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Sample records for neutrino-heating supernova mechanism

  1. INFLUENCE OF MAGNETOROTATIONAL INSTABILITY ON NEUTRINO HEATING: A NEW MECHANISM FOR WEAKLY MAGNETIZED CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Sawai, Hidetomo; Yamada, Shoichi

    2014-03-20

    We investigated the impact of magnetorotational instability (MRI) on the dynamics of weakly magnetized, rapidly rotating core-collapse supernovae by conducting high-resolution axisymmetric MHD simulations with simplified neutrino transfer. We found that an initially sub-magnetar-class magnetic field is drastically amplified by MRI and substantially affects the dynamics thereafter. Although the magnetic pressure is not strong enough to eject matter, the amplified magnetic field efficiently transfers angular momentum from small to large radii and from higher to lower latitudes, which causes the expansion of the heating region due to the extra centrifugal force. This then enhances the efficiency of neutrino heating and eventually leads to neutrino-driven explosion. This is a new scenario of core-collapse supernovae that has never been demonstrated by past numerical simulations.

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

    NASA Astrophysics Data System (ADS)

    Janka, H.-Th.

    2001-03-01

    Energy deposition by neutrinos can rejuvenate the stalled bounce shock and can provide the energy for the supernova explosion of a massive star. This neutrino-heating mechanism, though investigated by numerical simulations and analytic studies, is not finally accepted or proven as the trigger of the explosion. Part of the problem is that different groups have obtained seemingly discrepant results, and the complexity of the hydrodynamic models often hampers a clear and simple interpretation of the results. This demands a deeper theoretical understanding of the requirements of a successful shock revival. A toy model is developed here for discussing the neutrino heating phase analytically. The neutron star atmosphere between the neutrinosphere and the supernova shock can well be considered to be in hydrostatic equilibrium, with a layer of net neutrino cooling below the gain radius and a layer of net neutrino heating above. Since the mass infall rate to the shock is in general different from the rate at which gas is advected into the neutron star, the mass in the gain layer varies with time. Moreover, the gain layer receives additional energy input by neutrinos emitted from the neutrinosphere and the cooling layer. Therefore the determination of the shock evolution requires a time-dependent treatment. To this end the hydrodynamical equations of continuity and energy are integrated over the volume of the gain layer to obtain conservation laws for the total mass and energy in this layer. The radius and velocity of the supernova shock can then be calculated from global properties of the gain layer as solutions of an initial value problem, which expresses the fact that the behavior of the shock is controlled by the cumulative effects of neutrino heating and mass accumulation in the gain layer. The described toy model produces steady-state accretion and mass outflow from the nascent neutron star as special cases. The approach is useful to illuminate the conditions that can

  3. NEW TWO-DIMENSIONAL MODELS OF SUPERNOVA EXPLOSIONS BY THE NEUTRINO-HEATING MECHANISM: EVIDENCE FOR DIFFERENT INSTABILITY REGIMES IN COLLAPSING STELLAR CORES

    SciTech Connect

    Mueller, Bernhard; Janka, Hans-Thomas; Heger, Alexander E-mail: thj@mpa-garching.mpg.de

    2012-12-10

    The neutrino-driven explosion mechanism for core-collapse supernovae in its modern flavor relies on the additional support of hydrodynamical instabilities in achieving shock revival. Two possible candidates, convection and the so-called standing accretion shock instability (SASI), have been proposed for this role. In this paper, we discuss new successful simulations of supernova explosions that shed light on the relative importance of these two instabilities. While convection has so far been observed to grow first in self-consistent hydrodynamical models with multi-group neutrino transport, we here present the first such simulation in which the SASI grows faster while the development of convection is initially inhibited. We illustrate the features of this SASI-dominated regime using an explosion model of a 27 M{sub Sun} progenitor, which is contrasted with a convectively dominated model of an 8.1 M{sub Sun} progenitor with subsolar metallicity, whose early post-bounce behavior is more in line with previous 11.2 M{sub Sun} and 15 M{sub Sun} explosion models. We analyze the conditions discriminating between the two different regimes, showing that a high mass-accretion rate and a short advection timescale are conducive for strong SASI activity. We also briefly discuss some important factors for capturing the SASI-driven regime, such as general relativity, the progenitor structure, a nuclear equation of state leading to a compact proto-neutron star, and the neutrino treatment. Finally, we evaluate possible implications of our findings for two-dimensional and three-dimensional supernova simulations.

  4. New Two-dimensional Models of Supernova Explosions by the Neutrino-heating Mechanism: Evidence for Different Instability Regimes in Collapsing Stellar Cores

    NASA Astrophysics Data System (ADS)

    Müller, Bernhard; Janka, Hans-Thomas; Heger, Alexander

    2012-12-01

    The neutrino-driven explosion mechanism for core-collapse supernovae in its modern flavor relies on the additional support of hydrodynamical instabilities in achieving shock revival. Two possible candidates, convection and the so-called standing accretion shock instability (SASI), have been proposed for this role. In this paper, we discuss new successful simulations of supernova explosions that shed light on the relative importance of these two instabilities. While convection has so far been observed to grow first in self-consistent hydrodynamical models with multi-group neutrino transport, we here present the first such simulation in which the SASI grows faster while the development of convection is initially inhibited. We illustrate the features of this SASI-dominated regime using an explosion model of a 27 M ⊙ progenitor, which is contrasted with a convectively dominated model of an 8.1 M ⊙ progenitor with subsolar metallicity, whose early post-bounce behavior is more in line with previous 11.2 M ⊙ and 15 M ⊙ explosion models. We analyze the conditions discriminating between the two different regimes, showing that a high mass-accretion rate and a short advection timescale are conducive for strong SASI activity. We also briefly discuss some important factors for capturing the SASI-driven regime, such as general relativity, the progenitor structure, a nuclear equation of state leading to a compact proto-neutron star, and the neutrino treatment. Finally, we evaluate possible implications of our findings for two-dimensional and three-dimensional supernova simulations.

  5. The r-process and neutrino-heated supernova ejecta

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.; Wilson, J. R.; Mathews, G. J.; Hoffman, R. D.; Meyer, B. S.

    1994-01-01

    As a neutron star is formed by the collapse of the iron core of a massive star, its Kelvin-Helmholtz evolution is characterized by the release of gravitational binding energy as neutrinos. The interaction of these neutrinos with heated material above the neutron star generates a hot bubble in an atmosphere that is nearly in hydrostatic equilibrium and heated, after approximately 10 s, to an entropy of S/N(sub AS)k greater than or approximately = 400. The neutron-to-proton ratio for material moving outward through this bubble is set by the balance between neutrino and antineutrino capture on nucleons. Because the electron antineutrino spectrum at this time is hotter than the electron neutrino spectrum, the bubble is neutron-rich (0.38 less than or approximately = Y(sub e) less than or approximately = 0.47). Previous work using a schematic model has shown that these conditions are well suited to the production of heavy elements by the r-process. In this paper we have advanced the numerical modeling of a 20 solar mass 'delayed' supernova explosion to the point that we can follow the detailed evolution of material moving through the bubble at the late times appropiate to r-process nucleosynthesis. The supernova model predicts a final kinetic energy for the ejecta of 1.5 x 10(exp 51) ergs and leaves behind a remnant with a baryon mass of 1.50 solar mass (and a gravitational mass of 1.445 solar mass). We follow the thermodynamic and compositional evolution of 40 trajectories in rho(t), T(t), Y(sub e)(t) for a logarithmic grid of mass elements for the last approximately = 0.03 solar mass to be ejected by the proto-neutron star down to the last less than 10(exp -6) solar mass of material expelled at up to approximately = 18 s after core collapse. We find that an excellent fit to the solar r-process abundance distribution is obtained with no adjustable parameters in the nucleosynthesis calculations. Moreover, the abundances are produced in the quantities required to account

  6. Numerical Analysis of Standing Accretion Shock Instability with Neutrino Heating in Supernova Cores

    NASA Astrophysics Data System (ADS)

    Ohnishi, Naofumi; Kotake, Kei; Yamada, Shoichi

    2006-04-01

    We have numerically studied the instability of the spherically symmetric standing accretion shock wave against nonspherical perturbations. We have in mind the application to collapse-driven supernovae in the postbounce phase, where the prompt shock wave generated by core bounce is commonly stalled. We take an experimental standpoint in this paper. Using spherically symmetric, completely steady, shocked accretion flows as unperturbed states, we have clearly observed both the linear growth and the subsequent nonlinear saturation of the instability. In so doing, we have employed a realistic equation of state, together with heating and cooling via neutrino reactions with nucleons. We have performed a mode analysis based on the spherical harmonics decomposition and found that the modes with l=1,2 are dominant not only in the linear regime but also after nonlinear couplings generate various modes and saturation occurs. By varying the neutrino luminosity, we have constructed unperturbed states both with and without a negative entropy gradient. We have found that in both cases the growth of the instability is similar, suggesting that convection does not play a dominant role, which also appears to be supported by the recent linear analysis of the convection in accretion flows by Foglizzo et al. The oscillation period of the unstable l=1 mode is found to fit better with the advection time rather than with the sound crossing time. Whatever the cause may be, the instability favors a shock revival.

  7. DYNAMICS OF A SPHERICAL ACCRETION SHOCK WITH NEUTRINO HEATING AND ALPHA-PARTICLE RECOMBINATION

    SciTech Connect

    Fernandez, Rodrigo; Thompson, Christopher

    2009-10-01

    We investigate the effects of neutrino heating and alpha-particle recombination on the hydrodynamics of core-collapse supernovae. Our focus is on the nonlinear dynamics of the shock wave that forms in the collapse and the assembly of positive energy material below it. To this end, we perform time-dependent hydrodynamic simulations with FLASH2.5 in spherical and axial symmetry. These generalize our previous calculations by allowing for bulk neutrino heating and for nuclear statistical equilibrium between n, p, and alpha. The heating rate is freely tunable, as is the starting radius of the shock relative to the recombination radius of alpha-particles. An explosion in spherical symmetry involves the excitation of an overstable mode, which may be viewed as the l = 0 version of the 'Standing Accretion Shock Instability'. In two-dimensional simulations, nonspherical deformations of the shock are driven by plumes of material with positive Bernoulli parameter, which are concentrated well outside the zone of strong neutrino heating. The nonspherical modes of the shock reach a large amplitude only when the heating rate is also high enough to excite convection below the shock. The critical heating rate that causes an explosion depends sensitively on the initial position of the shock relative to the recombination radius. Weaker heating is required to drive an explosion in two dimensions than in one, but the difference also depends on the size of the shock. Forcing the infalling heavy nuclei to break up into n and p below the shock only causes a slight increase in the critical heating rate, except when the shock starts out at a large radius. This shows that heating by neutrinos (or some other mechanism) must play a significant role in pushing the shock far enough out that recombination heating takes over.

  8. The potential role of spatial dimension in the neutrino-driving mechanism of core-collapse supernova explosions

    NASA Astrophysics Data System (ADS)

    Burrows, Adam; Nordhaus, Jason; Almgren, Ann; Bell, John

    2011-09-01

    We have hydrodynamically explored the dependence on spatial dimension of the viability of the neutrino heating mechanism of core-collapse supernova explosions and find that the tendency to explode is a monotonically increasing function of dimension. Moreover, we find that the delay to explosion for a given neutrino luminosity is always shorter in 3D than 2D, sometimes by many hundreds of milliseconds. The magnitude of this dimensional effect is much larger than the purported magnitude of a variety of other effects sometimes invoked to bridge the gap between the current ambiguous and uncertain theoretical situation and the fact of robust supernova explosions in Nature. Our finding, facilitated by access to state-of-the-art codes and large computers, may be an important step towards unraveling one of the most problematic puzzles in stellar astrophysics.

  9. DIMENSION AS A KEY TO THE NEUTRINO MECHANISM OF CORE-COLLAPSE SUPERNOVA EXPLOSIONS

    SciTech Connect

    Nordhaus, J.; Burrows, A.; Almgren, A.; Bell, J. E-mail: burrows@astro.princeton.ed E-mail: JBBell@lbl.go

    2010-09-01

    We explore the dependence on spatial dimension of the viability of the neutrino heating mechanism of core-collapse supernova explosions. We find that the tendency to explode is a monotonically increasing function of dimension, with three dimensions (3D) requiring {approx}40%-50% lower driving neutrino luminosity than one dimension and {approx}15%-25% lower driving neutrino luminosity than two dimensions (2D). Moreover, we find that the delay to explosion for a given neutrino luminosity is always shorter in 3D than 2D, sometimes by many hundreds of milliseconds. The magnitude of this dimensional effect is much larger than the purported magnitude of a variety of other effects, such as nuclear burning, inelastic scattering, or general relativity, which are sometimes invoked to bridge the gap between the current ambiguous and uncertain theoretical situation and the fact of robust supernova explosions. Since real supernovae occur in three dimensions, our finding may be an important step toward unraveling one of the most problematic puzzles in stellar astrophysics. In addition, even though in 3D, we do see pre-explosion instabilities and blast asymmetries, unlike the situation in 2D, we do not see an obvious axially symmetric dipolar shock oscillation. Rather, the free energy available to power instabilities seems to be shared by more and more degrees of freedom as the dimension increases. Hence, the strong dipolar axisymmetry seen in 2D and previously identified as a fundamental characteristic of the shock hydrodynamics may not survive in 3D as a prominent feature.

  10. The Dependence of the Neutrino Mechanism of Core-collapse Supernovae on the Equation of State

    NASA Astrophysics Data System (ADS)

    Couch, Sean M.

    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 ⊙ progenitor in 1D and 2D. We test the EOS most commonly used in core-collapse simulations: the models of Lattimer & 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 not 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 & Swesty EOS models. Amongst the Lattimer & 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.

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

    SciTech Connect

    Couch, Sean M.

    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 not 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.

  12. Physical processes in collapse driven supernova

    SciTech Connect

    Mayle, R.W.

    1985-11-01

    A model of the supernova explosion is discussed. The method of neutrino transport is discussed, since the explosive mechanism depends on neutrino heating of the material behind the accretion shock. The core region of these exploding stars becomes unstable to convective motions during the supernova evolution. Convective mixing allows more neutrinos to escape from under the neutrinosphere, and thus increases the amount of heating by neutrinos. An approximate method of incorporating convection is described, and some results of including convection in a computer model is presented. Another phenomena is seen in computer simulations of supernova, oscillations in the neutrino luminosity and mass accretion rate onto the protoneutron star. The last topic discussed in this thesis describes the attempt to understand this oscillation by perturbation of the steady state solution to equations approximating the complex physical processes occurring in the late time supernova. 42 refs., 31 figs.

  13. Supernovae in Binary Systems: An Application of Classical Mechanics.

    ERIC Educational Resources Information Center

    Mitalas, R.

    1980-01-01

    Presents the supernova explosion in a binary system as an application of classical mechanics. This presentation is intended to illustrate the power of the equivalent one-body problem and provide undergraduate students with a variety of insights into elementary classical mechanics. (HM)

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

    NASA Astrophysics Data System (ADS)

    Foglizzo, Thierry; Kazeroni, Rémi; Guilet, Jérôme; Masset, Frédéric; González, Matthias; Krueger, Brendan K.; Novak, Jérôme; Oertel, Micaela; Margueron, Jérôme; Faure, Julien; Martin, Noël; Blottiau, Patrick; Peres, Bruno; Durand, Gilles

    2015-03-01

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

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

    SciTech Connect

    Foglizzo, Thierry; Kazeroni, Rémi; Guilet, Jérôme; Masset, Frédéric; González, Matthias; Krueger, Brendan K.; Novak, Jérôme; Faure, Julien; Martin, Noël; Blottiau, Patrick; Peres, Bruno; Durand, Gilles

    2015-03-17

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

  16. Supernova Explosions and the Birth of Neutron Stars

    SciTech Connect

    Janka, H.-Thomas; Marek, Andreas; Mueller, Bernhard; Scheck, Leonhard

    2008-02-27

    We report here on recent progress in understanding the birth conditions of neutron stars and the way how supernovae explode. More sophisticated numerical models have led to the discovery of new phenomena in the supernova core, for example a generic hydrodynamic instability of the stagnant supernova shock against low-mode nonradial deformation and the excitation of gravity-wave activity in the surface and core of the nascent neutron star. Both can have supportive or decisive influence on the inauguration of the explosion, the former by improving the conditions for energy deposition by neutrino heating in the postshock gas, the latter by supplying the developing blast with a flux of acoustic power that adds to the energy transfer by neutrinos. While recent two-dimensional models suggest that the neutrino-driven mechanism may be viable for stars from {approx}8M{sub {center_dot}} to at least 15M{sub {center_dot}}, acoustic energy input has been advocated as an alternative if neutrino heating fails. Magnetohydrodynamic effects constitute another way to trigger explosions in connection with the collapse of sufficiently rapidly rotating stellar cores, perhaps linked to the birth of magnetars. The global explosion asymmetries seen in the recent simulations offer an explanation of even the highest measured kick velocities of young neutron stars.

  17. Supernova mechanisms: Before and after SN1987a

    SciTech Connect

    Kahana, S.H.

    1987-01-01

    The impact of SN1987a on theoretical studies of the specific mechanism generating Type II supernovae is examined. The explosion energy extracted from analysis of the light curve for SN 1987a is on the edge of distinguishing between a prompt explosion from a hydrodynamic shock and a delayed, neutrino-induced, explosion. The detection of neutrinos from 1987a is also reanalyzed. 30 refs., 2 tabs.

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

    DOE PAGESBeta

    Foglizzo, Thierry; Kazeroni, Rémi; Guilet, Jérôme; Masset, Frédéric; González, Matthias; Krueger, Brendan K.; Novak, Jérôme; Oertel, Micaela; Margueron, Jérôme; Faure, Julien; et al

    2015-03-17

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

  19. Pulsar recoil by large-scale anisotropies in supernova explosions.

    PubMed

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

    2004-01-01

    Assuming that the neutrino luminosity from the neutron star core is sufficiently high to drive supernova explosions by the neutrino-heating mechanism, we show that low-mode (l=1,2) convection can develop from random seed perturbations behind the shock. A slow onset of the explosion is crucial, requiring the core luminosity to vary slowly with time, in contrast to the burstlike exponential decay assumed in previous work. Gravitational and hydrodynamic forces by the globally asymmetric supernova ejecta were found to accelerate the remnant neutron star on a time scale of more than a second to velocities above 500 km s(-1), in agreement with observed pulsar proper motions. PMID:14753979

  20. Neutrino Heat Conduction and Inhomogeneities in the Early Universe

    NASA Technical Reports Server (NTRS)

    Heckler, A.; Hogan, C. J.

    1993-01-01

    Constraints on parameters of inhomogeneous nucteosynthesis, namely, the overdensity and size of baryon lumps, are found by calculatig the blackbody neutrino heat conduction into the lumps, which tends to inflate them away. The scale size for efficient heat conduction is determined by the mean free path lambda of the neutrino, and so we compute lambda in our case of a high-temperature plasma with low chemical potential, and find a general result that many-body effects are unimportant, simplifying the calculation. We find that in the region of interest for nucleosynthesis, neutrino inflation is important for overdensities greater than 10(exp 4).

  1. Supernovae

    NASA Astrophysics Data System (ADS)

    March, Marisa

    2014-03-01

    We live in a Universe that is getting bigger faster. This astonishing discovery of Universal acceleration was made in the late 1990s by two teams who made observations of a special type of exploded star known as a `Supernova Type Ia'. (SNeIa) Since the discovery of the accelerating Universe, one of the biggest questions in modern cosmology has been to determine the cause of that acceleration - the answer to this question will have far reaching implications for our theories of cosmology and fundamental physics more broadly. The two main competing explanations for this apparent late time acceleration of the Universe are modified gravity and dark energy. The Dark Energy Survey (DES) has been designed and commissioned to find to find answers to these questions about the nature of dark energy and modified gravity. The new 570 megapixel Dark Energy Camera is currently operating with the Cerro-Tololo Inter American Observatory's 4m Blanco teleccope, carrying out a systematic search for SNeIa, and mapping out the large scale structure of the Universe by making observations of galaxies. The DES science program program which saw first light in September 2013 will run for five years in total. DES SNeIa data in combination with the other DES observations of large scale structure will enable us to put increasingly accurate constraints on the expansion history of the Universe and will help us distinguish between competing theories of dark energy and modified gravity. As we draw to the close of the first observing season of DES in March 2014, we will report on the current status of the DES supernova survey, presenting first year supernovae data, preliminary results, survey strategy, discovery pipeline, spectroscopic target selection and data quality. This talk will give the first glimpse of the DES SN first year data and initial results as we begin our five year survey in search of dark energy. On behalf of the Dark Energy Survey collaboration.

  2. MISSING BLACK HOLES UNVEIL THE SUPERNOVA EXPLOSION MECHANISM

    SciTech Connect

    Belczynski, Krzysztof; Wiktorowicz, Grzegorz; Fryer, Chris L.; Holz, Daniel E.; Kalogera, Vassiliki

    2012-09-20

    It is firmly established that the stellar mass distribution is smooth, covering the range 0.1-100 M{sub Sun }. It is to be expected that the masses of the ensuing compact remnants correlate with the masses of their progenitor stars, and thus it is generally thought that the remnant masses should be smoothly distributed from the lightest white dwarfs to the heaviest black holes (BHs). However, this intuitive prediction is not borne out by observed data. In the rapidly growing population of remnants with observationally determined masses, a striking mass gap has emerged at the boundary between neutron stars (NSs) and BHs. The heaviest NSs reach a maximum of two solar masses, while the lightest BHs are at least five solar masses. Over a decade after the discovery, the gap has become a significant challenge to our understanding of compact object formation. We offer new insights into the physical processes that bifurcate the formation of remnants into lower-mass NSs and heavier BHs. Combining the results of stellar modeling with hydrodynamic simulations of supernovae, we both explain the existence of the gap and also put stringent constraints on the inner workings of the supernova explosion mechanism. In particular, we show that core-collapse supernovae are launched within 100-200 ms of the initial stellar collapse, implying that the explosions are driven by instabilities with a rapid (10-20 ms) growth time. Alternatively, if future observations fill in the gap, this will be an indication that these instabilities develop over a longer (>200 ms) timescale.

  3. Two Dimensional Simulations of Core-Collapse Supernovae with Neutrino Transport in FLASH

    NASA Astrophysics Data System (ADS)

    O'Connor, Evan; Couch, Sean

    2016-03-01

    Core-collapse supernovae are the end stage of massive star evolution and are central to many aspects of astrophysics. They are the birth site of both neutron stars and black holes and their shocks are responsible for spreading the products of stellar evolution throughout the Galaxy and regulating star formation. Despite their importance and decades of research, the precise mechanism that converts the initial implosion of the collapsing iron core to an explosion that unbinds the majority of the star is unknown. However, we know that the majority of the energy released is ultimately radiated in neutrinos and that the physics of neutrino transport and neutrino heating-among many other aspects-must be treated carefully when modelling the core-collapse supernova central engine. In this talk, I will present recent simulations of core-collapse supernovae from the FLASH hydrodynamics code. We perform two dimensional, neutrino transport simulations using several progenitors. We test the influence of general relativity by using a pseudorelativistic potential that effectively models GR. We show that the more compact protoneutron star predicted from GR increases the neutrino heating and can lead to explosions where the corresponding Newtonian simulations fail.

  4. On the Importance of the Equation of State for the Neutrino-driven Supernova Explosion Mechanism

    NASA Astrophysics Data System (ADS)

    Suwa, Yudai; Takiwaki, Tomoya; Kotake, Kei; Fischer, Tobias; Liebendörfer, Matthias; Sato, Katsuhiko

    2013-02-01

    By implementing the widely used equations of state (EOS) from Lattimer & Swesty (LS) and H. Shen et al. (SHEN) in core-collapse supernova simulations, we explore possible impacts of these EOS on the post-bounce dynamics prior to the onset of neutrino-driven explosions. Our spherically symmetric (1D) and axially symmetric (2D) models are based on neutrino radiation hydrodynamics including spectral transport, which is solved by the isotropic diffusion source approximation. We confirm that in 1D simulations neutrino-driven explosions cannot be obtained for any of the employed EOS. Impacts of the EOS on the post-bounce hydrodynamics are more clearly visible in 2D simulations. In 2D models of a 15 M ⊙ progenitor using the LS EOS, the stalled bounce shock expands to increasingly larger radii, which is not the case when using the SHEN EOS. Keeping in mind that the omission of the energy drain by heavy-lepton neutrinos in the present scheme could facilitate explosions, we find that 2D models of an 11.2 M ⊙ progenitor produce neutrino-driven explosions for all the EOS under investigation. Models using the LS EOS are slightly more energetic compared with those with the SHEN EOS. The more efficient neutrino heating in the LS models coincides with a higher electron antineutrino luminosity and a larger mass that is enclosed within the gain region. The models based on the LS EOS also show a more vigorous and aspherical downflow of accreting matter to the surface of the protoneutron star (PNS). The accretion pattern is essential for the production and strength of outgoing pressure waves, which can push in turn the shock to larger radii and provide more favorable conditions for the explosion. Based on our models, we investigate several diagnostic indicators of the explosion that have been suggested in the literature, e.g., the amplitude of the standing accretion shock instability mode, the mass-weighted average entropy in the gain region, the PNS radius, the antesonic

  5. A common explosion mechanism for type Ia supernovae.

    PubMed

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

    2007-02-01

    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. PMID:17289993

  6. 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.

  7. Constraints on the explosion mechanism and progenitors of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Blondin, S.

    2015-12-01

    We present 1D non-LTE time-dependent radiative-transfer simulations of Type Ia supernova ejecta resulting from different explosion mechanisms and white dwarf (WD) progenitor masses, and confront our results to Type Ia supernova observations over the first ˜ 100 d of their evolution. While the ``standard'' Chandrasekhar-mass delayed-detonation model reproduces the observed properties of Type Ia supernova ejecta near maximum light over a wide range of peak luminosities, the high luminosity and blue optical colours seen at early times in several Type Ia supernova ejecta appears to require some hydrodynamical interaction affecting the outermost ejecta layers, here in the form of a strong pulsation. Moreover, the fast light-curve evolution of the least luminous Type Ia supernova ejecta seem to require WD progenitors below the Chandrasekhar mass. The observed diversity of the Type Ia supernova population can thus be reproduced with multiple progenitor channels and explosion mechanisms. In this context, departures from spherical symmetry only play a minor role.

  8. Towards the Core-Collapse Supernova Explosion Mechanism

    SciTech Connect

    Cardall, Christian Y; Endeve, Eirik; Budiardja, R. D.; Marronetti, Pedro; Mezzacappa, Anthony

    2012-01-01

    Core-collapse supernovae are amazing displays of astrohysical fireworks - and the optical emission is only a tiny part of the story. These events involve virtually all branches of physics and spawn phenomena observale by every kind of astronomical observation. This richness of theory and observation presents a formidable challenge to their understanding via computer simulations, but we are entering a new era of realism and maturity in modeling the key processes by collapse and explosion.

  9. ASCERTAINING THE CORE COLLAPSE SUPERNOVA MECHANISM: The State of the Art and the Road Ahead

    NASA Astrophysics Data System (ADS)

    Mezzacappa, Anthony

    2005-12-01

    More than four decades have elapsed since modeling of the core collapse supernova mechanism began in earnest. To date, the mechanism remains elusive, at least in detail, although significant progress has been made in understanding these multiscale, multiphysics events. One-, two-, and three-dimensional simulations of or relevant to core collapse supernovae have shown that (a) neutrino transport, (b) fluid instabilities, (c) rotation, and (d) magnetic fields, together with proper treatments of (e) the sub- and super- nuclear density stellar core equation of state, (f) the neutrino interactions, and (g) gravity are all important. The importance of these ingredients applies to both the explosion mechanism and to phenomena directly associated with the mechanism, such as neutron star kicks, supernova neutrino and gravitational wave emission, and supernova spectropolarimetry.Not surprisingly, current two- and three-dimensional models have yet to include (a) (d) with sufficient realism. One-dimensional spherically symmetric models have achieved a significant level of sophistication but, by definition, cannot incorporate (b) (d), except phenomenologically. Fully general relativistic spherically symmetric simulations with Boltzmann neutrino transport do not yield explosions, demonstrating that some combination of (b), (c), and (d) is required to achieve this. Systematic layering of the dimensionality and the physics will be needed to achieve a complete understanding of the supernova mechanism and phenomenology. The past modeling efforts alluded to above have illuminated that core collapse supernovae may be neutrino driven, magnetohydrodynamically (MHD) driven, or both, but uncertainties in the current models prevent us from being able to answer even this most basic question. And it may be that more than one possibility is realized in nature. Nonetheless, if a supernova is neutrino driven, magnetic fields will likely have an impact on the dynamics of the explosion. Similarly

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

    SciTech Connect

    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 the 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.

