind the theoretical mass-radius (M-R) relations of a super-massive WD. I start with different equations of state with at most three Landau levels occupied and then construct stellar models of magnetic WDs (MWDs) using the same. I also show the M-R relations of these stars for a particular chosen value of maximum electron Fermi energy. Once a multiple Landau level system of electrons is considered, I find that it leads to such an EoS that gives multiple branches in the MR relations. Super-massive MWDs are obtained only when the Landau level occupancy is limited to just one level and some of the mass values fall within the mass range given above.

Modified Regge calculus as an explanation of dark energy

NASA Astrophysics Data System (ADS)

Stuckey, W. M.; McDevitt, T. J.; Silberstein, M.

2012-03-01

Using the Regge calculus, we construct a Regge differential equation for the time evolution of the scale factor a(t) in the Einstein-de Sitter cosmology model (EdS). We propose two modifications to the Regge calculus approach: (1) we allow the graphical links on spatial hypersurfaces to be large, as in direct particle interaction when the interacting particles reside in different galaxies, and (2) we assume that luminosity distance DL is related to graphical proper distance Dp by the equation D_L = (1+z)\\sqrt{\\overrightarrow{D_p}\\cdot \\overrightarrow{D_p}}, where the inner product can differ from its usual trivial form. The modified Regge calculus model (MORC), EdS and ΛCDM are compared using the data from the Union2 Compilation, i.e. distance moduli and redshifts for type Ia supernovae. We find that a best fit line through log {\\big(\\frac{D_L}{{Gpc}}\\big)} versus log z gives a correlation of 0.9955 and a sum of squares error (SSE) of 1.95. By comparison, the best fit ΛCDM gives SSE = 1.79 using Ho = 69.2 km s-1 Mpc, ΩM = 0.29 and ΩΛ = 0.71. The best fit EdS gives SSE = 2.68 using Ho = 60.9 km s-1 Mpc. The best-fit MORC gives SSE = 1.77 and Ho = 73.9 km s-1 Mpc using R = A-1 = 8.38 Gcy and m = 1.71 × 1052 kg, where R is the current graphical proper distance between nodes, A-1 is the scaling factor from our non-trivial inner product, and m is the nodal mass. Thus, the MORC improves the EdS as well as ΛCDM in accounting for distance moduli and redshifts for type Ia supernovae without having to invoke accelerated expansion, i.e. there is no dark energy and the universe is always decelerating.

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

Constraining the dark energy equation of state using Bayes theorem and the Kullback-Leibler divergence

NASA Astrophysics Data System (ADS)

Hee, S.; Vázquez, J. A.; Handley, W. J.; Hobson, M. P.; Lasenby, A. N.

2017-04-01

Data-driven model-independent reconstructions of the dark energy equation of state w(z) are presented using Planck 2015 era cosmic microwave background, baryonic acoustic oscillations (BAO), Type Ia supernova (SNIa) and Lyman α (Lyα) data. These reconstructions identify the w(z) behaviour supported by the data and show a bifurcation of the equation of state posterior in the range 1.5 < z < 3. Although the concordance Λ cold dark matter (ΛCDM) model is consistent with the data at all redshifts in one of the bifurcated spaces, in the other, a supernegative equation of state (also known as 'phantom dark energy') is identified within the 1.5σ confidence intervals of the posterior distribution. To identify the power of different data sets in constraining the dark energy equation of state, we use a novel formulation of the Kullback-Leibler divergence. This formalism quantifies the information the data add when moving from priors to posteriors for each possible data set combination. The SNIa and BAO data sets are shown to provide much more constraining power in comparison to the Lyα data sets. Further, SNIa and BAO constrain most strongly around redshift range 0.1-0.5, whilst the Lyα data constrain weakly over a broader range. We do not attribute the supernegative favouring to any particular data set, and note that the ΛCDM model was favoured at more than 2 log-units in Bayes factors over all the models tested despite the weakly preferred w(z) structure in the data.

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

Remming, Ian S.; Khokhlov, Alexei M.

We present general equations for non-ideal, reactive flow magnetohydrodynamics (RFMHD) in the form best suited for describing thermonuclear combustion in high-density degenerate matter of SNe Ia. The relative importance of various non-ideal effects is analyzed as a function of characteristic spatial and temporal scales of the problem. From the general RFMHD equations, we derive the one-dimensional ordinary differential equations describing the steady-state propagation of a planar thermonuclear flame front in a magnetic field. The physics of the flame is first studied qualitatively using a simple case of one-step Arrhenius kinetics, a perfect gas equation of state (EOS), and constant thermalmore » conductivity coefficients. After that, the equations are solved, the internal flame front structure is calculated, and the flame velocity, S {sub l} , and flame thickness, δ {sub l} , are found for carbon–oxygen degenerate material of supernovae using a realistic EOS, transport properties, and detailed nuclear kinetics. The magnetic field changes the flame behavior significantly, both qualitatively and quantitatively, as compared to the non-magnetic case of classical combustion. (1) The magnetic field influences the evolutionarity of a flame front and makes it impossible for a flame to propagate steadily in a wide range of magnetic field strengths and orientations relative to the front. (2) When the flame moves steadily, it can propagate in several distinct modes, the most important being the slow C {sub S} and super-Alfvénic C {sub sup} modes. (3) The speed of the flame can be diminished or enhanced by up to several factors relative to the non-magnetic laminar flame speed.« less

Delayed detonation models for normal and subluminous type Ia sueprnovae: Absolute brightness, light curves, and molecule formation

NASA Technical Reports Server (NTRS)

Hoflich, P.; Khokhlov, A. M.; Wheeler, J. C.

1995-01-01

We compute optical and infrared light curves of the pulsating class of delayed detonation models for Type Ia supernovae (SN Ia's) using an elaborate treatment of the Local Thermodynamic Equilbrium (LTE) radiation transport, equation of state and ionization balance, expansion opacity including the cooling by CO, Co(+), and SiO, and a Monte Carlo gamma-ray deposition scheme. The models have an amount of Ni-56 in the range from approximately or equal to 0.1 solar mass up to 0.7 solar mass depending on the density at which the transition from a deflagration to a detonation occurs. Models with a large nickel production give light curves comparable to those of typical Type Ia supernovae. Subluminous supernovae can be explained by models with a low nickel production. Multiband light curves are presented in comparison with the normally bright event SN 1992bc and the subluminous events Sn 1991bg and SN 1992bo to establish the principle that the delayed detonation paradigm in Chandrasekhar mass models may give a common explosion mechanism accounting for both normal and subluminous SN Ia's. Secondary IR-maxima are formed in the models of normal SN Ia's as a photospheric effect if the photospheric radius continues to increase well after maximum light. Secondary maxima appear later and stronger in models with moderate expansion velocities and with radioactive material closer to the surface. Model light curves for subluminous SN Ia's tend to show only one 'late' IR-maximum. In some delayed detonation models shell-like envelopes form, which consist of unburned carbon and oxygen. The formation of molecules in these envelopes is addressed. If the model retains a C/O-envelope and is subluminous, strong vibration bands of CO may appear, typically several weeks past maximum light. CO should be very weak or absent in normal Sn Ia's.

A COMPARATIVE ANALYSIS OF THE SUPERNOVA LEGACY SURVEY SAMPLE WITH ΛCDM AND THE R{sub h}=ct UNIVERSE

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

Wei, Jun-Jie; Wu, Xue-Feng; Melia, Fulvio

The use of Type Ia supernovae (SNe Ia) has thus far produced the most reliable measurement of the expansion history of the universe, suggesting that ΛCDM offers the best explanation for the redshift–luminosity distribution observed in these events. However, analysis of other kinds of sources, such as cosmic chronometers, gamma-ray bursts, and high-z quasars, conflicts with this conclusion, indicating instead that the constant expansion rate implied by the R{sub h} = ct universe is a better fit to the data. The central difficulty with the use of SNe Ia as standard candles is that one must optimize three or fourmore » nuisance parameters characterizing supernova (SN) luminosities simultaneously with the parameters of an expansion model. Hence, in comparing competing models, one must reduce the data independently for each. We carry out such a comparison of ΛCDM and the R{sub h} = ct universe using the SN Legacy Survey sample of 252 SN events, and show that each model fits its individually reduced data very well. However, since R{sub h} = ct has only one free parameter (the Hubble constant), it follows from a standard model selection technique that it is to be preferred over ΛCDM, the minimalist version of which has three (the Hubble constant, the scaled matter density, and either the spatial curvature constant or the dark energy equation-of-state parameter). We estimate using the Bayes Information Criterion that in a pairwise comparison, the likelihood of R{sub h} = ct is ∼90%, compared with only ∼10% for a minimalist form of ΛCDM, in which dark energy is simply a cosmological constant. Compared to R{sub h} = ct, versions of the standard model with more elaborate parametrizations of dark energy are judged to be even less likely.« less

High Redshift Supernova Search

Science.gov Websites

;on schedule." Before-and-after pictures (and Hubble Space Telescope picture) of a high-redshift High Redshift Supernova Search Home Page of the Supernova Cosmology Project This is the Lawrence Foretell Fate of the Universe." Pictures from the ground and from the Hubble Space Telescope: [PDF

"Type Ia Supernovae: Tools for Studying Dark Energy" Final Technical Report

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

Woosley, Stan; Kasen, Dan

2017-05-10

Final technical report for project "Type Ia Supernovae: Tools for the Study of Dark Energy" awarded jointly to scientists at the University of California, Santa Cruz and Berkeley, for computer modeling, theory and data analysis relevant to the use of Type Ia supernovae as standard candles for cosmology.

Gamma-line emission from radioactivities produced in supernovae

NASA Technical Reports Server (NTRS)

Woosley, S. E.; Timmes, F. X.

1997-01-01

The major targets for the gamma ray spectroscopy of supernovae are reviewed. The principle benefit of such observations is the insight provided into the mechanisms of supernova explosions, the distribution and nature of star forming regions in our Galaxy, and the history of the nucleosynthesis of our Galaxy. The emphasis is on two short lived species, Co-56 and Ti-44 which may be seen in individual events and two longer lived species, Al-26 and Fe-60, which can be seen as the cumulative production of many supernovae.

Supernova explosions.

NASA Technical Reports Server (NTRS)

Cameron, A. G. W.

1971-01-01

The recent history of theoretical investigations of the supernova mechanism is considered, giving attention also to a number of nuclear physical problems which have yet to be solved in connection with the thermonuclear detonation. A variety of different processes of nucleo-synthesis are expected to occur in association with the supernova explosions. Aspects of the chemical evolution of the galaxy are discussed including the cosmic ray production of lithium, beryllium, and boron in the interstellar medium. Various hypotheses to account for the very large amount of light that comes from a supernova explosion are also examined.

Initial statistics from the Perth Automated Supernova Search

NASA Astrophysics Data System (ADS)

Williams, A. J.

1997-08-01

The Perth Automated Supernova Search uses the 61-cm PLAT (Perth Lowell Automated Telescope) at Perth Observatory, Western Australia. Since 1993 January 1, five confirmed supernovae have been found by the search. The analysis of the first three years of data is discussed, and preliminary results presented. We find a Type Ib/c rate of 0.43 +/- 0.43 SNu, and a Type IIP rate of 0.86 +/- 0.49 SNu, where SNu are 'supernova units'. These values are for a Hubble constant of 75 km per sec per Mpc.

Fritz Zwicky: Novae Become Supernovae

NASA Astrophysics Data System (ADS)

Koenig, T.

2005-12-01

The Swiss physicist Fritz Zwicky (1898-1974) dabbled in a plethora of disciplines, including astronomy and astrophysics. His dabblings were with vested interest and he has left quite an impact. His first great success was his nova research. In the early 1930s, while supermarkets and Superman were flying, he labelled the distinctly brighter nova Supernova. It had been believed that novae were the collision of two stars, but Zwicky came to recognize supernovae as a phenomenon quite distinct from novae. He and Walter Baade explained supernova by melding astronomy and physics and in this aim they created neutron stars, explained the origin of cosmic rays, initiated the first sky survey, and confirmed that a number of historical novae were indeed supernovae. This was truly an important work in the history of astrophysics.

The ν process in the innermost supernova ejecta

NASA Astrophysics Data System (ADS)

Sieverding, Andre; Martínez Pinedo, Gabriel; Langanke, Karlheinz; Harris, J. Austin; Hix, W. Raphael

2018-01-01

The neutrino-induced nucleosynthesis (ν process) in supernova explosions of massive stars of solar metallicity with initial main sequence masses between 13 and 30 M⊙ has been studied with an analytic explosion model using a new extensive set of neutrino-nucleus cross-sections and spectral properties that agree with modern supernova simulations. The production factors for the nuclei 7Li, 11B, 19F, 138La and 180Ta, are still significantly enhanced but do not reproduce the full solar abundances. We study the possible contribution of the innermost supernova eject to the production of the light elements 7Li and 11B with tracer particles based on a 2D supernova simulation of a 12 M⊙ progenitor and conclude, that a contribution exists but is negligible for the total yield for this explosion model.

How to See a Recently Discovered Supernova

ScienceCinema

Nugent, Peter

2017-12-12

Berkeley Lab scientist Peter Nugent discusses a recently discovered supernova that is closer to Earth — approximately 21 million light-years away — than any other of its kind in a generation. Astronomers believe they caught the supernova within hours of its explosion, a rare feat made possible with a specialized survey telescope and state-of-the-art computational tools. The finding of such a supernova so early and so close has energized the astronomical community as they are scrambling to observe it with as many telescopes as possible, including the Hubble Space Telescope. More info on how to see it: http://newscenter.lbl.gov/feature-stories/2011/08/31/glimpse-cosmic-explosion/ News release: http://newscenter.lbl.gov/feature-stories/2011/08/25/supernova/

How to See a Recently Discovered Supernova

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

Nugent, Peter

2011-08-31

Berkeley Lab scientist Peter Nugent discusses a recently discovered supernova that is closer to Earth — approximately 21 million light-years away — than any other of its kind in a generation. Astronomers believe they caught the supernova within hours of its explosion, a rare feat made possible with a specialized survey telescope and state-of-the-art computational tools. The finding of such a supernova so early and so close has energized the astronomical community as they are scrambling to observe it with as many telescopes as possible, including the Hubble Space Telescope. More info on how to see it: http://newscenter.lbl.gov/feature-stories/2011/08/31/glimpse-cosmic-explosion/ News release:more » http://newscenter.lbl.gov/feature-stories/2011/08/25/supernova/« less

Toward an efficient Photometric Supernova Classifier

NASA Astrophysics Data System (ADS)

McClain, Bradley

2018-01-01

The Sloan Digital Sky Survey Supernova Survey (SDSS) discovered more than 1,000 Type Ia Supernovae, yet less than half of these have spectroscopic measurements. As wide-field imaging telescopes such as The Dark Energy Survey (DES) and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) discover more supernovae, the need for accurate and computationally cheap photometric classifiers increases. My goal is to use a photometric classification algorithm based on Sncosmo, a python library for supernova cosmology analysis, to reclassify previously identified Hubble SN and other non-spectroscopically confirmed surveys. My results will be compared to other photometric classifiers such as PSNID and STARDUST. In the near future, I expect to have the algorithm validated with simulated data, optimized for efficiency, and applied with high performance computing to real data.

Detection of the gravitational lens magnifying a type Ia supernova.

PubMed

Quimby, Robert M; Oguri, Masamune; More, Anupreeta; More, Surhud; Moriya, Takashi J; Werner, Marcus C; Tanaka, Masayuki; Folatelli, Gaston; Bersten, Melina C; Maeda, Keiichi; Nomoto, Ken'ichi

2014-04-25

Objects of known brightness, like type Ia supernovae (SNIa), can be used to measure distances. If a massive object warps spacetime to form multiple images of a background SNIa, a direct test of cosmic expansion is also possible. However, these lensing events must first be distinguished from other rare phenomena. Recently, a supernova was found to shine much brighter than normal for its distance, which resulted in a debate: Was it a new type of superluminous supernova or a normal SNIa magnified by a hidden gravitational lens? Here, we report that a spectrum obtained after the supernova faded away shows the presence of a foreground galaxy-the first found to strongly magnify a SNIa. We discuss how more lensed SNIa can be found than previously predicted.

An earlier explosion date for the Crab Nebula supernova

NASA Astrophysics Data System (ADS)

Abt, Helmut A.; Fountain, John W.

2018-04-01

The Chinese first reported the Crab Nebula supernova on 1054 July 5. Ecclesiastical documents from the near east reported it in April and May of 1054. More than 33 petroglyphs made by Native Americans in the US and Mexico are consistent with sightings both before and after conjunction with the Sun on 1054 May 27. We found a petroglyph showing the new star close to Venus and the Moon, which occurred on 1054 April 12 and April 13, respectively. Collins et al., using the four historical dates, derived a light curve that is like that of a Type Ia supernova. The only remaining problem with this identification is that this supernova was near maximum light for 85 d, which is unlike the behavior of any known supernova.

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

Supernova remnant S 147 and its associated neutron star(s)

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

2006-07-01

The supernova remnant S 147 harbors the pulsar PSR J 0538+2817 whose characteristic age is more than an order of magnitude greater than the kinematic age of the system (inferred from the angular offset of the pulsar from the geometric center of the supernova remnant and the pulsar proper motion). To reconcile this discrepancy we propose that PSR J 0538+2817 could be the stellar remnant of the first supernova explosion in a massive binary system and therefore could be as old as its characteristic age. Our proposal implies that S 147 is the diffuse remnant of the second supernova explosion (that disrupted the binary system) and that a much younger second neutron star (not necessarily manifesting itself as a radio pulsar) should be associated with S 147. We use the existing observational data on the system to suggest that the progenitor of the supernova that formed S 147 was a Wolf-Rayet star (so that the supernova explosion occurred within a wind bubble surrounded by a massive shell) and to constrain the parameters of the binary system. We also restrict the magnitude and direction of the kick velocity received by the young neutron star at birth and find that the kick vector should not strongly deviate from the orbital plane of the binary system.

