Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session R9: Invited Session: Understanding Core-Collapse Supernovae from the Inside Out |
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Sponsoring Units: DAP DNP Chair: John Beacom, Ohio State University Room: Key 5 |
Monday, April 13, 2015 10:45AM - 11:21AM |
R9.00001: Hans A. Bethe Prize: Neutron Stars and Core-Collapse Supernovae Invited Speaker: James Lattimer Core-collapse supernovae lead to the formation of neutron stars, and both are sensitive to the dense matter equation of state. Hans Bethe first recognized that the matter in the collapsing core of a massive star has a relatively low entropy which prevents nuclear dissociation until nuclei merge near the nuclear saturation density. This recognition means that collapse continues until the core exceeds the saturation density. This prediction forms the foundation for modern simulations of supernovae. These supernovae sample matter up to about twice nuclear saturation density, but neutron stars are sensitive to the equation of state both near the saturation density and at several times higher densities. Two important recent developments are the discovery of two-solar mass neutron stars and refined experimental determinations of the behavior of the symmetry energy of nuclear matter near the saturation density. Combined with the assumption of causality, they imply that the radii of observed neutron stars are largely independent of their mass, and that this radius is in the range of 11 to 13 km. These theoretical results are not only consistent with expectations from theoretical studies of pure neutron matter, but also accumulated observations of both bursting and cooling neutron stars. In the near future, new pulsar timing data, which could lead to larger measured masses as well as measurements of moments of inertia, X-ray observations, such as from NICER, of bursting and other sources, and gravitational wave observations of neutron stars in merging compact binaries, will provide important new constraints on neutron stars and the dense matter equation of state. [Preview Abstract] |
Monday, April 13, 2015 11:21AM - 11:57AM |
R9.00002: The Critical Neutrino Luminosity of the Core-Collapse Supernova Explosions Invited Speaker: Ondrej Pejcha All massive stars end their lives with core collapse and many as supernova explosions. Despite observations of thousands of supernovae, detailed numerical calculations and theoretical efforts, the mechanism of explosion is poorly understood. In the most-investigated ``neutrino explosion mechanism,'' the collapse turns into explosion when the neutrino luminosity from the proto-neutron star exceeds a critical value $L_{\rm crit}$. I will explain the connection between the steady-state isothermal accretion flows with bounding shocks and the neutrino mechanism, and present a new ``antesonic'' explosion condition, which characterizes the transition to explosion over a broad range in accretion rate, proto-neutron star properties and microphysics. The formalism of the critical neutrino minosity offers a convenient way to qualitatively investigate the importance of individual physical effects and progenitor structure on the outcomes of the core collapse. I will briefly review the importance of multi-dimensional effects and collective neutrino oscillations. Finally, by parameterizing the systematic uncertainty in the explosion mechanism and by using spherical quasi-static evolutionary sequences for many hundreds of progenitors over a wide range of metallicities, I will show how the explosion threshold maps onto observables - fraction of successful explosions, remnant neutron star and black hole mass functions, explosion energies, nickel yields - and their mutual correlations. Successful explosions are intertwined with failures in a complex but well-defined pattern that is not well described by the progenitor initial mass and other supernova properties show a similar pattern. [Preview Abstract] |
Monday, April 13, 2015 11:57AM - 12:33PM |
R9.00003: Remnants of Core-Collapse Supernovae Invited Speaker: Laura Lopez Supernovae (SNe) play an essential role in the Universe, and they are detected routinely through dedicated surveys. However, most of these SNe are often too distant ($\sim$1-100 Mpc) to resolve the SN ejecta and immediate surroundings of the exploded stars. Fortunately, supernova remnants (SNRs) offer the means to study explosions and dynamics at sub-pc scales. SNRs are observable for up to 10$^{5}$ years after the explosions across the electromagnetic spectrum, and almost 400 SNRs have now been identified in the Milky Way and nearby galaxies. In this talk, I will review recent advances in the understanding of core-collapse (CC) SNe based on studies of SNRs. In particular, I will highlight investigations of SNR (a)symmetry and of heavy metal (like iron and titanium) abundances which give insight to the nature and mechanisms of the originating explosions. [Preview Abstract] |
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