  11. Aspherical supernovae

    SciTech Connect

    Kasen, Daniel Nathan

    2004-05-21

    Although we know that many supernovae are aspherical, the exact nature of their geometry is undetermined. Because all the supernovae we observe are too distant to be resolved, the ejecta structure can't be directly imaged, and asymmetry must be inferred from signatures in the spectral features and polarization of the supernova light. The empirical interpretation of this data, however, is rather limited--to learn more about the detailed supernova geometry, theoretical modeling must been undertaken. One expects the geometry to be closely tied to the explosion mechanism and the progenitor star system, both of which are still under debate. Studying the 3-dimensional structure of supernovae should therefore provide new break throughs in our understanding. The goal of this thesis is to advance new techniques for calculating radiative transfer in 3-dimensional expanding atmospheres, and use them to study the flux and polarization signatures of aspherical supernovae. We develop a 3-D Monte Carlo transfer code and use it to directly fit recent spectropolarimetric observations, as well as calculate the observable properties of detailed multi-dimensional hydrodynamical explosion simulations. While previous theoretical efforts have been restricted to ellipsoidal models, we study several more complicated configurations that are tied to specific physical scenarios. We explore clumpy and toroidal geometries in fitting the spectropolarimetry of the Type Ia supernova SN 2001el. We then calculate the observable consequences of a supernova that has been rendered asymmetric by crashing into a nearby companion star. Finally, we fit the spectrum of a peculiar and extraordinarily luminous Type Ic supernova. The results are brought to bear on three broader astrophysical questions: (1) What are the progenitors and the explosion processes of Type Ia supernovae? (2) What effect does asymmetry have on the observational diversity of Type Ia supernovae, and hence their use in cosmology? (3) And

  12. Aspherical supernovae

    NASA Astrophysics Data System (ADS)

    Kasen, Daniel Nathan

    Although we know that many supernovae are aspherical, the exact nature of their geometry is undetermined. Because all the supernovae we observe are too distant to be resolved, the ejecta structure can't be directly imaged, and asymmetry must be inferred from signatures in the spectral features and polarization of the supernova light. The empirical interpretation of this data, however, is rather limited--to learn more about the detailed supernova geometry, theoretical modeling must be undertaken. One expects the geometry to be closely tied to the explosion mechanism and the progenitor star system, both of which are still under debate. Studying the 3-dimensional structure of supernovae should therefore provide new breakthroughs in our understanding. The goal of this thesis is to advance new techniques for calculating radiative transfer in 3-dimensional expanding atmospheres, and use them to study the flux and polarization signatures of aspherical supernovae. We develop a 3-D Monte Carlo transfer code and use it to directly fit recent spectropolarimetric observations, as well as calculate the observable properties of detailed multi- dimensional hydrodynamical explosion simulations. While previous theoretical efforts have been restricted to ellipsoidal models, we study several more complicated configurations that are tied to specific physical scenarios. We explore clumpy and toroidal geometries in fitting the spectropolarimetry of the Type Ia supernova SN 2001el. We then calculate the observable consequences of a supernova that has been rendered asymmetric by crashing into a nearby companion star. Finally we fit the spectrum of a peculiar and extraordinarily luminous Type Ic supernova. The results are brought to bear on three broader astrophysical questions: (1) What are the progenitors and the explosion processes of Type Ia supernovae? (2) What effect does asymmetry have on the observational diversity of Type Ia supernovae, and hence their use in cosmology? (3) And

  13. The convective engine paradigm for the supernova explosion mechanism and its consequences.

    NASA Astrophysics Data System (ADS)

    Herant, M.

    1995-05-01

    The convective engine paradigm for the explosion mechanism in core collapse supernovae is presented in a pedagogical manner. A candid evaluation of its strengths and weaknesses is attempted. The case where the convective mode corresponds to l=1, m=0 (one inflow, one outflow) is explored in more detail. The author also discusses the potential importance of such a convective pattern for neutron star kicks.

  14. YOUNG SUPERNOVAE AS EXPERIMENTAL SITES FOR STUDYING THE ELECTRON ACCELERATION MECHANISM

    SciTech Connect

    Maeda, Keiichi

    2013-01-10

    Radio emissions from young supernovae ({approx}<1 year after the explosion) show a peculiar feature in the relativistic electron population at a shock wave, where their energy distribution is steeper than typically found in supernova remnants and than that predicted from the standard diffusive shock acceleration (DSA) mechanism. This has been especially established for the case for a class of stripped envelope supernovae (SNe IIb/Ib/Ic), where a combination of high shock velocity and low circumstellar material density makes it easier to derive the intrinsic energy distribution than in other classes of SNe. We suggest that this apparent discrepancy reflects a situation where the low energy electrons, before being accelerated by the DSA-like mechanism, are responsible for the radio synchrotron emission from young SNe, and that studying young SNe sheds light on the still-unresolved electron injection problem in the acceleration theory of cosmic rays. We suggest that the electron's energy distribution could be flattened toward high energy, most likely around 100 MeV, which marks a transition from inefficient to efficient acceleration. Identifying this feature will be a major advance in understanding the electron acceleration mechanism. We suggest two further probes: (1) millimeter/submillimeter observations in the first year after the explosion and (2) X-ray observations at about one year and thereafter. We show that these are reachable by ALMA and Chandra for nearby SNe.

  15. Accreting white dwarf models for type 1 supernovae. 1: Presupernova evolution and triggering mechanisms

    NASA Technical Reports Server (NTRS)

    Nomoto, K.

    1981-01-01

    As a plausible explosion model for a Type I supernova, the evolution of carbon-oxygen white dwarfs accreting helium in binary systems was investigated from the onset of accretion up to the point at which a thermonuclear explosion occurs. The relationship between the conditions in the binary system and the triggering mechanism for the supernova explosion is discussed, especially for the cases with relatively slow accretion rate. It is found that the growth of a helium zone on the carbon-oxygen core leads to a supernova explosion which is triggered either by the off-center helium detonation for slow and intermediate accretion rates or by the carbon deflagration for slow and rapid accretion rates. Both helium detonation and carbon deflagration are possible for the case of slow accretion, since in this case the initial mass of the white dwarf is an important parameter for determining the mode of ignition. Finally, various modes of building up the helium zone on the white dwarf, namely, direct transfer of helium from the companion star and the various types and strength of the hydrogen shell flashes are discussed in some detail.

  16. r-process nucleosynthesis in the MHD+neutrino-heated collapsar jet

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Kajino, T.; Mathews, G. J.; Sato, S.; Harikae, S.

    2015-10-01

    It has been proposed that the collapsar scenario for long-duration gamma ray bursts is a possible astrophysical site for r-process nucleosynthesis. Here we present r-process nucleosynthesis calculations based upon a model for a MHD+neutrino-heated collapsar jet. We utilize a relativistic magnetohydrodynamic model that includes ray-tracing neutrino transport to describe the development of the black hole accretion disk and the neutrino heating of the funnel region above the black hole. The late time evolution of the collapsar jet is then evolved using axisymmetric special relativistic hydrodynamics. We employ representative test particles to follow the trajectories in density, temperature, entropy, and electron fraction for material flowing from the accretion disk into the jet until they are several thousand km above the black hole. The evolution of nuclear abundances from nucleons to heavy nuclei for ejected test particle trajectories was solved in a large nuclear reaction network as temperatures fall from 9 × 109 to 3 × 108 K. We show that an r-process-like abundance distribution forms in material ejected in the collapsar jet. The possibility for a signature of collapsar r-process material to be found in metal-poor stars is discussed.

  17. Photon-axion conversion as a mechanism for supernova dimming: Limits from CMB spectral distortion

    SciTech Connect

    Mirizzi, Alessandro; Raffelt, Georg G.; Serpico, Pasquale D.

    2005-07-15

    Axion-photon conversion induced by intergalactic magnetic fields has been proposed as an explanation for the dimming of distant supernovae of type Ia (SNe Ia) without cosmic acceleration. The effect depends on the intergalactic electron density n{sub e} as well as the B-field strength and domain size. We show that for n{sub e} < or approx. 10{sup -9} cm{sup -3} the same mechanism would cause excessive spectral distortion of the cosmic microwave background (CMB). This small-n{sub e} parameter region had been left open by the most restrictive previous constraints based on the dispersion of quasar (QSO) spectra. The combination of CMB and QSO limits suggests that the photon-axion conversion mechanism can only play a subleading role for SN Ia dimming. A combined analysis of all the observables affected by the photon-axion oscillations would be required to give a final verdict on the viability of this model.

  18. Explaining the Most Energetic Supernovae with an Inefficient Jet-feedback Mechanism

    NASA Astrophysics Data System (ADS)

    Gilkis, Avishai; Soker, Noam; Papish, Oded

    2016-08-01

    We suggest that the energetic radiation from core-collapse super-energetic supernovae (SESNe) is due to a long-lasting accretion process onto the newly born neutron star (NS), resulting from an inefficient operation of the jet-feedback mechanism (JFM). The jets that are launched by the accreting NS or black hole maintain their axis due to a rapidly rotating pre-collapse core and do not manage to eject core material from near the equatorial plane. The jets are able to eject material from the core along the polar directions and reduce the gravity near the equatorial plane. The equatorial gas expands, and part of it falls back over a timescale of minutes to days to prolong the jet-launching episode. According to the model for SESNe proposed in the present paper, the principal parameter that distinguishes between the different cases of core-collapse supernova (CCSN) explosions, such as between normal CCSNe and SESNe, is the efficiency of the JFM. This efficiency, in turn, depends on the pre-collapse core mass, envelope mass, core convection, and, most of all, the angular momentum profile in the core. One prediction of the inefficient JFM for SESNe is the formation of a slow equatorial outflow in the explosion. The typical velocity and mass of this outflow are estimated to be v eq ≈ 1000 km s‑1 and M eq ≳ 1 M ⊙, respectively, though quantitative values will have to be checked in future hydrodynamic simulations.

  19. Mechanisms for the initiation of detonations in the degenerate matter of supernovae

    NASA Astrophysics Data System (ADS)

    Khokhlov, A. M.

    1991-06-01

    The mechanisms and critical conditions for the initiation of thermonuclear detonations in C-O stars are investigated using a statistical approach which takes into account small scale fluctuations of induction time (a time for the local development of the thermonuclear runaway) and describes the feedback between mean hydrodynamical flow and burning. Results suggest that both processes, the direct initiation and the transition from deflagration to detonation, can take place at certain conditions. The direct initiation of a detonation at the center of dense C-O white dwarfs was ruled out by the fact that spectra of Type Ia supernovae show presence of intermediate mass elements. Using this fact, a lower bound is derived for the amplitude of the spatial spectrum of temperature fluctuations inside the interior of massive degenerate Type Ia progenitors before explosion. The possibility of a 'delayed detonation' mode of SNIa explosions is discussed.

  20. Supernova remnants

    NASA Astrophysics Data System (ADS)

    Decourchelle, A.

    2016-06-01

    Supernova remnants result from the explosion of a star and keep trace, in their young ejecta-dominated phase, both of the explosion mechanism and to a lesser extent of the nature of the progenitor. They inject a large amount of energy into their surroundings, which impacts significantly the interstellar medium and to a larger extent the working of the galaxy by distributing heavy elements, heating to tens of million degrees large fractions of gas, accelerating high-energy particles, generating turbulence and amplification of the magnetic field. I will review the observational results on supernova remnants and their related scientific issues before suggesting directions for future ambitious XMM-Newton observations.

  1. THE PHYSICS OF THE NEUTRINO MECHANISM OF CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Pejcha, Ondrej; Thompson, Todd A.

    2012-02-10

    Although it is known that the stalled accretion shock in models of core-collapse supernovae turns into explosion when the neutrino luminosity from the proto-neutron star (PNS) exceeds a critical value (L{sup crit}{sub {nu},core}) (the 'neutrino mechanism'), the physics of L{sup crit}{sub {nu},core} has never been systematically explored. We solve the accretion problem between the PNS surface and the accretion shock. We quantify the deep connection between the general problem of accretion flows with bounding shocks and the neutrino mechanism. In particular, we show that there is a maximum, critical sound speed above which the shock jump conditions cannot be satisfied and steady-state accretion is impossible. This physics is general and does not depend on a specific heating mechanism. For the simple model of pressure-less free fall onto a shock bounding an isothermal accretion flow, we show that shock solutions are possible only for sound speed c{sub T} < c{sup crit}{sub T} and that c{sup 2}{sub T}/v{sub esc}{sup 2} = 3/16 = 0.1875 at c{sup crit}{sub T}. We generalize this result to the supernova problem, showing that the same physics determines L{sup crit}{sub {nu},core}. The critical condition for explosion can be written as c{sup 2}{sub S}/v{sup 2}{sub esc} {approx_equal} 0.19, where c{sub S} is the adiabatic sound speed. This 'antesonic' condition describes L{sup crit}{sub {nu},core} over a broad range of parameters, and other criteria proposed in the literature fail to capture this physics. We show that the accretion luminosity reduces L{sup crit}{sub {nu},core} non-trivially. A larger PNS radius decreases L{sup crit}{sub {nu},core}, implying that a stiff high-density equation of state may be preferred. Finally, using an analytic model, we provide evidence that the reduction of L{sup crit}{sub {nu},core} seen in recent multi-dimensional simulations results from reduced cooling efficiency, rather than an increased heating rate.

  2. Determination of acceleration mechanism characteristics directly and nonparametrically from observations: Application to supernova remnants

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahé; Chen, Qingrong

    2014-05-01

    We have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and nonparametrically from observations, in contrast to the usual forward fitting of parametric model variables to observations. In two recent papers [V. Petrosian and Q. Chen, Astrophys. J. 712, L131 (2010); Q. Chen and V. Petrosian, Astrophys. J. 777, 33 (2013)], we demonstrated the efficacy of this inversion method by its application to acceleration of electrons in solar flares based on stochastic acceleration by turbulence. Here we explore its application for determining the characteristics of shock acceleration in supernova remnants (SNRs) based on the electron spectra deduced from the observed nonthermal radiation from SNRs and the spectrum of the cosmic ray electrons observed near the Earth. These spectra are related by the process of escape of the electrons from SNRs and energy loss during their transport in the Galaxy. Thus, these observations allow us to determine spectral characteristics of the momentum and pitch angle diffusion coefficients, which play crucial roles in both direct acceleration by turbulence and in high Mach number shocks. Assuming that the average electron spectrum deduced from a few well-known SNRs is representative of those in the solar neighborhood, we find interesting discrepancies between our deduced forms for these coefficients and those expected from well-known wave-particle interactions. This may indicate that the standard assumptions made in the treatment of shock acceleration need revision. In particular, the escape of particles from SNRs may be more complex than generally assumed.

  3. Type Ia Supernovae: Can Coriolis Force Break the Symmetry of the Gravitational Confined Detonation Explosion Mechanism?

    NASA Astrophysics Data System (ADS)

    García-Senz, D.; Cabezón, R. M.; Domínguez, I.; Thielemann, F. K.

    2016-03-01

    Currently the number of models aimed at explaining the phenomena of type Ia supernovae is high and distinguishing between them is a must. In this work we explore the influence of rotation on the evolution of the nuclear flame that drives the explosion in the so-called gravitational confined detonation models. Assuming that the flame starts in a pointlike region slightly above the center of the white dwarf (WD) and adding a moderate amount of angular velocity to the star we follow the evolution of the deflagration using a smoothed particle hydrodynamics code. We find that the results are very dependent on the angle between the rotational axis and the line connecting the initial bubble of burned material with the center of the WD at the moment of ignition. The impact of rotation is larger for angles close to 90° because the Coriolis force on a floating element of fluid is maximum and its principal effect is to break the symmetry of the deflagration. Such symmetry breaking weakens the convergence of the nuclear flame at the antipodes of the initial ignition volume, changing the environmental conditions around the convergence region with respect to non-rotating models. These changes seem to disfavor the emergence of a detonation in the compressed volume at the antipodes and may compromise the viability of the so-called gravitational confined detonation mechanism.

  4. THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE

    SciTech Connect

    Jordan, G. C. IV; Graziani, C.; Weide, K.; Norris, J.; Hudson, R.; Lamb, D. Q.; Fisher, R. T.; Townsley, D. M.; Meakin, C.; Reid, L. B.

    2012-11-01

    We describe the detonation mechanism composing the 'pulsationally assisted' gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and {sup 56}Ni yields conform better to observational values than is the case for the 'classical' GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, including the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.

  5. Neutrino-heated stars and broad-line emission from active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Macdonald, James; Stanev, Todor; Biermann, Peter L.

    1991-01-01

    Nonthermal radiation from active galactic nuclei indicates the presence of highly relativistic particles. The interaction of these high-energy particles with matter and photons gives rise to a flux of high-energy neutrinos. In this paper, the influence of the expected high neutrino fluxes on the structure and evolution of single, main-sequence stars is investigated. Sequences of models of neutrino-heated stars in thermal equilibrium are presented for masses 0.25, 0.5, 0.8, and 1.0 solar mass. In addition, a set of evolutionary sequences for mass 0.5 solar mass have been computed for different assumed values for the incident neutrino energy flux. It is found that winds driven by the heating due to high-energy particles and hard electromagnetic radiation of the outer layers of neutrino-bloated stars may satisfy the requirements of the model of Kazanas (1989) for the broad-line emission clouds in active galactic nuclei.

  6. Explosive nucleosynthesis in a neutrino-driven core collapse supernova

    SciTech Connect

    Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

    2010-06-01

    We investigate explosive nucleosynthesis in a delayed neutrino-driven, supernova explosion aided by standing accretion shock instability (SASI), based on two-dimensional hydrodynamic simulations of the explosion of a 15 M{sub c}entre dot star. We take into accounts neutrino heating and cooling as well as change in electron fraction due to weak interactions appropriately, in the two-dimensional simulations. We assume the isotropic emission of neutrinos from the neutrino spheres with given luminosities. and the Fermi-Dirac distribution of given temperatures. We find that the stalled shock revives due to the neutrino heating aided by SASI for cases with L{sub n}u{sub e}>=3.9x10{sup 52}ergss{sup -1} and the as-pherical shock passes through the outer layers of the star (>=10,000 km), with the explosion energies of approx10{sup 51}ergs.Next we examine abundances and masses of the supernova ejecta. We find that masses of the ejecta and {sup 56}Ni correlate with the neutrino luminosity, and {sup 56}Ni mass is comparable to that observed in SN 1987A. We also find that abundance pattern of the supernova ejecta is similar to that of the solar system, for cases with high explosion energies of >10{sup 51}ergs. We emphasize that {sup 64}Zn, which is underproduced in the spherical case, is abundantly produced in slightly neutron-rich ejecta.

  7. THE ORIGIN OF COSMIC RAYS: EXPLOSIONS OF MASSIVE STARS WITH MAGNETIC WINDS AND THEIR SUPERNOVA MECHANISM

    SciTech Connect

    Biermann, Peter L.; Becker, Julia K.; Dreyer, Jens; Meli, Athina; Seo, Eun-Suk; Stanev, Todor

    2010-12-10

    One prediction of particle acceleration in the supernova (SN) remnants in the magnetic wind of exploding Wolf-Rayet and red supergiant stars is that the final spectrum is a composition of a spectrum E {sup -7/3} and a polar cap component of E {sup -2} at the source. This polar cap component contributes to the total energy content with only a few percent, but dominates the spectrum at higher energy. The sum of both components gives spectra which curve upward. The upturn was predicted to occur always at the same rigidity. An additional component of cosmic rays from acceleration by SNe exploding into the interstellar medium adds another component for hydrogen and for helium. After transport, the predicted spectra J(E) for the wind-SN cosmic rays are E {sup -8/3} and E {sup -7/3}; the sum leads to an upturn from the steeper spectrum. An upturn has now been seen by the CREAM mission. Here, we test the observations against the predictions and show that the observed properties are consistent with the predictions. Hydrogen can be shown to also have a noticeable wind-SN component. The observation of the upturn in the heavy element spectra being compatible with the same rigidity for all heavy elements supports the magneto-rotational mechanism for these SNe. This interpretation predicts the observed upturn to continue to curve upward and approach the E {sup -7/3} spectrum. If confirmed, this would strengthen the case that SNe of very massive stars with magnetic winds are important sources of Galactic cosmic rays.

  8. Neutrino-induced nucleosynthesis as a probe into the mechanism of supernovae

    NASA Astrophysics Data System (ADS)

    Nadyozhin, Dmitrij; Panov, I.

    The neutrino nucleosynthesis yields depend on a number of factors. Apart from the onion-like presupernova chemical structure, they are sensitive to temporal and spectral properties of the neu- trino "light curve" and to such hydrodynamic parameters as the supernova explosion energy and the delay in passing of the shock wave through successive presupernova chemical shells. More- over, possible intrusions of other chemicals into the shells (e.g., hydrogen into the helium shell) can appreciably modify the final yields. We report the results of our systematic quantitative study of some of these effects with special attention to the supernova explosion energy and characteristic time of the neutrino flux.

  9. Topics in Core-Collapse Supernova Theory: The Formation of Black Holes and the Transport of Neutrinos

    NASA Astrophysics Data System (ADS)

    O'Connor, Evan Patrick

    raising the maximum protoneutron star mass by up to 25% above the cold neutron star 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. This establishes, albeit approximately, for the first time based on actual collapse simulations, the mapping between ZAMS parameters and the outcome of core collapse. We also use GR1D to study proposed progenitors of long-duration gamma-ray bursts. We find that many of the proposed progenitors have core structures similar to garden-variety core-collapse supernovae. These are not expected to form black holes, a key ingredient of the collapsar model of long-duration gamma-ray bursts. The small fraction of proposed progenitors that are compact enough to form black holes have fast rotating iron cores, making them prone to a magneto-rotational explosion and the formation of a protomagnetar rather than a black hole. Finally, we present preliminary work on a fully general-relativistic neutrino transport code and neutrino-interaction library. Following along with the trends explored in our black hole formation study, we look at the dependence of the neutrino observables on the bounce compactness. We find clear relationships that will allow us to extract details of the core structure from the next galactic supernova. Following the open approach of GR1D, the neutrino transport code will be made open-source upon completion. The open-source neutrino-interaction library, NuLib, is already available at http://www.nulib.org.

  10. Role of nucleon strangeness in supernova explosions

    NASA Astrophysics Data System (ADS)

    Hobbs, T. J.; Alberg, Mary; Miller, Gerald A.

    2016-05-01

    Recent hydrodynamical simulations of core-collapse supernova (CCSN) evolution have highlighted the importance of thorough control over the microscopic physics responsible for such internal processes as neutrino heating. In particular, it has been suggested that modifications to the neutrino-nucleon elastic cross section can potentially play a crucial role in producing successful CCSN explosions. One possible source of such corrections can be found in a nonzero value for the nucleon's strange helicity content Δ s . In the present analysis, however, we show that theoretical and experimental progress over the past decade has suggested a comparatively small magnitude for Δ s , such that its sole effect is not sufficient to provide the physics leading to CCSN explosions.

  11. Historical Supernovae

    NASA Astrophysics Data System (ADS)

    Green, D. A.; Stephenson, F. R.

    The available historical records of supernovae occurring in our own Galaxy over the past two thousand years are reviewed. These accounts include the well-recorded supernovae of AD1604 (Kepler's SN), AD1572 (Tycho's SN), AD1181 AD1054 (which produced the Crab Nebula) and AD1006, together with less certain events dating back to AD185. In the case of the supernovae of AD1604 and AD1572 it is European records that provide the most accurate information available, whereas for earlier supernovae records are principally from East Asian sources. Also discussed briefly are several spurious supernova candidates, and the future prospects for studies of historical supernovae.

  12. THE ROLE OF TURBULENCE IN NEUTRINO-DRIVEN CORE-COLLAPSE SUPERNOVA EXPLOSIONS

    SciTech Connect

    Couch, Sean M.; Ott, Christian D. E-mail: cott@tapir.caltech.edu

    2015-01-20

    The neutrino-heated ''gain layer'' immediately behind the stalled shock in a core-collapse supernova is unstable to high-Reynolds-number turbulent convection. We carry out and analyze a new set of 19 high-resolution three-dimensional (3D) simulations with a three-species neutrino leakage/heating scheme and compare with spherically symmetric (one-dimensional, 1D) and axisymmetric (two-dimensional, 2D) simulations carried out with the same methods. We study the postbounce supernova evolution in a 15 M {sub ☉} progenitor star and vary the local neutrino heating rate, the magnitude and spatial dependence of asphericity from convective burning in the Si/O shell, and spatial resolution. Our simulations suggest that there is a direct correlation between the strength of turbulence in the gain layer and the susceptibility to explosion. 2D and 3D simulations explode at much lower neutrino heating rates than 1D simulations. This is commonly explained by the fact that nonradial dynamics allows accreting material to stay longer in the gain layer. We show that this explanation is incomplete. Our results indicate that the effective turbulent ram pressure exerted on the shock plays a crucial role by allowing multi-dimensional models to explode at a lower postshock thermal pressure and thus with less neutrino heating than 1D models. We connect the turbulent ram pressure with turbulent energy at large scales and in this way explain why 2D simulations are erroneously exploding more easily than 3D simulations.

  13. The Evolution and Impacts of Magnetorotational Instability in Magnetized Core-collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Sawai, Hidetomo; Yamada, Shoichi

    2016-02-01

    We carried out two-dimensional axisymmetric MHD simulations of core-collapse supernovae for rapidly rotating magnetized progenitors. By changing both the strength of the magnetic field and the spatial resolution, the evolution of the magnetorotational instability (MRI) and its impacts upon the dynamics are investigated. We found that the MRI greatly amplifies the seed magnetic fields in the regime where the buoyant mode, not the Alfvén mode, plays a primary role in the exponential growth phase. The MRI indeed has a powerful impact on the supernova dynamics. It makes the shock expansion faster and the explosion more energetic, with some models being accompanied by the collimated jet formations. These effects, however, are not made by the magnetic pressure except for the collimated jet formations. The angular momentum transfer induced by the MRI causes the expansion of the heating region, by which the accreting matter gain additional time to be heated by neutrinos. The MRI also drifts low-Yp matter from deep inside of the core to the heating region, which makes the net neutrino heating rate larger by the reduction of the cooling due to the electron capture. These two effects enhance the efficiency of the neutrino heating, which is found to be the key to boosting the explosion. Indeed, we found that our models explode far more weakly when the net neutrino heating is switched off. The contribution of the neutrino heating to the explosion energy could reach 60% even in the case of strongest magnetic field in the current simulations.

  14. Accelerating Our Understanding of Supernova Explosion Mechanism via Simulations and Visualizations with GenASiS

    SciTech Connect

    Budiardja, R. D.; Cardall, Christian Y; Endeve, Eirik

    2015-01-01

    Core-collapse supernovae are among the most powerful explosions in the Universe, releasing about 1053 erg of energy on timescales of a few tens of seconds. These explosion events are also responsible for the production and dissemination of most of the heavy elements, making life as we know it possible. Yet exactly how they work is still unresolved. One reason for this is the sheer complexity and cost of a self-consistent, multi-physics, and multi-dimensional core-collapse supernova simulation, which is impractical, and often impossible, even on the largest supercomputers we have available today. To advance our understanding we instead must often use simplified models, teasing out the most important ingredients for successful explosions, while helping us to interpret results from higher fidelity multi-physics models. In this paper we investigate the role of instabilities in the core-collapse supernova environment. We present here simulation and visualization results produced by our code GenASiS.

  15. Supernovae and Their Diversity

    NASA Astrophysics Data System (ADS)

    Garnavich, Peter M.

    2013-06-01

    The number of supernovae discovered annually has exploded and this has led to a growing diversity in observed supernova luminosities and properties. Stripped core-collapse supernovae show a range of expansion velocities with the broad-line events associated to gamma-ray bursts. Several types of extremely luminous supernovae have been identified in the past five years. Some may result from a pair-production instability in very massive stars while others appear to come from less massive progenitors and have an uncertain power source. Thermonuclear (type Ia) events are often thought of as uniform in their properties and that is what makes them good distance indicators. But type Ia supernovae are diverse in subtle and not so subtle ways that may reveal the nature of their explosion mechanism and progenitors. Wider, deeper time-domain sky surveys such as DES and LSST are likely to find even more variety in stellar explosions.

  16. Stochasticity and efficiency of convection-dominated vs. SASI-dominated supernova explosions

    SciTech Connect

    Cardall, Christian Y.; Budiardja, Reuben D.

    2015-10-22

    We present an initial report on 160 simulations of a highly simplified model of the post-bounce supernova environment in three position space dimensions (3D). We set different values of a parameter characterizing the impact of nuclear dissociation at the stalled shock in order to regulate the post-shock fluid velocity, thereby determining the relative importance of convection and the stationary accretion shock instability (SASI). While our convection-dominated runs comport with the paradigmatic notion of a `critical neutrino luminosity' for explosion at a given mass accretion rate (albeit with a nontrivial spread in explosion times just above threshold), the outcomes of our SASI-dominated runs are more stochastic: a sharp threshold critical luminosity is `smeared out' into a rising probability of explosion over a $\\sim 20\\%$ range of luminosity. We also find that the SASI-dominated models are able to explode with 3 to 4 times less efficient neutrino heating, indicating that progenitor properties, and fluid and neutrino microphysics, conducive to the SASI would make the neutrino-driven explosion mechanism more robust.

  17. Stochasticity and efficiency of convection-dominated vs. SASI-dominated supernova explosions

    DOE PAGESBeta

    Cardall, Christian Y.; Budiardja, Reuben D.