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.

Polarisation Spectral Synthesis For Type Ia Supernova Explosion Models

NASA Astrophysics Data System (ADS)

Bulla, Mattia

2017-02-01

Despite their relevance across a broad range of astrophysical research topics, Type Ia supernova explosions are still poorly understood and answers to the questions of when, why and how these events are triggered remain unclear. In this respect, polarisation offers a unique opportunity to discriminate between the variety of possible scenarios. The observational evidence that Type Ia supernovae are associated with rather low polarisation signals (smaller than a few per cent) places strong constraints for models and calls for modest asphericities in the progenitor system and/or explosion mechanism.The goal of this thesis is to assess the validity of contemporary Type Ia supernova explosion models by testing whether their predicted polarisation signatures can account for the small signals usually observed. To this end, we have implemented and tested an innovative Monte Carlo scheme in the radiative transfer code artis. Compared to previous Monte Carlo approaches, this technique produces synthetic observables (light curves, flux and polarisation spectra) with a substantial reduction in the Monte Carlo noise and therefore in the required computing time. This improvement is particularly crucial for our study as we aim to extract very weak polarisation signals, comparable to those detected in Type Ia supernovae. We have also demonstrated the applicability of this method to other classes of supernovae via a preliminary study of the first spectropolarimetry observations of superluminous supernovae.Using this scheme, we have calculated synthetic spectropolarimetry for three multi-dimensional explosion models recently proposed as promising candidates to explain Type Ia supernovae. Our findings highlight the power of spectropolarimetry in testing and discriminating between different scenarios. While all the three models predict light curves and flux spectra that are similar to each others and reproduce those observed in Type Ia supernovae comparably well, polarisation does provide a clear distinction. In particular, we find that one model is too strongly asymmetric and produces polarisation levels that are too high and clearly inconsistent with those detected for the bulk of Type Ia supernovae. Polarisation signals - and their time evolution - extracted for the remaining two models are instead in good agreement with the currently available spectropolarimetry data. Providing a powerful way to connect hydrodynamic explosion models to observed data, the study presented in this thesis is an important step towards a better understanding of Type Ia supernovae from a synthesis of theory and observations.

Measuring the dark matter equation of state and its cosmological consequences

NASA Astrophysics Data System (ADS)

Domínguez Romero, Mariano Javier de León; Ruiz, Andrés Nicolás

2012-10-01

We explore the consequences of the measurements of the equation of state of dark matter7, on the homogenous FRW universe dynamics and build an alternative cosmological scenario to the concordance ΛCDM universe. The new paradigm is based on the introduction of an effective scalar field replacing the undetected components of the dark sector: dark matter and dark energy in the form of a cosmological constant. The scalar field obeys a barotropic equation of state p = ωρ with ω = -1/3 and dominates the cosmological dynamics in the last 14.27 Gyr, in a universe with an age of 14.83 Gyr . Before that epoch, baryons and photons drove the general behaviour of the universe as in the standard ΛCDM scenario. We compute a minimal set of cosmological parameters which allow us to reproduce several observational results such us baryon abundance, constrains on the age of the universe, the astronomical scale of distance and the high redshift supernova data with a high degree of precision. However, it should be emphasized that the new model is not accelerating, instead expands asymptotically towards an Einstein Static Universe. We briefly mention the possible mechanisms behind the origin of such dominant component and analyze the prospective of reproducing the success of the standard cosmological model explaining the process of structure formation.

On the systematic approach to the classification of differential equations by group theoretical methods

NASA Astrophysics Data System (ADS)

Andriopoulos, K.; Dimas, S.; Leach, P. G. L.; Tsoubelis, D.

2009-08-01

Complete symmetry groups enable one to characterise fully a given differential equation. By considering the reversal of an approach based upon complete symmetry groups we construct new classes of differential equations which have the equations of Bateman, Monge-Ampère and Born-Infeld as special cases. We develop a symbolic algorithm to decrease the complexity of the calculations involved.

The locations of recent supernovae near the Sun from modelling (60)Fe transport.

PubMed

Breitschwerdt, D; Feige, J; Schulreich, M M; de Avillez, M A; Dettbarn, C; Fuchs, B

2016-04-07

The signature of (60)Fe in deep-sea crusts indicates that one or more supernovae exploded in the solar neighbourhood about 2.2 million years ago. Recent isotopic analysis is consistent with a core-collapse or electron-capture supernova that occurred 60 to 130 parsecs from the Sun. Moreover, peculiarities in the cosmic ray spectrum point to a nearby supernova about two million years ago. The Local Bubble of hot, diffuse plasma, in which the Solar System is embedded, originated from 14 to 20 supernovae within a moving group, whose surviving members are now in the Scorpius-Centaurus stellar association. Here we report calculations of the most probable trajectories and masses of the supernova progenitors, and hence their explosion times and sites. The (60)Fe signal arises from two supernovae at distances between 90 and 100 parsecs. The closest occurred 2.3 million years ago at present-day galactic coordinates l = 327°, b = 11°, and the second-closest exploded about 1.5 million years ago at l = 343°, b = 25°, with masses of 9.2 and 8.8 times the solar mass, respectively. The remaining supernovae, which formed the Local Bubble, contribute to a smaller extent because they happened at larger distances and longer ago ((60)Fe has a half-life of 2.6 million years). There are uncertainties relating to the nucleosynthesis yields and the loss of (60)Fe during transport, but they do not influence the relative distribution of (60)Fe in the crust layers, and therefore our model reproduces the measured relative abundances very well.

A hybrid type Ia supernova with an early flash triggered by helium-shell detonation

NASA Astrophysics Data System (ADS)

Jiang, Ji-An; Doi, Mamoru; Maeda, Keiichi; Shigeyama, Toshikazu; Nomoto, Ken'Ichi; Yasuda, Naoki; Jha, Saurabh W.; Tanaka, Masaomi; Morokuma, Tomoki; Tominaga, Nozomu; Ivezić, Željko; Ruiz-Lapuente, Pilar; Stritzinger, Maximilian D.; Mazzali, Paolo A.; Ashall, Christopher; Mould, Jeremy; Baade, Dietrich; Suzuki, Nao; Connolly, Andrew J.; Patat, Ferdinando; Wang, Lifan; Yoachim, Peter; Jones, David; Furusawa, Hisanori; Miyazaki, Satoshi

2017-10-01

Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen. The uniformity of their light curves makes these supernovae powerful cosmological distance indicators, but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved. For example, the recent detection of the early ultraviolet pulse of a peculiar, subluminous type Ia supernova has been claimed as evidence for an interaction between a red-giant or a main-sequence companion and ejecta from a white-dwarf explosion. Here we report observations of a prominent but red optical flash that appears about half a day after the explosion of a type Ia supernova. This supernova shows hybrid features of different supernova subclasses, namely a light curve that is typical of normal-brightness supernovae, but with strong titanium absorption, which is commonly seen in the spectra of subluminous ones. We argue that this early flash does not occur through previously suggested mechanisms such as the companion-ejecta interaction. Instead, our simulations show that it could occur through detonation of a thin helium shell either on a near-Chandrasekhar-mass white dwarf, or on a sub-Chandrasekhar-mass white dwarf merging with a less-massive white dwarf. Our finding provides evidence that one branch of previously proposed explosion models—the helium-ignition branch—does exist in nature, and that such a model may account for the explosions of white dwarfs in a mass range wider than previously supposed.

A hybrid type Ia supernova with an early flash triggered by helium-shell detonation.

PubMed

Jiang, Ji-An; Doi, Mamoru; Maeda, Keiichi; Shigeyama, Toshikazu; Nomoto, Ken'ichi; Yasuda, Naoki; Jha, Saurabh W; Tanaka, Masaomi; Morokuma, Tomoki; Tominaga, Nozomu; Ivezić, Željko; Ruiz-Lapuente, Pilar; Stritzinger, Maximilian D; Mazzali, Paolo A; Ashall, Christopher; Mould, Jeremy; Baade, Dietrich; Suzuki, Nao; Connolly, Andrew J; Patat, Ferdinando; Wang, Lifan; Yoachim, Peter; Jones, David; Furusawa, Hisanori; Miyazaki, Satoshi

2017-10-04

Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen. The uniformity of their light curves makes these supernovae powerful cosmological distance indicators, but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved. For example, the recent detection of the early ultraviolet pulse of a peculiar, subluminous type Ia supernova has been claimed as evidence for an interaction between a red-giant or a main-sequence companion and ejecta from a white-dwarf explosion. Here we report observations of a prominent but red optical flash that appears about half a day after the explosion of a type Ia supernova. This supernova shows hybrid features of different supernova subclasses, namely a light curve that is typical of normal-brightness supernovae, but with strong titanium absorption, which is commonly seen in the spectra of subluminous ones. We argue that this early flash does not occur through previously suggested mechanisms such as the companion-ejecta interaction. Instead, our simulations show that it could occur through detonation of a thin helium shell either on a near-Chandrasekhar-mass white dwarf, or on a sub-Chandrasekhar-mass white dwarf merging with a less-massive white dwarf. Our finding provides evidence that one branch of previously proposed explosion models-the helium-ignition branch-does exist in nature, and that such a model may account for the explosions of white dwarfs in a mass range wider than previously supposed.

An absence of ex-companion stars in the type Ia supernova remnant SNR 0509-67.5.

PubMed

Schaefer, Bradley E; Pagnotta, Ashley

2012-01-11

A type Ia supernova is thought to begin with the explosion of a white dwarf star. The explosion could be triggered by the merger of two white dwarfs (a 'double-degenerate' origin), or by mass transfer from a companion star (the 'single-degenerate' path). The identity of the progenitor is still controversial; for example, a recent argument against the single-degenerate origin has been widely rejected. One way to distinguish between the double- and single-degenerate progenitors is to look at the centre of a known type Ia supernova remnant to see whether any former companion star is present. A likely ex-companion star for the progenitor of the supernova observed by Tycho Brahe has been identified, but that claim is still controversial. Here we report that the central region of the supernova remnant SNR 0509-67.5 (the site of a type Ia supernova 400 ± 50 years ago, based on its light echo) in the Large Magellanic Cloud contains no ex-companion star to a visual magnitude limit of 26.9 (an absolute magnitude of M(V) = +8.4) within a region of radius 1.43 arcseconds. (This corresponds to the 3σ maximum distance to which a companion could have been 'kicked' by the explosion.) This lack of any ex-companion star to deep limits rules out all published single-degenerate models for this supernova. The only remaining possibility is that the progenitor of this particular type Ia supernova was a double-degenerate system.

Prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors

NASA Astrophysics Data System (ADS)

Fischer, V.; Chirac, T.; Lasserre, T.; Volpe, C.; Cribier, M.; Durero, M.; Gaffiot, J.; Houdy, T.; Letourneau, A.; Mention, G.; Pequignot, M.; Sibille, V.; Vivier, M.

2015-08-01

Core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-MeV range. Several Large Liquid Scintillator-based Detectors (LLSD) are currently operated worldwide, being very effective for low energy antineutrino detection through the Inverse Beta Decay (IBD) process. In this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of IBD kinematics over the broad energy range of supernova neutrinos. Combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% C.L.). After the addition of the next generation of scintillator-based detectors, the accuracy could reach 12 degrees (68% C.L.), therefore reaching the performances of the large water Čerenkov neutrino detectors. We also discuss a possible improvement of the SuperNova Early Warning System (SNEWS) inter-experiment network with the implementation of a directionality information in each experiment. Finally, we discuss the possibility to constrain the neutrino energy spectrum as well as the mass of the newly born neutron star with the LLSD data.

Slow-speed Supernovae from the Palomar Transient Factory: Two Channels

NASA Astrophysics Data System (ADS)

White, Christopher J.; Kasliwal, Mansi M.; Nugent, Peter E.; Gal-Yam, Avishay; Howell, D. Andrew; Sullivan, Mark; Goobar, Ariel; Piro, Anthony L.; Bloom, Joshua S.; Kulkarni, Shrinivas R.; Laher, Russ R.; Masci, Frank; Ofek, Eran O.; Surace, Jason; Ben-Ami, Sagi; Cao, Yi; Cenko, S. Bradley; Hook, Isobel M.; Jönsson, Jakob; Matheson, Thomas; Sternberg, Assaf; Quimby, Robert M.; Yaron, Ofer

2015-01-01

Since the discovery of the unusual prototype SN 2002cx, the eponymous class of Type I (hydrogen-poor) supernovae with low ejecta speeds has grown to include approximately two dozen members identified from several heterogeneous surveys, in some cases ambiguously. Here we present the results of a systematic study of 1077 Type I supernovae discovered by the Palomar Transient Factory, leading to nine new members of this peculiar class. Moreover, we find there are two distinct subclasses based on their spectroscopic, photometric, and host galaxy properties: "SN 2002cx-like" supernovae tend to be in later-type or more irregular hosts, have more varied and generally dimmer luminosities, have longer rise times, and lack a Ti II trough when compared to "SN 2002es-like" supernovae. None of our objects show helium, and we counter a previous claim of two such events. We also find that the occurrence rate of these transients relative to Type Ia supernovae is 5.6-3.8+22% (90% confidence), lower compared to earlier estimates. Combining our objects with the literature sample, we propose that these subclasses have two distinct physical origins.

Effect of Supernovae on the Local Interstellar Material

NASA Astrophysics Data System (ADS)

Frisch, Priscilla; Dwarkadas, Vikram V.

A range of astronomical data indicates that ancient supernovae created the galactic environment of the Sun and sculpted the physical properties of the interstellar medium near the heliosphere. In this paper, we review the characteristics of the local interstellar medium that have been affected by supernovae. The kinematics, magnetic field, elemental abundances, and configuration of the nearest interstellar material support the view that the Sun is at the edge of the Loop I superbubble, which has merged into the low-density Local Bubble. The energy source for the higher temperature X-ray-emitting plasma pervading the Local Bubble is uncertain. Winds from massive stars and nearby supernovae, perhaps from the Sco-Cen association, may have contributed radioisotopes found in the geologic record and galactic cosmic ray population. Nested supernova shells in the Orion and Sco-Cen regions suggest spatially distinct sites of episodic star formation. The heliosphere properties vary with the pressure of the surrounding interstellar cloud. A nearby supernova would modify this pressure equilibrium and thereby severely disrupt the heliosphere as well as the local interstellar medium.

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.

Density profiles of supernova matter and determination of neutrino parameters

NASA Astrophysics Data System (ADS)

Chiu, Shao-Hsuan

2007-08-01

The flavor conversion of supernova neutrinos can lead to observable signatures related to the unknown neutrino parameters. As one of the determinants in dictating the efficiency of resonant flavor conversion, the local density profile near the Mikheyev-Smirnov-Wolfenstein (MSW) resonance in a supernova environment is, however, not so well understood. In this analysis, variable power-law functions are adopted to represent the independent local density profiles near the locations of resonance. It is shown that the uncertain matter density profile in a supernova, the possible neutrino mass hierarchies, and the undetermined 1-3 mixing angle would result in six distinct scenarios in terms of the survival probabilities of νe and ν¯e. The feasibility of probing the undetermined neutrino mass hierarchy and the 1-3 mixing angle with the supernova neutrinos is then examined using several proposed experimental observables. Given the incomplete knowledge of the supernova matter profile, the analysis is further expanded to incorporate the Earth matter effect. The possible impact due to the choice of models, which differ in the average energy and in the luminosity of neutrinos, is also addressed in the analysis.

CRTS SNhunt: The First Five Years of Supernova Discoveries

NASA Astrophysics Data System (ADS)

Howerton, Stanley C.

2017-01-01

CRTS SNhunt: The First Five Years of Supernova Discoveries is a compilation of all supernova and supernova-like discoveries from the first five operational years of the supernova search SNhunt which is one project in the larger Catalina Real-Time Transient Survey (CRTS). SNhunt is perhaps one of the last traditional large-scale searches in which a person compares an image with a reference frame. This kind of search is time consuming as there is not a computer to narrow down the possibilities. The only help is a subtraction frame which shows differences between the two images. Images came from the Catalina Sky Survey, Mount Lemmon Survey, and Siding Spring Survey. Most of the discoveries were by the author. For many, a confirmation or a follow-up image is included. Where possible, a light curve was also created.

The ν process in the innermost supernova ejecta

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

Sieverding, Andre; Martínez-Pinedo, Gabriel; Langanke, Karlheinz

2017-12-01

The neutrino-induced nucleosynthesis (ν process) in supernova explosions of massive stars of solar metallicity with initial main sequence masses between 13 and 30 M⊙ has been studied with an analytic explosion model using a new extensive set of neutrino-nucleus cross-sections and spectral properties that agree with modern supernova simulations. The production factors for the nuclei 7Li, 11B, 19F, 138La and 180Ta, are still significantly enhanced but do not reproduce the full solar abundances. We study the possible contribution of the innermost supernova eject to the production of the light elements 7Li and 11B with tracer particles based on a 2Dmore » supernova simulation of a 12 M⊙ progenitor and conclude, that a contribution exists but is negligible for the total yield for this explosion model.« less

30 Dor B - A supernova remnant in a star formation region

NASA Technical Reports Server (NTRS)

Chu, You-Hua; Kennicutt, Robert C., Jr.; Schommer, Robert A.; Laff, Joshua

1992-01-01

The supernova remnant 30 Dor B is embedded in an H II region around the OB association LH 99, and has been suggested to be a Crab-type remnant. To determine the spatial extent and kinematic properties of this supernova remnant, long-slit echelle observations were obtained in the H-alpha and forbidden N II lines, along with imaging Fabry-Perot observations in the H-alpha line. It is found that 30 Dor B is partially obscured by a dark cloud with which the supernova remnant also interacts. The size of 30 Dor B is much larger than previously thought, making it much older than the Crab Nebula. If the progenitor of the supernova was formed coevally with LH 99, then it would have been more massive than the O3 members of the OB association.

