Bulletin of the American Physical Society
2005 47th Annual Meeting of the Division of Plasma Physics
Monday–Friday, October 24–28, 2005; Denver, Colorado
Session CZ2: Mini-conference on Astrophysical Explosions: From Engines to Remnants I |
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Chair: Eric Blackman, University of Rochester Room: Adam's Mark Hotel Governor's Square 14 |
Monday, October 24, 2005 2:00PM - 2:30PM |
CZ2.00001: The Energetics of Cosmic Explosions: Gamma-Ray Bursts and Type Ibc Supernovae Edo Berger The death of massive stars remains an open chapter in astronomy. Observationally, the problem may be addressed by studying different classes of cosmic explosions and their energy sources. Here we discuss recent results on the energetics of gamma-ray bursts (GRBs) and type Ibc core-collapse supernovae (SNe Ibc). In particular, we show that the energy output of most GRBs is nearly standard, but that the ultra-relativistic output varies considerably. On the other hand SNe Ibc exhibit a wide dispersion in the energy coupled to fast ejecta but none of those observed to date (with the exception of SN1998bw) produced relativistic ejecta. This allows us to place a firm limit of a few percent on the fraction of SNe Ibc that give rise to GRBs. [Preview Abstract] |
Monday, October 24, 2005 2:30PM - 3:00PM |
CZ2.00002: Rotation and Magnetic Fields in Supernovae and Gamma-ray Bursts J. Craig Wheeler Spectropolarimetry of core collapse supernovae has shown that they are asymmetric and often, but not universally, bi-polar; in some the dominant axes associated with hydrogen, oxygen, and calcium are oriented substantially differently. Jet-induced supernova models give a typical jet/torus structure that is reminiscent of some objects like the Crab nebula, SN~1987A and perhaps Cas A. Jets, in turn, may arise from the intrinsic rotation and magnetic fields that are expected to accompany core collapse. We summarize the potential importance of the magneto-rotational instability for the core collapse problem, stress the non- monotonic response of the final rotation and magnetic field to the initial iron core rotation, and the potential role of non-axisymmetric instabilities in the new-born neutron star. We sketch some of the effects that large magnetic fields, $\sim 10^{15} - 10^{17}$ G, may have on the physics at core bounce and in the subsequent cooling, de-leptonization phase. Production and dissipation of MHD waves in this strongly differentially rotating environment may affect the success of the supernova explosion, the nature of the compact remnant -- neutron star or black hole, pulsar or magnetar -- and whether the outcome is a normal supernova or a gamma-ray burst. In collaboration with Shizuka Akiyama, University of Texas at Austin. [Preview Abstract] |
Monday, October 24, 2005 3:00PM - 3:30PM |
CZ2.00003: Stellar Collapse and Explosion: Relativistic AMR Simulations Andrew MacFadyen, Weiqun Zhang Numerical simulations of the collapse of massive rotating stars, accretion disk formation and relativistic jet propagation relevant for explosions producing supernovae, gamma-ray bursts (GRBs) and their afterglows will be presented. Outflows driven from the accretion disk formed after core collapse may be responsible for accretion-powered supernova, independent of any GRB-producing jet which may also be produced. The simulations are performed with RAM, a newly written relativistic hydrodynamics code with adaptive mesh refinement (AMR). The importance of AMR for resolving thin structures in relativistic flow is emphasized. RAM will be described and test calculations presented. [Preview Abstract] |
Monday, October 24, 2005 3:30PM - 4:00PM |
CZ2.00004: State-of-the-Art Multi-Dimensional Core-Collapse and Supernova Simulations Adam Burrows We have performed the first 2D multi-group calculations of core collapse, bounce, and explosion (at times) that incorporate multi-D neutrino transfer. In addition, we have investigated the possible role of rotation of the core (using the code's ``2.5''-D capability), calculated the ``final'' rotational profiles of protoneutron stars, and calculated gravitational radiation signatures. Moreover, we have determined the growth and role of ``l=1'' anisotropies in the post-bounce configuration using realistic equations of state, multi-neutrino transport, realistic initial models, and state-of-the-art neutrino opacities. The mechanism of core-collapse supernovae, the origin of pulsar kick velocities, and the energy-dependent anisotropy of the neutrino spectra and fluxes are all addressed. Finally, new simulation capabilities that we are developing are discussed. [Preview Abstract] |
Monday, October 24, 2005 4:00PM - 4:30PM |
CZ2.00005: Asymmetries in Stellar Collapse Chris Fryer The observational evidence for asymmetries in stellar collapse has been growing dramatically since astronomers found a correlation between gamma-ray bursts and some type Ib/c supernovae. Here I review some of the mechanisms behind these asymmetries. I will argue that most stellar collapse explosions produce mild asymmetries and will show evidence and compare these mildly asymmetric explosions to observations. [Preview Abstract] |
Monday, October 24, 2005 4:30PM - 5:00PM |
CZ2.00006: Supernova Explosions in Two and Three Dimensions Alexei Khokhlov Type Ia supernovae (SNIa) - thermonuclear explosions of degenerate stars - are important tools of modern physics and cosmology. Use of SNIa as extragalactic ``standard'' candles has led to accurate determinations of the Hubble constant and to a discovery of the accelerating expansion of the universe. Science produced by SNIa critically depends on understanding of SNIa and on accurate calibration of intrinsic brightness of SNIa events. I will discuss (1) recent progress and new problems in multidimensional hydrodynamical modeling of SNIa, (2) input physics, scales involved, and computer power required for producing next generation of theoretical SNIa models, and (3) ways to calibrate SNIa models using terrestrial experiments. [Preview Abstract] |
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