    2015-10-22

    We present an initial report on 160 simulations of a highly simplified model of the post-bounce supernova environment in three position space dimensions (3D). We set different values of a parameter characterizing the impact of nuclear dissociation at the stalled shock in order to regulate the post-shock fluid velocity, thereby determining the relative importance of convection and the stationary accretion shock instability (SASI). While our convection-dominated runs comport with the paradigmatic notion of a `critical neutrino luminosity' for explosion at a given mass accretion rate (albeit with a nontrivial spread in explosion times just above threshold), the outcomes of our SASI-dominated runs are more stochastic: a sharp threshold critical luminosity is `smeared out' into a rising probability of explosion over amore » $$\\sim 20\\%$$ range of luminosity. We also find that the SASI-dominated models are able to explode with 3 to 4 times less efficient neutrino heating, indicating that progenitor properties, and fluid and neutrino microphysics, conducive to the SASI would make the neutrino-driven explosion mechanism more robust.« less

  18. THE DOMINANCE OF NEUTRINO-DRIVEN CONVECTION IN CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Murphy, Jeremiah W.; Dolence, Joshua C.; Burrows, Adam E-mail: jdolence@astro.princeton.edu

    2013-07-01

    Multi-dimensional instabilities have become an important ingredient in core-collapse supernova (CCSN) theory. Therefore, it is necessary to understand the driving mechanism of the dominant instability. We compare our parameterized three-dimensional CCSN simulations with other buoyancy-driven simulations and propose scaling relations for neutrino-driven convection. Through these comparisons, we infer that buoyancy-driven convection dominates post-shock turbulence in our simulations. In support of this inference, we present four major results. First, the convective fluxes and kinetic energies in the neutrino-heated region are consistent with expectations of buoyancy-driven convection. Second, the convective flux is positive where buoyancy actively drives convection, and the radial and tangential components of the kinetic energy are in rough equipartition (i.e., K{sub r} {approx} K{sub {theta}} + K{sub {phi}}). Both results are natural consequences of buoyancy-driven convection, and are commonly observed in simulations of convection. Third, buoyant driving is balanced by turbulent dissipation. Fourth, the convective luminosity and turbulent dissipation scale with the driving neutrino power. In all, these four results suggest that in neutrino-driven explosions, the multi-dimensional motions are consistent with neutrino-driven convection.

  19. Local Simulations of the Magnetorotational Instability in Core-collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Masada, Youhei; Takiwaki, Tomoya; Kotake, Kei; Sano, Takayoshi

    2012-11-01

    Bearing in mind the application of core-collapse supernovae, we study the nonlinear properties of the magnetorotational instability (MRI) by means of three-dimensional simulations in the framework of a local shearing box approximation. By systematically changing the shear rates that symbolize the degree of differential rotation in nascent proto-neutron stars (PNSs), we derive a scaling relation between the turbulent stress sustained by the MRI and the shear-vorticity ratio. Our parametric survey shows a power-law scaling between the turbulent stress (langlangw totrangrang) and the shear-vorticity ratio (gq ) as langlangw totrangrangvpropg δ q with an index of δ ~ 0.5. The MRI-amplified magnetic energy has a similar scaling relative to the turbulent stress, while the Maxwell stress has a slightly smaller power-law index (~0.36). By modeling the effect of viscous heating rates from MRI turbulence, we show that the stronger magnetic fields, or the larger shear rates initially imposed, lead to higher dissipation rates. For a rapidly rotating PNS with a spin period in milliseconds and with strong magnetic fields of 1015 G, the energy dissipation rate is estimated to exceed 1051 erg s-1. Our results suggest that the conventional magnetohydrodynamic (MHD) mechanism of core-collapse supernovae is likely to be affected by MRI-driven turbulence, which we speculate, on the one hand, could harm the MHD-driven explosions due to the dissipation of the shear rotational energy at the PNS surface; or, on the other hand, its energy deposition might be potentially favorable for the working of the neutrino-heating mechanism.

  20. The Multi-Dimensional Character of Core-Collapse Supernovae

    SciTech Connect

    Hix, William Raphael; Lentz, E. J.; Bruenn, S. W.; Mezzacappa, Anthony; Messer, Bronson; Endeve, Eirik; Blondin, J. M.; Harris, James Austin; Marronetti, Pedro; Yakunin, Konstantin N

    2016-01-01

    Core-collapse supernovae, the culmination of massive stellar evolution, are spectacular astronomical events and the principle actors in the story of our elemental origins. Our understanding of these events, while still incomplete, centers around a neutrino-driven central engine that is highly hydrodynamically unstable. Increasingly sophisticated simulations reveal a shock that stalls for hundreds of milliseconds before reviving. Though brought back to life by neutrino heating, the development of the supernova explosion is inextricably linked to multi-dimensional fluid flows. In this paper, the outcomes of three-dimensional simulations that include sophisticated nuclear physics and spectral neutrino transport are juxtaposed to learn about the nature of the three dimensional fluid flow that shapes the explosion. Comparison is also made between the results of simulations in spherical symmetry from several groups, to give ourselves confidence in the understanding derived from this juxtaposition.

  1. 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.

  2. Core-collapse supernovae and nucleosynthesis

    SciTech Connect

    Haxton, W.C.

    1994-12-01

    I discuss some of the physics that governs the collapse and explosion of a massive star, including issues such as lepton number losses in the infall stage and neutrino heating and convection following the core bounce. I review recent work on the neutrino process and the r-process, describing how the nucleosynthesis depends on the explosion mechanism. Some of the interesting possibilities for oscillations of closure mass {nu}{sub {tau}}s are discussed, along with their signatures in terrestrial detectors and in nucleosynthesis.

  3. SUPERNOVAE IN THE CENTRAL PARSEC: A MECHANISM FOR PRODUCING SPATIALLY ANISOTROPIC HYPERVELOCITY STARS

    SciTech Connect

    Zubovas, Kastytis; Wynn, Graham A.; Gualandris, Alessia

    2013-07-10

    Several tens of hypervelocity stars (HVSs) have been discovered escaping our Galaxy. These stars share a common origin in the Galactic center and are distributed anisotropically in Galactic longitude and latitude. We examine the possibility that HVSs may be created as the result of supernovae (SNe) occurring within binary systems in a disk of stars around Sgr A* over the last 100 Myr. Monte Carlo simulations show that the rate of binary disruption is {approx}10{sup -4} yr{sup -1}, comparable to that of tidal disruption models. The SN-induced HVS production rate ({Gamma}{sub HVS}) is significantly increased if the binaries are hardened via migration through a gaseous disk. Moderate hardening gives {Gamma}{sub HVS} {approx_equal} 2 Multiplication-Sign 10{sup -7} yr{sup -1} and an estimated population of {approx}20 HVSs in the last 100 Myr. SN-induced HVS production requires the internal and external orbital velocity vectors of the secondary binary component to be aligned when the binary is disrupted. This leaves an imprint of the disk geometry on the spatial distribution of the HVSs, producing a distinct anisotropy.

  4. 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

  5. Supernova Flashback

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Annotated Version

    The Cassiopeia A supernova's first flash of radiation makes six clumps of dust (circled in annotated version) unusually hot. The supernova remnant is the large white ball in the center. This infrared picture was taken by NASA's Spitzer Space Telescope.

  6. Understanding the Progenitor Systems, Explosion Mechanisms, and Cosmological Utility of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Foley, Ryan

    2014-10-01

    Despite using Type Ia supernovae (SN Ia) to precisely measure cosmological parameters, we still do not know basic facts about the progenitor systems and explosions. Theory suggests that SN Ia progenitor metallicity is correlated with its peak luminosity, but not its light-curve shape. As a result, this effect should lead to an increased Hubble scatter, reducing the precision with which we measure distances. If the average progenitor metallicity changes with redshift, cosmological measurements could be biased. Models also indicate that changing the progenitor metallicity will have little effect on the appearance of optical SN data, but significantly change UV spectra. These data can only be obtained with HST.We recently published the first detection of 2 SN Ia with different progenitor metallicities. These "twin" SN had nearly identical optical spectra and light-curve shapes, but different UV spectra and peak luminosities, consistent with the models. We now must increase the sample of SN Ia with UV spectral time series to investigate the impact of metallicity on SN properties. To do this, we plan to obtain UV spectral time series of 3 SN Ia, nearly doubling the sample. UV observations are critical to the understanding of SN Ia explosions and progenitors. This is our best opportunity to further our understanding of SN Ia while directly improving the utility of SN Ia for cosmology.Using parallel observations, we will obtain Cepheid distances to a subset of the SN for free, providing precise SN luminosities and a better measurement of the Hubble constant. The UV Initiative is an excellent opportunity for HST to address significant questions in SN physics and cosmology.

  7. Constraints on the explosion mechanism and progenitors of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Dessart, Luc; Blondin, Stéphane; Hillier, D. John; Khokhlov, Alexei

    2014-06-01

    Observations of SN 2011fe at early times reveal an evolution analogous to a fireball model of constant colour. In contrast, our unmixed delayed detonations of Chandrasekhar-mass white dwarfs (DDC series) exhibit a faster brightening concomitant with a shift in colour to the blue. In this paper, we study the origin of these discrepancies. We find that strong chemical mixing largely resolves the photometric mismatch at early times, but it leads to an enhanced line broadening that contrasts, for example, with the markedly narrow Si II 6355 Å line of SN 2011fe. We also explore an alternative configuration with pulsational-delayed detonations (PDDEL model series). Because of the pulsation, PDDEL models retain more unburnt carbon, have little mass at high velocity, and have a much hotter outer ejecta after the explosion. The pulsation does not influence the inner ejecta, so PDDEL and DDC models exhibit similar radiative properties beyond maximum. However, at early times, PDDEL models show bluer optical colours and a higher luminosity, even for weak mixing. Their early-time radiation is derived primarily from the initial shock-deposited energy in the outer ejecta rather than radioactive-decay heating. Furthermore, PDDEL models show short-lived C II lines, reminiscent of SN 2013dy. They typically exhibit lines that are weaker, narrower, and of near-constant width, reminiscent of SN 2011fe. In addition to multidimensional effects, varying configurations for such `pulsations' offer a source of spectral diversity amongst Type Ia supernovae (SNe Ia). PDDEL and DDC models also provide one explanation for low- and high-velocity-gradient SNe Ia.

  8. 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.

  9. BLACK HOLE FORMATION IN FAILING CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    O'Connor, Evan; Ott, Christian D. E-mail: cott@tapir.caltech.edu

    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{sup 2} = 1 by the appearance of nonaxisymmetric rotational instabilities.

  10. A call for a paradigm shift from neutrino-driven to jet-driven core-collapse supernova mechanisms

    NASA Astrophysics Data System (ADS)

    Papish, Oded; Nordhaus, Jason; Soker, Noam

    2015-04-01

    Three-dimensional (3D) simulations in recent years have shown severe difficulties producing 1051 erg explosions of massive stars with neutrino-based mechanisms while on the other hand demonstrated the large potential of mechanical effects, such as winds and jets in driving explosions. In this paper, we study the typical time-scale and energy for accelerating gas by neutrinos in core-collapse supernovae (CCSNe) and find that under the most extremely favourable (and probably unrealistic) conditions, the energy of the ejected mass can reach at most 5 × 1050 erg. More typical conditions yield explosion energies an order of magnitude below the observed 1051 erg explosions. On the other hand, non-spherical effects with directional outflows hold promise to reach the desired explosion energy and beyond. Such directional outflows, which in some simulations are produced by numerical effects of 2D grids, can be attained by angular momentum and jet launching. Our results therefore call for a paradigm shift from neutrino-based explosions to jet-driven explosions for CCSNe.

  11. Supernova models

    SciTech Connect

    Woosley, S.E.; Weaver, T.A.

    1980-01-01

    Recent progress in understanding the observed properties of Type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the /sup 56/Ni produced therein is reviewed. Within the context of this model for Type I explosions and the 1978 model for Type II explosions, the expected nucleosynthesis and gamma-line spectra from both kinds of supernovae are presented. Finally, a qualitatively new approach to the problem of massive star death and Type II supernovae based upon a combination of rotation and thermonuclear burning is discussed.

  12. TWO-DIMENSIONAL CORE-COLLAPSE SUPERNOVA MODELS WITH MULTI-DIMENSIONAL TRANSPORT

    SciTech Connect

    Dolence, Joshua C.; Burrows, Adam; Zhang, Weiqun E-mail: burrows@astro.princeton.edu

    2015-02-10

    We present new two-dimensional (2D) axisymmetric neutrino radiation/hydrodynamic models of core-collapse supernova (CCSN) cores. We use the CASTRO code, which incorporates truly multi-dimensional, multi-group, flux-limited diffusion (MGFLD) neutrino transport, including all relevant O(v/c) terms. Our main motivation for carrying out this study is to compare with recent 2D models produced by other groups who have obtained explosions for some progenitor stars and with recent 2D VULCAN results that did not incorporate O(v/c) terms. We follow the evolution of 12, 15, 20, and 25 solar-mass progenitors to approximately 600 ms after bounce and do not obtain an explosion in any of these models. Though the reason for the qualitative disagreement among the groups engaged in CCSN modeling remains unclear, we speculate that the simplifying ''ray-by-ray'' approach employed by all other groups may be compromising their results. We show that ''ray-by-ray'' calculations greatly exaggerate the angular and temporal variations of the neutrino fluxes, which we argue are better captured by our multi-dimensional MGFLD approach. On the other hand, our 2D models also make approximations, making it difficult to draw definitive conclusions concerning the root of the differences between groups. We discuss some of the diagnostics often employed in the analyses of CCSN simulations and highlight the intimate relationship between the various explosion conditions that have been proposed. Finally, we explore the ingredients that may be missing in current calculations that may be important in reproducing the properties of the average CCSNe, should the delayed neutrino-heating mechanism be the correct mechanism of explosion.

  13. Two-dimensional Core-collapse Supernova Models with Multi-dimensional Transport

    NASA Astrophysics Data System (ADS)

    Dolence, Joshua C.; Burrows, Adam; Zhang, Weiqun

    2015-02-01

    We present new two-dimensional (2D) axisymmetric neutrino radiation/hydrodynamic models of core-collapse supernova (CCSN) cores. We use the CASTRO code, which incorporates truly multi-dimensional, multi-group, flux-limited diffusion (MGFLD) neutrino transport, including all relevant {O}(v/c) terms. Our main motivation for carrying out this study is to compare with recent 2D models produced by other groups who have obtained explosions for some progenitor stars and with recent 2D VULCAN results that did not incorporate {O}(v/c) terms. We follow the evolution of 12, 15, 20, and 25 solar-mass progenitors to approximately 600 ms after bounce and do not obtain an explosion in any of these models. Though the reason for the qualitative disagreement among the groups engaged in CCSN modeling remains unclear, we speculate that the simplifying "ray-by-ray" approach employed by all other groups may be compromising their results. We show that "ray-by-ray" calculations greatly exaggerate the angular and temporal variations of the neutrino fluxes, which we argue are better captured by our multi-dimensional MGFLD approach. On the other hand, our 2D models also make approximations, making it difficult to draw definitive conclusions concerning the root of the differences between groups. We discuss some of the diagnostics often employed in the analyses of CCSN simulations and highlight the intimate relationship between the various explosion conditions that have been proposed. Finally, we explore the ingredients that may be missing in current calculations that may be important in reproducing the properties of the average CCSNe, should the delayed neutrino-heating mechanism be the correct mechanism of explosion.

  14. Two-neutron capture reactions in supernovae neutrino bubbles

    NASA Astrophysics Data System (ADS)

    Görres, J.; Herndl, H.; Thompson, I. J.; Wiescher, M.

    1995-10-01

    Recent calculations suggest that the neutrino heated bubbles in the postcollapse phase of type II supernovae may be the site of the r process. The nucleosynthesis process depends on the expansion and cooling rates as well as on the rates of the α-particle and neutron recombination processes that bridge the mass gaps at A = 5 and 8. We have reexamined the rate for the important reaction 4He(αn,γ)9Be, and estimated the rates for the two neutron capture reactions on 6He and 8He which could provide an alternative reaction path. We find that the most important reaction for initiating the α process is the 4He(αn,γ)9Be reaction, as suggested by earlier work.

  15. Supernova and cosmic rays

    NASA Technical Reports Server (NTRS)

    Wefel, J. P.

    1981-01-01

    A general overview of supernova astronomy is presented, followed by a discussion of the relationship between SN and galactic cosmic rays. Pre-supernova evolution is traced to core collapse, explosion, and mass ejection. The two types of SN light curves are discussed in terms of their causes, and the different nucleosynthetic processes inside SNs are reviewed. Physical events in SN remnants are discussed. The three main connections between cosmic rays and SNs, the energy requirement, the acceleration mechanism, and the detailed composition of CR, are detailed.

  16. MSW Process in Supernovae

    NASA Astrophysics Data System (ADS)

    Buccella, F.; Esposito, S.; Gualdi, C.; Santorelli, P.

    We show that with the muon neutrino mass which is necessary for explaining the solar neutrino problem through MSW mechanism, mν μ ˜ 2× 10-3\\ eV and mν τ ˜ (mt/m_c)2 mν μ , we expect different spectra for νe and /line{ν e} coming from supernovae.

  17. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    SciTech Connect

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-02

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M{sub Ms} ∼ 7 - 9.5M{sub ⊙}. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 10{sup 50} erg and the small {sup 56}Ni mass of 2.5 × 10{sup −3} M{sub ⊙}, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ∼ 2 × 10{sup 44} erg s{sup −1} and can evaporate circumstellar dust up to R ∼ 10{sup 17} cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ∼ 10{sup 42} erg s{sup −1} and {sup t} ∼ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ∼ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ∼ 10{sup 48} erg.

  18. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-01

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass MMs ˜ 7 - 9.5M⊙. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 1050 erg and the small 56Ni mass of 2.5 × 10-3 M⊙, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ˜ 2 × 1044 erg s-1 and can evaporate circumstellar dust up to R ˜ 1017 cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ˜ 1042 erg s-1 and t ˜ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ˜ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ˜ 1048 erg.

  19. The Explosion Mechanism of Core-Collapse Supernovae and its Observational Signatures

    NASA Astrophysics Data System (ADS)

    Pejcha, Ondrej

    2013-01-01

    The core of a massive star at the end of its life collapses and launches an outgoing shockwave. Simulations show that the shock wave evolves into a quasi-static accretion shock, but it proves difficult to revive its outward propagation. The stalled accretion shock turns into explosion when the neutrino luminosity from the collapsed core exceeds a critical value (L_crit) (the "neutrino mechanism"). We study the physics of L_crit and its parameter dependence. We quantify the connection between the steady-state isothermal accretion flows with bounding shocks and the neutrino mechanism. We show that there is a maximum, critical sound speed above which it is impossible to maintain accretion with a standoff shock. We derive this "antesonic" condition, which characterizes the transition to explosion over a broad range in accretion rate, PNS properties and microphysics. Additionally, we characterize the effects of collective neutrino oscillations on L_crit, which can decrease L_crit by a sizeable amount, but they are generally suppressed by matter effects. The physics of the explosion mechanism and the progenitor structure are imprinted in the observed distribution of neutron star masses. We use Bayesian analysis to model the double neutron star mass distribution and we infer the properties of the progenitor binary population, fallback during the explosion, and constrain the mass coordinate where the explosion develops.

  20. REVIEWS OF TOPICAL PROBLEMS Rotational explosion mechanism for collapsing supernovae and the two-stage neutrino signal from supernova 1987A in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Imshennik, Vladimir S.

    2011-02-01

    The two-stage (double) signal produced by the outburst of the close supernova (SN) in the Large Magellanic Cloud, which started on and involved two neutrino signals during the night of 23 February 1987 UT, is theoretically interpreted in terms of a scenario of rotationally exploding collapsing SNs, to whose class the outburst undoubtedly belongs. This scenario consists of a set of hydrodynamic and kinetic models in which key results are obtained by numerically solving non-one-dimensional and nonstationary problems. Of vital importance in this context is the inclusion of rotation effects, their role being particularly significant precisely in terms of the question of the transformation of the original collapse of the presupernova iron core to the explosion of the SN shell, with an energy release on a familiar scale of 1051 erg. The collapse in itself leads to the birth of neutron stars (black holes) emitting neutrino and gravitational radiation signals of gigantic intensity, whose total energy significantly (by a factor of hundreds) exceeds the above-cited SN burst energy. The proposed rotational scenario is described briefly by artificially dividing it into three (or four) characteristic stages. This division is dictated by the physical meaning of the chain of events a rotating iron core of a sufficiently massive (more than 10M) star triggers when it collapses. An attempt is made to quantitatively describe the properties of the associated neutrino and gravitational radiations. The review highlights the interpretation of the two-stage neutrino signal from SN 1987A, a problem which, given the present status of theoretical astrophysics, cannot, in the author's view, be solved without including rotation effects.

  1. High-resolution three-dimensional simulations of core-collapse supernovae in multiple progenitors

    SciTech Connect

    Couch, Sean M.; O'Connor, Evan P.

    2014-04-20

    Three-dimensional (3D) simulations of core-collapse supernovae (CCSNe) are granting new insight into the as-yet-uncertain mechanism that drives successful explosions. While there is still debate about whether explosions are obtained more easily in 3D than in 2D, it is undeniable that there exist qualitative and quantitative differences between the results of 3D and 2D simulations. We present an extensive set of high-resolution 1D, 2D, and 3D CCSN simulations with multispecies neutrino leakage carried out in two different progenitors. Our simulations confirm the results of Couch indicating that 2D explodes more readily than 3D. We argue that this is due to the inadequacies of 2D to accurately capture important aspects of the 3D dynamics. We find that without artificially enhancing the neutrino heating rate, we do not obtain explosions in 3D. We examine the development of neutrino-driven convection and the standing accretion shock instability (SASI) and find that, in separate regimes, either instability can dominate. We find evidence for growth of the SASI for both 15 M {sub ☉} and 27 M {sub ☉} progenitors; however, it is weaker in 3D exploding models. The growth rate of both instabilities is artificially enhanced along the symmetry axis in 2D as compared with our axis-free 3D Cartesian simulations. Our work highlights the growing consensus that CCSNe must be studied in 3D if we hope to solve the mystery of how the explosions are powered.

  2. Shock Revival in Core-collapse Supernovae: A Phase-diagram Analysis

    NASA Astrophysics Data System (ADS)

    Gabay, Daniel; Balberg, Shmuel; Keshet, Uri

    2015-12-01

    We examine the conditions for the revival of the stalled accretion shock in core-collapse supernovae, in the context of the neutrino heating mechanism. We combine one-dimensional simulations of the shock revival process with a derivation of a quasi-stationary approximation, which is both accurate and efficient in predicting the flow. In particular, this approach is used to explore how the evolution of the accretion shock depends on the shock radius, RS, and velocity, VS (in addition to other global properties of the system). We do so through a phase-space analysis of the shock acceleration, aS, in the {R}S{--}{V}S plane, shown to provide quantitative insights into the initiation and nature of runaway expansion. In the particular case of an initially stationary ({V}S=0, {a}S=0) profile, the prospects for an explosion can be assessed by the initial signs of the partial derivatives of the shock acceleration, in analogy to a linear damped/anti-damped oscillator. If \\partial {a}S/\\partial {R}S\\lt 0 and \\partial {a}S/\\partial {V}S\\gt 0, runaway will likely occur after several oscillations, while if \\partial {a}S/\\partial {R}S\\gt 0, runaway expansion will commence in a non-oscillatory fashion. These two modes of runaway correspond to low and high mass accretion rates, respectively. We also use the quasi-stationary approximation to assess the advection-to-heating timescale ratio in the gain region, often used as an explosion proxy. Indeed, this ratio does tend to ˜1 in conjunction with runaway conditions, but neither this unit value nor the specific choice of the gain region as a point of reference appear to be unique in this regard.

  3. Monte Carlo methods for neutrino transport in type-II supernovae

    NASA Astrophysics Data System (ADS)

    Janka, Hans-Thomas

    Neutrinos play an important role in the type-II supernova scenario. Numerous approaches have been made in order to treat the generation and transport of neutrinos and the interactions between neutrinos and matter during stellar collapse and the shock propagation phase. However, all computationally fast methods have in common the fact that they cannot avoid simplifications in describing the interactions and, furthermore, have to use parameterizations in handling the Boltzmann transport equation. In order to provide an instrument for calibrating these treatments and for calculating neutrino spectra emitted from given stellar configurations, a Monte Carlo transport code was designed. Special attention was paid to an accurate computation of scattering kernels and source functions. Neutrino spectra for a hydrostatic stage of a 20 solar mass supernova simulation were generated and conclusions drawn concerning a late time revival of the stalled shock by neutrino heating.

  4. The rp-Process in Core-collapse Supernovae

    SciTech Connect

    Wanajo, Shinya

    2006-07-12

    Recent hydrodynamic simulations of core-collapse supernovae with accurate neutrino transport suggest that the bulk of the neutrino-heated ejecta is proton rich, in which the production of some interesting proton-rich nuclei is expected. However, there are a number of waiting point nuclei with the {beta}+-lives of a few minutes, which prevent the production of heavy proton-rich nuclei beyond iron in explosive events such as core-collapse supernovae. In this study, it is shown that the rapid proton-capture (rp) process takes place by bypassing these waiting points via neutron-capture reactions even in the proton-rich environment, if there is an intense neutrino flux as expected during the early phase of the neutrino-driven winds of core-collapse supernovae. The nucleosynthesis calculations imply that the neutrino-driven winds can be potentially the origin of light p-nuclei including 92,94Mo and 96,98Ru, which cannot be explained by other astrophysical sites.

  5. Core-collapse Supernovae

    SciTech Connect

    Hix, William Raphael; Lentz, E. J.; Baird, Mark L; Chertkow, Merek A; Lee, Ching-Tsai; Blondin, J. M.; Bruenn, S. W.; Messer, Bronson; Mezzacappa, Anthony

    2013-01-01

    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 (growing to gigameter scale) down to femtometer scale nuclear reactions. Carrying 10$^{51}$ ergs 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.

  6. 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)

  7. Supernova Acceleration Probe: Studying Dark Energy with Type Ia Supernovae

    SciTech Connect

    Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Aumeunier, M.; Bailey, S.; Baltay, C.; Barrelet, E.; Basa, S.; Bebek, C.; Bergstom, L.; Bernstein, G.; Bester, M.; Besuner, B.; Bigelow, B.; Blandford, R.; Bohlin, R.; Bonissent, A.; /Caltech /LBL, Berkeley /Fermilab /SLAC /Stockholm U. /Paris, IN2P3 /Marseille, CPPM /Marseille, Lab. Astrophys. /Yale U. /Pennsylvania U. /UC, Berkeley /Michigan U. /Baltimore, Space Telescope Sci. /Indiana U. /Caltech, JPL /Australian Natl. U., Canberra /American Astron. Society /Chicago U. /Cambridge U. /Saclay /Lyon, IPN

    2005-08-08

    compared to give confidence that the results are free from significant systematics. Conversely, analysis between supernova subsets at the same redshift can identify further systematics controls. While theories of the supernova progenitor and explosion mechanism can guide the establishment of subset criteria, such understanding is not required--only comprehensive measurements are--for robustness of the cosmological results. The level of robustness is tied to the quality of data with which supernovae are distinguished. Statistical mission requirements are fundamentally bound by the systematic limitations of the experiment.

  8. Core bounce supernovae

    SciTech Connect

    Cooperstein, J.

    1987-01-01

    The gravitational collapse mechanism for Type II supernovae is considered, concentrating on the direct implosion - core bounce - hydrodynamic explosion picture. We examine the influence of the stiffness of the dense matter equation of state and discuss how the shock wave is formed. Its chances of success are determined by the equation of state, general relativistic effects, neutrino transport, and the size of presupernova iron core. 12 refs., 1 tab.

  9. Supernova Forensics

    NASA Astrophysics Data System (ADS)

    Soderberg, Alicia M.

    2014-01-01

    For decades, the study of stellar explosions -- supernovae -- have focused almost exclusively on the strong optical emission that dominates the bolometric luminosity in the days following the ultimate demise of the star. Yet many of the leading breakthroughs in our understanding of stellar death have been enabled by obtaining data at other wavelengths. For example, I have shown that 1% of all supernovae give rise to powerful relativistic jets, representing the biggest bangs in the Universe since the Big Bang. My recent serendipitous X-ray discovery of a supernova in the act of exploding (“in flagrante delicto”) revealed a novel technique to discover new events and provide clues on the shock physics at the heart of the explosion. With the advent of sensitive new radio telescopes, my research group combines clues from across the electromagnetic spectrum (radio to gamma-ray), leading us to a holistic study of stellar death, the physics of the explosions, and their role in fertilizing the Universe with new elements, by providing the community with cosmic autopsy reports.

  10. Core-Collapse Supernovae -- the Outliers

    NASA Astrophysics Data System (ADS)

    Woosley, Stan

    2011-04-01

    After a brief review of current efforts to model the explosion mechanism for "ordinary," core collapse supernovae and the neutrino signal expected from them, some of the outliers predicted by current theory will be discussed. Chief among these are the pulsational-pair instability supernovae, which can occur for stars as light as 80 solar masses or as heavy as 140 solar masses, or more. These explosions, which would have been common in the early universe and persist today, can make supernovae that do or do not recur, and that can be either exceptionally faint or bright or both. They leave behind black holes with masses near 40 solar masses, and produce an abundance pattern that is rich in CNO, much like that seen in the ultra-iron poor stars. Other models for unusual supernovae, including magnetar-powered supernovae and 8 - 10 solar mass supernovae will be mentioned as time allows.