Cosmology with Strong-lensing Systems

NASA Astrophysics Data System (ADS)

Cao, Shuo; Biesiada, Marek; Gavazzi, Raphaël; Piórkowska, Aleksandra; Zhu, Zong-Hong

2015-06-01

In this paper, we assemble a catalog of 118 strong gravitational lensing systems from the Sloan Lens ACS Survey, BOSS emission-line lens survey, Lens Structure and Dynamics, and Strong Lensing Legacy Survey and use them to constrain the cosmic equation of state. In particular, we consider two cases of dark energy phenomenology: the XCDM model, where dark energy is modeled by a fluid with constant w equation-of-state parameter, and in the Chevalier-Polarski-Linder (CPL) parameterization, where w is allowed to evolve with redshift, w(z)={{w}0}+{{w}1}\\frac{z}{1 + z} . We assume spherically symmetric mass distribution in lensing galaxies, but we relax the rigid assumption of the SIS model in favor of a more general power-law index γ, also allowing it to evolve with redshifts γ (z). Our results for the XCDM cosmology show agreement with values (concerning both w and γ parameters) obtained by other authors. We go further and constrain the CPL parameters jointly with γ (z). The resulting confidence regions for the parameters are much better than those obtained with a similar method in the past. They are also showing a trend of being complementary to the Type Ia supernova data. Our analysis demonstrates that strong gravitational lensing systems can be used to probe cosmological parameters like the cosmic equation of state for dark energy. Moreover, they have a potential to judge whether the cosmic equation of state evolved with time or not.

A GLOBAL GALACTIC DYNAMO WITH A CORONA CONSTRAINED BY RELATIVE HELICITY

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

Prasad, A.; Mangalam, A., E-mail: avijeet@iiap.res.in, E-mail: mangalam@iiap.res.in

We present a model for a global axisymmetric turbulent dynamo operating in a galaxy with a corona that treats the parameters of turbulence driven by supernovae and by magneto-rotational instability under a common formalism. The nonlinear quenching of the dynamo is alleviated by the inclusion of small-scale advective and diffusive magnetic helicity fluxes, which allow the gauge-invariant magnetic helicity to be transferred outside the disk and consequently to build up a corona during the course of dynamo action. The time-dependent dynamo equations are expressed in a separable form and solved through an eigenvector expansion constructed using the steady-state solutions ofmore » the dynamo equation. The parametric evolution of the dynamo solution allows us to estimate the final structure of the global magnetic field and the saturated value of the turbulence parameter α{sub m}, even before solving the dynamical equations for evolution of magnetic fields in the disk and the corona, along with α-quenching. We then solve these equations simultaneously to study the saturation of the large-scale magnetic field, its dependence on the small-scale magnetic helicity fluxes, and the corresponding evolution of the force-free field in the corona. The quadrupolar large-scale magnetic field in the disk is found to reach equipartition strength within a timescale of 1 Gyr. The large-scale magnetic field in the corona obtained is much weaker than the field inside the disk and has only a weak impact on the dynamo operation.« less

Discovery of Most Recent Supernova in Our Galaxy

NASA Astrophysics Data System (ADS)

2008-05-01

The most recent supernova in our Galaxy has been discovered by tracking the rapid expansion of its remains. This result, using NASA's Chandra X-ray Observatory and NRAO's Very Large Array (VLA), has implications for understanding how often supernovas explode in the Milky Way galaxy. The supernova explosion occurred about 140 years ago, making it the most recent supernova in the Milky Way as measured in Earth's time frame. Previously, the last known galactic supernova occurred around 1680, based on studying the expansion of its remnant Cassiopeia A. X-ray Image Radio and X-ray Images The recent supernova explosion was not seen in optical light about 140 years ago because it occurred close to the center of the Galaxy, and is embedded in a dense field of gas and dust. This made it about a trillion times fainter, in optical light, than an unobscured supernova. However, the supernova remnant it caused, G1.9+0.3, is now seen in X-ray and radio images. "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 backyard," said Stephen Reynolds of North Carolina State University, who led the Chandra study. "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." Astronomers regularly observe supernovas in other galaxies like ours, and based on those rates, estimate that about three should explode every century in our Milky Way, although these estimates have large margins of error. People Who Read This Also Read... Milky Way's Super-efficient Particle Accelerators Caught in The Act Oldest Known Objects Are Surprisingly Immature Action Replay of Powerful Stellar Explosion Milky Way’s Giant Black Hole Awoke from Slumber 300 Years Ago "If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions that are younger than Cassiopeia A," said David Green of the University of Cambridge in the United Kingdom, who led the VLA study. "It's great to finally track one of them down." The tracking of this source began in 1985 when astronomers, led by Green, used the VLA to identify G1.9+0.3 as the remnant of a supernova explosion near the center of our Galaxy. Based on its small size, it was thought to have resulted from a supernova that exploded about 400 to 1000 years ago. Twenty two years later, Chandra observations of this object revealed that the remnant had expanded by a surprisingly large amount, about 16% since 1985. This indicates that the supernova remnant is much younger than previously thought. The young age was confirmed when new radio observations from the VLA were made just within the past several weeks. This "apples to apples" comparison nails the age of the remnant to be about 140 years (less if it has been slowing down), making it the youngest on record in the Milky Way. Finding such a recent, obscured supernova is a vital first step in making a better estimate of the supernova rate in our Galaxy. Knowing this rate is important because supernovas heat and redistribute large amounts of gas, pump large amounts of heavy elements out into their surroundings, and can trigger the formation of new stars, closing the cycle of stellar death and rebirth. The explosion may also leave behind, in addition to the expanding remnant, a central neutron star or black hole. In addition to being a record holder for youth, G1.9+0.3 is of considerable interest for other reasons. The high expansion velocities and the extreme particle energies that have been generated are unprecedented and should stimulate deeper studies of this object with Chandra and the VLA. "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. Scientists can also use it to probe the environment into which it exploded. At perhaps only a few thousand light years from the center of the Galaxy, it appears to be embedded in the dense environment near the Milky Way's supermassive black hole. These results will appear in 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 controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Dissipative dark matter halos: The steady state solution

NASA Astrophysics Data System (ADS)

Foot, R.

2018-02-01

Dissipative dark matter, where dark matter particle properties closely resemble familiar baryonic matter, is considered. Mirror dark matter, which arises from an isomorphic hidden sector, is a specific and theoretically constrained scenario. Other possibilities include models with more generic hidden sectors that contain massless dark photons [unbroken U (1 ) gauge interactions]. Such dark matter not only features dissipative cooling processes but also is assumed to have nontrivial heating sourced by ordinary supernovae (facilitated by the kinetic mixing interaction). The dynamics of dissipative dark matter halos around rotationally supported galaxies, influenced by heating as well as cooling processes, can be modeled by fluid equations. For a sufficiently isolated galaxy with a stable star formation rate, the dissipative dark matter halos are expected to evolve to a steady state configuration which is in hydrostatic equilibrium and where heating and cooling rates locally balance. Here, we take into account the major cooling and heating processes, and numerically solve for the steady state solution under the assumptions of spherical symmetry, negligible dark magnetic fields, and that supernova sourced energy is transported to the halo via dark radiation. For the parameters considered, and assumptions made, we were unable to find a physically realistic solution for the constrained case of mirror dark matter halos. Halo cooling generally exceeds heating at realistic halo mass densities. This problem can be rectified in more generic dissipative dark matter models, and we discuss a specific example in some detail.

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.

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.

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)].

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.

Nuclear pasta in hot dense matter and its implications for neutrino scattering

NASA Astrophysics Data System (ADS)

Roggero, Alessandro; Margueron, Jérôme; Roberts, Luke F.; Reddy, Sanjay

2018-04-01

The abundance of large clusters of nucleons in neutron-rich matter at subnuclear density is found to be greatly reduced by finite-temperature effects when matter is close to β equilibrium, compared to the case where the electron fraction is fixed at Ye>0.1 , as often considered in the literature. Large nuclei and exotic nonspherical nuclear configurations called pasta, favored in the vicinity of the transition to uniform matter at T =0 , dissolve at a relatively low temperature Tu as protons leak out of nuclei and pasta. For matter at β equilibrium with a negligible neutrino chemical potential we find that Tuβ≃4 ±1 MeV for realistic equations of state. This is lower than the maximum temperature Tmaxβ≃9 ±1 MeV at which nuclei can coexist with a gas of nucleons and can be explained by a change in the nature of the transition to uniform matter called retrograde condensation. An important new finding is that coherent neutrino scattering from nuclei and pasta makes a modest contribution to the opacity under the conditions encountered in supernovas and neutron star mergers. This is because large nuclear clusters dissolve at most relevant temperatures, and at lower temperatures, when clusters are present, Coulomb correlations between them suppress coherent neutrino scattering off individual clusters. Implications for neutrino signals from galactic supernovas are briefly discussed.

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 Progenitor of the New COMPTEL/ROSAT Supernova Remnant in Vela

NASA Technical Reports Server (NTRS)

Chen, Wan; Gehrels, Neil

1999-01-01

We show that (1) the newly discovered supernova remnant (SNR) GROJ0852-4642/RXJ0852.0-4622 was created by a core-collapse supernova of a massive star and (2) the same supernova event that produced the Ti-44 detected by COMPTEL from this source is probably also responsible for a large fraction of the observed Al-26 emission in the Vela region detected by the same instrument. The first conclusion is based on the fact that the remnant is currently expanding too slowly given its young age for it to be caused by a Type la supernova. If the current SNR shell expansion speed is greater than 3000 km/s, a 15 solar mass. Type II supernova with a moderate kinetic energy exploding at about 150 pc away is favored. If the SNR expansion speed is lower than 2000 km/s, as derived naively from X-ray data, a much more energetic supernova is required to have occurred at approximately 250 pc away in a dense environment at the edge of the Gum Nebula. This progenitor has a preferred ejecta mass of less than or equal to 10(Solar Mass), and therefore it is probably a Type Ib or Type Ic supernova. However, the required high ambient density of n(sub H) greater than or equal to 100 cu cm in this scenario is difficult to reconcile with the regional CO data. A combination of our estimates of the age/energetics of the new SNR and the almost perfect positional coincidence of the new SNR with the centroid of the COMPTEL Al-26 emission feature of the Vela region strongly favors a causal connection. If confirmed, this will be the first case in which both Ti-44 and Al-26 are detected from the same young SNR, and together they can be used to select preferred theoretical core-collapse supernova models.

Handbook of Supernovae

NASA Astrophysics Data System (ADS)

Athem Alsabti, Abdul

2015-08-01

Since the discovery of pulsars in 1967, few celestial phenomena have fascinated amateur and professional astronomers, and the public, more than supernovae - dying stars that explode spectacularly and, in so doing, may outshine a whole galaxy. Thousands of research papers, reviews, monographs and books have been published on this subject. These publications are often written either for a highly specific level of expertise or education, or with respect to a particular aspect of supernovae research. However, the study of supernovae is a very broad topic involving many integral yet connected aspects, including physics, mathematics, computation, history, theoretical studies and observation. More specifically, areas of study include historical supernovae, the different types and light curves, nucleosynthesis, explosion mechanisms, formation of black holes, neutron stars, cosmic rays, neutrinos and gravitational waves. Related questions include how supernovae remnants interact with interstellar matter nearby and how do these events affect the formation of new stars or planetary systems? Could they affect existing planetary systems? Closer to home, did any supernovae affect life on earth in the past or could they do so in the future? And on the larger scale, how did supernovae observations help measure the size and expansion of the universe? All these topics, and more, are to be covered in a new reference work, consisting of more than 100 articles and more than 1700 pages. It is intended to cover all the main facets of current supernovae research. It will be pitched at or above the level of a new postgraduate student, who will have successfully studied physics (or a similar scientific subject) to Bachelor degree level. It will be available in both print and electronic (updatable) formats, with the exception of the first section, which will consist of a review of all the topics of the handbook at a level that allows anyone with basic scientific knowledge to grasp the subject. This work is contracted with Springer to be published by end of 2016.

Ti-44 Gamma-Ray Emission Lines from SN1987A Reveal an Asymmetric Explosion

NASA Technical Reports Server (NTRS)

Boggs, S. E.; Harrison, F. A.; Miyasaka, H.; Grefenstette, B. W.; Zoglauer, A.; Fryer, C. L.; Reynolds, S. P.; Alexander, D. M.; An, H.; Barret, D.;

TAROT Discovery of the Ia supernova PSN J11290437+1714095 in UGC 6483

NASA Astrophysics Data System (ADS)

Turpin, D.; Klotz, A.; Vachier, F.; Sautot, G.

2013-12-01

From images taken on 2013 December 11.09 with the TAROT Calern telescope D. Turpin reports the discovery of a supernova in UGC 6483, R=16.0. The presence of the supernova was confirmed from images taken by F. Vachier, G. Sautot with the 1 meter telescope at Pic du Midi Observatory and they locate the supernova at R.A. = 11h29m04s.44, Decl. = +17o14'08".9 (equinox 2000.0) which is offset of 30" E and 15" N from the nucleus of UGC 6483.

The triple-ring nebula around SN 1987A: fingerprint of a binary merger.

PubMed

Morris, Thomas; Podsiadlowski, Philipp

2007-02-23

Supernova 1987A, the first naked-eye supernova observed since Kepler's supernova in 1604, defies a number of theoretical expectations. Its anomalies have long been attributed to a merger between two massive stars that occurred some 20,000 years before the explosion, but so far there has been no conclusive proof that this merger took place. Here, we present three-dimensional hydrodynamical simulations of the mass ejection associated with such a merger and the subsequent evolution of the ejecta, and we show that this accurately reproduces the properties of the triple-ring nebula surrounding the supernova.

The Progenitor Systems and Explosion Mechanisms of Supernovae

NASA Astrophysics Data System (ADS)

Milisavljevic, D.

2013-10-01

Supernovae are among the most powerful explosions in the universe. They affect the energy balance, global structure, and chemical make-up of galaxies, they produce neutron stars, black holes, and some gamma-ray bursts, and they have been used as cosmological yardsticks to detect the accelerating expansion of the universe. Fundamental properties of these cosmic engines, however, remain uncertain. In this review we discuss the progress made over the last two decades in understanding supernova progenitor systems and explosion mechanisms. We also comment on anticipated future directions of research and highlight alternative methods of investigation using young supernova remnants.

Supernova Neutrino-Process and Implication in Neutrino Oscillation

NASA Astrophysics Data System (ADS)

Kajino, T.; Aoki, W.; Fujiya, W.; Mathews, G. J.; Yoshida, T.; Shaku, K.; Nakamura, K.; Hayakawa, T.

2012-08-01

We studied the supernova nucleosynthesis induced by neutrino interactions and found that several isotopes of rare elements like 7Li, 11B, 138La, 180Ta and many others are predominantly produced by the neutrino-process in core-collapse supernovae. These isotopes are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect. We here propose a new novel method to determine the unknown neutrino oscillation parameters, θ13 and mass hierarchy simultaneously from the supernova neutrino-process, combined with the r-process for heavy-element synthsis and the Galactic chemical evolution on light nuclei.

The Dark Energy Survey and Operations: Years 1 to 3

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

Diehl, H. T.

2016-01-01

The Dark Energy Survey (DES) is an operating optical survey aimed at understanding the accelerating expansion of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the 5000 sq-degree wide field and 30 sq-degree supernova surveys, the DES Collaboration built the Dark Energy Camera (DECam), a 3 square-degree, 570-Megapixel CCD camera that was installed at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO). DES has completed its third observing season out of a nominal five. This paper describes DES “Year 1”more » (Y1) to “Year 3” (Y3), the strategy, an outline of the survey operations procedures, the efficiency of operations and the causes of lost observing time. It provides details about the quality of the first three season's data, and describes how we are adjusting the survey strategy in the face of the El Niño Southern Oscillation« less

When Disorder Looks Like Order: A New Model to Explain Radial Magnetic Fields in Young Supernova Remnants

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

West, J. L.; Gaensler, B. M.; Jaffe, T.

Radial magnetic fields are observed in all known young, shell-type supernova remnants in our Galaxy, including Cas A, Tycho, Kepler, and SN1006, and yet the nature of these radial fields has not been thoroughly explored. Using a 3D model, we consider the existence and observational implications of an intrinsically radial field. We also present a new explanation of the origin of the radial pattern observed from polarization data as resulting from a selection effect due to the distribution of cosmic-ray electrons (CREs). We show that quasi-parallel acceleration can concentrate CREs at regions where the magnetic field is radial, making amore » completely turbulent field appear ordered, when it is in fact disordered. We discuss observational properties that may help distinguish between an intrinsically radial magnetic field and the case where it only appears radial due to the CRE distribution. We also show that the case of an intrinsically radial field with a quasi-perpendicular CRE acceleration mechanism has intriguing similarities to the observed polarization properties of SN1006.« less

A study of ultraviolet absorption lines through the complete Galactic halo by the analysis of HST faint object spectrograph spectra of active Galactic nuclei, 1

NASA Technical Reports Server (NTRS)

Burks, Geoffrey S.; Bartko, Frank; Shull, J. Michael; Stocke, John T.; Sachs, Elise R.; Burbidge, E. Margaret; Cohen, Ross D.; Junkkarinen, Vesa T.; Harms, Richard J.; Massa, Derck

1994-01-01

The ultraviolet (1150 - 2850 A) spectra of a number of active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) have been used to study the properties of the Galactic halo. The objects that served as probes are 3C 273, PKS 0454-220, Pg 1211+143, CSO 251, Ton 951, and PG 1351+640. The equivalent widths of certain interstellar ions have been measured, with special attention paid to the C IV/C II and Si IV/Si II ratios. These ratios have been intercompared, and the highest values are found in the direction of 3C 273, where C IV/C II = 1.2 and Si IV/Si II greater than 1. These high ratios may be due to a nearby supernova remnant, rather than to ionized gas higher up in the Galactic halo. Our data give some support to the notion that QSO metal-line systems may arise from intervening galaxies which contain high supernova rates, galactic fountains, and turbulent mixing layers.