  11. The r-PROCESS in Core-Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Wanajo, Shinya; Kajino, Toshitaka; Mathews, Grant J.; Otsuki, Kaori

    We present calculations of r-process nucleosynthesis in neutrino-driven winds from the nascent neutron stars of core-collapse supernovae. A full dynamical reaction network for both the α-rich freezeout and the subsequent r-process is employed. The physical properties of the neutrino-heated ejecta are deduced from a general relativistic model in which spherical symmetry and steady flow are assumed. Our results suggest that proto-neutron stars with a large compaction ratio provide the most robust physical conditions for the r-process. This is due to the short dynamical timescale of material in the wind. Our results have confirmed that the neutrino-driven wind scenario is still a promising site in which to form the solar r-process abundances. However, our best results seem to imply both a rather soft neutron-star equation of state and a massive proto-neutron star which is difficult to achieve with standard core-collapse models. We propose that the most favorable conditions perhaps require that a massive supernova progenitor forms a massive proto-neutron star by accretion after a failed initial neutrino burst.

  12. Three-dimensional simulation of a rotating supernova

    SciTech Connect

    Nakamura, K.; Kuroda, T.; Takiwaki, T.; Kotake, K.

    2014-05-02

    We investigate the effects of rotation on the evolution of core-collapse supernova explosion using a 15 solar mass progenitor model with a variety of neutrino luminosity and rotational velocity. Stars should have some amount of angular momentum, which would affect stellar evolution and its final explosion. In this paper we focus on the effect of rotation on gravitational collapse of a core, on a core bounce of accreting matter, and on subsequent generation and evolution of a shock wave. We find that the rotation plays a positive role for supernova explosions. More rapidly rotating models present more rapid expansion of the shock front and more energetic explosions. When the rotational speed is moderate, the shock once stalls at about 200 km away from the center similarly to a non-rotating model. Then the rotating progenitor experiences effective neutrino heating especially around an equatorial plane and explodes even with somewhat low neutrino luminosity for which the non-rotating model cannot overcome accreting matter and finally collapses. When the rotational speed is fast, the shock expands to about 300 km immediately after the core bounce and then evolves to move outward without shock stalling. We conclude that this positive effect of rotation to explosions is dominant against some possible negative aspects, for example, lower neutrino luminosity caused by less contraction of the rotating core.

  13. Supernovae. Old supernova dust factory revealed at the Galactic center.

    PubMed

    Lau, R M; Herter, T L; Morris, M R; Li, Z; Adams, J D

    2015-04-24

    Dust formation in supernova ejecta is currently the leading candidate to explain the large quantities of dust observed in the distant, early universe. However, it is unclear whether the ejecta-formed dust can survive the hot interior of the supernova remnant (SNR). We present infrared observations of ~0.02 solar masses of warm (~100 kelvin) dust seen near the center of the ~10,000-year-old Sagittarius A East SNR at the Galactic center. Our findings indicate the detection of dust within an older SNR that is expanding into a relatively dense surrounding medium (electron density ~10(3) centimeters(-3)) and has survived the passage of the reverse shock. The results suggest that supernovae may be the dominant dust-production mechanism in the dense environment of galaxies of the early universe. PMID:25791082

  14. Neutrino-driven explosions of ultra-stripped Type Ic supernovae generating binary neutron stars

    NASA Astrophysics Data System (ADS)

    Suwa, Yudai; Yoshida, Takashi; Shibata, Masaru; Umeda, Hideyuki; Takahashi, Koh

    2015-12-01

    We study explosion characteristics of ultra-stripped supernovae (SNe), which are candidates of SNe generating binary neutron stars (NSs). As a first step, we perform stellar evolutionary simulations of bare carbon-oxygen cores of mass from 1.45 to 2.0 M⊙ until the iron cores become unstable and start collapsing. We then perform axisymmetric hydrodynamics simulations with spectral neutrino transport using these stellar evolution outcomes as initial conditions. All models exhibit successful explosions driven by neutrino heating. The diagnostic explosion energy, ejecta mass, Ni mass, and NS mass are typically ˜1050 erg, ˜0.1 M⊙, ˜0.01 M⊙, and ≈1.3 M⊙, which are compatible with observations of rapidly evolving and luminous transient such as SN 2005ek. We also find that the ultra-stripped SN is a candidate for producing the secondary low-mass NS in the observed compact binary NSs like PSR J0737-3039.

  15. Convection- and SASI-driven flows in parametrized models of core-collapse supernova explosions

    NASA Astrophysics Data System (ADS)

    Endeve, E.; Cardall, C. Y.; Budiardja, R. D.; Mezzacappa, A.

    2016-02-01

    We present initial results from three-dimensional simulations of parametrized core-collapse supernova (CCSN) explosions obtained with our astrophysical simulation code General Astrophysical Simulation System (GenASIS). We are interested in nonlinear flows resulting from neutrino-driven convection and the standing accretion shock instability (SASI) in the CCSN environment prior to and during the explosion. By varying parameters in our model that control neutrino heating and shock dissociation, our simulations result in convection-dominated and SASI-dominated evolution. We describe this initial set of simulation results in some detail. To characterize the turbulent flows in the simulations, we compute and compare velocity power spectra from convection-dominated and SASI-dominated (both non-exploding and exploding) models. When compared to SASI-dominated models, convection-dominated models exhibit significantly more power on small spatial scales.

  16. How Bright Can Supernovae Get?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-04-01

    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

  17. Supernova Explosions of Super-asymptotic Giant Branch Stars: Multicolor Light Curves of Electron-capture Supernovae

    NASA Astrophysics Data System (ADS)

    Tominaga, Nozomu; Blinnikov, Sergei I.; Nomoto, Ken'ichi

    2013-07-01

    An electron-capture supernova (ECSN) is a core-collapse supernova (CCSN) explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M MS ~ 7-9.5 M ⊙. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curve of a CCSN. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 1050 erg and the small 56Ni mass of 2.5 × 10-3 M ⊙, we perform a multi-group radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope masses and hydrogen abundances. We demonstrate that a shock breakout has a peak luminosity of L ~ 2 × 1044 erg s-1 and can evaporate circumstellar dust up to R ~ 1017 cm for the case of carbon dust, that the plateau luminosity and plateau duration of ECSNe are L ~ 1042 erg s-1 and t ~ 60-100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ~4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by the spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires an ECSN model with a significantly low explosion energy of E ~ 1048 erg.

  18. 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

  19. TeraScale Supernova Initiative

    NASA Astrophysics Data System (ADS)

    Mezzacappa, A.; TeraScale Supernova Initiative Collaboration

    2002-05-01

    The TeraScale Supernova Initiative is a national collaboration centered at the Oak Ridge National Laboratory and involves eight universities. TSI has as its central focus to ascertain the explosion mechanism(s) for core collapse supernovae and to understand and predict their associated phenomenology, including neutrino signatures, gravitational radiation emission, and nucleosynthesis. TSI is an interdisciplinary effort of astrophysicists, nuclear physicists, applied mathematicians, and computer scientists. Multidimensional hydrodynamics, magnetohydrodynamics, and radiation hydrodynamics simulations that implement state of the art nuclear and weak interaction physics are planned in order to understand the roles of neutrino transport, stellar convection and rotation, and magnetic fields in the supernova mechanism. Scalable algorithms for the solution of the large sparse linear systems of equations that arise in radiation transport applications and a customized collaborative visualization environment will be developed also. TSI's latest results and future efforts will be discussed. The TeraScale Supernova Initiative is funded by grants from the DoE (1) High Energy and Nuclear Physics and (2) Mathematics, Information, and Computational Sciences SciDAC Programs.

  20. Supernova neutrino detection

    SciTech Connect

    Scholberg, K.

    2015-07-15

    In this presentation I summarize the main detection channels for neutrinos from core-collapse supernovae, and describe current status of and future prospects for supernova-neutrino-sensitive detectors worldwide.

  1. EXPLOSIVE NUCLEOSYNTHESIS IN THE NEUTRINO-DRIVEN ASPHERICAL SUPERNOVA EXPLOSION OF A NON-ROTATING 15 M{sub sun} STAR WITH SOLAR METALLICITY

    SciTech Connect

    Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

    2011-09-01

    We investigate explosive nucleosynthesis in a non-rotating 15 M{sub sun} star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with a mass number {<=}70, employing a large nuclear reaction network. Aspherical abundance distributions, which are observed in nearby core-collapse SN remnants, are obtained for the non-rotating spherically symmetric progenitor, due to the growth of a low-mode SASI. The abundance pattern of the SN ejecta is similar to that of the solar system for models whose masses range between (0.4-0.5) M{sub sun} of the ejecta from the inner region ({<=}10, 000 km) of the precollapse core. For the models, the explosion energies and the {sup 56}Ni masses are {approx_equal} 10{sup 51}erg and (0.05-0.06) M{sub sun}, respectively; their estimated baryonic masses of the neutron star are comparable to the ones observed in neutron-star binaries. These findings may have little uncertainty because most of the ejecta is composed of matter that is heated via the shock wave and has relatively definite abundances. The abundance ratios for Ne, Mg, Si, and Fe observed in the Cygnus loop are reproduced well with the SN ejecta from an inner region of the 15 M{sub sun} progenitor.

  2. Impact of active-sterile neutrino mixing on supernova explosion and nucleosynthesis

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    We show that for the active-sterile flavor mixing parameters suggested by the reactor neutrino anomaly, substantial νe-νs and ν¯e-ν¯s conversion occurs in regions with an electron fraction of ≈1/3 near the core of an 8.8M⊙ electron-capture supernova. We explicitly include the feedback of such conversion on the evolution of the electron fraction in supernova ejecta. Compared to the case without such conversion, the neutron richness of the ejecta is enhanced to allow production of elements from Sr, Y, and Zr up to Cd in broad agreement with observations of the metal-poor star HD 122563 for a wide range of mixing parameters. Active-sterile flavor conversion can also strongly suppress neutrino heating at times when it is important for the revival of the shock. Our results suggest that simulations of a supernova explosion and the associated nucleosynthesis may be used to constrain active-sterile mixing parameters in combination with neutrino experiments and cosmological considerations.

  3. Toward connecting core-collapse supernova theory with observations

    NASA Astrophysics Data System (ADS)

    Handy, Timothy A.

    We study the evolution of the collapsing core of a 15 solar mass blue supergiant supernova progenitor from the moment shortly after core bounce until 1.5 seconds later. We present a sample of two- and three-dimensional hydrodynamic models parameterized to match the explosion energetics of supernova SN 1987A. We focus on the characteristics of the flow inside the gain region and the interplay between hydrodynamics, self-gravity, and neutrino heating, taking into account uncertainty in the nuclear equation of state. We characterize the evolution and structure of the flow behind the shock in terms the accretion flow dynamics, shock perturbations, energy transport and neutrino heating effects, and convective and turbulent motions. We also analyze information provided by particle tracers embedded in the flow. Our models are computed with a high-resolution finite volume shock capturing hydrodynamic code. The code includes source terms due to neutrino-matter interactions from a light-bulb neutrino scheme that is used to prescribe the luminosities and energies of the neutrinos emerging from the core of the proto-neutron star. The proto-neutron star is excised from the computational domain, and its contraction is modeled by a time-dependent inner boundary condition. We find the spatial dimensionality of the models to be an important contributing factor in the explosion process. Compared to two-dimensional simulations, our three-dimensional models require lower neutrino luminosities to produce equally energetic explosions. We estimate that the convective engine in our models is 4% more efficient in three dimensions than in two dimensions. We propose that this is due to the difference of morphology of convection between two- and three-dimensional models. Specifically, the greater efficiency of the convective engine found in three-dimensional simulations might be due to the larger surface-to-volume ratio of convective plumes, which aids in distributing energy deposited by

  4. Neutrino Physics in Supernovae

    NASA Astrophysics Data System (ADS)

    Dineva, Tamara Simeonova

    1997-11-01

    The models of exploding stars-supernovae-do not explode. This dissertation investigates the transfer of energy from the interior to the outer layers in such stars to try to understand what is missing in these models that would solve the supernova problem. Hydrodynamic instabilities and aspects in the microphysics of the neutrino transport in postcollapsed stellar matter are considered. In Chapter II we derive criteria for the presence of doubly diffusive instabilities believed to be essential for producing a supernova explosion. Contrary to the widely accepted view, we find that the core, if unstable, is unstable to semiconvection, rather than to neutron fingers. A critical value for the lepton fraction, Yl, is found for a given density and entropy, below which the stellar core is completely stable to instabilities. A considerable fraction of the stellar core is found to lie below the critical Yl. As the core evolves this fraction quickly encompasses the entire core. Thus doubly diffusive instabilities of any kind are unlikely to play a role in the supernova explosion mechanism. A strong magnetic field may modify the neutrino-nucleon absorption rates which are critical for shock reheating. In Chapter III we derive the cross section of neutrino absorption on neutrons in the presence of a strong magnetic field. We calculate values for the neutrino inverse mean free path and numerically compare them to the values in the non magnetic case. We find that they exhibit an oscillatory behavior, with huge peaks present due to discontinuities in the density of state. We conclude that the presence of a strong magnetic field does not yield a dramatic reduction in the inverse mean free paths which would be necessary to substantially increase the neutrino luminosity and revive the shock. Neutrino-neutrino scattering in the vicinity of the neutrino sphere may modify the neutrino luminosities and therefore affect shock reheating. In the last Chapter we calculate the neutrino

  5. DISENTANGLING THE ORIGIN AND HEATING MECHANISM OF SUPERNOVA DUST: LATE-TIME SPITZER SPECTROSCOPY OF THE TYPE IIn SN 2005ip

    SciTech Connect

    Fox, Ori D.; Chevalier, Roger A.; Skrutskie, Michael F.; Leisenring, Jarron M.; Dwek, Eli; Sugerman, Ben E. K.

    2010-12-20

    This paper presents late-time near-infrared and Spitzer mid-infrared photometric and spectroscopic observations of warm dust in the Type IIn SN 2005ip in NGC 2906. The spectra show evidence for two dust components with different temperatures. Spanning the peak of the thermal emission, these observations provide strong constraints on the dust mass, temperature, and luminosity, which serve as critical diagnostics for disentangling the origin and heating mechanism of each component. The results suggest that the warmer dust has a mass of {approx}5 x 10{sup -4} M{sub sun}, originates from newly formed dust in the ejecta, or possibly the cool, dense shell, and is continuously heated by the circumstellar interaction. By contrast, the cooler component likely originates from a circumstellar shock echo that forms from the heating of a large, pre-existing dust shell {approx}0.01-0.05 M{sub sun} by the late-time circumstellar interaction. The progenitor wind velocity derived from the blue edge of the He I 1.083 {mu}m P Cygni profile indicates a progenitor eruption likely formed this dust shell {approx}100 years prior to the supernova explosion, which is consistent with a Luminous Blue Variable progenitor star.

  6. Disentangling the Origin and Heating Mechanism of Supernova Dust: Late-Time Spitzer Spectroscopy of the Type IIn SN 2005ip

    NASA Technical Reports Server (NTRS)

    Fox, Ori D.; Chevalier, Roger A.; Dwek, Eli; Skrutskie, Michael F.; Sugerman, Ben E. K.; Leisenring, Jarron M.

    2010-01-01

    This paper presents late-time near-infrared and Spitzer mid-infrared photometric and spectroscopic observations of warm dust in the Type IIn SN 2005ip in NGC 2906. The spectra show evidence for two dust components with different temperatures. Spanning the peak of the thermal emission, these observations provide strong constraints on the dust mass, temperature, and luminosity, which serve as critical diagnostics for disentangling the origin and heating mechanism of each component. The results suggest the warmer dust has a mass of approx. 5 x 10(exp -4) Solar Mass and originates from newly formed dust in the ejecta, continuously heated by the circumstellar interaction. By contrast, the cooler component likely originates from a circumstellar shock echo that forms from the heating of a large, pre-existing dust shell approx. 0.01 - 0.05 Solar Mass by the late-time circumstellar interaction. The progenitor wind velocity derived from the blue edge of the He I 1.083 micro P Cygni profile indicates a progenitor eruption likely formed this dust shell approx.100 years prior to the supernova explosion, which is consistent with a Luminous Blue Variable (LBV) progenitor star. Subject

  7. Red-Supergiant and Supernova Rate Problems: Implication for the Relic Supernova Neutrino Spectrum

    NASA Astrophysics Data System (ADS)

    Hidaka, J.; Kajino, T.; Mathews, G. J.

    2016-08-01

    Direct observations of core-collapse supernovae (SNe) and their red supergiant (RSG) progenitors suggest that the upper mass limit of RSGs may be only about 16.5{--}18{M}ȯ , while the standard theoretical value is as much as 25{M}ȯ . We investigate the possibility that RSGs with m\\gt 16.5{--}18{M}ȯ end their lives as failed supernovae (fSNe) and analyze their contribution to the relic supernova neutrino spectrum. We show that adopting this mass limit simultaneously solves both the RSG problem and the supernova rate problem. In addition, energetic neutrinos that originated from fSNe are sensitive to the explosion mechanism, and in particular, to the nuclear equation of state (EOS). We show that this solution to the RSG problem might also be used to constrain the EOS for failed supernovae.

  8. The Supernova Spectropolarimetry Project: Probing the Evolution of Asymmetries in Supernovae

    NASA Astrophysics Data System (ADS)

    Hoffman, Jennifer; Williams, G. G.; Bilinski, C.; Dessart, L.; Huk, L. N.; Leonard, D. C.; Mauerhan, J.; Smith, N.; Smith, P. S.

    2014-07-01

    Nearly all supernovae possess spectropolarimetric signatures that indicate the presence of aspherical morphologies in the ejecta and/or surrounding circumstellar material. Interpreting the time variations of these spectropolarimetric signatures can yield unprecedentedly detailed information about supernova explosion mechanisms, the physical processes that shape the ejecta's density and velocity distributions, and the properties of the progenitor star.The Supernova Spectropolarimetry Project (SNSPOL) is a collaboration between observers and theorists that focuses on understanding the time-dependent spectropolarimetric behavior of supernovae. Using the CCD Imaging/Spectropolarimeter (SPOL) at the 61" Kuiper, the 90" Bok, and the 6.5-m MMT telescopes, we have obtained multi-epoch observations of over 50 supernovae of various types. I will present observational results from this project and discuss ongoing modeling efforts. Initial analysis reveals complex variable line polarization signatures that probe the distributions of different chemical species and thereby trace the detailed structure of the ejecta as these supernovae evolve. Our continuing observations will form the most comprehensive survey to date of supernovae in polarized light, allowing us to illuminate previously obscured relationships among subtypes, constrain progenitor properties, and build a more complete picture of the supernova population as a whole.

  9. Supernovae and mass extinctions

    NASA Technical Reports Server (NTRS)

    Vandenbergh, S.

    1994-01-01

    Shklovsky and others have suggested that some of the major extinctions in the geological record might have been triggered by explosions of nearby supernovae. The frequency of such extinction events will depend on the galactic supernova frequency and on the distance up to which a supernova explosion will produce lethal effects upon terrestrial life. In the present note it will be assumed that a killer supernova has to occur so close to Earth that it will be embedded in a young, active, supernova remnant. Such young remnants typically have radii approximately less than 3 pc (1 x 10(exp 19) cm). Larger (more pessimistic?) killer radii have been adopted by Ruderman, Romig, and by Ellis and Schramm. From observations of historical supernovae, van den Bergh finds that core-collapse (types Ib and II) supernovae occur within 4 kpc of the Sun at a rate of 0.2 plus or minus 0.1 per century. Adopting a layer thickness of 0.3 kpc for the galacitc disk, this corresponds to a rate of approximately 1.3 x 10(exp -4) supernovae pc(exp -3) g.y.(exp -1). Including supernovae of type Ia will increase the total supernovae rate to approximately 1.5 x 10(exp -4) supernovae pc(exp -3) g.y.(exp -1). For a lethal radius of R pc the rate of killer events will therefore be 1.7 (R/3)(exp 3) x 10(exp -2) supernovae per g.y. However, a frequency of a few extinctions per g.y. is required to account for the extinctions observed during the phanerozoic. With R (extinction) approximately 3 pc, the galactic supernova frequency is therefore too low by 2 orders of magnitude to account for the major extinctions in the geological record.

  10. Supernovae and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Panagia, Nino; Sahu, Kailash

    2001-07-01

    Participants; Preface; Gamma-ray burst-supernova relation B. Paczynski; Observations of gamma-ray bursts G. Fishman; Fireballs T. Piran; Gamma-ray mechanisms M. Rees; Prompt optical emission from gamma-ray bursts R. Kehoe, C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson, T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, K. Hurley, B. Lee, S. Marshall, T. McKay, A. Pawl, L. Piro, B. Priedhorsky, J. Szymanski and J. Wren; X-ray afterglows of gamma-ray bursts L. Piro; The first year of optical-IR observations of SN1998bw I. Danziger, T. Augusteijn, J. Brewer, E. Cappellaro, V. Doublier, T. Galama, J. Gonzalez, O. Hainaut, B. Leibundgut, C. Lidman, P. Mazzali, K. Nomoto, F. Patat, J. Spyromilio, M. Turatto, J. Van Paradijs, P. Vreeswijk and J. Walsh; X-ray emission of Supernova 1998bw in the error box of GRB980425 E. Pian; Direct analysis of spectra of type Ic supernovae D. Branch; The interaction of supernovae and gamma-ray bursts with their surroundings R. Chevalier; Magnetars, soft gamma-ray repeaters and gamma-ray bursts A. Harding; Super-luminous supernova remnants Y. -H. Chu, C. -H. Chen and S. -P. Lai; The properties of hypernovae: SNe Ic 1998bw, 1997ef, and SN IIn 1997cy K. Nomoto, P. Mazzali, T. Nakamura, K. Iwanmoto, K. Maeda, T. Suzuki, M. Turatto, I. Danziger and F. Patat; Collapsars, Gamma-Ray Bursts, and Supernovae S. Woosley, A. MacFadyen and A. Heger; Pre-supernova evolution of massive stars N. Panagia and G. Bono; Radio supernovae and GRB 980425 K. Weiler, N. Panagia, R. Sramek, S. Van Dyk, M. Montes and C. Lacey; Models for Ia supernovae and evolutionary effects P. Hoflich and I. Dominguez; Deflagration to detonation A. Khokhlov; Universality in SN Iae and the Phillips relation D. Arnett; Abundances from supernovae F. -K. Thielemann, F. Brachwitz, C. Freiburghaus, S. Rosswog, K. Iwamoto, T. Nakamura, K. Nomoto, H. Umeda, K. Langanke, G. Martinez-Pinedo, D. Dean, W. Hix and M. Strayer; Sne, GRBs, and the

  11. 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.

  12. Atomic and molecular supernovae

    SciTech Connect

    Liu, W.

    1997-12-01

    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.

  13. Interacting supernovae and supernova impostors: Evidence of incoming supernova explosions?

    NASA Astrophysics Data System (ADS)

    Tartaglia, L.

    2015-02-01

    Violent eruptions, and consequently major mass loss, are a common feature of the so-called Luminous Blue Variable (LBV) stars. During major eruptive episodes LBVs mimic the behavior of real type IIn supernovae (SNe), showing comparable radiated energy and similar spectroscopic properties. For this reason these events are frequently labelled as SN impostors. Type IIn SN spectra are characterized by the presence of prominent narrow Balmer lines in emission. In most cases, SNe IIn arise from massive stars (M>8⊙) exploding in a dense H-rich circumstellar medium (CSM), produced by progenitor's mass loss prior to the SN explosion. Although the mechanisms triggering these eruptions are still unknown, recently we had direct proofs of the connection between very massive stars, their eruptions and ejecta-CSM interacting SNe. SNe 2006jc, 2010mc, 2011ht and the controversial SN 2009ip are famous cases in which we observed the explosion of the star months to years after major outbursts. In this context, the case of a recent transient event, LSQ13zm, is extremely interesting since we observed an outburst just ˜3 weeks before the terminal SN explosion. All of this may suggest that SN impostors occasionally herald true SN explosions. Nonetheless, there are several cases where major eruptions are followed by a quiescent phase in the LBV life. The impostor SN 2007sv is one of these cases, since it showed a single outburst event. Its photometric (a relatively faint absolute magnitude at the maximum) and spectroscopic properties (low velocity and temperature of the ejecta, and the absence of the typical elements produced in the explosive nucleosynthesis) strongly suggest that SN 2007sv was the giant eruption of an LBV, which has then returned in a quiescent stage.

  14. Interacting supernovae and supernova impostors: Evidence of incoming supernova explosions?

    SciTech Connect

    Tartaglia, L.

    2015-02-24

    Violent eruptions, and consequently major mass loss, are a common feature of the so–called Luminous Blue Variable (LBV) stars. During major eruptive episodes LBVs mimic the behavior of real type IIn supernovae (SNe), showing comparable radiated energy and similar spectroscopic properties. For this reason these events are frequently labelled as SN impostors. Type IIn SN spectra are characterized by the presence of prominent narrow Balmer lines in emission. In most cases, SNe IIn arise from massive stars (M>8{sub ⊙}) exploding in a dense H–rich circumstellar medium (CSM), produced by progenitor’s mass loss prior to the SN explosion. Although the mechanisms triggering these eruptions are still unknown, recently we had direct proofs of the connection between very massive stars, their eruptions and ejecta-CSM interacting SNe. SNe 2006jc, 2010mc, 2011ht and the controversial SN 2009ip are famous cases in which we observed the explosion of the star months to years after major outbursts. In this context, the case of a recent transient event, LSQ13zm, is extremely interesting since we observed an outburst just ∼3 weeks before the terminal SN explosion. All of this may suggest that SN impostors occasionally herald true SN explosions. Nonetheless, there are several cases where major eruptions are followed by a quiescent phase in the LBV life. The impostor SN 2007sv is one of these cases, since it showed a single outburst event. Its photometric (a relatively faint absolute magnitude at the maximum) and spectroscopic properties (low velocity and temperature of the ejecta, and the absence of the typical elements produced in the explosive nucleosynthesis) strongly suggest that SN 2007sv was the giant eruption of an LBV, which has then returned in a quiescent stage.

  15. Degeneracy effects of neutrino mass ejection in supernovae

    NASA Technical Reports Server (NTRS)

    Mazurek, T. J.

    1974-01-01

    A neutrino mechanism is discussed in order to explain supernovae in massive stars. An argument is presented for supernova mass ejection through leptonic neutrino transport characteristics suppressed by the arbitrary zero chemical potential condition. Results show that lepton conservation effects may be important in supernova neutrino transport. At low temperature and density the diffusion approximation becomes less precise because of the long mean free paths of low energy neutrinos. The amount of equilibrium neutrino spectrum affected here is small over most of the collapsing supernova structure.

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

    NASA Astrophysics Data System (ADS)

    Diamond, Patrick

    2005-10-01

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

  17. A SEMI-DYNAMICAL APPROACH TO THE SHOCK REVIVAL IN CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Nagakura, Hiroki; Yamamoto, Yu; Yamada, Shoichi

    2013-03-10

    We develop a new semi-dynamical method to study shock revival by neutrino heating in core-collapse supernovae. Our new approach is an extension of the previous studies that employ spherically symmetric, steady, shocked accretion flows together with the light-bulb approximation. The latter has been widely used in the supernova community for the phenomenological investigation of the criteria for successful supernova explosions. In the present approach, we get rid of the steady-state condition and take into account shock wave motions instead. We have in mind a scenario in which it is not the critical luminosity but the critical fluctuation generated by hydrodynamical instabilities such as standing accretion shock instability and neutrino-driven convection in the post-shock region that determines the onset of shock revival. After confirming that the new approach indeed captures the dynamics of revived shock wave qualitatively, we then apply the method to various initial conditions and find that there is a critical fluctuation for shock revival, which can be well fit by the following formula: f{sub crit} {approx} 0.8 Multiplication-Sign (M{sub in}/1.4 M{sub Sun }) Multiplication-Sign {l_brace}1 - (r{sub sh}/10{sup 8} cm){r_brace}, where f{sub crit} denotes the critical pressure fluctuation normalized by the unperturbed post-shock value. M{sub in} and r{sub sh} stand for the mass of the central compact object and the shock radius, respectively. The critical fluctuation decreases with the shock radius, whereas it increases with the mass of the central object. We discuss the possible implications of our results for three-dimensional effects on shock revival, which is currently controversial in the supernova community.

  18. 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.

  19. Supernova-driven interstellar turbulence

    NASA Astrophysics Data System (ADS)

    Joung, M. K. Ryan

    efficient mechanical and chemical feedback from supernovae, but a successful theory for the feedback has been difficult to obtain. As a result, simple phenomenological treatments have often been used. We propose to improve our understanding of feedback in two steps. First, we perform a suite of numerical experiments in which the supernova rates and gas column densities are systematically varied according to the Kennicutt relation. Our simulations have a sufficiently high spatial resolution (1.95 pc) to follow detailed hydrodynamic interactions that structure the interstellar medium. At a given supernova rate, both thermal and turbulent pressures are nearly constant in the midplane, i.e., the equation of state is isobaric. In contrast, across our four models having different supernova rates, the gas averaged over ~100 pc regions shows P [is proportional to] [rho] 1. x , that is, the equation of state is less compressible than isothermal. Based on these local stratified ISM models, we construct a subgrid model for turbulent pressure, which will be a useful tool for including supernova feedback in cosmological simulations.

  20. SPECTRA AND LIGHT CURVES OF FAILED SUPERNOVAE

    SciTech Connect

    Fryer, Chris L.; Dahl, Jon A.; Fontes, Christopher J. E-mail: dahl@lanl.go

    2009-12-10

    Astronomers have proposed a number of mechanisms to produce supernova explosions. Although many of these mechanisms are now not considered primary engines behind supernovae (SNe), they do produce transients that will be observed by upcoming ground-based surveys and NASA satellites. Here, we present the first radiation-hydrodynamics calculations of the spectra and light curves from three of these 'failed' SNe: SNe with considerable fallback, accretion-induced collapse of white dwarfs, and energetic helium flashes (also known as type Ia SNe).

  1. HUBBLE PINPOINTS DISTANT SUPERNOVAE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These Hubble Space Telescope images pinpoint three distant supernovae, which exploded and died billions of years ago. Scientists are using these faraway light sources to estimate if the universe was expanding at a faster rate long ago and is now slowing down. Images of SN 1997cj are in the left hand column; SN 1997ce, in the middle; and SN 1997ck, on the right. All images were taken by the Hubble telescope's Wide Field and Planetary Camera 2. The top row of images are wider views of the supernovae. The supernovae were discovered in April 1997 in a ground-based survey at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. Once the supernovae were discovered, the Hubble telescope was used to distinguish the supernovae from the light of their host galaxies. A series of Hubble telescope images were taken in May and June 1997 as the supernovae faded. Six Hubble telescope observations spanning five weeks were taken for each supernova. This time series enabled scientists to measure the brightness and create a light curve. Scientists then used the light curve to make an accurate estimate of the distances to the supernovae. Scientists combined the estimated distance with the measured velocity of the supernova's host galaxy to determine the expansion rate of the universe in the past (5 to 7 billion years ago) and compare it with the current rate. These supernovae belong to a class called Type Ia, which are considered reliable distance indicators. Looking at great distances also means looking back in time because of the finite velocity of light. SN 1997ck exploded when the universe was half its present age. It is the most distant supernova ever discovered (at a redshift of 0.97), erupting 7.7 billion years ago. The two other supernovae exploded about 5 billion years ago. SN 1997ce has a redshift of 0.44; SN 1997cj, 0.50. SN 1997ck is in the constellation Hercules, SN 1997ce is in Lynx, just north of Gemini; and SN 1997cj is in Ursa Major, near the Hubble Deep Field

  2. Convection in Type 2 supernovae

    SciTech Connect

    Miller, D.S.

    1993-10-15

    Results are presented here from several two dimensional numerical calculations of events in Type II supernovae. A new 2-D hydrodynamics and neutrino transport code has been used to compute the effect on the supernova explosion mechanism of convection between the neutrinosphere and the shock. This convection is referred to as exterior convection to distinguish it from convection beneath the neutrinosphere. The model equations and initial and boundary conditions are presented along with the simulation results. The 2-D code was used to compute an exterior convective velocity to compare with the convective model of the Mayle and Wilson 1-D code. Results are presented from several runs with varying sizes of initial perturbation, as well as a case with no initial perturbation but including the effects of rotation. The M&W code does not produce an explosion using the 2-D convective velocity. Exterior convection enhances the outward propagation of the shock, but not enough to ensure a successful explosion. Analytic estimates of the growth rate of the neutron finger instability axe presented. It is shown that this instability can occur beneath the neutrinosphere of the proto-neutron star in a supernova explosion with a growth time of {approximately} 3 microseconds. The behavior of the high entropy bubble that forms between the shock and the neutrinosphere in one dimensional calculations of supernova is investigated. It has been speculated that this bubble is a site for {gamma}-process generation of heavy elements. Two dimensional calculations are presented of the time evolution of the hot bubble and the surrounding stellar material. Unlike one dimensional calculations, the 2D code fails to achieve high entropies in the bubble. When run in a spherically symmetric mode the 2-D code reaches entropies of {approximately} 200. When convection is allowed, the bubble reaches {approximately} 60 then the bubble begins to move upward into the cooler, denser material above it.

  3. Light Curves of Supernovae

    NASA Astrophysics Data System (ADS)

    Spencer, Michelle; Joner, Michael; Laney, David; Stoker, Emily

    2012-10-01

    Photometric Data were secured for the supernovae 2010hh, 2011dh, 2011fe and 2012aw before the dates which each individual maxima occur. The data for all supernovae were secured using the 0.9-meter telescope at the BYU West Mountain Observatory in Utah. 2010hh data were secured during the summer 2010 over the months of August to October. 2011dh and 2011fe data were secured during the summer of 2011. 2012aw data were secured during the summer of 2012. The data exposures from 2010 were secured using standard B,V and R filters. The frames for 2011 were secured using B,V, R and I filters. The 2012 supernova frames were secured in B,V and R filters. Using the data I will compare and contrast these four different supernovae and discuss their possible uses for distance determinations for the host galaxies.

  4. Berkeley automated supernova search

    SciTech Connect

    Kare, J.T.; Pennypacker, C.R.; Muller, R.A.; Mast, T.S.; Crawford, F.S.; Burns, M.S.

    1981-01-01

    The Berkeley automated supernova search employs a computer controlled 36-inch telescope and charge coupled device (CCD) detector to image 2500 galaxies per night. A dedicated minicomputer compares each galaxy image with stored reference data to identify supernovae in real time. The threshold for detection is m/sub v/ = 18.8. We plan to monitor roughly 500 galaxies in Virgo and closer every night, and an additional 6000 galaxies out to 70 Mpc on a three night cycle. This should yield very early detection of several supernovae per year for detailed study, and reliable premaximum detection of roughly 100 supernovae per year for statistical studies. The search should be operational in mid-1982.

  5. The Historical Supernovae

    NASA Astrophysics Data System (ADS)

    Clark, D. H.; Stephenson, F. R.

    1982-11-01

    A survey was made of pretelescopic astronomical records from Europe, China, Korea, Japan, Babylon, and the Arab countries to search for historical evidence of supernovae. A Roman, Claudian, reported a new star in 393 AD, the same year that Chinese astronomers noted a new star, together with its location and duration. Most European records were made in monasteries after 1000 AD, and one supernova was sighted in 1006 AD. A similar sighting was made in the Arab world at the same time. A total of twenty candidate events were found in the nearly 2000 yr of Chinese records. An analysis of the recorded events characteristics indicates that in 185, 393, 1006, 1054, 1181, 1572, and 1604 AD supernovae were seen. The 1054 AD explosion was corroborated by Arab records, while all others (except for the 393 AD and 1006 AD supernovae) were confined to Oriental observations.

  6. Nucleosynthesis in Thermonuclear Supernovae

    SciTech Connect

    Claudia, Travaglio; Hix, William Raphael

    2013-01-01

    We review our understanding of the nucleosynthesis that occurs in thermonuclear supernovae and their contribution to Galactic Chemical evolution. We discuss the prospects to improve the modeling of the nucleosynthesis within simulations of these events.

  7. Automated search for supernovae

    SciTech Connect

    Kare, J.T.

    1984-11-15

    This thesis describes the design, development, and testing of a search system for supernovae, based on the use of current computer and detector technology. This search uses a computer-controlled telescope and charge coupled device (CCD) detector to collect images of hundreds of galaxies per night of observation, and a dedicated minicomputer to process these images in real time. The system is now collecting test images of up to several hundred fields per night, with a sensitivity corresponding to a limiting magnitude (visual) of 17. At full speed and sensitivity, the search will examine some 6000 galaxies every three nights, with a limiting magnitude of 18 or fainter, yielding roughly two supernovae per week (assuming one supernova per galaxy per 50 years) at 5 to 50 percent of maximum light. An additional 500 nearby galaxies will be searched every night, to locate about 10 supernovae per year at one or two percent of maximum light, within hours of the initial explosion.

  8. Dark matter triggers of supernovae

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Rajendran, Surjeet; Varela, Jaime

    2015-09-01

    The transit of primordial black holes through a white dwarf causes localized heating around the trajectory of the black hole through dynamical friction. For sufficiently massive black holes, this heat can initiate runaway thermonuclear fusion causing the white dwarf to explode as a supernova. The shape of the observed distribution of white dwarfs with masses up to 1.25 M⊙ rules out primordial black holes with masses ˜1019- 1020 gm as a dominant constituent of the local dark matter density. Black holes with masses as large as 1024 gm will be excluded if recent observations by the NuStar Collaboration of a population of white dwarfs near the galactic center are confirmed. Black holes in the mass range 1020- 1022 gm are also constrained by the observed supernova rate, though these bounds are subject to astrophysical uncertainties. These bounds can be further strengthened through measurements of white dwarf binaries in gravitational wave observatories. The mechanism proposed in this paper can constrain a variety of other dark matter scenarios such as Q balls, annihilation/collision of large composite states of dark matter and models of dark matter where the accretion of dark matter leads to the formation of compact cores within the star. White dwarfs, with their astronomical lifetimes and sizes, can thus act as large spacetime volume detectors enabling a unique probe of the properties of dark matter, especially of dark matter candidates that have low number density. This mechanism also raises the intriguing possibility that a class of supernova may be triggered through rare events induced by dark matter rather than the conventional mechanism of accreting white dwarfs that explode upon reaching the Chandrasekhar mass.

  9. Physics of supernovae

    SciTech Connect

    Woosley, S.E.; Weaver, T.A.

    1985-12-13

    Presupernova models of massive stars are presented and their explosion by ''delayed neutrino transport'' examined. A new form of long duration Type II supernova model is also explored based upon repeated encounter with the electron-positron pair instability in stars heavier than about 60 Msub solar. Carbon deflagration in white dwarfs is discussed as the probable explanation of Type I supernovae and special attention is paid to the physical processes whereby a nuclear flame propagates through degenerate carbon. 89 refs., 12 figs.

  10. Positrons from supernovae

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing; Lingenfelter, Richard E.

    1993-01-01

    Positrons are produced in the ejecta of supernovae by the decay of nucleosynthetic Co-56, Ti-44, and Al-26. We calculate the probability that these positrons can survive without annihilating in the supernova ejecta, and we show that enough of these positrons should escape into the interstellar medium to account for the observed diffuse Galactic annihilation radiation. The surviving positrons are carried by the expanding ejecta into the interstellar medium where their annihilation lifetime of 10 exp 5 - 10 exp 6 yr is much longer than the average supernovae occurrence time of about 100 yr. Thus, annihilating positrons from thousands of supernovae throughout the Galaxy produce a steady diffuse flux of annihilation radiation. We further show that combining the calculated positron survival fractions and nucleosynthetic yields for current supernova models with the estimated supernova rates and the observed flux of diffuse Galactic annihilation radiation suggests that the present Galactic rate of Fe-56 nucleosynthesis is about 0.8 +/- 0.6 solar mass per 100 yr.

  11. Dynamics of supernova driven superbubbles

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  12. Deflagrations and detonations in thermonuclear supernovae.

    PubMed

    Gamezo, Vadim N; Khokhlov, Alexei M; Oran, Elaine S

    2004-05-28

    We study a type Ia supernova explosion using three-dimensional numerical simulations based on reactive fluid dynamics. We consider a delayed-detonation model that assumes a deflagration-to-detonation transition. In contrast with the pure deflagration model, the delayed-detonation model releases enough energy to account for a healthy explosion, and does not leave carbon, oxygen, and intermediate-mass elements in central parts of a white dwarf. This removes the key disagreement between simulations and observations, and makes a delayed detonation the mostly likely mechanism for type Ia supernovae. PMID:15245271

  13. Dark matter balls help supernovae to explode

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  14. Turbulence in Type Ia Supernovae Simulations

    NASA Astrophysics Data System (ADS)

    Fisher, Robert

    2012-03-01

    Type Ia supernovae are among the most energetic explosions in the known universe, releasing 10^51 ergs of kinetic energy in their ejecta, with 0.7 solar masses of radioactive Ni-56 synthesized during the explosion. The discovery of the Phillips relation enabled the use of Type Ia supernova (SN Ia) as standardizable cosmological candles, and has ushered in a new era of astronomy leading to the discovery of the acceleration of the universe, leading to the 2011 Nobel Prize in physics. The nature of the Type Ia progenitors, as well as their precise explosion mechanism, remains a subject of active investigation, both observationally as well as theoretically. It is known that the progenitors of Type Ia supernovae are near-Chandrasekhar mass white dwarfs in binary systems, though competing models suggest the companion is either a red giant or main sequence star (the so-called ``single-degenerate channel'') or another white dwarf (the ``double-degenerate channel''). In this talk, I will present recent results of three -dimensional models of the single-degenerate channel of Type Ia supernovae. I will also discuss prospects for modeling the double-degenerate channel of Type Ia supernovae, which have recently enjoyed increased favor from observers and theorists.

  15. Swift X-Ray Telescope Observations of Superluminous Supernovae

    NASA Astrophysics Data System (ADS)

    Kae Batara Olaes, Melanie; Quimby, Robert

    2016-06-01

    Superluminous Supernovae (SLSNe) are a part of an emerging class of exceptionally bright supernovae with peak luminosities 10 times brighter than typical Type Ia supernovae. Similar to supernovae, SLSNe are divided into two subclasses: hydrogen poor SLSN-I and hydrogen rich SLSN-II. However, the luminosity of these events is far too high to be explained by the models for normal supernovae. New models developed to explain SLSNe predict high luminosity X-ray emission at late times. A consistent analysis of incoming SLSNe is essential in order to place constraints on the mechanisms behind these events. Here we present the results of X-ray analysis on SLSNe using a Bayesian method of statistical inference for low count rate events.

  16. Stellar clustering as induced by a supernova

    NASA Technical Reports Server (NTRS)

    Baierlein, R.; Schwing, E.; Herbst, W.

    1981-01-01

    A possible mechanism for the fragmentation of the expanding shock wave from a supernova to form stellar clusters is considered. A model of supernova shell expansion is constructed in which the ratio of magnetic field intensity to gas density remains constant during the one-dimensional compression of the interstellar medium by the shock, and the gas and field adjust to a quasi-equilibrium within the shell following shock passage. It is shown that the quasi-equilibrium, which may be considered as an isothermal atmosphere, is unstable to a hydromagnetic instability representing a form of the Parker instability, which results in a clumping of gas at intervals on the order of parsecs. The length and time scales of the instability are consistent with the clustering of newly formed stars observed in Canis Major R1, where there is evidence for supernova-induced star formation.

  17. Observing Supernovae and Supernova Remnants with JWST

    NASA Astrophysics Data System (ADS)

    Sonneborn, George; Temim, Tea; Williams, Brian J.; Blair, William P.

    2015-01-01

    The James Webb Space Telescope (JWST) will enable near- and mid-infrared studies of supernovae (SN) and supernova remnants (SNR) in the Milky Way and galaxies throughout the local universe and to high redshift. JWST's instrumentation provides imaging, coronography, and spectroscopy (R<3000) over the wavelength range 1-29 microns. The unprecedented sensitivity and angular resolution will enable spectroscopic study of new and recent supernovae, including molecule and dust formation, in galaxies at least out to 30 Mpc, and imaging to much greater distances. The Target of Opportunity response time can be as short as 48 hours, enabling quick follow-up observations of important SN events. JWST will be ideal for the study of Galactic and Magellanic Clouds supernova remnants, particularly young remnants with hot dust. Its high angular resolution (0.07" at 2 microns, 0.7" at 20 microns) will allow direct comparison between the IR, optical, and X-ray morphologies, identifying sites of dust emission in both the ejecta and the shocked ISM unresolved by previous IR telescopes. There is a rich spectrum of atomic lines (H, He I, [Si I], [Fe II], [Ni I-III], [Co II-III], [S III-IV], [Ar II-III], [Ne II, III, V], [O IV]) and molecules (CO, SiO, H2) of importance for SN and SNR studies. JWST is a large aperture (6.5m), cryogenic, infrared-optimized space observatory under construction by NASA, ESA, and CSA for launch in 2018. The JWST observatory will be placed in an Earth-Sun L2 orbit by an Ariane 5 launch vehicle provided by ESA. The observatory is designed for a 5-year prime science mission, with consumables for 10 years of science operations. The first call for proposals for JWST observations will be released in 2017.

  18. PROGENITORS OF RECOMBINING SUPERNOVA REMNANTS

    SciTech Connect

    Moriya, Takashi J.

    2012-05-01

    Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

  19. The Most Luminous Supernovae

    NASA Astrophysics Data System (ADS)

    Sukhbold, Tuguldur; Woosley, S. E.

    2016-04-01

    Recent observations have revealed a stunning diversity of extremely luminous supernovae, seemingly increasing in radiant energy without bound. We consider simple approximate limits for what existing models can provide for the peak luminosity and total radiated energy for non-relativistic, isotropic stellar explosions. The brightest possible supernova is a Type I explosion powered by a sub-millisecond magnetar with field strength B ∼ few × {10}13 G. In extreme cases, such models might reach a peak luminosity of 2× {10}46 {erg} {{{s}}}-1 and radiate a total energy of up to 4× {10}52 {erg}. Other less luminous models are also explored, including prompt hyper-energetic explosions in red supergiants, pulsational-pair instability supernovae, pair-instability supernovae, and colliding shells. Approximate analytic expressions and limits are given for each case. Excluding magnetars, the peak luminosity is near 3× {10}44 {erg} {{{s}}}-1 for the brightest models and the corresponding limit on total radiated energy is 3× {10}51 {erg}. Barring new physics, supernovae with a light output over 3× {10}51 erg must be rotationally powered, either during the explosion itself or after, the most obvious candidate being a rapidly rotating magnetar. A magnetar-based model for the recent transient event, ASASSN-15lh is presented that strains, but does not exceed the limits of what the model can provide.

  20. Neutrino and gamma-ray signatures of supernova explosions

    NASA Astrophysics Data System (ADS)

    Lu, Yu

    2007-08-01

    A supernova occurs when the core of a massive star collapses into a compact neutron star. Nearly all the gravitational binding energy of the neutron star is emitted in neutrinos. This is approximately 100 times larger than the explosion energy as measured by the total energy of the ejecta. A prevalent paradigm is that a fraction of the neutrino energy is absorbed by the material above the neutron star, thereby delivering the explosion. We test this neutrino driven supernova mechanism by analyzing the signal induced by supernova electron antineutrinos in terrestrial detectors such as SuperKamiokande. We perform detailed Monte Carlo simulations of such signals and identify the potential signatures of this mechanism by comparing the event rates and energy spectra before and after explosion. Before the neutrinos reach terrestrial detectors, a fraction of them interact with protons and nuclei in the supernova envelope. Some of these interactions result in gamma-ray emission. The gamma-rays produced in the outmost layer escape and may be detected. We calculate the time evolution for the fluxes of gamma-rays produced by neutron capture on protons and positron annihilation following the absorption of electron antineutrinos on protons. Because these gamma-rays are produced before the supernova shock arrives at the envelope, their detection can help identify the supernova before it is seen optically. In addition, they may provide a useful probe of the conditions in the surface layer of the supernova progenitor.

  1. Essential Ingredients in Core-collapse Supernovae

    SciTech Connect

    Hix, William Raphael; Lentz, E. J.; Endeve, Eirik; Baird, Mark L.; Chertkow, Merek A.; Harris, James A.; Messer, Bronson; Mezzacappa, Anthony; Bruenn, S. W.; Blondin, J. M.

    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 10$^{44}$ 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.

  2. Essential ingredients in core-collapse supernovae

    SciTech Connect

    Hix, W. Raphael; Lentz, Eric J.; Chertkow, M. Austin; Harris, J. Austin; Endeve, Eirik; Baird, Mark; Messer, O. E. Bronson; Mezzacappa, Anthony; Bruenn, Stephen; Blondin, John

    2014-04-15

    Carrying 10{sup 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 our solar system and ourselves. Signaling the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae combine physics over a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale) down to femtometer-scale nuclear reactions. 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. Multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have recently 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 the births of neutron stars and the supernovae that result. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

  3. Neutron star recoils from anisotropic supernovae.

    NASA Astrophysics Data System (ADS)

    Janka, H.-T.; Mueller, E.

    1994-10-01

    Refering to recent hydrodynamical computations (Herant et al. 1992; Janka & Mueller 1993a) it is argued that neutron star kicks up to a few hundred km/s might be caused by a turbulent overturn of the matter between proto-neutron star and supernova shock during the early phase of the supernova explosion. These recoil speeds ("kick velocities") may be of the right size to explain the measured proper motions of most pulsars and do not require the presence of magnetic fields in the star. It is also possible that anisotropic neutrino emission associated with convective processes in the surface layers of the nascent neutron star (Burrows & Fryxell 1992; Janka & Mueller 1993b; Mueller 1993) provides an acceleration mechanism (Woosley 1987), although our estimates indicate that the maximum attainable velocities are around 200km/s. Yet, it turns out to be very unlikely that the considered stochastic asymmetries of supernova explosions are able to produce large enough recoils to account for pulsar velocities in excess of about 500km/s, which can be found in the samples of Harrison et al. (1993) and Taylor et al. (1993). It is concluded that other acceleration mechanisms have to be devised to explain the fast motion of PSR 2224+65 (transverse speed >=800km/s Cordes et al. 1993) and the high-velocities deduced from associations between supernova remnants and nearby young pulsars (e.g., Frail & Kulkarni 1991; Stewart et al. 1993; Caraveo 1993).

  4. Essential Ingredients in Core-collapse Supernovae

    DOE PAGESBeta

    Hix, William Raphael; Lentz, E. J.; Endeve, Eirik; Baird, Mark L.; Chertkow, Merek A.; Harris, James A.; Messer, Bronson; Mezzacappa, Anthony; Bruenn, S. W.; Blondin, J. M.

    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

  5. Essential ingredients in core-collapse supernovae

    NASA Astrophysics Data System (ADS)

    Hix, W. Raphael; Lentz, Eric J.; Endeve, Eirik; Baird, Mark; Chertkow, M. Austin; Harris, J. Austin; Messer, O. E. Bronson; Mezzacappa, Anthony; Bruenn, Stephen; Blondin, John

    2014-04-01

    Carrying 1044 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 our solar system and ourselves. Signaling the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae combine physics over a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale) down to femtometer-scale nuclear reactions. 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. Multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have recently 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 the births of neutron stars and the supernovae that result. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

  6. Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Mccray, Richard; Li, Hong Wei

    1988-01-01

    Supernova 1987A (February 23, 1987) in the Large Magellanic Cloud is the brightest supernova to be observed since SN 1604 AD (Kepler). Detection of a burst of neutrinos indicates that a neutron star was formed. Radioactive decay of about 0.07 solar mass of Co-56 is responsible for the observed optical light as well as hard X-rays and gamma-ray lines. Ultraviolet, optical, and infrared 'light echoes' and soft X-rays provide information on the distribution of circumstellar matter and the evolution of the progenitor star.

  7. What Shapes Supernova Remnants?

    NASA Astrophysics Data System (ADS)

    Lopez, Laura A.

    2014-01-01

    Evidence has mounted that Type Ia and core-collapse (CC) supernovae (SNe) can have substantial deviations from spherical symmetry; one such piece of evidence is the complex morphologies of supernova remnants (SNRs). However, the relative role of the explosion geometry and the environment in shaping SNRs remains an outstanding question. Recently, we have developed techniques to quantify the morphologies of SNRs, and we have applied these methods to the extensive X-ray and infrared archival images available of Milky Way and Magellanic Cloud SNRs. In this proceeding, we highlight some results from these studies, with particular emphasis on SNR asymmetries and whether they arise from ``nature'' or ``nurture''.

  8. Supernova science with LCOGT

    NASA Astrophysics Data System (ADS)

    Howell, Dale A.; Valenti, S.; Sand, D. J.; Parrent, J. T.; Arcavi, I.; Graham, M. L.

    2014-01-01

    Las Cumbres Observatory Global Telescope Network (LCOGT.net) is a collection of nine robotic one meter telescopes with imagers spaced around the world in longitude, operated as a single network. There are also two robotic FLOYDS spectrographs on the two meter Faulkes telescopes in Siding Spring, Australia, and Haleakala, Hawaii. Here we describe recent supernova lightcurves and spectra with taken with LCOGT after being triggered from Pan-STARRS1, the La Silla-QUEST survey, the intermediate Palomar Transient Factory, and the IAU circulars. Since at least one telescope is always in the dark, and the facilities are robotic, LCOGT is uniquely suited to early-time supernova science.

  9. Neutrinos in supernovae

    SciTech Connect

    Cooperstein, J.

    1986-10-01

    The role of neutrinos in Type II supernovae is discussed. An overall view of the neutrino luminosity as expected theoretically is presented. The different weak interactions involved are assessed from the standpoint of how they exchange energy, momentum, and lepton number. Particular attention is paid to entropy generation and the path to thermal and chemical equilibration, and to the phenomenon of trapping. Various methods used to calculate the neutrino flows are considered. These include trapping and leakage schemes, distribution-averaged transfer, and multi-energy group methods. The information obtained from the neutrinos caught from Supernova 1987a is briefly evaluated. 55 refs., 7 figs.

  10. TYPING SUPERNOVA REMNANTS USING X-RAY LINE EMISSION MORPHOLOGIES

    SciTech Connect

    Lopez, L. A.; Ramirez-Ruiz, E.; Badenes, C.; Huppenkothen, D.; Jeltema, T. E.

    2009-11-20

    We present a new observational method to type the explosions of young supernova remnants (SNRs). By measuring the morphology of the Chandra X-ray line emission in 17 Galactic and Large Magellanic Cloud SNRs with a multipole expansion analysis (using power ratios), we find that the core-collapse SNRs are statistically more asymmetric than the Type Ia SNRs. We show that the two classes of supernovae can be separated naturally using this technique because X-ray line morphologies reflect the distinct explosion mechanisms and structure of the circumstellar material. These findings are consistent with recent spectropolarimetry results showing that core-collapse supernovae explosions are intrinsically more asymmetric.

  11. 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.

  12. Neutrino Leakage and Supernova Explosion

    NASA Astrophysics Data System (ADS)

    Liao, Dao-Bing; Zhang, Miao-Jing; Li, Yan; Pan, Jiang-Hong; Chen, Xiu

    2015-04-01

    In the process of supernova explosion the leakage of neutrinos is very important. Adopting an one-dimensional spherically symmetrical model, and under the different neutrino leakage modes, the explosion processes of type II supernovae with masses of 12 M⊙, 14 M⊙, and 15 M⊙ are simulated numerically. The results indicate that all these different neutrino leakage modes have influences on the supernova collapse, shock propagation, and supernova explosion. The best values of the related parameters which are propitious for the type II supernova explosion are given. In addition, the impacts of the equation of state and the compression modulus on the simulated results are discussed.

  13. Properties of unusually luminous supernovae

    NASA Astrophysics Data System (ADS)

    Pan, Tony Shih Arng

    This thesis is a theoretical study of the progenitors, event rates, and observational properties of unusually luminous supernova (SN), and aims to identify promising directions for future observations. In Chapter 2, we present model light curves and spectra of pair-instability supernovae (PISNe) over a range of progenitor masses and envelope structures for Pop III stars. We calculate the rates and detectability of PISNe, core-collapse supernovae (CCSNe), and Type Ia SNe at the Epoch of Reionization with the James Webb Space Telescope (JWST), which can be used to determine the contribution of Pop III versus Pop II stars toward ionizing the universe. Although CCSNe are the least intrinsically luminous supernovae, Chapter 5 shows that a JWST survey targeting known galaxy clusters with Einstein radii > 35" should discover gravitationally lensed CCSNe at redshifts exceeding z = 7--8. In Chapter 3, we explain the Pop II/I progenitors of observed PISNe in the local universe can be created via mergers in runaway collisions in young, dense star clusters, despite copious mass loss via line-driven winds. The PISN rate from this mechanism is consistent with the observed volumetric rate, and the Large Synoptic Survey Telescope could discover ~102 such PISNe per year. In Chapter 4, we identify 10 star clusters which may host PISN progenitors with masses up to 600 solar masses formed via runaway collisions. We estimate the probabilities of these very massive stars being in eclipsing binaries to be ≳ 30%, and find that their transits can be detected even under the contamination of the background cluster light, due to mean transit depths of ~10 6 solar luminosities. In Chapter 6, we show that there could be X-ray analogues of optically super-luminous SNe that are powered by the conversion of the kinetic energy of SN ejecta into radiation upon its collision with a dense but optically-thin circumstellar shell. We find shell configurations that can convert a large fraction of the SN

  14. Spectral ID of Supernova

    NASA Astrophysics Data System (ADS)

    Challis, P.; Kirshner, R.; Falco, E.; Irwin, J.; Prieto, J. L.; Stanek, K. Z.

    2015-02-01

    Spectra (range 350-760 nm) of supernovae ASASSN-15dc (ATel #7090), ASASSN-15dd and ASASSN-15de (ATel #7094), and ASASSN-15df (ATel #7097), were obtained on Feb 19, 2015 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST).