The disk-halo connection and the nature of the interstellar medium

NASA Technical Reports Server (NTRS)

Norman, Colin A.; Ikeuchi, Satoru

1988-01-01

Some results on the nature of the interstellar medium that are specifically concerned with the disk-halo interaction are discussed. Over the last five years or so it has become clear that the supernovae rate in our Galaxy is spatially clumped and the consequences of such clumping are superbubbles and supershells fed by tens or hundreds of supernovae per shell. These objects evolve and expand rapidly and soon break out of the disk of the Galaxy, feeding the halo with very significant mass, energy, and momentum. As cooling occurs, gas will rain down onto the disk of the Galaxy completing the cycle. The basic flow of physical quantities from disk to halo and vice versa are discussed. Some of the many implications are noted including aspects of dynamo theory, quasar absorption lines, the theory of galactic coronae, and the nature of the x ray background. The essential difference here with the McKee-Ostriker (1977) theory is that the filling factor of the hot gas in the disk is significantly less than unity.

Identification of the central compact object in the young supernova remnant 1E 0102.2-7219

NASA Astrophysics Data System (ADS)

Vogt, Frédéric P. A.; Bartlett, Elizabeth S.; Seitenzahl, Ivo R.; Dopita, Michael A.; Ghavamian, Parviz; Ruiter, Ashley J.; Terry, Jason P.

2018-04-01

Oxygen-rich young supernova remnants1 are valuable objects for probing the outcome of nucleosynthetic processes in massive stars, as well as the physics of supernova explosions. Observed within a few thousand years after the supernova explosion2, these systems contain fast-moving oxygen-rich and hydrogen-poor filaments visible at optical wavelengths: fragments of the progenitor's interior expelled at a few thousand kilometres per second during the supernova explosion. Here we report the identification of the compact object in the supernova remnant 1E 0102.2-7219 in reprocessed Chandra X-ray Observatory data, enabled by the discovery of a ring-shaped structure visible primarily in optical recombination lines of Ne i and O i. The optical ring has a radius of (2.10 ± 0.35)″ ≡ (0.63 ± 0.11) pc, and is expanding at a velocity of 90 .5-30+40 km s-1. It surrounds an X-ray point source with an intrinsic X-ray luminosity Li (1.2-2.0 keV) = (1.4 ± 0.2) × 1033 erg s-1. The energy distribution of the source indicates that this object is an isolated neutron star: a central compact object akin to those present in the Cas A3-5 and Pup A6 supernova remnants, and the first of its kind to be identified outside of our Galaxy.

Recording of Supernovae in Rock Art, A Case Study at the Paint Rock Pictograph Site

NASA Astrophysics Data System (ADS)

Houston, Gordon L.; Simonia, Irakli; NA

2017-01-01

The Paint Rock pictographs in central Texas and their use as solar markers were formally reported for the first time by Dr. R. Robert Robbins at the 1999 AAS meeting #193 in Austin, Texas. He reported the operations of the winter solstice marker and suggested the possibility of more, including a summer solstice solar marker. Since this first report, there have been many informal studies of the Paint Rock site. In 1955, William C. Miller made the first interpretation of rock art as depicting images of the Crab supernova of AD 1054, which has produced many reports at other rock art sites in the American Southwest, including one at Paint Rock. All of these claims have a star and crescent configuration. Recently, these claims have been dismissed. We propose that the second panel at Paint Rock is representative of Tycho Brahe's supernovae SN1572. Miller set up a set of restrictions and criteria to evaluate these potential claims. We discuss Miller's criteria and two additional sets of criteria to evaluate representations of historical records of supernovae sightings. Two sets of characteristics of supernovae are provided, the first being galactic location and the second observational characteristics of naked eye supernovae. Employing astronomical software, we show that the panel at Paint Rock meets the restrictions and criteria discussed, that leads to high confidence in stating it records Tycho Brahe's supernova SN1572.

Highlight on Supernova Early Warning at Daya Bay

NASA Astrophysics Data System (ADS)

Wei, Hanyu

Providing an early warning of supernova burst neutrinos is of importance in studying both supernova dynamics and neutrino physics. The Daya Bay Reactor Neutrino Experiment, with a unique feature of multiple liquid scintillator detectors, is sensitive to the full energy spectrum of supernova burst electron-antineutrinos. By utilizing 8 Antineutrino Detectors (ADs) in the three different experimental halls which are about 1 km's apart from each other, we obtain a powerful and prompt rejection of muon spallation background than single-detector experiments with the same target volume. A dedicated trigger system embedded in the data acquisition system has been installed to allow the detection of a coincidence of neutrino signals of all ADs via an inverse beta-decay (IBD) within a 10-second window, thus providing a robust early warning of a supernova occurrence within the Milky Way. An 8-AD associated supernova trigger table has been established theoretically to tabulate the 8-AD event counts' coincidence vs. the trigger rate. As a result, a golden trigger threshold, i.e. with a false alarm rate < 1/3-months, can be set as low as 6 candidates among the 8 detectors, leading to a 100% detection probability for all 1987A type supernova bursts at the distance to the Milky Way center and a 96% detection probability to those at the edge of the Milky Way.

Bridging the gap: from massive stars to supernovae

PubMed Central

Crowther, Paul A.; Janka, Hans-Thomas; Langer, Norbert

2017-01-01

Almost since the beginning, massive stars and their resultant supernovae have played a crucial role in the Universe. These objects produce tremendous amounts of energy and new, heavy elements that enrich galaxies, encourage new stars to form and sculpt the shapes of galaxies that we see today. The end of millions of years of massive star evolution and the beginning of hundreds or thousands of years of supernova evolution are separated by a matter of a few seconds, in which some of the most extreme physics found in the Universe causes the explosive and terminal disruption of the star. Key questions remain unanswered in both the studies of how massive stars evolve and the behaviour of supernovae, and it appears the solutions may not lie on just one side of the explosion or the other or in just the domain of the stellar evolution or the supernova astrophysics communities. The need to view massive star evolution and supernovae as continuous phases in a single narrative motivated the Theo Murphy international scientific meeting ‘Bridging the gap: from massive stars to supernovae’ at Chicheley Hall, UK, in June 2016, with the specific purpose of simultaneously addressing the scientific connections between theoretical and observational studies of massive stars and their supernovae, through engaging astronomers from both communities. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’. PMID:28923995

Three-generation study of neutrino spin-flavor conversion in supernovae and implication for the neutrino magnetic moment

NASA Astrophysics Data System (ADS)

Ando, Shin'ichiro; Sato, Katsuhiko

2003-01-01

We investigate resonant spin-flavor (RSF) conversions of supernova neutrinos which are induced by the interaction of neutrino magnetic moment and supernova magnetic fields. From the formulation which includes all three-flavor neutrinos and antineutrinos, we give a new crossing diagram that includes not only ordinary Mikheyev-Smirnov-Wolfenstein (MSW) resonance but also a magnetically induced RSF effect. With the diagram, it is found that four conversions occur in supernovae: two are induced by the RSF effect and two by the pure MSW effect. We also numerically calculate neutrino conversions in supernova matter, using neutrino mixing parameters inferred from recent experimental results and a realistic supernova progenitor model. The results indicate that until 0.5 sec after the core bounce, the RSF-induced ν¯e↔ντ transition occurs efficiently (adiabatic resonance), when μν≳10- 12μB(B0/5×109 G)-1, where B0 is the strength of the magnetic field at the surface of iron core. We also evaluate the energy spectrum as a function of μνB0 at the super-Kamiokande detector and the Sudbury Neutrino Observatory using the calculated conversion probabilities, and find that the spectral deformation might have the possibility to provide useful information on the neutrino magnetic moment as well as the magnetic field strength in supernovae.

Effects of neutrino oscillations on nucleosynthesis and neutrino signals for an 18 M⊙ supernova model

NASA Astrophysics Data System (ADS)

Wu, Meng-Ru; Qian, Yong-Zhong; Martínez-Pinedo, Gabriel; Fischer, Tobias; Huther, Lutz

2015-03-01

In this paper, we explore the effects of neutrino flavor oscillations on supernova nucleosynthesis and on the neutrino signals. Our study is based on detailed information about the neutrino spectra and their time evolution from a spherically symmetric supernova model for an 18 M⊙ progenitor. We find that collective neutrino oscillations are not only sensitive to the detailed neutrino energy and angular distributions at emission, but also to the time evolution of both the neutrino spectra and the electron density profile. We apply the results of neutrino oscillations to study the impact on supernova nucleosynthesis and on the neutrino signals from a Galactic supernova. We show that in our supernova model, collective neutrino oscillations enhance the production of rare isotopes 138La and 180Ta but have little impact on the ν p -process nucleosynthesis. In addition, the adiabatic Mikheyev-Smirnov-Wolfenstein flavor transformation, which occurs in the C /O and He shells of the supernova, may affect the production of light nuclei such as 7Li and 11B. For the neutrino signals, we calculate the rate of neutrino events in the Super-Kamiokande detector and in a hypothetical liquid argon detector. Our results suggest the possibility of using the time profiles of the events in both detectors, along with the spectral information of the detected neutrinos, to infer the neutrino mass hierarchy.

Identification of the central compact object in the young supernova remnant 1E 0102.2-7219

NASA Astrophysics Data System (ADS)

Vogt, Frédéric P. A.; Bartlett, Elizabeth S.; Seitenzahl, Ivo R.; Dopita, Michael A.; Ghavamian, Parviz; Ruiter, Ashley J.; Terry, Jason P.

2018-06-01

Oxygen-rich young supernova remnants1 are valuable objects for probing the outcome of nucleosynthetic processes in massive stars, as well as the physics of supernova explosions. Observed within a few thousand years after the supernova explosion2, these systems contain fast-moving oxygen-rich and hydrogen-poor filaments visible at optical wavelengths: fragments of the progenitor's interior expelled at a few thousand kilometres per second during the supernova explosion. Here we report the identification of the compact object in the supernova remnant 1E 0102.2-7219 in reprocessed Chandra X-ray Observatory data, enabled by the discovery of a ring-shaped structure visible primarily in optical recombination lines of Ne i and O i. The optical ring has a radius of (2.10 ± 0.35)″ ≡ (0.63 ± 0.11) pc, and is expanding at a velocity of 90 .5-30+40 km s-1. It surrounds an X-ray point source with an intrinsic X-ray luminosity Li (1.2-2.0 keV) = (1.4 ± 0.2) × 1033 erg s-1. The energy distribution of the source indicates that this object is an isolated neutron star: a central compact object akin to those present in the Cas A3-5 and Pup A6 supernova remnants, and the first of its kind to be identified outside of our Galaxy.

Astronomical bounds on a cosmological model allowing a general interaction in the dark sector

NASA Astrophysics Data System (ADS)

Pan, Supriya; Mukherjee, Ankan; Banerjee, Narayan

2018-06-01

Non-gravitational interaction between two barotropic dark fluids, namely the pressureless dust and the dark energy in a spatially flat Friedmann-Lemaître-Robertson-Walker model, has been discussed. It is shown that for the interactions that are linear in terms the energy densities of the dark components and their first order derivatives, the net energy density is governed by a second-order differential equation with constant coefficients. Taking a generalized interaction, which includes a number of already known interactions as special cases, the dynamics of the universe is described for three types of the dark energy equation of state, namely that of interacting quintessence, interacting vacuum energy density, and interacting phantom. The models have been constrained using the standard cosmological probes, Supernovae Type Ia data from joint light curve analysis and the observational Hubble parameter data. Two geometric tests, the cosmographic studies, and the Om diagnostic have been invoked so as to ascertain the behaviour of the present model vis-a-vis the Λ-cold dark matter model. We further discussed the interacting scenarios taking into account the thermodynamic considerations.

Collective neutrino oscillations and neutrino wave packets

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

Akhmedov, Evgeny; Lindner, Manfred; Kopp, Joachim, E-mail: akhmedov@mpi-hd.mpg.de, E-mail: jkopp@uni-mainz.de, E-mail: lindner@mpi-hd.mpg.de

Effects of decoherence by wave packet separation on collective neutrino oscillations in dense neutrino gases are considered. We estimate the length of the wave packets of neutrinos produced in core collapse supernovae and the expected neutrino coherence length, and then proceed to consider the decoherence effects within the density matrix formalism of neutrino flavour transitions. First, we demonstrate that for neutrino oscillations in vacuum the decoherence effects are described by a damping term in the equation of motion of the density matrix of a neutrino as a whole (as contrasted to that of the fixed-momentum components of the neutrino densitymore » matrix). Next, we consider neutrino oscillations in ordinary matter and dense neutrino backgrounds, both in the adiabatic and non-adiabatic regimes. In the latter case we study two specific models of adiabaticity violation—one with short-term and another with extended non-adiabaticity. It is demonstrated that, while in the adiabatic case a damping term is present in the equation of motion of the neutrino density matrix (just like in the vacuum oscillation case), no such term in general appears in the non-adiabatic regime.« less

A new baryonic equation of state at sub-nuclear densities for core-collapse simulations

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

2012-11-01

We construct a new equation of state for baryons at sub-nuclear densities for the use in core-collapse simulations of massive stars. The formulation is based on the nuclear statistical equilibrium description and the liquid drop approximation of nuclei. The model free energy to minimize is calculated by using relativistic mean field theory for nucleons and the mass formula for nuclei with atomic number up to ~ 1000. We have also taken into account the pasta phase. We find that the free energy and other thermodynamical quantities are not very different from those given in the standard EOSs that adopt the single nucleus approximation. On the other hand, the average mass is systematically different, which may have an important effect to the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. It is also interesting that the root mean square of the mass number is not very different from the average mass number, since the former is important for the evaluation of coherent scattering rates on nuclei but has been unavailable so far.

Separating Dark Physics from Physical Darkness: Minimalist Modified Gravity vs. Dark Energy

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

Huterer, Dragan; Linder, Eric V.

The acceleration of the cosmic expansion may be due to a new component of physical energy density or a modification of physics itself. Mapping the expansion of cosmic scales and the growth of large scale structure in tandem can provide insights to distinguish between the two origins. Using Minimal Modified Gravity (MMG) - a single parameter gravitational growth index formalism to parameterize modified gravity theories - we examine the constraints that cosmological data can place on the nature of the new physics. For next generation measurements combining weak lensing, supernovae distances, and the cosmic microwave background we can extend themore » reach of physics to allow for fitting gravity simultaneously with the expansion equation of state, diluting the equation of state estimation by less than 25percent relative to when general relativity is assumed, and determining the growth index to 8percent. For weak lensing we examine the level of understanding needed of quasi- and nonlinear structure formation in modified gravity theories, and the trade off between stronger precision but greater susceptibility to bias as progressively more nonlinear information is used.« less

Separating dark physics from physical darkness: Minimalist modified gravity versus dark energy

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

Huterer, Dragan; Linder, Eric V.

The acceleration of the cosmic expansion may be due to a new component of physical energy density or a modification of physics itself. Mapping the expansion of cosmic scales and the growth of large scale structure in tandem can provide insights to distinguish between the two origins. Using Minimal Modified Gravity (MMG) - a single parameter gravitational growth index formalism to parametrize modified gravity theories - we examine the constraints that cosmological data can place on the nature of the new physics. For next generation measurements combining weak lensing, supernovae distances, and the cosmic microwave background we can extend themore » reach of physics to allow for fitting gravity simultaneously with the expansion equation of state, diluting the equation of state estimation by less than 25% relative to when general relativity is assumed, and determining the growth index to 8%. For weak lensing we examine the level of understanding needed of quasi- and nonlinear structure formation in modified gravity theories, and the trade off between stronger precision but greater susceptibility to bias as progressively more nonlinear information is used.« less

Catalog of Interstellar HI Shells Discovered in the SETHI Database

NASA Astrophysics Data System (ADS)

Sallmen, Shauna; Korpela, E. J.; Lo, C.; Tennyson, E.; Bellehumeur, B.; Douglas, K. A.

2013-01-01

The interstellar medium (ISM) plays a key role in the development and evolution of galaxies, including our own. The effects of supernovae and stellar winds from generations of stars produce a turbulent, multiphase medium filled with complex interacting structures. As hot gas expands outward, it sweeps up cold neutral material into a shell. Over time, the shells expand and cool, mixing with the ambient material. Shells and other features are therefore evidence of how energy and matter released by stars are redistributed, eventually resulting in the formation of new generations of stars. Several models have contributed to our broad understanding of the physical state and evolution of gas phases in our Galaxy, but a complete, detailed picture remains elusive. In general, random supernovae result in a turbulent ISM with hot, low-density gas surrounding warm & cool clouds. However, the extent to which supernovae disrupt the ambient medium is controversial, the energy inputs of shells are poorly understood, and the role of magnetic fields is unclear. Clearly, HI (neutral hydrogen) shells are central to our understanding of the ISM, so we need to study as many as possible, at all stages of evolution. Our census of Galactic HI shells ISM is incomplete because: (1) Many searches for shells use expansion as key criterion for shell identification, biasing against older, more evolved shells. (2) Shells with broken outlines are missed in most computer-based searches. The human eye is better at searching for such large, irregular features. (3) Most searches carried out in high-resolution data are restricted to the Galactic plane. We have visually examined the SETHI (Search for Extraterrestrial HI) database, searching for shell-like structures. This 21-cm radio survey has an angular resolution of 0.03° and a velocity resolution of 1.5 km/s. We present basic information (location, radial velocity, angular size, shape) for over 70 previously unidentified HI shells. We also discuss the kinematic distances and expansion velocities of shells in the catalog, and its completeness. This work has been supported by NSF grants AST/RUI-0507326, AST-0307596, and AST-0709347, Research Corporation award CC6476/6255, and a WSGC seed grant.