  15. Supernova Photometric Lightcurve Classification

    NASA Astrophysics Data System (ADS)

    Zaidi, Tayeb; Narayan, Gautham

    2016-01-01

    This is a preliminary report on photometric supernova classification. We first explore the properties of supernova light curves, and attempt to restructure the unevenly sampled and sparse data from assorted datasets to allow for processing and classification. The data was primarily drawn from the Dark Energy Survey (DES) simulated data, created for the Supernova Photometric Classification Challenge. This poster shows a method for producing a non-parametric representation of the light curve data, and applying a Random Forest classifier algorithm to distinguish between supernovae types. We examine the impact of Principal Component Analysis to reduce the dimensionality of the dataset, for future classification work. The classification code will be used in a stage of the ANTARES pipeline, created for use on the Large Synoptic Survey Telescope alert data and other wide-field surveys. The final figure-of-merit for the DES data in the r band was 60% for binary classification (Type I vs II).Zaidi was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829).

  16. Supernova Confetti in Meteorites

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2010-11-01

    Chromium has four isotopes, with atomic weights of 50, 52, 53, and 54. In terrestrial rocks the isotopes behave in predictable ways, with their variations in relative abundance governed by geochemical processes. In contrast, some meteorites have deviant abundances of the heaviest (hence the one with the most neutrons) Cr isotope, chromium-54. These anomalies in isotopic composition are almost certainly caused by nuclear reactions in stars that existed before our Sun was formed. However, the mineralogical carrier of the special chromium-54 was not known until Nicolas Dauphas (University of Chicago) and eight colleagues there and at the California Institute of Technology, the Museum National d'Histoire Naturelle in Paris, the Jet Propulsion Laboratory, and the Universite de Lille (France) made detailed analyses of chemical and physical separates from the Orgueil and Murchison carbonaceous chondrites. They found that the carrier of the isotopically-anomalous Cr is spinel, Cr-bearing oxide grains generally smaller than 100 nanometers. Only supernovae can produce the chromium-54 anomalies, although which specific type of supernova is not clear. An intriguing possibility is that the chromium-54-rich nano-oxide particles were produced in the same supernova that made two other short-lived isotopes, iron-60 and aluminum-26, which also existed in the Solar System when it formed. This suggests that formation of the Solar System was triggered by a supernova explosion.

  17. Pair production of helicity-flipped neutrinos in supernovae

    SciTech Connect

    Perez, A.; Gandhi, R.

    1989-07-03

    We calculate the emissivity for the pair production of helicity-flipped neutrinos, in a way that can be used in supernova calculations. We also present some simple estimates which show that such processes can act as an efficient energy-loss mechanism in the shocked supernova core, and we use this fact to extract neutrino mass limits from SN1987A neutrino observations. 24 refs., 2 figs.

  18. THE ENGINES BEHIND SUPERNOVAE AND GAMMA-RAY BURSTS

    SciTech Connect

    FRYER, CHRISTOPHER LEE

    2007-01-23

    The authors review the different engines behind supernova (SNe) and gamma-ray bursts (GRBs), focusing on those engines driving explosions in massive stars: core-collapse SNe and long-duration GRBs. Convection and rotation play important roles in the engines of both these explosions. They outline the basic physics and discuss the wide variety of ways scientists have proposed that this physics can affect the supernova explosion mechanism, concluding with a review of the current status in these fields.

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

    DOE PAGESBeta

    Lentz, Eric J.; Bruenn, Stephen W.; Hix, W. Raphael; Mezzacappa, Anthony; Messer, O. E. Bronson; Endeve, Eirik; Blondin, John M.; Harris, J. Austin; Marronetti, Pedro; Yakunin, Konstantin N.

    2015-07-10

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

  20. GRAVITATIONAL FIELD SHIELDING AND SUPERNOVA EXPLOSIONS

    SciTech Connect

    Zhang, T. X.

    2010-12-20

    A new mechanism for supernova explosions called gravitational field shielding is proposed, in accord with a five-dimensional fully covariant Kaluza-Klein theory with a scalar field that unifies the four-dimensional Einsteinian general relativity and Maxwellian electromagnetic theory. It is shown that a dense compact collapsing core of a star will suddenly turn off or completely shield its gravitational field when the core collapses to a critical density, which is inversely proportional to the square of mass of the core. As the core suddenly turns off its gravity, the extremely large pressure immediately stops the core collapse and pushes the mantle material of supernova moving outward. The work done by the pressure in the expansion can be the order of energy released in a supernova explosion. The gravity will resume and stop the core from a further expansion when the core density becomes less than the critical density. Therefore, the gravitational field shielding leads a supernova to impulsively explode and form a compact object such as a neutron star as a remnant. It works such that a compressed spring will shoot the oscillator out when the compressed force is suddenly removed.

  1. Supernovae: lights in the darkness

    NASA Astrophysics Data System (ADS)

    Every year, at the end of the summer, the Section of Physics and Technique of the "Institut Menorquí d'Estudis" and the "Societat Catalana de Física" organize the "Trobades Científiques de la Mediterrània" with the support of several academic institutions. The 2007 edition has been devoted to stellar explosions, the true evolutionary engines of galaxies. Whenever a star explodes, it injects into the interstellar medium a kinetic energy of 1051 erg and between one and several solar masses of newly synthesized elements as a result of the thermonuclear reactions that have taken place within the stellar interior. Two mechanisms are able to provide these enormous amounts of energy: one of them thermonuclear and the other, gravitational. Thermonuclear supernovae are the result of the incineration of a carbon-oxygen white dwarf that is the compact star of a binary stellar system. If the two stars are sufficiently close to each other, the white dwarf accretes matter from its companion, approaches the mass of Chandrasekhar, and ends up exploding. The processes previous to the explosion, the explosion itself, as well as the exact nature of the double stellar system that explodes, are still a matter of discussion. This point is particularly important because these explosions, known as Type Ia Supernovae, are very homogenous and can be used to measure cosmological distances. The most spectacular result obtained, is the discovery of the accelerated expansion of the Universe, but it still feels uncomfortable that such a fundamental result is based on a "measuring system" whose origin and behaviour in time is unknown. At the end of their lives, massive stars generate an iron nucleus that gets unstable when approaching the Chandrasekhar mass. Its collapse gives rise to the formation of a neutron star or a black hole, and the external manifestation of the energy that is released, about a 1053 erg, consists of a Type II or Ib/c supernova, of a Gamma Ray Burst (GRB) or even of

  2. A Comparative Study of Hyperon Equations of State in Supernova Simulations

    NASA Astrophysics Data System (ADS)

    Char, Prasanta; Banik, Sarmistha; Bandyopadhyay, Debades

    2015-08-01

    A comparative study of the Λ hyperon equations of state of Banik, Hempel and Banyopadhyay (BHB), Banik et al., and Shen et al. (denoted as HShen Λ) for core-collapse supernova (CCSN) simulations is carried out in this work. The dynamical evolution of a protoneutron star (PNS) into a black hole is investigated in CCSN simulations in the general relativistic one-dimensional code using the {BHB}{{Λ }}φ and HShen Λ equation of state (EOS) tables and different progenitor models from Woosley & Heger. Radial profiles of the mass fractions of baryons, the density, as well as the temperature in the PNS at different moments in time, are compared for both EOS tables. The behavior of the central density of the PNS with time is demonstrated for these two Λ hyperon EOS tables and compared with their corresponding nuclear EOS tables. It is observed that the black hole formation time is higher in the {BHB}{{Λ }}φ case than in the HShen Λ EOS case for the entire set of progenitor models adopted here, because the repulsive Λ-Λ interaction makes the {BHB}{{Λ }}φ EOS stiffer. Neutrino emission with the Λ hyperon EOS ceases earlier than that of its nuclear counterpart. The long-duration evolution of the shock radius and the gravitational mass of the PNS after a successful supernova explosion with enhanced neutrino heating are studied with the {BHB}{{Λ }}φ EOS and s20WH07 progenitor model. The PNS is found to remain stable for 4 s and might evolve into a cold neutron star.

  3. Charge transfer in helium-rich supernova plasma

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.

    1994-01-01

    Charge transfer rate coefficients are estimated using Landau-Zener and modified Demkov approximations. The coefficients, augmented by those available from the literature, are used in statistical equilibrium equations describing the state of helium-rich supernova plasma. Such a plasma may describe both Type Ib and Type Ic supernova ejecta. The hypothesis that extensive mixing of metals with helium in Type Ic supernovae may provide a catalyst for rapid charge transfer that weakens the helium line emission by altering the excitation balance is tested. It is shown that charge transfer as a mechanism for suppressing helium line emission is ineffective unless the metal abundance is comparable to or larger than the helium abundance. This result supports an earlier conclusion that Type Ic supernovae must be helium poor relative to Type Ib events.

  4. Historical Records of Re-Explosions of Supernovae

    NASA Astrophysics Data System (ADS)

    Wang, Jian-min

    1980-12-01

    Of the supernovae recorded in history, there are at least two for which re-explosions have been documented. One is the supernova which appeared on 1006 May 1 (Northern Song Dynasty, Reign Jingde, Year 3) in the asterism Qiguan, south of the lunar mansion Di, which, after 10 years, in 1016 May (Reign Dazhongxiangfu, Year 9) was recorded to have "re-appeared". The other is the object which appeared by the side of the asterism Tianjiang of the (sixth) lunar mansion Wei (the object known in the West as Kepler's supernova), and which after 60 years in 1664 was again recorded as undergoing an explosion. Therefore, for some type of supernovae, there should exist a mechanism of re-explosions.

  5. The Challenges of Coupling Supernova Nucleosynthesis to the Central Engine

    NASA Astrophysics Data System (ADS)

    Hix, W. R.; Parete-Koon, S.; Fröhlich, C.; Thielemann, F.-K.; Martínez-Pinedo, G.

    2005-12-01

    Core collapse supernovae are the leading actor in the story of the cosmic origin of the chemical elements. The existing models, which assume spherical symmetry and parameterize the explosion, have been remarkably able to replicate the gross elemental pattern observed in core collapse supernovae. However, recent improvements in the modeling of core collapse supernovae, including detailed tracking of the neutrino distributions and better accounting for the multi-dimensional nature of the hydrodynamic flows, will have noticeable impact on the predicted composition and distribution of the ejecta. We will review recent explorations of these effects and discuss the means needed to achieve self-consistent models of the core collapse supernova mechanism together with the concomitant nucleosynthesis.

  6. Supernova Science Center

    SciTech Connect

    S. E. Woosley

    2008-05-05

    The Supernova Science Center (SNSC) was founded in 2001 to carry out theoretical and computational research leading to a better understanding of supernovae and related transients. The SNSC, a four-institutional collaboration, included scientists from LANL, LLNL, the University of Arizona (UA), and the University of California at Santa Cruz (UCSC). Intitially, the SNSC was funded for three years of operation, but in 2004 an opportunity was provided to submit a renewal proposal for two years. That proposal was funded and subsequently, at UCSC, a one year no-cost extension was granted. The total operational time of the SNSC was thus July 15, 2001 - July 15, 2007. This document summarizes the research and findings of the SNSC and provides a cummulative publication list.

  7. An infrared study of dust in Type IIn supernovae

    NASA Astrophysics Data System (ADS)

    Fox, Ori Dosovitz

    2010-11-01

    Given their high sensitivity to warm dust, infrared observations serve as important probes of supernovae and the surrounding supernova environment. Warm dust can trace progenitor mass loss rates, circumstellar interaction, and dust formation in the supernova environment, ultimately contributing to a broader understanding of stellar evolution, supernova explosion mechanics, and the origin of dust in the universe. The Type IIn supernova subclass, named for the "narrow" emission lines, tends to exhibit late-time infrared emission from warm dust more often than other subclasses. These supernovae, however, are particularly rare, consisting of only ˜2--3% of all core-collapse events. With only a handful of Type IIn observations at infrared wavelengths, the nature of the Type IIn environments and progenitors remain relatively unknown. This thesis presents an infrared study of Type IIn supernovae, beginning with a case study of SN 2005ip. A combination of Spitzer/IRS and IRAC, APO/TripleSpec, and FanCam data constrain the dust mass, temperature, and luminosity, identify the origin and heating mechanism of the warm dust, and characterize the progenitor system. Expanding on this work, a warm Spitzer/IRAC mission surveys the coordinates of 68 Type IIn supernovae within 250 Mpc from the past ten years. The detection of late-time emission from nine targets (>10%) nearly doubles the database of existing mid-infrared observations of Type IIn events. Pre-exisiting dust produced by massive progenitor eruptions (i.e., luminous blue variables) and heated by an infrared echo likely dominates the observed mid-infraraed flux. Finally, a characterization of the next generation of near-infrared detectors identifies several non-ideal noise sources and calibrations procedures. The resulting improvement in detector sensitivity paves the way for the next generation of transient observations as they trend towards cooler objects and higher redshifts.

  8. Radio emission from supernovae.

    NASA Astrophysics Data System (ADS)

    Weiler, K. W.; Panagia, N.; Sramek, R. A.; Van Dyk, S. D.; Stockdale, C. J.; Williams, C. L.

    Study of radio supernovae over the past 30 years includes more than three dozen detected objects and more than 150 upper limits. From this work it is possible to identify classes of radio properties, demonstrate conformance to and deviations from existing models, estimate the density and structure of the circumstellar material and, by inference, the evolution of the presupernova stellar wind, and reveal the last stages of stellar evolution before explosion. Along with reviewing these general properties of the radio emission from supernovae, we present our extensive observations of the radio emission from supernova (SN) 1993J in M 81 (NGC 3031) made with the Very Large Array and other radio telescopes. The SN 1993J radio emission evolves regularly in both time and frequency, and the usual interpretation in terms of shock interaction with a circumstellar medium (CSM) formed by a pre-supernova stellar wind describes the observations rather well considering the complexity of the phenomenon. However: 1) The highest frequency measurements at 85 - 110 GHz at early times (<40 days) are not well fitted by the parameterization which describes the cm wavelength measurements. 2) At a time ˜3100 days after shock breakout, the decline rate of the radio emission steepens from (t+beta ) beta ˜ -0.7 to beta ˜ -2.7 without change in the spectral index (nu +alpha ; alpha ˜ -0.81). This decline is best described not as a power-law, but as an exponential decay with an e-folding time of ˜ 1100 days. 3) The best overall fit to all of the data is a model including both non-thermal synchrotron self-absorption (SSA) and a thermal free-free absorbing (FFA) components at early times, evolving to a constant spectral index, optically thin decline rate, until a break in that decline rate at day ˜3100, as mentioned above.

  9. 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.

  10. Supernovae and neutrinos

    SciTech Connect

    John F. Beacom

    2002-09-19

    A long-standing problem in supernova physics is how to measure the total energy and temperature of {nu}{sub {mu}}, {nu}{sub {tau}}, {bar {nu}}{sub {mu}}, and {bar {nu}}{sub {tau}}. While of the highest importance, this is very difficult because these flavors only have neutral-current detector interactions. We propose that neutrino-proton elastic scattering, {nu} + p {yields} {nu} + p, can be used for the detection of supernova neutrinos in scintillator detectors. It should be emphasized immediately that the dominant signal is on free protons. Though the proton recoil kinetic energy spectrum is soft, with T{sub p} {approx_equal} 2E{sub {nu}}{sup 2}/M{sub p}, and the scintillation light output from slow, heavily ionizing protons is quenched, the yield above a realistic threshold is nearly as large as that from {bar {nu}}{sub e} + p {yields} e{sup +} + n. In addition, the measured proton spectrum is related to the incident neutrino spectrum. The ability to detect this signal would give detectors like KamLAND and Borexino a crucial and unique role in the quest to detect supernova neutrinos.

  11. Galaxy Outflows Without Supernovae

    NASA Astrophysics Data System (ADS)

    Sur, Sharanya; Scannapieco, Evan; Ostriker, Eve C.

    2016-02-01

    High surface density, rapidly star-forming galaxies are observed to have ≈50-100 km s-1 line of sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds ≈35 km s-1, as occurs in the dense disks that have star-formation rate (SFR) densities above ≈0.1 M⊙ yr-1 kpc-2. These outflows are triggered by a thermal runaway, arising from the inefficient cooling of hot material coupled with successive heating from turbulent driving. Thus, even in the absence of stellar feedback, a critical value of the SFR density for outflow generation can arise due to a turbulent heating instability. This suggests that in strongly self-gravitating disks, outflows may be enhanced by, but need not caused by, energy input from supernovae.

  12. Type IA Supernovae

    NASA Technical Reports Server (NTRS)

    Wheeler, J. Craig

    1992-01-01

    Spectral calculations show that a model based on the thermonuclear explosion of a degenerate carbon/oxygen white dwarf provides excellent agreement with observations of Type Ia supernovae. Identification of suitable evolutionary progenitors remains a severe problem. General problems with estimation of supernova rates are outlined and the origin of Type Ia supernovae from double degenerate systems are discussed in the context of new rates of explosion per H band luminosity, the lack of observed candidates, and the likely presence of H in the vicinity of some SN Ia events. Re-examination of the problems of triggering Type Ia by accretion of hydrogen from a companion shows that there may be an avenue involving cataclysmic variables, especially if extreme hibernation occurs. Novae may channel accreting white dwarfs to a unique locus in accretion rate/mass space. Systems that undergo secular evolution to higher mass transfer rates could lead to just the conditions necessary for a Type Ia explosion. Tests involving fluorescence or absorption in a surrounding circumstellar medium and the detection of hydrogen stripped from a companion, which should appear at low velocity inside the white dwarf ejecta, are suggested. Possible observational confirmation of the former is described.

  13. ACCELERATING COMPACT OBJECT MERGERS IN TRIPLE SYSTEMS WITH THE KOZAI RESONANCE: A MECHANISM FOR 'PROMPT' TYPE Ia SUPERNOVAE, GAMMA-RAY BURSTS, AND OTHER EXOTICA

    SciTech Connect

    Thompson, Todd A.

    2011-11-10

    White dwarf-white dwarf (WD-WD) and neutron star-neutron star (NS-NS) mergers may produce Type Ia supernovae and gamma-ray bursts (GRBs), respectively. A general problem is how to produce binaries with semi-major axes small enough to merge in significantly less than the Hubble time (t{sub H}), and thus accommodate the observation that these events closely follow episodes of star formation. I explore the possibility that such systems are not binaries at all, but actually coeval, or dynamical formed, triple systems. The tertiary induces Kozai oscillations in the inner binary, driving it to high eccentricity, and reducing its gravitational wave (GW) merger timescale. This effect significantly increases the allowed range of binary period P such that the merger time is t{sub merge} < t{sub H}. In principle, Chandrasekhar-mass binaries with P {approx} 300 days can merge in {approx}< t{sub H} if they contain a prograde solar-mass tertiary at high enough inclination. For retrograde tertiaries, the maximum P such that t{sub merge} {approx}< t{sub H} is yet larger. In contrast, P {approx}< 0.3 days is required in the absence of a tertiary. I discuss implications of these findings for the production of transients formed via compact object binary mergers. Based on the statistics of solar-type binaries, I argue that many such binaries should be in triple systems affected by the Kozai resonance. If true, expectations for the mHz GW signal from individual sources, the diffuse background, and the foreground for GW experiments like LISA are modified. This work motivates future studies of triples systems of A, B, and O stars, and new types of searches for WD-WD binaries in triple systems.

  14. Accelerating Compact Object Mergers in Triple Systems with the Kozai Resonance: A Mechanism for "Prompt" Type Ia Supernovae, Gamma-Ray Bursts, and Other Exotica

    NASA Astrophysics Data System (ADS)

    Thompson, Todd A.

    2011-11-01

    White dwarf-white dwarf (WD-WD) and neutron star-neutron star (NS-NS) mergers may produce Type Ia supernovae and gamma-ray bursts (GRBs), respectively. A general problem is how to produce binaries with semi-major axes small enough to merge in significantly less than the Hubble time (t H), and thus accommodate the observation that these events closely follow episodes of star formation. I explore the possibility that such systems are not binaries at all, but actually coeval, or dynamical formed, triple systems. The tertiary induces Kozai oscillations in the inner binary, driving it to high eccentricity, and reducing its gravitational wave (GW) merger timescale. This effect significantly increases the allowed range of binary period P such that the merger time is t merge < t H. In principle, Chandrasekhar-mass binaries with P ~ 300 days can merge in <~ t H if they contain a prograde solar-mass tertiary at high enough inclination. For retrograde tertiaries, the maximum P such that t merge <~ t H is yet larger. In contrast, P <~ 0.3 days is required in the absence of a tertiary. I discuss implications of these findings for the production of transients formed via compact object binary mergers. Based on the statistics of solar-type binaries, I argue that many such binaries should be in triple systems affected by the Kozai resonance. If true, expectations for the mHz GW signal from individual sources, the diffuse background, and the foreground for GW experiments like LISA are modified. This work motivates future studies of triples systems of A, B, and O stars, and new types of searches for WD-WD binaries in triple systems.

  15. Supernova explosions and hydrodynamical instabilities: From core bounce to 90 days

    SciTech Connect

    Benz, W.; Colgate, S.A.; Herant, M.

    1993-01-08

    Since the advent of SN 1987A considerable progress has been made in our understanding of supernova explosions. It is now realized that they are intrinsically multidimensional in nature due to the various hydrodynamical instabilities which take place at almost all stages of the explosion. These instabilities not only modify the observables from the supernova, but are also thought to be at the heart of the supernova mechanism itself, in a way which guarantees robust and self-regulated explosions. In this paper, we review these instabilities placing them into their appropriate context and identifying their role in the genesis of core collapse supernovas.

  16. Supernova Discoveries from the Nearby Supernova Factory (SNfactory)

    DOE Data Explorer

    SNfactory International Collaboration,

    The Nearby Supernova Factory is an experiment designed to collect data on more Type Ia supernovae than have ever been studied in a single project before, and in so doing, to answer some fundamental questions about the nature of the universe. Type Ia supernovae are extraordinarily bright, remarkably uniform objects which make excellent "standard candles" for measuring the expansion rate of the universe. However, such stellar explosions are very rare, occurring only a couple of times per millenium in a typical galaxy, and remaining bright enough to detect only for a few weeks. Previous studies of Type Ia supernovae led to the discovery of the mysterious "dark energy" that is causing the universe to expand at an accelerating rate. To reduce the statistical uncertainties in previous experimental data, extensive spectral and photometric monitoring of more Type Ia supernovae is required. The SNfactory collaboration has built an automated system consisting of specialized software and custom-built hardware that systematically searches the sky for new supernovae, screens potential candidates, then performs multiple spectral and photometric observations on each supernova. These observations are stored in a database to be made available to supernova researchers world-wide for further study and analysis [copied from http://snfactory.lbl.gov/snf/snf-about.html]. Users must register and agree to the open access honor system. Finding charts are in FITS format and may not be accessible through normal browser settings.

  17. Radio emission from supernova remnants

    NASA Astrophysics Data System (ADS)

    Dubner, Gloria; Giacani, Elsa

    2015-09-01

    The explosion of a supernova releases almost instantaneously about 10^{51} ergs of mechanic energy, changing irreversibly the physical and chemical properties of large regions in the galaxies. The stellar ejecta, the nebula resulting from the powerful shock waves, and sometimes a compact stellar remnant, constitute a supernova remnant (SNR). They can radiate their energy across the whole electromagnetic spectrum, but the great majority are radio sources. Almost 70 years after the first detection of radio emission coming from an SNR, great progress has been achieved in the comprehension of their physical characteristics and evolution. We review the present knowledge of different aspects of radio remnants, focusing on sources of the Milky Way and the Magellanic Clouds, where the SNRs can be spatially resolved. We present a brief overview of theoretical background, analyze morphology and polarization properties, and review and critically discuss different methods applied to determine the radio spectrum and distances. The consequences of the interaction between the SNR shocks and the surrounding medium are examined, including the question of whether SNRs can trigger the formation of new stars. Cases of multispectral comparison are presented. A section is devoted to reviewing recent results of radio SNRs in the Magellanic Clouds, with particular emphasis on the radio properties of SN 1987A, an ideal laboratory to investigate dynamical evolution of an SNR in near real time. The review concludes with a summary of issues on radio SNRs that deserve further study, and analysis of the prospects for future research with the latest-generation radio telescopes.

  18. Petascale Core-Collapse Supernova Simulation

    NASA Astrophysics Data System (ADS)

    Messer, Bronson

    2009-11-01

    The advent of petascale computing brings with it the promise of substantial increases in physical fidelity for a host of scientific problems. However, the realities of computing on these resources are daunting, and the architectural features of petascale machines will require considerable innovation for effective use. Nevertheless, there exists a class of scientific problems whose ultimate answer requires the application of petascale (and beyond) computing. One example is ascertaining the core-collapse supernova mechanism and explaining the rich phenomenology associated with these events. These stellar explosions produce and disseminate a dominant fraction of the elements in the Universe; are prodigious sources of neutrinos, gravitational waves, and photons across the electromagnetic spectrum; and lead to the formation of neutron stars and black holes. I will describe our recent multidimensional supernova simulations performed on petascale platforms fielded by the DOE and NSF.

  19. Radiation Transport in Type IA Supernovae

    SciTech Connect

    Eastman, R

    1999-11-16

    It has been said more than once that the critical link between explosion models and observations is the ability to accurately simulate cooling and radiation transport in the expanding ejecta of Type Ia supernovae. It is perhaps frustrating to some of the theorists who study explosion mechanisms, and to some of the observers too, that more definitive conclusions have not been reached about the agreement, or lack thereof, between various Type Ia supernova models and the data. Although claims of superlative accuracy in transport simulations are sometimes made, I will argue here that there are outstanding issues of critical importance and in need of addressing before radiation transport calculations are accurate enough to discriminate between subtly different explosion models.

  20. Gamma ray lines from buried supernovae

    NASA Technical Reports Server (NTRS)

    Morfill, G. E.; Meyer, P.

    1982-01-01

    An investigation is conducted concerning the possibility that supernovae (SN), located in dense interstellar clouds, might become the sources of gamma ray lines. The SN progenitor, in such a case, has to be an O or B star so that its evolutionary lifetime is short, and an explosion inside the cloud is still possible. It is shown that, in principle, a measurement of the abundances in the ejecta is possible. Attention is given to the characteristics of a model, the expected luminosity of gamma-ray lines, and the study of specific numerical examples for testing the feasibility of the considered mechanism. On the basis of the obtained results, it is concluded that gamma-ray line production by collisional excitation in confined supernovae remnants may be quite important.

  1. Pair-instability supernovae in the local universe

    SciTech Connect

    Whalen, Daniel J.; Smidt, Joseph; Heger, Alexander; Hirschi, Raphael; Yusof, Norhasliza; Even, Wesley; Fryer, Chris L.; Stiavelli, Massimo; Chen, Ke-Jung; Joggerst, Candace C.

    2014-12-10

    The discovery of 150-300 M {sub ☉} stars in the Local Group and pair-instability supernova candidates at low redshifts has excited interest in this exotic explosion mechanism. Realistic light curves for pair-instability supernovae at near-solar metallicities are key to identifying and properly interpreting these events as more are found. We have modeled pair-instability supernovae of 150-500 M {sub ☉} Z ∼ 0.1-0.4 Z {sub ☉} stars. These stars lose up to 80% of their mass to strong line-driven winds and explode as bare He cores. We find that their light curves and spectra are quite different from those of Population III pair-instability explosions, which therefore cannot be used as templates for low-redshift events. Although non-zero metallicity pair-instability supernovae are generally dimmer than their Population III counterparts, in some cases they will be bright enough to be detected at the earliest epochs at which they can occur, the formation of the first galaxies at z ∼ 10-15. Others can masquerade as dim, short duration supernovae that are only visible in the local universe and that under the right conditions could be hidden in a wide variety of supernova classes. We also report for the first time that some pair-instability explosions can create black holes with masses of ∼100 M {sub ☉}.

  2. 3D Simulations of Supernovae into the Young Remnant Phase

    NASA Astrophysics Data System (ADS)

    Ellinger, Carola I.; Young, P. A.; Fryer, C.; Rockefeller, G.; Park, S.

    2013-01-01

    The explosion of massive stars as core-collapse supernovae is an inherently three dimensional phenomenon. Observations of the young, ejecta dominated remnants of those explosions unambiguously demonstrate that asymmetry on large and small scales is the rule, rather than the exception. Numerical models of supernova remnants connect the observed remnants to models of the exploding stellar system and thus facilitate both improved interpretations of the observations as well as improve our understanding of the explosion mechanism. We present first 3D simulations of core- collapse supernovae evolving into supernova remnants calculated with SNSPH. The calculations were started from 1D collapsed models of 2 progenitor stars of different types, and follow the explosion from revival of the shock wave to shock break out in 3D. Two different interstellar media, a cold neutral medium and a dense molecular cloud, as well as a red supergiant stellar wind profile, were added to the explosion calculations shortly before shock breakout, so that the blast wave stays in the simulation. With this setup we can follow the dispersal of the nucleosynthesis products from the explosion into the Sedov stage of the supernova remnant evolution starting from realistic initial conditions for the supernova ejecta. We will present a first investigation in the mixing between stellar and interstellar matter as the supernova evolves into the young supernova remnant phase, and contrasts differences that are observed between the scenarios that are investigated. One of the goals is to distinguish between features that arose in instabilities during the explosion from those that were created in the interaction with the surrounding medium.