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

Wright, Warren P.; Nagaraj, Gautam; Kneller, James P.

It has long been recognized that the neutrinos detected from the next core-collapse supernova in the Galaxy have the potential to reveal important information about the dynamics of the explosion and the nucleosynthesis conditions as well as allowing us to probe the properties of the neutrino itself. The neutrinos emitted from thermonuclear—type Ia—supernovae also possess the same potential, although these supernovae are dimmer neutrino sources. For the first time, we calculate the time, energy, line of sight, and neutrino-flavor-dependent features of the neutrino signal expected from a three-dimensional delayed-detonation explosion simulation, where a deflagration-to-detonation transition triggers the complete disruption ofmore » a near-Chandrasekhar mass carbon-oxygen white dwarf. We also calculate the neutrino flavor evolution along eight lines of sight through the simulation as a function of time and energy using an exact three-flavor transformation code. We identify a characteristic spectral peak at ˜10 MeV as a signature of electron captures on copper. This peak is a potentially distinguishing feature of explosion models since it reflects the nucleosynthesis conditions early in the explosion. We simulate the event rates in the Super-K, Hyper-K, JUNO, and DUNE neutrino detectors with the SNOwGLoBES event rate calculation software and also compute the IceCube signal. Hyper-K will be able to detect neutrinos from our model out to a distance of ˜10 kpc. Here, at 1 kpc, JUNO, Super-K, and DUNE would register a few events while IceCube and Hyper-K would register several tens of events.« less

LOFAR 150-MHz observations of SS 433 and W 50

NASA Astrophysics Data System (ADS)

Broderick, J. W.; Fender, R. P.; Miller-Jones, J. C. A.; Trushkin, S. A.; Stewart, A. J.; Anderson, G. E.; Staley, T. D.; Blundell, K. M.; Pietka, M.; Markoff, S.; Rowlinson, A.; Swinbank, J. D.; van der Horst, A. J.; Bell, M. E.; Breton, R. P.; Carbone, D.; Corbel, S.; Eislöffel, J.; Falcke, H.; Grießmeier, J.-M.; Hessels, J. W. T.; Kondratiev, V. I.; Law, C. J.; Molenaar, G. J.; Serylak, M.; Stappers, B. W.; van Leeuwen, J.; Wijers, R. A. M. J.; Wijnands, R.; Wise, M. W.; Zarka, P.

2018-04-01

We present Low-Frequency Array (LOFAR) high-band data over the frequency range 115-189 MHz for the X-ray binary SS 433, obtained in an observing campaign from 2013 February to 2014 May. Our results include a deep, wide-field map, allowing a detailed view of the surrounding supernova remnant W 50 at low radio frequencies, as well as a light curve for SS 433 determined from shorter monitoring runs. The complex morphology of W 50 is in excellent agreement with previously published higher frequency maps; we find additional evidence for a spectral turnover in the eastern wing, potentially due to foreground free-free absorption. Furthermore, SS 433 is tentatively variable at 150 MHz, with both a debiased modulation index of 11 per cent and a χ2 probability of a flat light curve of 8.2 × 10-3. By comparing the LOFAR flux densities with contemporaneous observations carried out at 4800 MHz with the RATAN-600 telescope, we suggest that an observed ˜0.5-1 Jy rise in the 150-MHz flux density may correspond to sustained flaring activity over a period of approximately 6 months at 4800 MHz. However, the increase is too large to be explained with a standard synchrotron bubble model. We also detect a wealth of structure along the nearby Galactic plane, including the most complete detection to date of the radio shell of the candidate supernova remnant G 38.7-1.4. This further demonstrates the potential of supernova remnant studies with the current generation of low-frequency radio telescopes.

LOSS Revisited. II. The Relative Rates of Different Types of Supernovae Vary between Low- and High-mass Galaxies

NASA Astrophysics Data System (ADS)

Graur, Or; Bianco, Federica B.; Modjaz, Maryam; Shivvers, Isaac; Filippenko, Alexei V.; Li, Weidong; Smith, Nathan

2017-03-01

In Paper I of this series, we showed that the ratio between stripped-envelope (SE) supernova (SN) and Type II SN rates reveals a significant SE SN deficiency in galaxies with stellar masses ≲ {10}10 {M}⊙ . Here, we test this result by splitting the volume-limited subsample of the Lick Observatory Supernova Search (LOSS) SN sample into low- and high-mass galaxies and comparing the relative rates of various SN types found in them. The LOSS volume-limited sample contains 180 SNe and SN impostors and is complete for SNe Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients were recently reclassified by us in Shivvers et al. We find that the relative rates of some types of SNe differ between low- and high-mass galaxies: SNe Ib and Ic are underrepresented by a factor of ˜3 in low-mass galaxies. These galaxies also contain the only examples of SN 1987A-like SNe in the sample and host about nine times as many SN impostors. Normal SNe Ia seem to be ˜30% more common in low-mass galaxies, making these galaxies better sources for homogeneous SN Ia cosmology samples. The relative rates of SNe IIb are consistent in both low- and high-mass galaxies. The same is true for broad-line SNe Ic, although our sample includes only two such objects. The results presented here are in tension with a similar analysis from the Palomar Transient Factory, especially as regards SNe IIb.

The Shape of Superluminous Supernovae

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-11-01

What causes the tremendous explosions of superluminous supernovae? New observations reveal the geometry of one such explosion, SN 2015bn, providing clues as to its source.A New Class of ExplosionsImage of a type Ia supernova in the galaxy NGC 4526. [NASA/ESA]Supernovae are powerful explosions that can briefly outshine the galaxies that host them. There are several different classifications of supernovae, each with a different physical source such as thermonuclear instability in a white dwarf, caused by accretion of too much mass, or the exhaustion of fuel in the core of a massive star, leading to the cores collapse and expulsion of its outer layers.In recent years, however, weve detected another type of supernovae, referred to as superluminous supernovae. These particularly energetic explosions last longer months instead of weeks and are brighter at their peaks than normal supernovae by factors of tens to hundreds.The physical cause of these unusual explosions is still a topic of debate. Recently, however, a team of scientists led by Cosimo Inserra (Queens University Belfast) has obtained new observations of a superluminous supernova that might help address this question.The flux and the polarization level (black lines) along the dominant axis of SN 2015bn, 24 days before peak flux (left) and 28 days after peak flux (right). Blue lines show the authors best-fitting model. [Inserra et al. 2016]Probing GeometryInserra and collaborators obtained two sets of observations of SN 2015bn one roughly a month before and one a month after the superluminous supernovas peak brightness using a spectrograph on the Very Large Telescope in Chile. These observations mark the first spectropolarimetric data for a superluminous supernova.Spectropolarimetry is the practice of obtaining information about the polarization of radiation from an objects spectrum. Polarization carries information about broken spatial symmetries in the object: only if the object is perfectly symmetric can it emit an unpolarized spectrum. Otherwise, the polarization of an objects spectrum reveals information about its geometry.Modeling EjectaThe authors best model of the geometry of SN 2015bn 24 days before (top) and 28 days after (bottom) peak flux. The model consists of two ellipsoidal layers of ejecta material. [Inserra et al. 2016]Based on their observations, Inserra and collaborators find that SN 2015bn is not spherically symmetric but it does appear to be axisymmetric around a single dominant axis. They also find that the polarization level of the object changes both with wavelength and over time.To explain these dependencies, the authors produce a simple toy model of SN 2015bn. In the best-fitting model, the supernova has a two-layered ellipsoidal or bipolar geometry. The inner region becomes more and more aspherical as time passes.What does this model tell us about the physical cause of this superluminous supernova? Inserra and collaborators argue that the axisymmetric shape favors a core-collapse explosion. A central inner engine of a spinning magnetar (a highly magnetized neutron star) or black hole then remains at the center of this explosion, pumping energy into it and causing the increase of the inner asymmetry over time.The authors caution that their models are very preliminary but these observations should drive future, more detailed modeling, as well as further spectropolarimetric observations of future nearby superluminous supernovae. With luck, we will soon better understand what drives these unusual explosions.CitationC. Inserra et al 2016 ApJ 831 79. doi:10.3847/0004-637X/831/1/79

Abundances of presolar graphite and SiC from supernovae and AGB stars in the Murchison meteorite

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

Amari, Sachiko; Zinner, Ernst; Gallino, Roberto

2014-05-02

Pesolar graphite grains exhibit a range of densities (1.65 – 2.20 g/cm{sup 3}). We investigated abundances of presolar graphite grains formed in supernovae and in asymptotic giant branch (AGB) stars in the four density fractions KE3, KFA1, KFB1 and KFC1 extracted from the Murchison meteorite to probe dust productions in these stellar sources. Seventy-six and 50% of the grains in the low-density fractions KE3 and KFA1, respectively, are supernova grains, while only 7.2% and 0.9% of the grains in the high-density fractions KFB1 and KFC1 have a supernova origin. Grains of AGB star origin are concentrated in the high-density fractionsmore » KFB1 and KFC1. From the C isotopic distributions of these fractions and the presence of s-process Kr with {sup 86}Kr/{sup 82}Kr = 4.43±0.46 in KFC1, we estimate that 76% and 80% of the grains in KFB1 and KFC1, respectively, formed in AGB stars. From the abundance of graphite grains in the Murchison meteorite, 0.88 ppm, the abundances of graphite from supernovae and AGB stars are 0.24 ppm and 0.44 ppm, respectively: the abundances of graphite in supernovae and AGB stars are comparable. In contrast, it has been known that 1% of SiC grains formed in supernovae and 95% formed in AGB stars in meteorites. Since the abundance of SiC grains is 5.85 ppm in the Murchison meteorite, the abundances of SiC from supernovae and AGB stars are 0.063 ppm and 5.6 ppm, respectively: the dominant source of SiC grains is AGB stars. Since SiC grains are harder and likely to survive better in space than graphite grains, the abundance of supernova graphite grains, which is higher than that of supernova SiC grains, indicates that supernovae proficiently produce graphite grains. Graphite grains from AGB stars are, in contrast, less abundant that SiC grains from AGB stars (0.44 ppm vs. 5.6 ppm). It is difficult to derive firm conclusions for graphite and SiC formation in AGB stars due to the difference in susceptibility to grain destruction. Metallicity of the parent AGB stars of graphite grains is much lower than that of SiC grains and the difference in metallicity might also have affected to the difference in the abundances in the Murchison meteorite.« less

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

Nucleosynthesis in Supernovae

NASA Astrophysics Data System (ADS)

Thielemann, Friedrich-Karl; Isern, Jordi; Perego, Albino; von Ballmoos, Peter

2018-04-01

We present the status and open problems of nucleosynthesis in supernova explosions of both types, responsible for the production of the intermediate mass, Fe-group and heavier elements (with the exception of the main s-process). Constraints from observations can be provided through individual supernovae (SNe) or their remnants (e.g. via spectra and gamma-rays of decaying unstable isotopes) and through surface abundances of stars which witness the composition of the interstellar gas at their formation. With a changing fraction of elements heavier than He in these stars (known as metallicity) the evolution of the nucleosynthesis in galaxies over time can be determined. A complementary way, related to gamma-rays from radioactive decays, is the observation of positrons released in β+-decays, as e.g. from ^{26}Al, ^{44}Ti, ^{56,57}Ni and possibly further isotopes of their decay chains (in competition with the production of e+e- pairs in acceleration shocks from SN remnants, pulsars, magnetars or even of particle physics origin). We discuss (a) the role of the core-collapse supernova explosion mechanism for the composition of intermediate mass, Fe-group (and heavier?) ejecta, (b) the transition from neutron stars to black holes as the final result of the collapse of massive stars, and the relation of the latter to supernovae, faint supernovae, and gamma-ray bursts/hypernovae, (c) Type Ia supernovae and their nucleosynthesis (e.g. addressing the ^{55}Mn puzzle), plus (d) further constraints from galactic evolution, γ-ray and positron observations. This is complemented by the role of rare magneto-rotational supernovae (related to magnetars) in comparison with the nucleosynthesis of compact binary mergers, especially with respect to forming the heaviest r-process elements in galactic evolution.

Multi-epoch very long baseline interferometric observations of the nuclear starburst region of NGC 253: Improved modeling of the supernova and star formation rates

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

Rampadarath, H.; Morgan, J. S.; Tingay, S. J.

2014-01-01

The results of multi-epoch observations of the southern starburst galaxy, NGC 253, with the Australian Long Baseline Array at 2.3 GHz are presented. As with previous radio interferometric observations of this galaxy, no new sources were discovered. By combining the results of this survey with Very Large Array observations at higher frequencies from the literature, spectra were derived and a free-free absorption model was fitted of 20 known sources in NGC 253. The results were found to be consistent with previous studies. The supernova remnant, 5.48-43.3, was imaged with the highest sensitivity and resolution to date, revealing a two-lobed morphology.more » Comparisons with previous observations of similar resolution give an upper limit of 10{sup 4} km s{sup –1} for the expansion speed of this remnant. We derive a supernova rate of <0.2 yr{sup –1} for the inner 300 pc using a model that improves on previous methods by incorporating an improved radio supernova peak luminosity distribution and by making use of multi-wavelength radio data spanning 21 yr. A star formation rate of SFR(M ≥ 5 M {sub ☉}) < 4.9 M {sub ☉} yr{sup –1} was also estimated using the standard relation between supernova and star formation rates. Our improved estimates of supernova and star formation rates are consistent with studies at other wavelengths. The results of our study point to the possible existence of a small population of undetected supernova remnants, suggesting a low rate of radio supernova production in NGC 253.« less

Constraining the Final Fates of Massive Stars by Oxygen and Iron Enrichment History in the Galaxy

NASA Astrophysics Data System (ADS)

Suzuki, Akihiro; Maeda, Keiichi

2018-01-01

Recent observational studies of core-collapse supernovae suggest that only stars with zero-age main-sequence masses smaller than 16–18 {M}ȯ explode when they are red supergiants, producing Type IIP supernovae. This may imply that more massive stars produce other types of supernovae or they simply collapse to black holes without giving rise to bright supernovae. This failed supernova hypothesis can lead to significantly inefficient oxygen production because oxygen abundantly produced in inner layers of massive stars with zero-age main-sequence masses around 20–30 {M}ȯ might not be ejected into the surrounding interstellar space. We first assume an unspecified population of oxygen injection events related to massive stars and obtain a model-independent constraint on how much oxygen should be released in a single event and how frequently such events should happen. We further carry out one-box galactic chemical enrichment calculations with different mass ranges of massive stars exploding as core-collapse supernovae. Our results suggest that the model assuming that all massive stars with 9–100 {M}ȯ explode as core-collapse supernovae is still most appropriate in explaining the solar abundances of oxygen and iron and their enrichment history in the Galaxy. The oxygen mass in the Galaxy is not explained when assuming that only massive stars with zero-age main-sequence masses in the range of 9–17 {M}ȯ contribute to the galactic oxygen enrichment. This finding implies that a good fraction of stars more massive than 17 {M}ȯ should eject their oxygen layers in either supernova explosions or some other mass-loss processes.

KamLAND Sensitivity to Neutrinos from Pre-supernova Stars

NASA Astrophysics Data System (ADS)

Asakura, K.; Gando, A.; Gando, Y.; Hachiya, T.; Hayashida, S.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Ishikawa, T.; Ishio, S.; Koga, M.; Matsuda, S.; Mitsui, T.; Motoki, D.; Nakamura, K.; Obara, S.; Oura, T.; Shimizu, I.; Shirahata, Y.; Shirai, J.; Suzuki, A.; Tachibana, H.; Tamae, K.; Ueshima, K.; Watanabe, H.; Xu, B. D.; Kozlov, A.; Takemoto, Y.; Yoshida, S.; Fushimi, K.; Piepke, A.; Banks, T. I.; Berger, B. E.; Fujikawa, B. K.; O'Donnell, T.; Learned, J. G.; Maricic, J.; Matsuno, S.; Sakai, M.; Winslow, L. A.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.; KamLAND Collaboration

2016-02-01

In the late stages of nuclear burning for massive stars (M > 8 M⊙), the production of neutrino-antineutrino pairs through various processes becomes the dominant stellar cooling mechanism. As the star evolves, the energy of these neutrinos increases and in the days preceding the supernova a significant fraction of emitted electron anti-neutrinos exceeds the energy threshold for inverse beta decay on free hydrogen. This is the golden channel for liquid scintillator detectors because the coincidence signature allows for significant reductions in background signals. We find that the kiloton-scale liquid scintillator detector KamLAND can detect these pre-supernova neutrinos from a star with a mass of 25 M⊙ at a distance less than 690 pc with 3σ significance before the supernova. This limit is dependent on the neutrino mass ordering and background levels. KamLAND takes data continuously and can provide a supernova alert to the community.

Supernova brightening from chameleon-photon mixing

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

Burrage, C.

2008-02-15

Measurements of standard candles and measurements of standard rulers give an inconsistent picture of the history of the universe. This discrepancy can be explained if photon number is not conserved as computations of the luminosity distance must be modified. I show that photon number is not conserved when photons mix with chameleons in the presence of a magnetic field. The strong magnetic fields in a supernova mean that the probability of a photon converting into a chameleon in the interior of the supernova is high, this results in a large flux of chameleons at the surface of the supernova. Chameleonsmore » and photons also mix as a result of the intergalactic magnetic field. These two effects combined cause the image of the supernova to be brightened resulting in a model which fits both observations of standard candles and observations of standard rulers.« less

Cosmic rays from supernovae and comments on the Vela X pre-supernova

NASA Technical Reports Server (NTRS)

Cameron, A. G. W.