  3. Gravitational Lensing of Supernova Neutrinos

    SciTech Connect

    Mena, Olga; Mocioiu, Irina; Quigg, Chris; /Fermilab

    2006-10-01

    The black hole at the center of the galaxy is a powerful lens for supernova neutrinos. In the very special circumstance of a supernova near the extended line of sight from Earth to the galactic center, lensing could dramatically enhance the neutrino flux at Earth and stretch the neutrino pulse.

  4. Collective neutrino oscillations in supernovae

    SciTech Connect

    Duan, Huaiyu

    2014-06-24

    In a dense neutrino medium neutrinos can experience collective flavor transformation through the neutrino-neutrino forward scattering. In this talk we present some basic features of collective neutrino flavor transformation in the context in core-collapse supernovae. We also give some qualitative arguments for why and when this interesting phenomenon may occur and how it may affect supernova nucleosynthesis.

  5. Neutrino Reactions on Two-Nucleon System and Core-Collapse Supernova

    NASA Astrophysics Data System (ADS)

    Nasu, Shota

    2011-10-01

    The neutrino reactions on nucleon and nucleus play important role in core-collapse supernova. Recently it is pointed that light nuclei(A = 2,3) can be abundant at the various stage of supernova environment. As an important mechanism of neutrino reaction on a few nucleon system, we study the neutrino emissivity on neutron fusion reaction nn-->de-νe.

  6. 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

  7. Cosmology with superluminous supernovae

    NASA Astrophysics Data System (ADS)

    Scovacricchi, D.; Nichol, R. C.; Bacon, D.; Sullivan, M.; Prajs, S.

    2016-02-01

    We predict cosmological constraints for forthcoming surveys using superluminous supernovae (SLSNe) as standardizable candles. Due to their high peak luminosity, these events can be observed to high redshift (z ˜ 3), opening up new possibilities to probe the Universe in the deceleration epoch. We describe our methodology for creating mock Hubble diagrams for the Dark Energy Survey (DES), the `Search Using DECam for Superluminous Supernovae' (SUDSS) and a sample of SLSNe possible from the Large Synoptic Survey Telescope (LSST), exploring a range of standardization values for SLSNe. We include uncertainties due to gravitational lensing and marginalize over possible uncertainties in the magnitude scale of the observations (e.g. uncertain absolute peak magnitude, calibration errors). We find that the addition of only ≃100 SLSNe from SUDSS to 3800 Type Ia Supernovae (SNe Ia) from DES can improve the constraints on w and Ωm by at least 20 per cent (assuming a flat wCDM universe). Moreover, the combination of DES SNe Ia and 10 000 LSST-like SLSNe can measure Ωm and w to 2 and 4 per cent, respectively. The real power of SLSNe becomes evident when we consider possible temporal variations in w(a), giving possible uncertainties of only 2, 5 and 14 per cent on Ωm, w0 and wa, respectively, from the combination of DES SNe Ia, LSST-like SLSNe and Planck. These errors are competitive with predicted Euclid constraints, indicating a future role for SLSNe for probing the high-redshift Universe.

  8. Cosmological and supernova neutrinos

    SciTech Connect

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

    2014-06-24

    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 {sup 7}Li 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 {sup 7}Li 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 {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta 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 θ{sub 13} with predicted and observed supernova-produced abundance ratio {sup 11}B/{sup 7}Li 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.

  9. 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.

  10. Nuclear astrophysics of supernovae

    SciTech Connect

    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 it 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.

  11. Radio Emission from Supernovae

    NASA Astrophysics Data System (ADS)

    Weiler, Kurt W.; Panagia, Nino; Sramek, Richard A.; van Dyk, Schuyler D.; Williams, Christopher L.; Stockdale, Christopher J.; Kelley, Matthew T.

    2007-10-01

    Study of radio supernovae over the past 27 years includes more than three dozen detected objects and more than 150 upper limits. From this work it is possible to identify classes of radio properties, demonstrate conformance to and deviations from existing models, estimate the density and structure of the circumstellar material and, by inference, the evolution of the presupernova stellar wind, and reveal the last stages of stellar evolution before explosion. It is also possible to detect ionized hydrogen along the line of sight, to demonstrate binary properties of the presupernova stellar system, and to detect clumpiness of the circumstellar material. Along with reviewing these general properties of the radio emission from supernovae, we present our extensive observations of the radio emission from supernova (SN) 1993J in M 81 (NGC 3031) made with the Very Large Array and other radio telescopes. The SN 1993J radio emission evolves regularly in both time and frequency, and the usual interpretation in terms of shock interaction with a circumstellar medium (CSM) formed by a pre-supernova stellar wind describes the observations rather well considering the complexity of the phenomenon. However: 1) The highest frequency measurements at 85-110 GHz at early times (<40 days) are not well fitted by the parameterization which describes the cm wavelength measurements rather well. 2) At mid-cm wavelengths there is often deviation from the fitted radio light curves, particularly near the peak flux density, and considerable shorter term deviations in the declining portion when the emission has become optically thin. 3) At a time ~3100 days after shock breakout, the decline rate of the radio emission steepens from (t+β)β~-0.7 to β~-2.7 without change in the spectral index (ν+αα~-0.81). However, this decline is best described not as a power-law, but as an exponential decay starting at day ~3100 with an e-folding time of ~1100 days. 4) The best overall fit to all of the data is

  12. Radio Emission from Supernovae

    SciTech Connect

    Weiler, Kurt W.; Panagia, Nino; Sramek, Richard A.; Van Dyk, Schuyler D.; Stockdale, Christopher J.; Kelley, Matthew T.

    2009-05-03

    Study of radio supernovae over the past 27 years includes more than three dozen detected objects and more than 150 upper limits. From this work it is possible to identify classes of radio properties, demonstrate conformance to and deviations from existing models, estimate the density and structure of the circumstellar material and, by inference, the evolution of the presupernova stellar wind, and reveal the last stages of stellar evolution before explosion. It is also possible to detect ionized hydrogen along the line of sight, to demonstrate binary properties of the presupernova stellar system, and to detect dumpiness of the circumstellar material.

  13. Nearby Supernova Factory II classification of Five Supernovae

    NASA Astrophysics Data System (ADS)

    Benitez, S.; Hillebrandt, W.; Kromer, M.; Sasdelli, M.; Sternberg, A.; Taubenberger, S.; Baugh, D.; Chen, J.; Chotard, N.; Wu, C.; Tao, C.; Fouchez, D.; Tilquin, A.; Hadjiyska, E.; Rabinowitz, D.; Baltay, C.; Ellman, N.; McKinnon, R.; Walker, E.; Effron, A.; Cellier-Holzem, F.; Canto, A.; Antilogus, P.; Bongard, S.; Pain, R.; Copin, Y.; Gangler, E.; Pereira, R.; Rigault, M.; Smadja, G.; Aldering, G.; Birchall, D.; Fakhouri, H.; Kim, A.; Nordin, J.; Nugent, P.; Perlmutter, S.; Runge, K.; Saunders, C.; Suzuki, N.; Pecontal, R. C. Thomas E.; Feindt, U.; Kowalski, M.

    2013-04-01

    ports the following spectroscopic observations of supernovae based on spectra (range 320-1000 nm) obtained with the SuperNova Integral Field Spectrograph (Aldering et al 2002, SPIE, 4836, 61) on the University of Hawaii 2.2-meter telescope. Classifications were performed using Superfit (Howell et al 2002, BAAS, 34, 1256) or SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). Heliocentric redshifts listed to two decimal places are measured from supernova features; all others are published values or measured by us from host galaxy features.

  14. The nearby supernova factory

    SciTech Connect

    Wood-Vasey, W.M.; Aldering, G.; Lee, B.C.; Loken, S.; Nugent, P.; Perlmutter, S.; Siegrist, J.; Wang, L.; Antilogus, P.; Astier, P.; Hardin, D.; Pain, R.; Copin, Y.; Smadja, G.; Gangler, E.; Castera, A.; Adam, G.; Bacon, R.; Lemonnier, J.-P.; Pecontal, A.; Pecontal, E.; Kessler, R.

    2004-01-23

    The Nearby Supernova Factory (SNfactory) is an ambitious project to find and study in detail approximately 300 nearby Type Ia supernovae (SNe Ia) at redshifts 0.03 < z < 0.08. This program will provide an exceptional data set of well-studied SNe in the nearby smooth Hubble flow that can be used as calibration for the current and future programs designed to use SNe to measure the cosmological parameters. The first key ingredient for this program is a reliable supply of Hubble-flow SNe systematically discovered in unprecedented numbers using the same techniques as those used in distant SNe searches. In 2002, 35 SNe were found using our test-bed pipeline for automated SN search and discovery. The pipeline uses images from the asteroid search conducted by the Near Earth Asteroid Tracking group at JPL. Improvements in our subtraction techniques and analysis have allowed us to increase our effective SN discovery rate to {approx}12 SNe/month in 2003.

  15. Automated Supernova Discovery (Abstract)

    NASA Astrophysics Data System (ADS)

    Post, R. S.

    2015-12-01

    (Abstract only) We are developing a system of robotic telescopes for automatic recognition of Supernovas as well as other transient events in collaboration with the Puckett Supernova Search Team. At the SAS2014 meeting, the discovery program, SNARE, was first described. Since then, it has been continuously improved to handle searches under a wide variety of atmospheric conditions. Currently, two telescopes are used to build a reference library while searching for PSN with a partial library. Since data is taken every night without clouds, we must deal with varying atmospheric and high background illumination from the moon. Software is configured to identify a PSN, reshoot for verification with options to change the run plan to acquire photometric or spectrographic data. The telescopes are 24-inch CDK24, with Alta U230 cameras, one in CA and one in NM. Images and run plans are sent between sites so the CA telescope can search while photometry is done in NM. Our goal is to find bright PSNs with magnitude 17.5 or less which is the limit of our planned spectroscopy. We present results from our first automated PSN discoveries and plans for PSN data acquisition.

  16. Supernova Explosion Physics

    NASA Astrophysics Data System (ADS)

    Kundt, Wolfgang

    Quite likely, all supernovae are core-collapse supernovae. When the progenitor star's burnt-out core contracts under its own gravity - on the time scale of seconds - angular-momentum conservation raises its spin energy as 1/r 2, towards some 1052.5erg, whilst neutron-degeneracy pressure halts the collapse at a neutron star's radius, some 106cm. Magnetic-flux winding will then tap the core's large spin energy - on the time scale of ≲ 30s - bringing the spin period P into the range of neutron-star birth periods - ms < P < 10 s - and transferring the excess angular momentum to the overlying mantle. Subsequent reconnection of the huge toroidal magnetic fields creates a magnetized relativistic cavity, both leptons and hadrons, with particle energies up to 1020eV, ready to launch the envelope (via adiabatic expansion, through some 107 in radius). Magnetic Rayleigh-Taylor instabilities tear and squeeze the ejected shell into a large number (> 104) of filamentary fragments, like a splinter bomb.

  17. HST Cluster Supernova Survey

    NASA Astrophysics Data System (ADS)

    Suzuki, Nao; Aldering, G.; Amanullah, R.; Barbary, K.; Barrientos, L.; Brodwin, M.; Connolly, N.; Dawson, K.; de Jong, R.; Dey, A.; Doi, M.; Donahue, M.; Eisenhardt, P.; Ellingson, E.; Faccioli, L.; Fadeyev, V.; Fakhouri, H.; Fruchter, A.; Gilbank, D.; Gladders, M.; Goldhaber, G.; Gonzalez, A.; Goobar, A.; Gude, A.; Hennawi, J.; Hoekstra, H.; Hsiao, E.; Huang, X.; Ihara, Y.; Jannuzi, B.; Jee, M. J.; Koester, B.; Kowalski, M.; Lidman, C.; Linder, E.; Lubin, L.; Morokuma, T.; Perlmutter, S.; Postman, M.; Rhodes, J.; Rosati, P.; Ripoche, P.; Rubin, D.; Schlegel, D.; Spadafora, A.; Stanford, A.; Stern, D.; Yasuda, N.; Yee, H.; Cosmology Project, Supernova

    2010-01-01

    We report results from the Hubble Space Telescope (HST) Cluster Supernova Survey with the Advanced Camera for Surveys (ACS) (PI: Perlmutter; see Dawson et al. AJ, 2009). We have introduced a novel approach to discover and follow Type Ia supernovae (SNeIa). With HST, we monitored 25 massive clusters (0.9 < z < 1.4) found by the RCS, XMM, IRAC, and RDCS surveys and conducted spectroscopic observations with the Keck, Subaru, and VLT telescopes. Sixteen SNe were discovered at 0.95 < z < 1.41, nine of which were in galaxy clusters (for a discussion of the rates, see K. Barbary, oral presentation at this meeting). The SNe in galaxy clusters are found primarily in early type galaxies in the cluster red-sequence that have been shown to be nearly dust-free and uniform populations (see poster presentation by Meyers et al.). The reduction and control of systematic error is an urgent task for the study of dark energy today (see Rubin et al. poster presentation), and we discuss how this unique SNe Ia data set reduces both statistical and more importantly systematic uncertainty at the highest redshifts. This work has been supported by the Office of Science, U.S. Department of Energy, through contract DE-AC02-05CH11231 and in part by NASA through grants associated with HST-GO-10496.

  18. Supernova Hydrodynamics on the Omega Laser

    SciTech Connect

    R. Paul Drake

    2004-01-16

    (B204)The fundamental motivation for our work is that supernovae are not well understood. Recent observations have clarified the depth of our ignorance, by producing observed phenomena that current theory and computer simulations cannot reproduce. Such theories and simulations involve, however, a number of physical mechanisms that have never been studied in isolation. We perform experiments, in compressible hydrodynamics and radiation hydrodynamics, relevant to supernovae and supernova remnants. These experiments produce phenomena in the laboratory that are believed, based on simulations, to be important to astrophysics but that have not been directly observed in either the laboratory or in an astrophysical system. During the period of this grant, we have focused on the scaling of an astrophysically relevant, radiative-precursor shock, on preliminary studies of collapsing radiative shocks, and on the multimode behavior and the three-dimensional, deeply nonlinear evolution of the Rayleigh-Taylor (RT) instability at a decelerating, embedded interface. These experiments required strong compression and decompression, strong shocks (Mach {approx}10 or greater), flexible geometries, and very smooth laser beams, which means that the 60-beam Omega laser is the only facility capable of carrying out this program.

  19. Du Pont Classifications of 6 Supernovae

    NASA Astrophysics Data System (ADS)

    Morrell, N.; Shappee, Benjamin J.

    2016-06-01

    We report optical spectroscopy (range 370-910 nm) of six supernovae from the Backyard Observatory Supernova Search (BOSS) and the All-Sky Automated Survey for Supernovae (ASAS-SN) using the du Pont 2.5-m telescope (+ WFCCD) at Las Campanas Observatory on June 17 2016 UT. We performed a cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J.

  20. Propagation of Turbulent Flames in Supernovae

    NASA Astrophysics Data System (ADS)

    Khokhlov, Alexei M.

    1995-08-01

    Turbulent thermonuclear burning is studied on scales relevant to the explosion of Type Ia supernovae. A scaling law is formulated for turbulent burning in a uniform gravitational field. The steady state turbulent flame speed is Dδt = f(α) √gL in the regime where the Froude number F = D2l/gL ≪ 1; g, L, Dl, and α = ρ0/P1 > 1 are the acceleration, characteristic scale of the problem, normal speed of the laminar flame, and ratio of the densities ahead and behind the flame, respectively; and f ≃ 1 is a universal function. In this regime, the turbulent flame speed does not depend on the laminar speed Dl and on details of burning on scales ≪L. A flame-capturing technique for modeling turbulent burning is described. It is used to numerically study the transition to turbulence and turbulent flame propagation in three dimensions. The results confirm the scaling law. The self-regulating mechanism underlying the scaling law is discussed. In Type Ia supernovae, steady state burning takes place on scales less than the radius of the flame, where the effects of spherical geometry and expansion are small. Larger scales influenced by these effects need to be resolved explicitly. Direct, ab initio three-dimensional numerical simulations of deflagration in supernovae thus become feasible. Effects of spherical geometry and expansion of matter on the propagation of turbulent flames are discussed. The expansion decreases large-scale turbulent motions and reduces the bulk rate of deflagration in a massive carbon-oxygen white dwarf. Results of a large-scale three-dimensional simulation of the deflagration explosion of a Type Ia supernova are presented.

  1. The LCOGT Supernova Key Project

    NASA Astrophysics Data System (ADS)

    Howell, Dale Andrew; Arcavi, Iair; Hosseinzadeh, Griffin; McCully, Curtis; Valenti, Stefano; Lcogt Supernova Key Project

    2015-01-01

    I present first results from the Las Cumbres Observatory Global Telescope Network (LCOGT) Supernova Key Project. LCOGT is a network of 11 robotic one and two meter telescopes spaced around the globe with imaging and spectroscopic capabilities. The supernova key project is a 3 year program to obtain lightcurves and spectra of at least 450 supernovae. About half are expected to be core-collapse supernovae, and half thermonuclear. We will start light curves and spectroscopy within hours of discovery, and focus on those SNe caught soon after explosion. The goals are fivefold: (1) observe supernovae soon after explosion to search for signs of their progenitors, (2) obtain a large homogeneous sample of supernovae for next generation cosmological studies, (3) obtain a large sample of supernovae for statistical studies comparing groups that are split into different populations, (4) obtain some of the first large samples of the recently discovered classes of rare and exotic explosions, (5) obtain the optical light curves and spectroscopy in support of studies at other wavelengths and using other facilities including UV observations, IR imaging and spectroscopy, host galaxy studies, high resolution spectroscopy, and late-time spectroscopy with large telescopes.

  2. Reconstructing core-collapse supernovae waveforms with advanced era interferometers

    NASA Astrophysics Data System (ADS)

    McIver, Jessica; LIGO Scientific Collaboration

    2015-04-01

    Among of the wide range of potentially interesting astrophysical sources for Advanced LIGO and Advanced Virgo are galactic core-collapse supernovae. Although detectable core-collapse supernovae have a low expected rate (a few per century, or less) these signals would yield a wealth of new physics in the form of many messengers. Of particular interest is the insight into the explosion mechanism driving core-collapse supernovae that can be gleaned from the reconstructed gravitational wave signal. A well-reconstructed waveform will allow us to assess the likelihood of different explosion models, perform model selection, and potentially map unexpected features to new physics. This talk will present a study evaluating the current performance of the reconstruction of core-collapse supernovae gravitational wave signals. We used simulated waveforms modeled after different explosion mechanisms that we first injected into fake strain data re-colored to the expected Advanced LIGO/Virgo noise curves and then reconstructed using the pipelines Coherent Waveburst 2G and BayesWave. We will discuss the impact of these results on our ability to accurately reconstruct core-collapse supernovae signals, and by extension, other potential astrophysical generators of rich, complex waveforms.

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

    SciTech Connect

    Lentz, Eric J.; Bruenn, Stephen W.; Hix, W. Raphael; Mezzacappa, Anthony; Messer, O. E. Bronson; Endeve, Eirik; Blondin, John M.; Harris, J. Austin; Marronetti, Pedro; Yakunin, Konstantin N.

    2015-07-10

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

  4. Supernovae in paired galaxies

    NASA Astrophysics Data System (ADS)

    Nazaryan, T. A.; Petrosian, A. R.; Hakobyan, A. A.; Adibekyan, V. Zh.; Kunth, D.; Mamon, G. A.; Turatto, M.; Aramyan, L. S.

    2014-07-01

    We investigate the influence of close neighbor galaxies on the properties of supernovae (SNe) and their host galaxies using 56 SNe located in pairs of galaxies with different levels of star formation (SF) and nuclear activity. The mean distance of type II SNe from nuclei of hosts is greater by about a factor of 2 than that of type Ibc SNe. The distributions and mean distances of SNe are consistent with previous results compiled with the larger sample. For the first time it is shown that SNe Ibc are located in pairs with significantly smaller difference of radial velocities between components than pairs containing SNe Ia and II. We consider this as a result of higher star formation rate (SFR) of these closer systems of galaxies.

  5. 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.

  6. Spectroscopic classification of supernova candidates

    NASA Astrophysics Data System (ADS)

    Hodgkin, S. T.; Hall, A.; Fraser, M.; Campbell, H.; Wyrzykowski, L.; Kostrzewa-Rutkowska, Z.; Pietro, N.

    2014-09-01

    We report the spectroscopic classification of four supernovae at the 2.5m Isaac Newton Telescope on La Palma, using the Intermediate Dispersion Spectrograph and the R300V grating (3500-8000 Ang; ~6 Ang resolution).

  7. Supernovae. Part I: the events

    NASA Astrophysics Data System (ADS)

    Trimble, Virginia

    1982-10-01

    Since the heroic era of Baade and Zwicky, our understanding of supernovae has advanced in hops and skips rather than steadily. The most recent jump has been into fairly general agreement that observations of Type I's can be interpreted as the manifestation of the decay of about 1Msolar of Ni56 and observations of Type II's as the manifestation of >~1051 ergs deposited at the bottom of a supergiant envelope by core bounce as a central neutron star forms. This paper explores the history of these and other ideas of what is going on in supernovae, the presupernova evolution of the parent stars and binary systems, observed properties of the events, and models for them. A later paper (Part II: the aftermath) will address the results of supernovae-their remnants, production of cosmic rays and gamma rays, nucleosynthesis, and galactic evolution-and the future of supernova research.

  8. Supernova olivine from cometary dust

    NASA Technical Reports Server (NTRS)

    Messenger, Scott; Keller, Lindsay P.; Lauretta, Dante S.

    2005-01-01

    An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (<0.8 times solar), indicative of formation from a type II supernova. The aggregate contains olivine (forsterite 83) grains <100 nanometers in size, with microstructures that are consistent with minimal thermal alteration. This unusually iron-rich olivine grain could have formed by equilibrium condensation from cooling supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud.

  9. Simulation of Kepler Supernova Explosion

    NASA Video Gallery

    This video shows a simulation of the Kepler supernova as it interacts with material expelled by the giant star companion to the white dwarf before the latter exploded. It was assumed that the bulk ...

  10. Turbulent Flames in Supernovae

    NASA Astrophysics Data System (ADS)

    Khokhlov, A. M.

    1994-05-01

    First results of three-dimensional simulations of a thermonuclear flame in Type Ia supernovae are obtained using a new flame-capturing algorithm, and a PPM hydrodynamical code. In the absence of gravity, the flame is stabilized with respect to the Landau (1944) instability due to the difference in the behaviour of convex and concave portions of the perturbed flame front. The transition to turbulence in supernovae occurs on scales =~ 0.1 - 10 km in agreement with the non-linear estimate lambda =~ 2pi D(2_l/geff) based on the Zeldovich (1966) model for a perturbed flame when the gravity acceleration increases; D_l is the normal speed of the laminar flame, and geff is the effective acceleration. The turbulent flame is mainly spread by large scale motions driven by the Rayleigh-Taylor instability. Small scale turbulence facilitates rapid incineration of the fuel left behind the front. The turbulent flame speed D_t approaches D_t =~ U', where U' is the root mean square velocity of turbulent motions, when the turbulent flame forgets initial conditions and reaches a steady state. The results indicate that in a steady state the turbulent flame speed should be independent of the normal laminar flame speed D_l. The three-dimensional results are in sharp contrast with the results of previous two-dimensional simulations which underestimate flame speed due to the lack of turbulent cascade directed in three dimensions from big to small spatial scales. The work was supported by the NSF grants AST 92-18035 and AST 93-005P.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  13. ON THE IMPACT OF THREE DIMENSIONS IN SIMULATIONS OF NEUTRINO-DRIVEN CORE-COLLAPSE SUPERNOVA EXPLOSIONS

    SciTech Connect

    Couch, Sean M.

    2013-09-20

    We present one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) hydrodynamical simulations of core-collapse supernovae including a parameterized neutrino heating and cooling scheme in order to investigate the critical core neutrino luminosity (L{sub crit}) required for explosion. In contrast to some previous works, we find that 3D simulations explode later than 2D simulations, and that L{sub crit} at fixed mass accretion rate is somewhat higher in three dimensions than in two dimensions. We find, however, that in two dimensions L{sub crit} increases as the numerical resolution of the simulation increases. In contrast to some previous works, we argue that the average entropy of the gain region is in fact not a good indicator of explosion but is rather a reflection of the greater mass in the gain region in two dimensions. We compare our simulations to semi-analytic explosion criteria and examine the nature of the convective motions in two dimensions and three dimensions. We discuss the balance between neutrino-driven buoyancy and drag forces. In particular, we show that the drag force will be proportional to a buoyant plume's surface area while the buoyant force is proportional to a plume's volume and, therefore, plumes with greater volume-to-surface-area ratios will rise more quickly. We show that buoyant plumes in two dimensions are inherently larger, with greater volume-to-surface-area ratios, than plumes in three dimensions. In the scenario that the supernova shock expansion is dominated by neutrino-driven buoyancy, this balance between buoyancy and drag forces may explain why 3D simulations explode later than 2D simulations and why L{sub crit} increases with resolution. Finally, we provide a comparison of our results with other calculations in the literature.

  14. Shocked Clouds in the Vela Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Nichols, Joy S.; Slavin, Jonathan D.

    2004-01-01

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

  15. The velocity and composition of supernova ejecta

    NASA Technical Reports Server (NTRS)

    Colgate, S. A.

    1971-01-01

    In case of the Gum nebula, a pulsar - a presumed neutron star - is believed to be a relic of the supernova explosion. Regardless of the mechanism of the explosion, the velocity distribution and composition of the ejected matter will be roughly the same. The reimploding mass fraction is presumed to be neutron rich. The final composition is thought to be roughly 1/3 iron and 2/3 silicon, with many small fractions of elements from helium to iron. The termination of helium shell burning occurs because the shell is expanded and cooled by radiation stress. The mass fraction of the helium burning shell was calculated.

  16. Supernova Spectroscopy with the Southern African Large Telescope

    NASA Astrophysics Data System (ADS)

    Pandya, Viraj; Jha, S.; McCully, C.; Patel, B.; Camacho, Y.

    2014-01-01

    Supernova (SN) spectroscopy is important not only for classification and redshifts, but it also allows us to probe explosion mechanisms and progenitors. Here we report on optical spectroscopy of recent SNe using the Southern African Large Telescope (SALT) with the Robert Stobie Spectrograph (RSS). We have developed an automated data reduction pipeline for our longslit SN observations, paying particular attention to combining multiple exposures with different wavelength settings spanning the optical range. Furthermore, we investigate and implement an automated method for removing telluric features in the spectra. Finally, we present results exploring spectrum synthesis to model our growing database of type Ia supernovae.

  17. Simulations of stripped core-collapse supernovae in close binaries

    NASA Astrophysics Data System (ADS)

    Rimoldi, Alex; Portegies Zwart, Simon; Rossi, Elena Maria

    2016-03-01

    We perform smoothed-particle hydrodynamical simulations of the explosion of a helium star in a close binary system, and study the effects of the explosion on the companion star as well as the effect of the presence of the companion on the supernova remnant. By simulating the mechanism of the supernova from just after core bounce until the remnant shell passes the stellar companion, we are able to separate the various phenomena leading to the final system parameters. In the final system, we measure the mass stripping and ablation from, and the additional velocity imparted to, the companion stars. Our results agree with recent work showing smaller values for these quantities compared to earlier estimates. We do find some differences, however, particularly in the velocity gained by the companion, which can be explained by the different ejecta structure that naturally results from the explosion in our simulations. These results indicate that predictions based on extrapolated Type Ia simulations should be revised. We also examine the structure of the supernova ejecta shell. The presence of the companion star produces a conical cavity in the expanding supernova remnant, and loss of material from the companion causes the supernova remnant to be more metal-rich on one side and more hydrogen-rich (from the companion material) around the cavity. Following the impact of the shell, we examine the state of the companion after being heated by the shock.

  18. Neutrinos and nucleosynthesis in core-collapse supernovae

    SciTech Connect

    Fröhlich, C.; Casanova, J.; Hempel, M.; Liebendörfer, M.; Melton, C. A.; Perego, A.

    2014-01-01

    Massive stars (M > 8-10 M{sub ⊙}) undergo core collapse at the end of their life and explode as supernova with ~ 10⁵¹ erg of kinetic energy. While the detailed supernova explosion mechanism is still under investigation, reliable nucleosynthesis calculations based on successful explosions are needed to explain the observed abundances in metal-poor stars and to predict supernova yields for galactic chemical evolution studies. To predict nucleosynthesis yields for a large number of progenitor stars, computationally efficient explosion models are required. We model the core collapse, bounce and subsequent explosion of massive stars assuming spherical symmetry and using detailed microphysics and neutrino physics combined with a novel method to artificially trigger the explosion (PUSH). We discuss the role of neutrinos, the conditions in the ejecta, and the resulting nucleosynthesis.