1971-01-01

A possible history of the production of elements in the galaxy is presented, based on assumptions about the end points of stellar evolution and of the general evolution of the galaxy. A wide range of quantities involving the relative abundances of nucleosynthesis products observed in the solar system, and various galactic quantities such as the current rate of supernova production and the present gas content of the galaxy, were considered. These assumptions were utilized in a computer program in which the gas content of the galaxy is gradually turned into stars. The stars are continually enriched in the products of nucleosynthesis as they approach the ends of their evolutionary lifetimes. It is suggested that supernova explosions are associated with the mass range of about 4-8 solar masses. Possible theories on the type of stellar explosive event represented by the Vela supernova are discussed.

Astronomy in Denver: The polarization evolution of the luminous Type Ib SN 2012au

NASA Astrophysics Data System (ADS)

Hoffman, Jennifer L.; DeKlotz, Sophia; Cooper, Kevin; Slay, Hannah; Williams, George Grant; Supernova Spectropolarimetry Project (SNSPOL)

2018-06-01

We present an analysis of the spectropolarimetric behavior of the Type Ib SN 2012au over the first 315 days of its evolution. Our data were obtained by the Supernova Spectropolarimetry Project using the CCD Imaging/Spectropolarimeter (SPOL) at the 61" Kuiper, the 90" Bok, and the 6.5-m MMT telescopes. SN 2012au was a very energetic, luminous, and slowly evolving event that may represent an intermediate case between normal core-collapse supernovae and the enigmatic superluminous supernovae. Strong, time-variable line polarization signatures, particularly in the He Il λ5876 line, support previous hypotheses of an asymmetric explosion and allow us to trace detailed structures within the supernova ejecta as they change over time. We compare the polarimetric evolution of the continuum and emission lines in SN 2012au and compare its behavior with that of other bright and polarimetrically variable supernovae.

An asymmetric energetic type Ic supernova viewed off-axis, and a link to gamma ray bursts.

PubMed

Mazzali, Paolo A; Kawabata, Koji S; Maeda, Keiichi; Nomoto, Ken'ichi; Filippenko, Alexei V; Ramirez-Ruiz, Enrico; Benetti, Stefano; Pian, Elena; Deng, Jinsong; Tominaga, Nozomu; Ohyama, Youichi; Iye, Masanori; Foley, Ryan J; Matheson, Thomas; Wang, Lifan; Gal-Yam, Avishay

2005-05-27

Type Ic supernovae, the explosions after the core collapse of massive stars that have previously lost their hydrogen and helium envelopes, are particularly interesting because of their link with long-duration gamma ray bursts. Although indications exist that these explosions are aspherical, direct evidence has been missing. Late-time observations of supernova SN 2003jd, a luminous type Ic supernova, provide such evidence. Recent Subaru and Keck spectra reveal double-peaked profiles in the nebular lines of neutral oxygen and magnesium. These profiles are different from those of known type Ic supernovae, with or without a gamma ray burst, and they can be understood if SN 2003jd was an aspherical axisymmetric explosion viewed from near the equatorial plane. If SN 2003jd was associated with a gamma ray burst, we missed the burst because it was pointing away from us.

Peculiar Supernovae

NASA Astrophysics Data System (ADS)

Milisavljevic, Dan; Margutti, Raffaella

2018-06-01

What makes a supernova truly "peculiar?" In this review we attempt to address this question by tracing the history of the use of "peculiar" as a descriptor of non-standard supernovae back to the original binary spectroscopic classification of Type I vs. Type II proposed by Minkowski (Publ. Astron. Soc. Pac., 53:224, 1941). A handful of noteworthy examples are highlighted to illustrate a general theme: classes of supernovae that were once thought to be peculiar are later seen as logical branches of standard events. This is not always the case, however, and we discuss ASASSN-15lh as an example of a transient with an origin that remains contentious. We remark on how late-time observations at all wavelengths (radio-through-X-ray) that probe 1) the kinematic and chemical properties of the supernova ejecta and 2) the progenitor star system's mass loss in the terminal phases preceding the explosion, have often been critical in understanding the nature of seemingly unusual events.

Is supernova 1987A a stripped asymptotic-branch giant in a binary system?

NASA Technical Reports Server (NTRS)

Joss, P. C.; Podsiadlowski, PH.; Hsu, J. J. L.; Rappaport, S.

1988-01-01

It is proposed that the progenitor of supernova 1987A was a previously undetected red star in orbit about a blue supergiant. The progenitor was the remnant of an asymptotic-branch giant that had lost most of its hydrogen-rich envelope to its blue companion by type C mass transfer. A detailed evolutionary model strongly supports the feasibility of this proposition. It is found that the original mass of the supernova precursor was 10-15 solar (unless a large fraction of the mass was ejected from the binary sytem), and its final mass, just before the supernova event, was 3-6 solar. The system remained bound, with a new orbital period of 3-10 yr and an eccentricity of 0.1-0.4. This picture can provide plausible qualitative explanations for several anomalies in the observational properties of this supernova.

Massive stars in their death throes.

PubMed

Eldridge, John J

2008-12-13

The study of the stars that explode as supernovae used to be a forensic study, working backwards from the remnants of the star. This changed in 1987 when the first progenitor star was identified in pre-explosion images. Currently, there are eight detected progenitors with another 21 non-detections, for which only a limit on the pre-explosion luminosity can be placed. This new avenue of supernova research has led to many interesting conclusions, most importantly that the progenitors of the most common supernovae, type IIP, are red supergiants, as theory has long predicted. However, no progenitors have been detected thus far for the hydrogen-free type Ib/c supernovae, which, given the expected progenitors, is an unlikely result. Also, observations have begun to show evidence that luminous blue variables, which are among the most massive stars, may directly explode as supernovae. These results contradict the current stellar evolution theory. This suggests that we may need to update our understanding.

Neutrino Emission from Supernovae

NASA Astrophysics Data System (ADS)

Janka, Hans-Thomas

Supernovae are the most powerful cosmic sources of MeV neutrinos. These elementary particles play a crucial role when the evolution of a massive star is terminated by the collapse of its core to a neutron star or a black hole and the star explodes as supernova. The release of electron neutrinos, which are abundantly produced by electron captures, accelerates the catastrophic infall and causes a gradual neutronization of the stellar plasma by converting protons to neutrons as dominant constituents of neutron star matter. The emission of neutrinos and antineutrinos of all flavors carries away the gravitational binding energy of the compact remnant and drives its evolution from the hot initial to the cold final state. The absorption of electron neutrinos and antineutrinos in the surroundings of the newly formed neutron star can power the supernova explosion and determines the conditions in the innermost supernova ejecta, making them an interesting site for the nucleosynthesis of iron-group elements and trans-iron nuclei.

Unusual Supernovae and Alternative Power Sources

NASA Astrophysics Data System (ADS)

Kasen, Daniel

Recent observations have revealed a diverse class of peculiar supernovae, among them transients that are extremely luminous and unusually dim, or that evolve remarkably rapidly or slowly over time. The light curves of some of these events cannot be powered by ordinary energy sources such as the decay of radioactive isotopes. This chapter begins with a brief description of certain types of unusual supernovae and then reviews the basic physics of supernova light curves, deriving in a pedagogical way the analytic scalings that characterize the peak brightness and duration. After illustrating that ordinary power sources cannot explain all of the observed events, we turn to theoretical ideas involving less common mechanisms, such as energy injection from a long-lived central engine (a rapidly rotating magnetar or an accreting black hole). We conclude by speculating how alternative power sources may be manifest in observations of the assorted classes of peculiar supernovae.

Kepler Beyond Planets: Finding Exploding Stars (Type Ia Supernova from a White Dwarf Merger)

NASA Image and Video Library

2018-03-26

This frame from an animation shows the merger of two white dwarfs. A white dwarf is an extremely dense remnant of a star that can no longer burn nuclear fuel at its core. This is another way that a "type Ia" supernova occurs. Stellar explosions forge and distribute materials that make up the world in which we live, and also hold clues to how fast the universe is expanding. By understanding supernovae, scientists can unlock mysteries that are key to what we are made of and the fate of our universe. But to get the full picture, scientists must observe supernovae from a variety of perspectives, especially in the first moments of the explosion. That's really difficult -- there's no telling when or where a supernova might happen next. An animation is available at https://photojournal.jpl.nasa.gov/catalog/PIA22353

Resonant Spin-Flavor Conversion of Supernova Neutrinos

NASA Astrophysics Data System (ADS)

Ando, Shin'ichiro; Sato, K.

2003-07-01

We investigate resonant spin-flavor (RSF) conversions of supernova neutrinos which are induced by the interaction of neutrino magnetic moment and supernova magnetic fields. With a new diagram we propose, it is found that four conversions occur in supernovae, two are induced by the RSF effect and two by the pure Mikheyev-Smirnov-Wolfenstein (MSW) effect. The realistic numerical calculation of neutrino conversions indicates that the RSF-induced νe ↔ ντ tran¯ -12 9 -1 sition occurs efficiently, when µν > 10 µB (B0 /5 × 10 G) , where B0 is the strength of the magnetic field at the surface of iron core. We also evaluate the energy spectrum as a function of µν B0 at the super-Kamiokande detector using the calculated conversion probabilities, and find that the spectral deformation might have possibility to provide useful information on the neutrino magnetic moment as well as the magnetic field strength in supernovae.

Action Replay of Powerful Stellar Explosion

NASA Astrophysics Data System (ADS)

2008-03-01

Astronomers have made the best ever determination of the power of a supernova explosion that was visible from Earth long ago. By observing the remnant of a supernova and a light echo from the initial outburst, they have established the validity of a powerful new method for studying supernovas. Using data from NASA's Chandra X-ray Observatory, ESA's XMM-Newton Observatory, and the Gemini Observatory, two teams of researchers studied the supernova remnant and the supernova light echo that are located in the Large Magellanic Cloud (LMC), a small galaxy about 160,000 light years from Earth. They concluded that the supernova occurred about 400 years ago (in Earth’s time frame), and was unusually bright and energetic. X-ray Image of SNR 0509-67.5 X-ray Image of SNR 0509-67.5 This result is the first time two methods - X-ray observations of a supernova remnant and optical observations of the expanding light echoes from the explosion - have both been used to estimate the energy of a supernova explosion. Up until now, scientists had only made such an estimate using the light seen soon after a star exploded, or using remnants that are several hundred years old, but not from both. "People didn't have advanced telescopes to study supernovas when they went off hundreds of years ago," said Armin Rest of Harvard University, who led the light echo observations using Gemini. "But we've done the next best thing by looking around the site of the explosion and constructing an action replay of it." People Who Read This Also Read... Milky Way's Super-efficient Particle Accelerators Caught in The Act Oldest Known Objects Are Surprisingly Immature Discovery of Most Recent Supernova in Our Galaxy NASA Unveils Cosmic Images Book in Braille for Blind Readers In 2004, scientists used Chandra to determine that a supernova remnant, known as SNR 0509-67.5 in the LMC, was a so-called Type Ia supernova, caused by a white dwarf star in a binary system that reaches a critical mass and explodes. In the new optical study, an estimate of the explosion's energy came from studying an echo of the original light of the explosion. Just as sound bounces off walls of a canyon, so too can light waves create an echo by bouncing off dust clouds in space. The light from these echoes travels a longer path than the light that travels straight toward us, and so can be seen hundreds of years after the supernova itself. First seen by the Cerro-Tololo Inter-American Observatory in Chile, the light echoes were observed in greater detail by Gemini Observatory in Chile. The optical spectra of the light echo were used to confirm that the supernova was a Type Ia and to unambiguously determine the particular class of explosion and therefore its energy. The Chandra data, along with XMM data obtained in 2000, were then independently used to calculate the amount of energy involved in the original explosion, using an analysis of the supernova remnant and state-of-the-art explosion models. Their conclusion confirmed the results from the optical data, namely that the explosion was an especially energetic and bright variety of Type Ia supernova. This agreement provides strong evidence that the detailed explosion models are accurate. "Having these two methods agree lets us breathe a sigh of relief," said Carlos Badenes of Princeton University who led the Chandra and XMM study. "It looks like we're on the right track with trying to understand these big explosions. Their stellar debris really can retain a memory of what created them hundreds of years earlier." Both methods estimated a similar time since the explosion of about 400 years. An extra constraint on the age comes from the lack of recorded historical evidence for a recent supernova in the LMC. Because this star appears in the Southern Hemisphere, it likely would have been seen by navigators who noted similarly bright celestial events if it had occurred less than about 400 years ago. Because Type Ia supernovas have nearly uniform intrinsic brightness, they are used as important tools by scientists to study the expansion of the universe and the nature of dark energy. "It's crucial to know that the basic assumptions about these explosions are correct, so they're not used just as black-boxes to measure distances," said Badenes. This work is also being extended to other supernova remnants and light echoes. "This is the first case where the conclusions that are drawn from the supernova remnant about the original explosion can be directly tested by looking at the original event itself," said Rest. "We'll be able to learn a lot about supernovas in our own galaxy by using this technique." These results appear in two recently accepted papers in The Astrophysical Journal. The first discusses the spectrum obtained by Gemini, led by Rest. The second, with Badenes as first author, details the Chandra and XMM observations of SNR 0509-67.5. NASA's Marshall Space Flight Center, 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.

Discovery and Spectroscopic Classification of DLT18q/AT2018aoz as a young type Ia Supernova

NASA Astrophysics Data System (ADS)

Sand, D.; Valenti, S.; Wyatt, S.; Bostroem, K. A.; Reichart, D. E.; Haislip, J. B.; Kouprianov, V.

2018-04-01

We report the discovery and classification of DLT18q/AT 2018aoz. The supernova was found on 2018 April 02.1 (UT) at r 15.1 mag during the ongoing D < 40 Mpc (DLT40) supernova search, using data from the PROMPT5 0.41m telescope located at CTIO.

Searching for Dark Energy with the Whole World's Supernova Dataset |

Science.gov Websites

room at the top for dynamical theories. One of the six new distant supernovae included in the Supernova ) with follow-up observations by the Hubble Space Telescope (bottom). Two views of one of the six new refinements compares ground-based infrared observations (in this case by Japan's Subaru Telescope on Mauna Kea

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…

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.

Spectroscopic Classification of SN2016igr as a Normal Type Ia Supernova

NASA Astrophysics Data System (ADS)

Bostroem, K. A.; Valenti, S.; Tartaglia, L.

2016-12-01

We report that a CCD spectrum (range 350-1050 nm) of SN2016igr was obtained on Dec 1, 5.95 UT, with the 3-m Shane reflector (+Kast) at Lick Observatory. We classified the event via cross-correlation with a library of supernova spectra using the "SuperNova IDentification" code (SNID; Blondin & Tonry 2007, Ap.J.

Spectrum synthesis of the Type Ia supernovae SN 1992A and SN 1981B

NASA Technical Reports Server (NTRS)

Nugent, Peter; Baron, E.; Hauschildt, Peter H.; Branch, David

1995-01-01

We present non-local thermodynamic equilibrium (non-LTE) synthetic spectra for the Type Ia supernovae SN 1992A and SN 1981B, near maximum light. At this epoch both supernovae were observed from the UV through the optical. This wide spectral coverage is essential for determining the density structure of a SN Ia. Our fits are in good agreement with observation and provide some insight as to the differences between these supernovae. We also discuss the application of the expanding photosphere method to SNe Ia which gives a distance that is independent of those based on the decay of Ni-56 and Cepheid variable stars.

Real-time supernova neutrino burst monitor at Super-Kamiokande

NASA Astrophysics Data System (ADS)

Abe, K.; Haga, Y.; Hayato, Y.; Ikeda, M.; Iyogi, K.; Kameda, J.; Kishimoto, Y.; Miura, M.; Moriyama, S.; Nakahata, M.; Nakano, Y.; Nakayama, S.; Sekiya, H.; Shiozawa, M.; Suzuki, Y.; Takeda, A.; Tanaka, H.; Tomura, T.; Ueno, K.; Wendell, R. A.; Yokozawa, T.; Irvine, T.; Kajita, T.; Kametani, I.; Kaneyuki, K.; Lee, K. P.; McLachlan, T.; Nishimura, Y.; Richard, E.; Okumura, K.; Labarga, L.; Fernandez, P.; Berkman, S.; Tanaka, H. A.; Tobayama, S.; Gustafson, J.; Kearns, E.; Raaf, J. L.; Stone, J. L.; Sulak, L. R.; Goldhaber, M.; Carminati, G.; Kropp, W. R.; Mine, S.; Weatherly, P.; Renshaw, A.; Smy, M. B.; Sobel, H. W.; Takhistov, V.; Ganezer, K. S.; Hartfiel, B. L.; Hill, J.; Keig, W. E.; Hong, N.; Kim, J. Y.; Lim, I. T.; Akiri, T.; Himmel, A.; Scholberg, K.; Walter, C. W.; Wongjirad, T.; Ishizuka, T.; Tasaka, S.; Jang, J. S.; Learned, J. G.; Matsuno, S.; Smith, S. N.; Hasegawa, T.; Ishida, T.; Ishii, T.; Kobayashi, T.; Nakadaira, T.; Nakamura, K.; Oyama, Y.; Sakashita, K.; Sekiguchi, T.; Tsukamoto, T.; Suzuki, A. T.; Takeuchi, Y.; Bronner, C.; Hirota, S.; Huang, K.; Ieki, K.; Kikawa, T.; Minamino, A.; Murakami, A.; Nakaya, T.; Suzuki, K.; Takahashi, S.; Tateishi, K.; Fukuda, Y.; Choi, K.; Itow, Y.; Mitsuka, G.; Mijakowski, P.; Hignight, J.; Imber, J.; Jung, C. K.; Yanagisawa, C.; Wilking, M. J.; Ishino, H.; Kibayashi, A.; Koshio, Y.; Mori, T.; Sakuda, M.; Yamaguchi, R.; Yano, T.; Kuno, Y.; Tacik, R.; Kim, S. B.; Okazawa, H.; Choi, Y.; Nishijima, K.; Koshiba, M.; Suda, Y.; Totsuka, Y.; Yokoyama, M.; Martens, K.; Marti, Ll.; Vagins, M. R.; Martin, J. F.; de Perio, P.; Konaka, A.; Chen, S.; Zhang, Y.; Connolly, K.; Wilkes, R. J.