  19. Multidimensional supernova simulations with approximative neutrino transport. I. Neutron star kicks and the anisotropy of neutrino-driven explosions in two spatial dimensions

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

    We study hydrodynamic instabilities during the first seconds of core-collapse supernovae by means of 2D simulations with approximative neutrino transport and boundary conditions that parameterize the effects of the contracting neutron star and allow us to obtain sufficiently strong neutrino heating and, hence, neutrino-driven explosions. Confirming more idealised studies, as well as supernova simulations with spectral transport, we find that random seed perturbations can grow by hydrodynamic instabilities to a globally asymmetric mass distribution in the region between the nascent neutron star and the accretion shock, leading to a dominance of dipole (l=1) and quadrupole (l=2) modes in the explosion ejecta, provided the onset of the supernova explosion is sufficiently slower than the growth time scale of the low-mode instability. By gravitational and hydrodynamic forces, the anisotropic mass distribution causes an acceleration of the nascent neutron star, which lasts for several seconds and can propel the neutron star to velocities of more than 1000 km s-1. Because the explosion anisotropies develop chaotically and change by small differences in the fluid flow, the magnitude of the kick varies stochastically. No systematic dependence of the average neutron star velocity on the explosion energy or the properties of the considered progenitors is found. Instead, the anisotropy of the mass ejection, and hence of the kick, seems to increase when the nascent neutron star contracts more quickly, and thus low-mode instabilities can grow more rapidly. Our more than 70 models separate into two groups, one with high and the other with low neutron star velocities and accelerations after one second of post-bounce evolution, depending on whether the l=1 mode is dominant in the ejecta or not. This leads to a bimodality of the distribution when the neutron star velocities are extrapolated to their terminal values. Establishing a link to the measured distribution of pulsar

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

    NASA Astrophysics Data System (ADS)

    Müller, B.; Janka, H.-Th.

    2015-04-01

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

  1. A GLOBAL TURBULENCE MODEL FOR NEUTRINO-DRIVEN CONVECTION IN CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Murphy, Jeremiah W.; Meakin, Casey

    2011-12-01

    Simulations of core-collapse supernovae (CCSNe) result in successful explosions once the neutrino luminosity exceeds a critical curve, and recent simulations indicate that turbulence further enables explosion by reducing this critical neutrino luminosity. We propose a theoretical framework to derive this result and take the first steps by deriving the governing mean-field equations. Using Reynolds decomposition, we decompose flow variables into background and turbulent flows and derive self-consistent averaged equations for their evolution. As basic requirements for the CCSN problem, these equations naturally incorporate steady-state accretion, neutrino heating and cooling, non-zero entropy gradients, and turbulence terms associated with buoyant driving, redistribution, and dissipation. Furthermore, analysis of two-dimensional (2D) CCSN simulations validate these Reynolds-averaged equations, and we show that the physics of turbulence entirely accounts for the differences between 1D and 2D CCSN simulations. As a prelude to deriving the reduction in the critical luminosity, we identify the turbulent terms that most influence the conditions for explosion. Generically, turbulence equations require closure models, but these closure models depend upon the macroscopic properties of the flow. To derive a closure model that is appropriate for CCSNe, we cull the literature for relevant closure models and compare each with 2D simulations. These models employ local closure approximations and fail to reproduce the global properties of neutrino-driven turbulence. Motivated by the generic failure of these local models, we propose an original model for turbulence which incorporates global properties of the flow. This global model accurately reproduces the turbulence profiles and evolution of 2D CCSN simulations.

  2. The ESSENCE Supernova Survey: Survey Optimization, Observations, and Supernova Photometry

    SciTech Connect

    Miknaitis, Gajus; Pignata, G.; Rest, A.; Wood-Vasey, W.M.; Blondin, S.; Challis, P.; Smith, R.C.; Stubbs, C.W.; Suntzeff, N.B.; Foley, R.J.; Matheson, T.; Tonry, J.L.; Aguilera, C.; Blackman, J.W.; Becker, A.C.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Filippenko, A.V.; Garg, A.; Garnavich, P.M.; /Fermilab /Chile U., Catolica /Cerro-Tololo InterAmerican Obs. /Harvard-Smithsonian Ctr. Astrophys. /Harvard U. /UC, Berkeley, Astron. Dept. /NOAO, Tucson /Inst. Astron., Honolulu /Res. Sch. Astron. Astrophys., Weston Creek /Washington U., Seattle, Astron. Dept. /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /Ohio State U., Dept. Astron. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Stockholm U.

    2007-01-08

    We describe the implementation and optimization of the ESSENCE supernova survey, which we have undertaken to measure the equation of state parameter of the dark energy. We present a method for optimizing the survey exposure times and cadence to maximize our sensitivity to the dark energy equation of state parameter w = P/{rho}c{sup 2} for a given fixed amount of telescope time. For our survey on the CTIO 4m telescope, measuring the luminosity distances and redshifts for supernovae at modest redshifts (z {approx} 0.5 {+-} 0.2) is optimal for determining w. We describe the data analysis pipeline based on using reliable and robust image subtraction to find supernovae automatically and in near real-time. Since making cosmological inferences with supernovae relies crucially on accurate measurement of their brightnesses, we describe our efforts to establish a thorough calibration of the CTIO 4m natural photometric system. In its first four years, ESSENCE has discovered and spectroscopically confirmed 102 type Ia SNe, at redshifts from 0.10 to 0.78, identified through an impartial, effective methodology for spectroscopic classification and redshift determination. We present the resulting light curves for the all type Ia supernovae found by ESSENCE and used in our measurement of w, presented in Wood-Vasey et al. (2007).

  3. Pulsar-supernova remnant associations

    NASA Astrophysics Data System (ADS)

    Manchester, R. N.

    1994-04-01

    Pulsars and supernova remnants (SNRs) are both believed to be formed in the supernova explosions of massive stars. Therefore one might expect to see associations between the two classes of object. In fact, up until a couple of years ago, there was only a handful of believable associations and even now there are only nine or ten. It is relatively easy to explain why such a small fraction of the 600 or so known pulsars are associated with supernova remnants. The average pulsar lifetime is of the order of 106 years, whereas the average supernova remnant is detectable for about 104 years. Therefore, one would expect only about one percent of pulsars to be still associated, as is observed. It is somewhat more difficult to explain why so few of the 150 known supernova remnants have associated pulsars. The main factor is that supernova remnants are seen throughout the Galaxy whereas most pulsars are detectable only relatively close to the Sun, within a few kiloparsec. Another factor is that pulsar emission is beamed, so even if a pulsar exists in a relatively nearby supernova remnant, it may be undetectable. The most believable of the suggested associations are listed. Associations which are possible but by no means certain are indicated by question mark. For the more certain associations, the pulsar position is within the SNR boundaries (an exception is 'The Duck', where the pulsar is at the tip of the 'beak'), the distance estimates for the pulsar and SNR are compatible, and the age estimates are likewise compatible. References to most of these associations may be found in the pulsar catalog of Taylor, Manchester and Lyne (1993, Astrophys. J. Suppl., 88, 529). Recent references not included in the catalog are for PSR B1706-44 (McAdam, Osborne and Parkinson, 1993, Nature, 361, 516) and PSR B2334+61 (Kulkarni et al., 1993, Nature, 362, 135).

  4. Light-echo spectroscopy of historic Supernovae

    NASA Astrophysics Data System (ADS)

    Krause, Oliver

    Young Galactic supernova remnants are unique laboratories for supernova physics. Due to their proximity they provide us with the most detailed view of the outcome of a supernova. However, the exact spectroscopic types of their original explosions have been undetermined so far -hindering to link the wealth of multi-wavelength knowledge about their remnants with the diverse population of supernovae. Light echoes, reflektions of the brilliant supernova burst of light by interstellar dust, provide a unique opportunity to reobserve today -with powerful scientific instruments of the 21st century -historic supernova exlosions even after hundreds of years and to conclude on their nature. We report on optical light-echo spectroscopy of two famous Galactic supernovae: Tycho Brahe's SN 1572 and the supernova that created the Cassiopeia A remnant around the year 1680. These observations finally recovered the missing spectroscopic classifications and provide new constraints on explosion models for future studies.

  5. A Supernova's Shockwaves

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Supernovae are the explosive deaths of the universe's most massive stars. In death, these volatile creatures blast tons of energetic waves into the cosmos, destroying much of the dust surrounding them.

    This false-color composite from NASA's Spitzer Space Telescope and NASA's Chandra X-ray Observatory shows the remnant of one such explosion. The remnant, called N132D, is the wispy pink shell of gas at the center of this image. The pinkish color reveals a clash between the explosion's high-energy shockwaves and surrounding dust grains.

    In the background, small organic molecules called polycyclic aromatic hydrocarbons are shown as tints of green. The blue spots represent stars in our galaxy along this line of sight.

    N132D is located 163,000 light-years away in a neighboring galaxy called, the Large Magellanic Cloud.

    In this image, infrared light at 4.5 microns is mapped to blue, 8.0 microns to green and 24 microns to red. Broadband X-ray light is mapped purple. The infrared data were taken by Spitzer's infrared array camera and multiband imaging photometer, while the X-ray data were captured by Chandra.

  6. Supernova Remnants And GLAST

    SciTech Connect

    Slane, Patrick; /Harvard-Smithsonian Ctr. Astrophys.

    2011-11-29

    It has long been speculated that supernova remnants represent a major source of cosmic rays in the Galaxy. Observations over the past decade have ceremoniously unveiled direct evidence of particle acceleration in SNRs to energies approaching the knee of the cosmic ray spectrum. Nonthermal X-ray emission from shell-type SNRs reveals multi-TeV electrons, and the dynamical properties of several SNRs point to efficient acceleration of ions. Observations of TeV gamma-ray emission have confirmed the presence of energetic particles in several remnants as well, but there remains considerable debate as to whether this emission originates with high energy electrons or ions. Equally uncertain are the exact conditions that lead to efficient particle acceleration. Based on the catalog of EGRET sources, we know that there is a large population of Galactic gamma-ray sources whose distribution is similar to that of SNRs.With the increased resolution and sensitivity of GLAST, the gamma-ray SNRs from this population will be identified. Their detailed emission structure, along with their spectra, will provide the link between their environments and their spectra in other wavebands to constrain emission models and to potentially identify direct evidence of ion acceleration in SNRs. Here I summarize recent observational and theoretical work in the area of cosmic ray acceleration by SNRs, and discuss the contributions GLAST will bring to our understanding of this problem.

  7. Spectral ID of supernova ASASSN-15kz

    NASA Astrophysics Data System (ADS)

    Challis, P.; Kirshner, R.; Falco, E.; Berlind, P.; Prieto, J. L.; Stanek, K. Z.

    2015-06-01

    Spectra (range 350-760 nm) of supernovae ASASSN-15kz (ATEL 7625) was obtained on June 13, 2015 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) indicates the spectrum of ASASSN-15kz is a IIP supernova at early phase.

  8. Supernova explosions in the Universe.

    PubMed

    Burrows, A

    2000-02-17

    During the lifetime of our Milky Way galaxy, there have been something like 100 million supernova explosions, which have enriched the Galaxy with the oxygen we breathe, the iron in our cars, the calcium in our bones and the silicon in the rocks beneath our feet. These exploding stars also influence the birth of new stars and are the source of the energetic cosmic rays that irradiate us on the Earth. The prodigious amount of energy (approximately 10(51), or approximately 2.5 x 10(28) megatonnes of TNT equivalent) and momentum associated with each supernova may even have helped to shape galaxies as they formed in the early Universe. Supernovae are now being used to measure the geometry of the Universe, and have recently been implicated in the decades-old mystery of the origin of the gamma-ray bursts. Together with major conceptual advances in our theoretical understanding of supernovae, these developments have made supernovae the centre of attention in astrophysics. PMID:10693794

  9. Supernova Nucleosynthesis and Galactic Evolution

    NASA Astrophysics Data System (ADS)

    Thielemann, F.-K.; Argast, D.; Brachwitz, F.; Hix, W. R.; Höflich, P.; Liebendörfer, M.; Martinez-Pinedo, G.; Mezzacappa, A.; Nomoto, K.; Panov, I.

    The understanding of the abundance evolution in the interstellar medium, and especially the enrichment of heavy elements, as a function of space and time reflects the history of star formation and the lifetimes of the diverse contributing stellar objects. Therefore, the understanding of the endpoints of stellar evolution is essential. These are mainly planetary nebulae and type II/Ib/Ic supernovae as evolutionary endpoints of single stars, but also events in binary systems can contribute, like e.g. supernovae of type Ia, novae and possibly X-ray bursts and neutron star or neutron star - black hole mergers. Despite many efforts, a full and self-consistent understanding of supernovae (the main contributors to nucleosynthesis in galaxies) is not existing, yet. However, observed spectra, light curves, radioactivities/decay gamma-rays and galactic evolution witness the composition of their ejecta and constrain model uncertainties. We focus on (i) neutrino-induced explosions for type II supernovae and the innermost ejected layers, (ii) electron captures in type Ia supernovae and neutron-rich Fe-group nuclei and finally (iii) galactic chemical evolution and possible r-process sites.

  10. Theory and phenomenology of supernova neutrinos

    SciTech Connect

    Lunardini, Cecilia

    2015-07-15

    The theory and phenomenology of supernova neutrinos is reviewed, with focus on the most recent advancements on the neutrino flux predicted by supernova numerical models, on neutrino oscillations inside the star and in the Earth, and on the physics of the diffuse supernova neutrino background. Future directions of research are briefly summarized.

  11. "Suzaku Highlight Results on Supernova Remnants"

    NASA Technical Reports Server (NTRS)

    Petre, Robert

    2006-01-01

    Highlights of the early Suzaku (formerly Astro-E2) observations of supernova remnants are presented. Suzaku offers unique capabilities for the study of supernova remnants. The unprecedented combination of imaging and spectral resolution below 1 keV in the X-ray Imaging Spectrometer (XIS) makes possible mapping of C, N and O abundances in Galactic remnants of all ages. The first detection of carbon lines in the Cygnus Loop and mapping of the O VII to O VIII ratio in SN 1006 demonstrate this capability. The XIS sensitivity to soft, low surface brightness emission is exemplified by spectroscopy in the 0.3-1.0 keV band of the North Polar Spur and other Galactic ISM structures. Such observations make possible inferences about plasma conditions and abundances. The sensitivity above 6 keV via a combination of the XIS (below 10 keV) and the Hard X-ray Detector (above 10 keV) allows broad band (2-40 keV) spectroscopy and mapping of extended remnants with hard emission components. These components are generally associated with sites of particle acceleration, and measuring their spectral shape potentially provides information about the TeV electron population and its acceleration and energy loss mechanisms. Examples of such remnants observed by Suzaku are the non-thermal emission dominated remnants RX J1713.7-3946 and RX J0852.0-4622, for which flux beyond 30 keV has been detected. The status of the mission and prospects for future groundbreaking observations of supernova remnants will be discussed.

  12. First supernova companion star found

    NASA Astrophysics Data System (ADS)

    2004-01-01

    Supernova 1993J exploding hi-res Size hi-res: 222 kb Credits: ESA and Justyn R. Maund (University of Cambridge) Supernova 1993J exploding (artist’s impression) New observations with the Hubble Space Telescope allow a look into a supernova explosion under development. In this artist’s view the red supergiant supernova progenitor star (left) is exploding after having transferred about 10 solar masses of hydrogen gas to the blue companion star (right). This interaction process happened over about 250 years and affected the supernova explosion to such an extent that SN 1993J was later known as one of the most peculiar supernovae ever seen. Supernova 1993J exploding hi-res Size hi-res: 4200 kb Credits: ESA and Justyn R. Maund (University of Cambridge) The site of the Supernova 1993J explosion A virtual journey into one of the spiral arms of the grand spiral Messier 81 (imaged with the Isaac Newton Telescope on La Palma, left) reveals the superb razor-sharp imaging power of the NASA/ESA Hubble Space Telescope (Hubble’s WFPC2 instrument, below). The close-up (with Hubble’s ACS, to the right) is centred on the newly discovered companion star to Supernova 1993J that itself is no longer visible. The quarter-circle around the supernova companion is a so-called light echo originating from sheets of dust in the galaxy reflecting light from the original supernova explosion. Supernova 1993J explosing site hi-res Size hi-res: 1502 kb Credits: ESA and Justyn R. Maund (University of Cambridge) Close-up of the Supernova 1993J explosion site (ACS/HRC image) This NASA/ESA Hubble Space Telescope image shows the area in Messier 81 where Supernova 1993J exploded. The companion to the supernova ‘mother star’ that remains after the explosion is seen in the centre of the image. The image is taken with Hubble’s Advanced Camera for Surveys and is a combination of four exposures taken with ACS’ High Resolution Camera. The exposures were taken through two near-UV filters (250W

  13. Featured Image: Modeling Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

    This image shows a computer simulation of the hydrodynamics within a supernova remnant. The mixing between the outer layers (where color represents the log of density) is caused by turbulence from the Rayleigh-Taylor instability, an effect that arises when the expanding core gas of the supernova is accelerated into denser shell gas. The past standard for supernova-evolution simulations was to perform them in one dimension and then, in post-processing, manually smooth out regions that undergo Rayleigh-Taylor turbulence (an intrinsically multidimensional effect). But in a recent study, Paul Duffell (University of California, Berkeley) has explored how a 1D model could be used to reproduce the multidimensional dynamics that occur in turbulence from this instability. For more information, check out the paper below!CitationPaul C. Duffell 2016 ApJ 821 76. doi:10.3847/0004-637X/821/2/76

  14. Standardization of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Coelho, Rodrigo C. V.; Calvão, Maurício O.; Reis, Ribamar R. R.; Siffert, Beatriz B.

    2015-01-01

    Type Ia supernovae (SNe Ia) have been intensively investigated due to their great homogeneity and high luminosity, which make it possible to use them as standardizable candles for the determination of cosmological parameters. In 2011, the physics Nobel prize was awarded ‘for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.’ This is a pedagogical article, aimed at those starting their study of that subject, in which we dwell on some topics related to the analysis of SNe Ia and their use in luminosity distance estimators. Here, we investigate their spectral properties and light curve standardization, paying careful attention to the fundamental quantities directly related to the SNe Ia observables. Finally, we describe our own step-by-step implementation of a classical light curve fitter, the stretch, applying it to real data from the Carnegie Supernova Project.

  15. Dynamics of Kepler's supernova remnant

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Blondin, John M.; Sarazin, Craig L.

    1992-01-01

    Observations of Kepler's SNR have revealed a strong interaction with the ambient medium, far in excess of that expected at a distance of about 600 pc away from the Galactic plane where Kepler's SNR is located. This has been interpreted as a result of the interaction of supernova ejecta with the dense circumstellar medium (CSM). Based on the bow-shock model of Bandiera (1985), we study the dynamics of this interaction. The CSM distribution consists of an undisturbed stellar wind of a moving supernova progenitor and a dense shell formed in its interaction with a tenuous interstellar medium. Supernova ejecta drive a blast wave through the stellar wind which splits into the transmitted and reflected shocks upon hitting this bow-shock shell. We identify the transmitted shock with the nonradiative, Balmer-dominated shocks found recently in Kepler's SNR. The transmitted shock most probably penetrated the shell in the vicinity of the stagnation point.

  16. Supernovae, young remnants, and nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Kirshner, R. P.

    1982-01-01

    Chemical abundance data from extragalactic supernovae and from supernova remnants (SNR) less than 1000 yrs old are employed to show that nuclear burning beyond helium synthesis actually occurs. Supernova (SN) are classified into types I or II, having no hydrogen lines or featuring hydrogen lines, respectively. The SN I's have been observed as having a preponderance of Fe lines, and emitting from a source at around 12,000 K with a center continuum of approximately 10 AU. Decay chains which could account for detected luminosities and spectra are presented, noting a good fit of Fe II spectrum with observed SN spectra. SNR pass through younger and older stages, going from the outpouring of material to diffusion in the interstellar medium. Expanding flocculi from young SNR show oxygen abundances as well as lines from sulfur, calcium, and argon, with a corresponding necessity of an explosive source of 15 solar masses.

  17. Tidally-Induced Thermonuclear Supernovae

    SciTech Connect

    Rosswog, S.; Ramirez-Ruiz, E.; Hix, William Raphael

    2009-01-01

    We discuss the results of 3D simulations of tidal disruptions of white dwarfs by moderate-mass black holes as they may exist in the cores of globular clusters or dwarf galaxies. Our simulations follow self-consistently the hydrodynamic and nuclear evolution from the initial parabolic orbit over the disruption to the build-up of an accretion disk around the black hole. For strong enough encounters (pericentre distances smaller than about 1/3 of the tidal radius) the tidal compression is reversed by a shock and finally results in a thermonuclear explosion. These explosions are not restricted to progenitor masses close to the Chandrasekhar limit, we find exploding examples throughout the whole white dwarf mass range. There is, however, a restriction on the masses of the involved black holes: black holes more massive than 2x105M{circle_dot} swallow a typical 0.6M{circle_dot} white dwarf before their tidal forces can overwhelm the star's selfgravity. Therefore, this mechanism is characteristic for black holes of moderate masses. The material that remains bound to the black hole settles into an accretion disk and produces an Xray flare close to the Eddington limit of L{sub Edd} {approx} 10{sup 41}erg/s (Mbh/1000M{circle_dot}), typically lasting for a few months. The combination of a peculiar thermonuclear supernova together with an X-ray flare thus whistle-blows the existence of such moderate-mass black holes. The next generation of wide field space-based instruments should be able to detect such events.

  18. Precision Constraints from Computational Cosmology and Type Ia Supernova Simulations

    NASA Astrophysics Data System (ADS)

    Bernstein, Joseph P.; Kuhlmann, S. E.; Norris, B.; Biswas, R.

    2011-01-01

    The evidence for dark energy represents one of the greatest mysteries of modern science. The research undertaken probes the implications of dark energy via analysis of large scale structure and detonation-based Type Ia supernova light curve simulations. It is presently an exciting time to be involved in cosmology because planned astronomical surveys will effectively result in dark sector probes becoming systematics-limited, making numerical simulations crucial to the formulation of precision constraints. This work aims to assist in reaching the community goal of 1% constraints on the dark energy equation of state parameter. Reaching this goal will require 1) hydrodynamic+N-body simulations with a minimum of a 1 Gpc box size, 20483 hydrodynamic cells, and 1011 dark matter particles, which push the limits of existing codes, and 2) a better understanding of the explosion mechanism(s) for Type Ia supernovae, together with larger, high-quality data sets from present and upcoming supernova surveys. Initial results are discussed from two projects. The first is computational cosmology studies aimed at enabling the large simulations discussed above. The second is radiative transfer calculations drawn from Type Ia supernova explosion simulations aimed at bridging the gap between simulated light curves and those observed from, e.g., the Sloan Digital Sky Survey II and, eventually, the Dark Energy Survey.

  19. Supernova neutrinos and nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Martínez-Pinedo, G.; Fischer, T.; Huther, L.

    2014-04-01

    Observations of metal-poor stars indicate that at least two different nucleosynthesis sites contribute to the production of r-process elements. One site is responsible for the production of light r-process elements Z ≲ 50, while the other produces the heavy r-process elements. We have analyzed recent observations of metal-poor stars selecting only stars that are enriched in light r-process elements and poor in heavy r-process elements. We find a strong correlation between the observed abundances of the N = 50 elements (Sr, Y and Zr) and Fe. It suggest that neutrino-driven winds from core-collapse supernova are the main site for the production of these elements. We explore this possibility by performing nucleosynthesis calculations based on long-term Boltzmann neutrino transport simulations. We use an equation of state that reproduces recent constrains on the nuclear symmetry energy. We predict that the early ejecta is neutron rich with Ye ˜ 0.48, it becomes proton rich around 4 s and reaches Ye = 0.586 at 9 s when our simulation stops. The nucleosynthesis in this model produces elements between Zn and Mo, including 92Mo. The elemental abundances are consistent with the observations of the metal-poor star HD 12263. For the elements between Ge and Mo, we produce mainly the neutron-deficient isotopes. This prediction can be confirmed by observations of isotopic abundances in metal-poor stars. No elements heavier than Mo (Z = 42) and no heavy r-process elements are produced in our calculations.

  20. Software Based Supernova Recognition

    NASA Astrophysics Data System (ADS)

    Walters, Stephen M.

    2014-05-01

    This paper describes software for detecting Supernova (SN) in images. The software can operate in real-time to discover SN while data is being collected so the instrumentation can immediately be re-tasked to perform spectroscopy or photometry of a discovery. Because the instrumentation captures two images per minute, the realtime budget is constrained to 30 seconds per target, a challenging goal. Using a set of two to four images, the program creates a "Reference" (REF) image and a "New" (NEW) image where all images are used in both NEW and REF but any SN survives the combination process only in the NEW image. This process produces good quality images having similar noise characteristics but without artifacts that might be interpreted as SN. The images are then adjusted for seeing and brightness differences using a variant of Tomaney and Crotts method of Point Spread Function (PSF) matching after which REF is subtracted from NEW to produce a Difference (DIF) image. A Classifier is then trained on a grid of artificial SN to estimate the statistical properties of four attributes and used in a process to mask false positives that can be clearly identified as such. Further training to avoid any remaining false positives sets the range, in standard deviations for each attribute, that the Classifier will accept as a valid SN. This training enables the Classifier to discriminate between SN and most subtraction residue. Lastly, the DIF image is scanned and measured by the Classifier to find locations where all four properties fall within their acceptance ranges. If multiple locations are found, the one best conforming to the training estimates is chosen. This location is then declared as a Candidate SN, the instrumentation re-tasked and the operator notified.

  1. Dust around Type Ia supernovae

    SciTech Connect

    Wang, Lifan

    2005-10-20

    An explanation is given of the low value of R lambda triple bond A lambda/E(B - V), the ratio of absolute to selective extinction deduced from Type Ia supernova observations. The idea involves scattering by dust clouds located in the circumstellar environment, or at the highest velocity shells of the supernova ejecta. The scattered light tends to reduce the effective R lambda in the optical, but has an opposite effect in the ultraviolet. The presence of circumstellar dust can be tested by ultraviolet to near infrared observations and by multi-epoch spectropolarimetry of SNe Ia.

  2. Nature of type 1 Supernovae

    NASA Technical Reports Server (NTRS)

    Shklovskiy, I. S.

    1980-01-01

    The nature of type 1 supernovae (SN 1) is discussed through a comparison of observational evidence and theoretical perspectives relating to both type 1 and 2 supernovae. In particular two hypotheses relating to SN 1 phenomenon are examined: the first proposing that SN 1 are components of binary systems in which, at a comparatively late stage of evolution, overflow of the mass occurs; the second considers pre-SN 1 to be recently evolved stars with a mass greater than 1.4 solar mass (white dwarfs). In addition, an explanation of the reduced frequency of flares of SN 1 in spiral galaxies as related to that in elliptical galaxies is presented.

  3. What can we learn from gravitational waves from nearby core-collapse supernovae?

    NASA Astrophysics Data System (ADS)

    Suwa, Yudai; Yokozawa, Takaaki; Asano, Mitsuhiro; Kayano, Tsubasa; Kanda, Nobuyuki; Koshio, Yusuke; Vagins, Mark R.

    2015-04-01

    Core-collapse supernova is one of the expected sources of gravitational wave (GW). The GW detection can be a smoking gun to probe the still unknown explosion mechanism. In the coming era of “multi-messenger astronomy”, we can use photons, neutrinos and GW simultaneously to investigate these objects. By performing multi-dimensional simulations of neutrino-radiation hydrodynamics systematically, we calculate the gravitational wave and neutrino signals from nearby (galactic) core-collapse supernova. Based on these signals we will discuss the extractable information about the very central part of core-collapse supernovae.

  4. 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.

  5. A New Empirical Model for Type Ia Supernovae Using Spectrophotometry from the Nearby Supernova Factory

    NASA Astrophysics Data System (ADS)

    Saunders, Clare; Nearby Supernova Factory

    2016-01-01

    Type Ia supernovae are currently limited in their use for cosmology by dispersion in standardized magnitudes. A large part of this dispersion is due to the fact that the current lightcurve fitters do not describe the full range of Type Ia supernova diversity. I will present an empirical model of Type Ia supernovae that captures a wider range of supernova behavior and can improve magnitude standardization. This model is constructed using over 2000 spectrophotometric observations of Type Ia supernovae from the Nearby Supernova Factory. The true spectral time series for each supernova is modeled using Gaussian Processes. The supernova model predictions are used to calculate the principal components of the full set of supernova spectral time series. K-fold cross-validation is used to determine how many components correlate to absolute magnitude. Future work will test this method on independent photometric data sets.

  6. 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.

  7. Supernova neutrinos and explosive nucleosynthesis

    SciTech Connect

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

    2014-05-09

    Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta 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 θ{sub 13}, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements {sup 11}B and {sup 7}Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ{sub 13}, 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.

  8. The supernova: A stellar spectacle

    NASA Technical Reports Server (NTRS)

    Straka, W. C.

    1976-01-01

    The life of a star, the supernova, related objects and their importance in astronomy and science in general are discussed. Written primarily for science teachers of secondary school chemistry, physics, and earth sciences, the booklet contains a glossary, reference sources, suggested topics for discussion, and projects for individual or group assignment.

  9. 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.

  10. The Supernova - A Stellar Spectacle.

    ERIC Educational Resources Information Center

    Straka, W. C.

    This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. The following topics concerning supernovae are included: the outburst as observed and according to theory, the stellar remnant, the nebular remnant, and a summary…