2016-08-01

We present a real-time supernova neutrino burst monitor at Super-Kamiokande (SK). Detecting supernova explosions by neutrinos in real time is crucial for giving a clear picture of the explosion mechanism. Since the neutrinos are expected to come earlier than light, a fast broadcasting of the detection may give astronomers a chance to make electromagnetic radiation observations of the explosions right at the onset. The role of the monitor includes a fast announcement of the neutrino burst detection to the world and a determination of the supernova direction. We present the online neutrino burst detection system and studies of the direction determination accuracy based on simulations at SK.

They Came from the Deep in the Supernova: The Origin of TiC and Metal Subgrains in Presolar Graphite Grains

NASA Astrophysics Data System (ADS)

Lodders, Katharina

2006-08-01

A new formation scenario for TiC and Fe-Ni metal inclusions in presolar graphite grains of supernova origin is described. The mineralogy and chemistry require condensation of Fe-Ni titanides from Fe-, Ni-, and Ti-rich gaseous ejecta, subsequent carburization to make TiC and metal, and encapsulation into graphite. Titanides only condense if Si is depleted relative to heavier elements, which requires α-rich freeze-out and a deep mass cut for the supernova ejecta. This Si-poor core material must remain unmixed with other supernova zones until the titanides condense. This can be accomplished by transport of core ejecta in bipolar jets through the major expanding supernova zone ejecta. If the jets stall in regions dominated by C-rich ejecta such as the C-He zone, where graphite condenses, thermochemically favored in situ carburization of the titanides-either before or during encapsulation into condensing graphite-leads to a TiC-and-metal composite. This scenario agrees with theoretical models and observations of asymmetric core collapse in supernovae that are associated with bipolar jets loaded with iron-peak elements.

A relativistic type Ibc supernova without a detected gamma-ray burst.

PubMed

Soderberg, A M; Chakraborti, S; Pignata, G; Chevalier, R A; Chandra, P; Ray, A; Wieringa, M H; Copete, A; Chaplin, V; Connaughton, V; Barthelmy, S D; Bietenholz, M F; Chugai, N; Stritzinger, M D; Hamuy, M; Fransson, C; Fox, O; Levesque, E M; Grindlay, J E; Challis, P; Foley, R J; Kirshner, R P; Milne, P A; Torres, M A P

2010-01-28

Long duration gamma-ray bursts (GRBs) mark the explosive death of some massive stars and are a rare sub-class of type Ibc supernovae. They are distinguished by the production of an energetic and collimated relativistic outflow powered by a central engine (an accreting black hole or neutron star). Observationally, this outflow is manifested in the pulse of gamma-rays and a long-lived radio afterglow. Until now, central-engine-driven supernovae have been discovered exclusively through their gamma-ray emission, yet it is expected that a larger population goes undetected because of limited satellite sensitivity or beaming of the collimated emission away from our line of sight. In this framework, the recovery of undetected GRBs may be possible through radio searches for type Ibc supernovae with relativistic outflows. Here we report the discovery of luminous radio emission from the seemingly ordinary type Ibc SN 2009bb, which requires a substantial relativistic outflow powered by a central engine. A comparison with our radio survey of type Ibc supernovae reveals that the fraction harbouring central engines is low, about one per cent, measured independently from, but consistent with, the inferred rate of nearby GRBs. Independently, a second mildly relativistic supernova has been reported.

Prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors

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

Fischer, V.; Chirac, T.; Lasserre, T., E-mail: vincent.fischer@cea.fr, E-mail: tchirac@gmail.fr, E-mail: thierry.lasserre@cea.fr

2015-08-01

Core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-MeV range. Several Large Liquid Scintillator-based Detectors (LLSD) are currently operated worldwide, being very effective for low energy antineutrino detection through the Inverse Beta Decay (IBD) process. In this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of IBD kinematics over the broad energy range of supernova neutrinos. Combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% C.L.). After the addition of the next generationmore » of scintillator-based detectors, the accuracy could reach 12 degrees (68% C.L.), therefore reaching the performances of the large water Čerenkov neutrino detectors. We also discuss a possible improvement of the SuperNova Early Warning System (SNEWS) inter-experiment network with the implementation of a directionality information in each experiment. Finally, we discuss the possibility to constrain the neutrino energy spectrum as well as the mass of the newly born neutron star with the LLSD data.« less

A Missing-link in the Supernova-GRB Connection: The Case of SN 2012ap

NASA Astrophysics Data System (ADS)

Chakraborti, Sayan; Soderberg, Alicia; Chomiuk, Laura; Kamble, Atish; Yadav, Naveen; Ray, Alak; Hurley, Kevin; Margutti, Raffaella; Milisavljevic, Dan; Bietenholz, Michael; Brunthaler, Andreas; Pignata, Giuliano; Pian, Elena; Mazzali, Paolo; Fransson, Claes; Bartel, Norbert; Hamuy, Mario; Levesque, Emily; MacFadyen, Andrew; Dittmann, Jason; Krauss, Miriam; Briggs, M. S.; Connaughton, V.; Yamaoka, K.; Takahashi, T.; Ohno, M.; Fukazawa, Y.; Tashiro, M.; Terada, Y.; Murakami, T.; Goldsten, J.; Barthelmy, S.; Gehrels, N.; Cummings, J.; Krimm, H.; Palmer, D.; Golenetskii, S.; Aptekar, R.; Frederiks, D.; Svinkin, D.; Cline, T.; Mitrofanov, I. G.; Golovin, D.; Litvak, M. L.; Sanin, A. B.; Boynton, W.; Fellows, C.; Harshman, K.; Enos, H.; von Kienlin, A.; Rau, A.; Zhang, X.; Savchenko, V.

2015-06-01

Gamma-ray bursts (GRBs) are characterized by ultra-relativistic outflows, while supernovae are generally characterized by non-relativistic ejecta. GRB afterglows decelerate rapidly, usually within days, because their low-mass ejecta rapidly sweep up a comparatively larger mass of circumstellar material. However, supernovae with heavy ejecta can be in nearly free expansion for centuries. Supernovae were thought to have non-relativistic outflows except for a few relativistic ones accompanied by GRBs. This clear division was blurred by SN 2009bb, the first supernova with a relativistic outflow without an observed GRB. However, the ejecta from SN 2009bb was baryon loaded and in nearly free expansion for a year, unlike GRBs. We report the first supernova discovered without a GRB but with rapidly decelerating mildly relativistic ejecta, SN 2012ap. We discovered a bright and rapidly evolving radio counterpart driven by the circumstellar interaction of the relativistic ejecta. However, we did not find any coincident GRB with an isotropic fluence of more than one-sixth of the fluence from GRB 980425. This shows for the first time that central engines in SNe Ic, even without an observed GRB, can produce both relativistic and rapidly decelerating outflows like GRBs.

Regulation of the X-ray luminosity of clusters of galaxies by cooling and supernova feedback.

PubMed

Voit, G M; Bryan, G L

2001-11-22

Clusters of galaxies are thought to contain about ten times as much dark matter as baryonic matter. The dark component therefore dominates the gravitational potential of a cluster, and the baryons confined by this potential radiate X-rays with a luminosity that depends mainly on the gas density in the cluster's core. Predictions of the X-rays' properties based on models of cluster formation do not, however, agree with the observations. If the models ignore the condensation of cooling gas into stars and feedback from the associated supernovae, they overestimate the X-ray luminosity because the density of the core gas is too high. An early episode of uniformly distributed supernova feedback could rectify this by heating the uncondensed gas and therefore making it harder to compress into the core, but such a process seems to require an implausibly large number of supernovae. Here we show how radiative cooling of intergalactic gas and subsequent supernova heating conspire to eliminate highly compressible low-entropy gas from the intracluster medium. This brings the core entropy and X-ray luminosities of clusters into agreement with the observations, in a way that depends little on the efficiency of supernova heating in the early Universe.

MAGNETAR-POWERED SUPERNOVAE IN TWO DIMENSIONS. I. SUPERLUMINOUS SUPERNOVAE

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

Chen, Ke-Jung; Woosley, S. E.; Sukhbold, Tuguldur, E-mail: ken.chen@nao.ac.jp

2016-11-20

Previous studies have shown that the radiation emitted by a rapidly rotating magnetar embedded in a young supernova can greatly amplify its luminosity. These one-dimensional studies have also revealed the existence of an instability arising from the piling up of radiatively accelerated matter in a thin dense shell deep inside the supernova. Here, we examine the problem in two dimensions and find that, while instabilities cause mixing and fracture this shell into filamentary structures that reduce the density contrast, the concentration of matter in a hollow shell persists. The extent of the mixing depends upon the relative energy input bymore » the magnetar and the kinetic energy of the inner ejecta. The light curve and spectrum of the resulting supernova will be appreciably altered, as will the appearance of the supernova remnant, which will be shellular and filamentary. A similar pile up and mixing might characterize other events where energy is input over an extended period by a centrally concentrated source, e.g., a pulsar, radioactive decay, a neutrino-powered wind, or colliding shells. The relevance of our models to the recent luminous transient ASASSN-15lh is briefly discussed.« less

Fast evolving pair-instability supernovae

DOE PAGES

Kozyreva, Alexandra; Gilmer, Matthew; Hirschi, Raphael; ...

2016-10-06

With an increasing number of superluminous supernovae (SLSNe) discovered the ques- tion of their origin remains open and causes heated debates in the supernova commu- nity. Currently, there are three proposed mechanisms for SLSNe: (1) pair-instability supernovae (PISN), (2) magnetar-driven supernovae, and (3) models in which the su- pernova ejecta interacts with a circumstellar material ejected before the explosion. Based on current observations of SLSNe, the PISN origin has been disfavoured for a number of reasons. Many PISN models provide overly broad light curves and too reddened spectra, because of massive ejecta and a high amount of nickel. In themore » cur- rent study we re-examine PISN properties using progenitor models computed with the GENEC code. We calculate supernova explosions with FLASH and light curve evolu- tion with the radiation hydrodynamics code STELLA. We find that high-mass models (200 M⊙ and 250 M⊙) at relatively high metallicity (Z=0.001) do not retain hydro- gen in the outer layers and produce relatively fast evolving PISNe Type I and might be suitable to explain some SLSNe. We also investigate uncertainties in light curve modelling due to codes, opacities, the nickel-bubble effect and progenitor structure and composition.« less

SN2005da: A Spectroscopic and Photometric Analysis of a Peculiar Type Ic Supernova

NASA Astrophysics Data System (ADS)

Williamson, Jacob

2017-12-01

Core collapse supernovae are an important class of objects in stellar evolution research as they are the final life stage of high mass stars. Supernovae in general are classified into several spectral types; this paper explores SN 2005da, classified as a Type Ic, meaning it lacks hydrogen and helium lines. The supernova was originally classified as a broad-lined Type Ic (Type Ic-BL), with expansion velocities near maximum light greater than or approximately equal to 15000 km/s. However, some of the elements present in the spectrum, namely carbon and oxygen, have narrower lines (FWHM approximately equal to 2300 km/s) than other elements, indicating an interaction with a previously ejected envelope. The supernova is also found to have a decay time, with a change in magnitude over 15 days following maximum light of about 1.4 magnitudes, that is significantly faster than typical Type Ic or Ic-BL. This is more akin to a rarer object type known as a Type Ibn, although it lacks the characteristic narrow helium lines of this type. Therefore, SN 2005da appears to be unlike known examples of Type Ic supernovae.

The locations of cosmic explosions

NASA Technical Reports Server (NTRS)

Fruchter, A. S.; Levan, A. J.; Strolger, L.; Vreeswijk, P. M.; Bersier, D.; Burud, I.; Castro-Ceron, J. M.; Consclice, C.; Dahlen, T.; Strolger, L.

2005-01-01

When massive stars exhaust their fuel they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. Recently, it has become apparent that stellar collapse can power the even more brilliant relativistic explosions known as long-duration gamma-ray bursts. In some cases, a gamma-ray burst and a supernova have been observed from the same event. One would thus expect that gamma-ray bursts and supernovae should be found in similar environments. Here we show that this expectation is wrong. Using Hubble Space Telescope imaging of the host galaxies of long-duration gamma-ray bursts and core-collapse supernovae, we demonstrate that while the distribution of the supernovae in their hosts traces the blue light of young stars, the gamma-ray bursts are much more concentrated on the very brightest regions of their hosts. Furthermore, the host galaxies of the gamma-ray bursts are significantly fainter and more irregular than the hosts of the supernovae. Together these results suggest that long-duration gamma-ray bursts are associated with the very most massive stars and may be restricted to galaxies of limited chemical evolution. Our results directly imply that long-duration gamma-ray bursts are relatively rare in galaxies such as our own Milky Way.

On the Interpretation of Supernova Light Echo Profiles and Spectra

NASA Astrophysics Data System (ADS)

Rest, A.; Sinnott, B.; Welch, D. L.; Foley, R. J.; Narayan, G.; Mandel, K.; Huber, M. E.; Blondin, S.

2011-05-01

The light echo (LE) systems of historical supernovae in the Milky Way and local group galaxies provide an unprecedented opportunity to reveal the effects of asymmetry on observables, particularly optical spectra. Scattering dust at different locations on the LE ellipsoid witnesses the supernova from different perspectives, and the light consequently scattered toward Earth preserves the shape of line profile variations introduced by asymmetries in the supernova photosphere. However, the interpretation of supernova LE spectra to date has not involved a detailed consideration of the effects of outburst duration and geometrical scattering modifications due to finite scattering dust filament dimension, inclination, and image point-spread function and spectrograph slit width. In this paper, we explore the implications of these factors and present a framework for future-resolved supernova LE spectra interpretation, and test it against Cas A and SN 1987A LE spectra. We conclude that the full modeling of the dimensions and orientation of the scattering dust using the observed LEs at two or more epochs is critical for the correct interpretation of LE spectra. Indeed, without doing so one might falsely conclude that differences exist when none are actually present.

Hubble Finds Supernova Companion Star after Two Decades of Searching

NASA Image and Video Library

2017-12-08

This is an artist's impression of supernova 1993J, an exploding star in the galaxy M81 whose light reached us 21 years ago. The supernova originated in a double-star system where one member was a massive star that exploded after siphoning most of its hydrogen envelope to its companion star. After two decades, astronomers have at last identified the blue helium-burning companion star, seen at the center of the expanding nebula of debris from the supernova. The Hubble Space Telescope identified the ultraviolet glow of the surviving companion embedded in the fading glow of the supernova. More info: Using NASA’s Hubble Space Telescope, astronomers have discovered a companion star to a rare type of supernova. The discovery confirms a long-held theory that the supernova, dubbed SN 1993J, occurred inside what is called a binary system, where two interacting stars caused a cosmic explosion. "This is like a crime scene, and we finally identified the robber," said Alex Filippenko, professor of astronomy at University of California (UC) at Berkeley. "The companion star stole a bunch of hydrogen before the primary star exploded." SN 1993J is an example of a Type IIb supernova, unusual stellar explosions that contains much less hydrogen than found in a typical supernova. Astronomers believe the companion star took most of the hydrogen surrounding the exploding main star and continued to burn as a super-hot helium star. “A binary system is likely required to lose the majority of the primary star’s hydrogen envelope prior to the explosion. The problem is that, to date, direct observations of the predicted binary companion star have been difficult to obtain since it is so faint relative to the supernova itself,” said lead researcher Ori Fox of UC Berkeley. Read more: 1.usa.gov/1Az5Qb9 Credit: NASA, ESA, G. Bacon (STScI) 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

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

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.

Suppression of star formation in dwarf galaxies by photoelectric grain heating feedback.

PubMed

Forbes, John C; Krumholz, Mark R; Goldbaum, Nathan J; Dekel, Avishai

2016-07-28

Photoelectric heating--heating of dust grains by far-ultraviolet photons--has long been recognized as the primary source of heating for the neutral interstellar medium. Simulations of spiral galaxies have shown some indication that photoelectric heating could suppress star formation; however, simulations that include photoelectric heating have typically shown that it has little effect on the rate of star formation in either spiral galaxies or dwarf galaxies, which suggests that supernovae are responsible for setting the gas depletion time in galaxies. This result is in contrast with recent work indicating that a star formation law that depends on galaxy metallicity--as is expected with photoelectric heating,but not with supernovae--reproduces the present-day galaxy population better than does a metallicity-independent one. Here we report a series of simulations of dwarf galaxies, the class of galaxy in which the effects of both photoelectric heating and supernovae are expected to be strongest. We simultaneously include space and time-dependent photoelectric heating in our simulations, and we resolve the energy-conserving phase of every supernova blast wave, which allows us to directly measure the relative importance of feedback by supernovae and photoelectric heating in suppressing star formation. We find that supernovae are unable to account for the observed large gas depletion times in dwarf galaxies. Instead, photoelectric heating is the dominant means by which dwarf galaxies regulate their star formation rate at any given time,suppressing the rate by more than an order of magnitude relative to simulations with only supernovae.

Deep Recurrent Neural Networks for Supernovae Classification

NASA Astrophysics Data System (ADS)

Charnock, Tom; Moss, Adam

2017-03-01

We apply deep recurrent neural networks, which are capable of learning complex sequential information, to classify supernovae (code available at https://github.com/adammoss/supernovae). The observational time and filter fluxes are used as inputs to the network, but since the inputs are agnostic, additional data such as host galaxy information can also be included. Using the Supernovae Photometric Classification Challenge (SPCC) data, we find that deep networks are capable of learning about light curves, however the performance of the network is highly sensitive to the amount of training data. For a training size of 50% of the representational SPCC data set (around 104 supernovae) we obtain a type-Ia versus non-type-Ia classification accuracy of 94.7%, an area under the Receiver Operating Characteristic curve AUC of 0.986 and an SPCC figure-of-merit F 1 = 0.64. When using only the data for the early-epoch challenge defined by the SPCC, we achieve a classification accuracy of 93.1%, AUC of 0.977, and F 1 = 0.58, results almost as good as with the whole light curve. By employing bidirectional neural networks, we can acquire impressive classification results between supernovae types I, II and III at an accuracy of 90.4% and AUC of 0.974. We also apply a pre-trained model to obtain classification probabilities as a function of time and show that it can give early indications of supernovae type. Our method is competitive with existing algorithms and has applications for future large-scale photometric surveys.

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.

Estimating dust distances to Type Ia supernovae from colour excess time evolution

NASA Astrophysics Data System (ADS)

Bulla, M.; Goobar, A.; Amanullah, R.; Feindt, U.; Ferretti, R.

2018-01-01

We present a new technique to infer dust locations towards reddened Type Ia supernovae and to help discriminate between an interstellar and a circumstellar origin for the observed extinction. Using Monte Carlo simulations, we show that the time evolution of the light-curve shape and especially of the colour excess E(B - V) places strong constraints on the distance between dust and the supernova. We apply our approach to two highly reddened Type Ia supernovae for which dust distance estimates are available in the literature: SN 2006X and SN 2014J. For the former, we obtain a time-variable E(B - V) and from this derive a distance of 27.5^{+9.0}_{-4.9} or 22.1^{+6.0}_{-3.8} pc depending on whether dust properties typical of the Large Magellanic Cloud (LMC) or the Milky Way (MW) are used. For the latter, instead, we obtain a constant E(B - V) consistent with dust at distances larger than ∼50 and 38 pc for LMC- and MW-type dust, respectively. Values thus extracted are in excellent agreement with previous estimates for the two supernovae. Our findings suggest that dust responsible for the extinction towards these supernovae is likely to be located within interstellar clouds. We also discuss how other properties of reddened Type Ia supernovae - such as their peculiar extinction and polarization behaviour and the detection of variable, blue-shifted sodium features in some of these events - might be compatible with dust and gas at interstellar-scale distances.

Detection of Broad Hα Emission Lines in the Late-Time Spectra of a Hydrogen-Poor Superluminous Supernova

DOE PAGES

Yan, Lin; Quimby, R.; Ofek, E.; ...

2015-11-23

iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83–148 days to reach a peak bolometric luminosity of ~1.3 × 10 44 erg s -1, then decays slowly at 0.015 mag day -1. The measured ejecta velocity is ~ 13,000 km s -1. The inferred explosion characteristics, such as the ejecta mass (70–220 M ⊙), and the total radiative and kinetic energy (E rad ~ 10 51 erg, E kin ~ 2 × 10 53 erg), are typical of slow-evolving H-poor SLSN events. However,more » the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer Hα emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ~4500 km s -1 and a ~300 km s -1 blueward shift relative to the narrow component. In this paper, we interpret this broad Hα emission with a luminosity of ~2 × 10 41 erg s -1 as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ~4 × 10 16 cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ≤1, thus setting upper limits on the shell mass ≤30 M ⊙. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 M ⊙ H-shell, ejected from a progenitor star with an initial mass of (95–150) M ⊙ about 40 years ago. Finally, we estimate that at least ~15% of all SLSNe-I may have late-time Balmer emission lines.« less

Suzaku Finds "Fossil" Fireballs from Supernovae

NASA Image and Video Library

2017-12-08

Suzaku Finds "Fossil" Fireballs from Supernovae In a supernova remnant known as the Jellyfish Nebula, Suzaku detected X-rays from fully ionized silicon and sulfur -- an imprint of higher-temperature conditions immediately following the star's explosion. The nebula is about 65 light-years across. (12/30/2009) Credit: JAXA/NASA/Suzaku To learn more go to: www.nasa.gov/mission_pages/astro-e2/news/fossil-fireballs...

SALT spectroscopic classification of SN 2017erp as a type-Ia supernova well before maximum light

NASA Astrophysics Data System (ADS)

Jha, S. W.; Camacho, Y.; Dettman, K.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Skelton, R.

2017-06-01

We obtained SALT (+RSS) spectroscopy of SN 2017erp (discovered by K. Itagaki) on 2017 Jun 13.9 UT, covering the wavelength range 350-940 nm. Cross-correlation of the supernova spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows SN 2017erp is a type-Ia supernova before maximum light.

The secondary supernova machine: Gravitational compression, stored Coulomb energy, and SNII displays

NASA Astrophysics Data System (ADS)

Clayton, Donald D.; Meyer, Bradley S.

2016-04-01

Radioactive power for several delayed optical displays of core-collapse supernovae is commonly described as having been provided by decays of 56Ni nuclei. This review analyses the provenance of that energy more deeply: the form in which that energy is stored; what mechanical work causes its storage; what conservation laws demand that it be stored; and why its release is fortuitously delayed for about 106 s into a greatly expanded supernova envelope. We call the unifying picture of those energy transfers the secondary supernova machine owing to its machine-like properties; namely, mechanical work forces storage of large increases of nuclear Coulomb energy, a positive energy component within new nuclei synthesized by the secondary machine. That positive-energy increase occurs despite the fusion decreasing negative total energy within nuclei. The excess of the Coulomb energy can later be radiated, accounting for the intense radioactivity in supernovae. Detailed familiarity with this machine is the focus of this review. The stored positive-energy component created by the machine will not be reduced until roughly 106 s later by radioactive emissions (EC and β +) owing to the slowness of weak decays. The delayed energy provided by the secondary supernova machine is a few × 1049 erg, much smaller than the one percent of the 1053 erg collapse that causes the prompt ejection of matter; however, that relatively small stored energy is vital for activation of the late displays. The conceptual basis of the secondary supernova machine provides a new framework for understanding the energy source for late SNII displays. We demonstrate the nuclear dynamics with nuclear network abundance calculations, with a model of sudden compression and reexpansion of the nuclear gas, and with nuclear energy decompositions of a nuclear-mass law. These tools identify excess Coulomb energy, a positive-energy component of the total negative nuclear energy, as the late activation energy. If the value of fundamental charge e were smaller, SNII would not be so profoundly radioactive. Excess Coulomb energy has been carried within nuclei radially for roughly 109 km before being radiated into greatly expanded supernova remnants. The Coulomb force claims heretofore unacknowledged significance for supernova physics.

The dark energy survey Y1 supernova search: Survey strategy compared to forecasts and the photometric type Is SN volumetric rate

NASA Astrophysics Data System (ADS)

Fischer, John Arthur

For 70 years, the physics community operated under the assumption that the expansion of the Universe must be slowing due to gravitational attraction. Then, in 1998, two teams of scientists used Type Ia supernovae to discover that cosmic expansion was actually acceler- ating due to a mysterious "dark energy." As a result, Type Ia supernovae have become the most cosmologically important transient events in the last 20 years, with a large amount of effort going into their discovery as well as understanding their progenitor systems. One such probe for understanding Type Ia supernovae is to use rate measurements to de- termine the time delay between star formation and supernova explosion. For the last 30 years, the discovery of individual Type Ia supernova events has been accelerating. How- ever, those discoveries were happening in time-domain surveys that probed only a portion of the redshift range where expansion was impacted by dark energy. The Dark Energy Survey (DES) is the first project in the "next generation" of time-domain surveys that will discovery thousands of Type Ia supernovae out to a redshift of 1.2 (where dark energy be- comes subdominant) and DES will have better systematic uncertainties over that redshift range than any survey to date. In order to gauge the discovery effectiveness of this survey, we will use the first season's 469 photometrically typed supernovee and compare it with simulations in order to update the full survey Type Ia projections from 3500 to 2250. We will then use 165 of the 469 supernovae out to a redshift of 0.6 to measure the supernovae rate both as a function of comoving volume and of the star formation rate as it evolves with redshift. We find the most statistically significant prompt fraction of any survey to date (with a 3.9? prompt fraction detection). We will also reinforce the already existing tension in the measurement of the delayed fraction between high (z > 1.2) and low red- shift rate measurements, where we find no significant evidence of a delayed fraction at all in our photometric sample.

VizieR Online Data Catalog: Absorption velocities for 21 super-luminous SNe Ic (Liu+, 2017)

NASA Astrophysics Data System (ADS)

Liu, Y.-Q.; Modjaz, M.; Bianco, F. B.

2018-04-01

We have collected the spectra of all available super-luminous supernovae (SLSNe) Ic that have a date of maximum light published before April of 2016. These SLSNe Ic were mainly discovered and observed by the All-Sky Automated Survey for Supernovae (ASAS-SN), the Catalina Real-Time Transient Survey, the Dark Energy Survey (DES), the Hubble Space Telescope Cluster Supernova Survey, the Pan-STARRS1 Medium Deep Survey (PS1), the Public ESO Spectroscopic Survey of Transient Objects (PESSTO), the Intermediate Palomar Transient Factory (iPTF) as well as the Palomar Transient Factory (PTF), and the Supernova Legacy Survey (SNLS). See table 1. (2 data files).

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.

A new supernova light curve modeling program

NASA Astrophysics Data System (ADS)

Jäger, Zoltán; Nagy, Andrea P.; Biro, Barna I.; Vinkó, József

2017-12-01

Supernovae are extremely energetic explosions that highlight the violent deaths of various types of stars. Studying such cosmic explosions may be important because of several reasons. Supernovae play a key role in cosmic nucleosynthesis processes, and they are also the anchors of methods of measuring extragalactic distances. Several exotic physical processes take place in the expanding ejecta produced by the explosion. We have developed a fast and simple semi-analytical code to model the the light curve of core collapse supernovae. This allows the determination of their most important basic physical parameters, like the the radius of the progenitor star, the mass of the ejected envelope, the mass of the radioactive nickel synthesized during the explosion, among others.

SN 1985f - Death of a Wolf-Rayet star

NASA Technical Reports Server (NTRS)

Begelman, M. C.; Sarazin, C. L.

1986-01-01

The optical spectrum of SN 1985f has been analyzed, and the supernova ejecta is shown to contain approximately 5 or more solar masses of oxygen and very little hydrogen. It is suggested that the explosion resulted from the pair instability supernova of a WO Wolf-Rayet star of about 50 solar masses, and that the optical luminosity of the supernova is powered by the radioactive decay of Co-56 synthesized in the explosion. As calculated from the rate of the optical emission decay, the explosion occurred about 350 days before its discovery in February, 1985. It is believed that some of the oxygen-rich supernova remnants may also have been produced by explosions of WO stars.

Detection of circumstellar material in a normal type Ia supernova.

PubMed

Patat, F; Chandra, P; Chevalier, R; Justham, S; Podsiadlowski, Ph; Wolf, C; Gal-Yam, A; Pasquini, L; Crawford, I A; Mazzali, P A; Pauldrach, A W A; Nomoto, K; Benetti, S; Cappellaro, E; Elias-Rosa, N; Hillebrandt, W; Leonard, D C; Pastorello, A; Renzini, A; Sabbadin, F; Simon, J D; Turatto, M

2007-08-17

Type Ia supernovae are important cosmological distance indicators. Each of these bright supernovae supposedly results from the thermonuclear explosion of a white dwarf star that, after accreting material from a companion star, exceeds some mass limit, but the true nature of the progenitor star system remains controversial. Here we report the spectroscopic detection of circumstellar material in a normal type Ia supernova explosion. The expansion velocities, densities, and dimensions of the circumstellar envelope indicate that this material was ejected from the progenitor system. In particular, the relatively low expansion velocities suggest that the white dwarf was accreting material from a companion star that was in the red-giant phase at the time of the explosion.

An integrable family of Monge-Ampère equations and their multi-Hamiltonian structure

NASA Astrophysics Data System (ADS)

Nutku, Y.; Sarioǧlu, Ö.

1993-02-01

We have identified a completely integrable family of Monge-Ampère equations through an examination of their Hamiltonian structure. Starting with a variational formulation of the Monge-Ampère equations we have constructed the first Hamiltonian operator through an application of Dirac's theory of constraints. The completely integrable class of Monge-Ampère equations are then obtained by solving the Jacobi identities for a sufficiently general form of the second Hamiltonian operator that is compatible with the first.

Stabilization of the Rayleigh-Taylor instability in quantum magnetized plasmas

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

Wang, L. F.; Ye, W. H.; He, X. T.

2012-07-15

In this research, stabilization of the Rayleigh-Taylor instability (RTI) due to density gradients, magnetic fields, and quantum effects, in an ideal incompressible plasma, is studied analytically and numerically. A second-order ordinary differential equation (ODE) for the RTI including quantum corrections, with a continuous density profile, in a uniform external magnetic field, is obtained. Analytic expressions of the linear growth rate of the RTI, considering modifications of density gradients, magnetic fields, and quantum effects, are presented. Numerical approaches are performed to solve the second-order ODE. The analytical model proposed here agrees with the numerical calculation. It is found that the densitymore » gradients, the magnetic fields, and the quantum effects, respectively, have a stabilizing effect on the RTI (reduce the linear growth of the RTI). The RTI can be completely quenched by the magnetic field stabilization and/or the quantum effect stabilization in proper circumstances leading to a cutoff wavelength. The quantum effect stabilization plays a central role in systems with large Atwood number and small normalized density gradient scale length. The presence of external transverse magnetic fields beside the quantum effects will bring about more stability on the RTI. The stabilization of the linear growth of the RTI, for parameters closely related to inertial confinement fusion and white dwarfs, is discussed. Results could potentially be valuable for the RTI treatment to analyze the mixing in supernovas and other RTI-driven objects.« less

Lichnerowicz-type equations with sign-changing nonlinearities on complete manifolds with boundary

NASA Astrophysics Data System (ADS)

Albanese, Guglielmo; Rigoli, Marco

2017-12-01

We prove an existence theorem for positive solutions to Lichnerowicz-type equations on complete manifolds with boundary (M , ∂ M , 〈 , 〉) and nonlinear Neumann conditions. This kind of nonlinear problems arise quite naturally in the study of solutions for the Einstein-scalar field equations of General Relativity in the framework of the so called Conformal Method.

NASA's Chandra Sees Brightest Supernova Ever

NASA Astrophysics Data System (ADS)

2007-05-01

WASHINGTON - The brightest stellar explosion ever recorded may be a long-sought new type of supernova, according to observations by NASA's Chandra X-ray Observatory and ground-based optical telescopes. This discovery indicates that violent explosions of extremely massive stars were relatively common in the early universe, and that a similar explosion may be ready to go off in our own galaxy. "This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas in Austin. "That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We've never seen that before." Chandra X-ray Image of SN 2006gy Chandra X-ray Image of SN 2006gy Astronomers think many of the first generation of stars were this massive, and this new supernova may thus provide a rare glimpse of how the first stars died. It is unprecedented, however, to find such a massive star and witness its death. The discovery of the supernova, known as SN 2006gy, provides evidence that the death of such massive stars is fundamentally different from theoretical predictions. "Of all exploding stars ever observed, this was the king," said Alex Filippenko, leader of the ground-based observations at the Lick Observatory at Mt. Hamilton, Calif., and the Keck Observatory in Mauna Kea, Hawaii. "We were astonished to see how bright it got, and how long it lasted." The Chandra observation allowed the team to rule out the most likely alternative explanation for the supernova: that a white dwarf star with a mass only slightly higher than the sun exploded into a dense, hydrogen-rich environment. In that event, SN 2006gy should have been 1,000 times brighter in X-rays than what Chandra detected. Animation of SN 2006gy Animation of SN 2006gy "This provides strong evidence that SN 2006gy was, in fact, the death of an extremely massive star," said Dave Pooley of the University of California at Berkeley, who led the Chandra observations. The star that produced SN 2006gy apparently expelled a large amount of mass prior to exploding. This large mass loss is similar to that seen from Eta Carinae, a massive star in our galaxy, raising suspicion that Eta Carinae may be poised to explode as a supernova. Although SN 2006gy is intrinsically the brightest supernova ever, it is in the galaxy NGC 1260, some 240 million light years away. However, Eta Carinae is only about 7,500 light years away in our own Milky Way galaxy. "We don't know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case," said Mario Livio of the Space Telescope Science Institute in Baltimore, who was not involved in the research. "Eta Carinae's explosion could be the best star-show in the history of modern civilization." A New Line of Stellar Evolution A New Line of Stellar Evolution Supernovas usually occur when massive stars exhaust their fuel and collapse under their own gravity. In the case of SN 2006gy, astronomers think that a very different effect may have triggered the explosion. Under some conditions, the core of a massive star produces so much gamma ray radiation that some of the energy from the radiation converts into particle and anti-particle pairs. The resulting drop in energy causes the star to collapse under its own huge gravity. After this violent collapse, runaway thermonuclear reactions ensue and the star explodes, spewing the remains into space. The SN 2006gy data suggest that spectacular supernovas from the first stars - rather than completely collapsing to a black hole as theorized - may be more common than previously believed. "In terms of the effect on the early universe, there's a huge difference between these two possibilities," said Smith. "One pollutes the galaxy with large quantities of newly made elements and the other locks them up forever in a black hole." The results from Smith and his colleagues will appear in The Astrophysical Journal. NASA's Marshall Space Flight Center, 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

Gamma-ray spectroscopy: The diffuse galactic glow

NASA Technical Reports Server (NTRS)

Hartmann, Dieter H.

1991-01-01

The goal of this project is the development of a numerical code that provides statistical models of the sky distribution of gamma-ray lines due to the production of radioactive isotopes by ongoing Galactic nucleosynthesis. We are particularly interested in quasi-steady emission from novae, supernovae, and stellar winds, but continuum radiation and transient sources must also be considered. We have made significant progress during the first half period of this project and expect the timely completion of a code that can be applied to Oriented Scintillation Spectrometer Experiment (OSSE) Galactic plane survey data.