Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session X3: Numerical Relativity Simulations of Neutron Star Binaries and Gravitational Collapse |
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Sponsoring Units: DGRAV Chair: Sean McWilliams, West Virginia University Room: Maryland C |
Tuesday, January 31, 2017 10:45AM - 10:57AM |
X3.00001: General Relativistic Simulations of Low-Mass Magnetized Binary Neutron Star Mergers Bruno Giacomazzo We will present general relativistic magnetohydrodynamic (GRMHD) simulations of binary neutron star (BNS) systems that produce long-lived neutron stars (NSs) after merger. While the standard scenario for short gamma-ray bursts (SGRBs) requires the formation after merger of a spinning black hole surrounded by an accretion disk, other theoretical models, such as the time-reversal scenario, predict the formation of a long-lived magnetar. The formation of a long-lived magnetar could in particular explain the X-ray plateaus that have been observed in some SGRBs. Moreover, observations of NSs with masses of ~2 solar masses indicate that the equation of state of NS matter should support masses larger than that. Therefore a significant fraction of BNS mergers will produce long-lived NSs. This has important consequences both on the emission of gravitational wave signals and on their electromagnetic counterparts. We will discuss GRMHD simulations of "low-mass" magnetized BNS systems with different equations of state and mass ratios. We will describe the properties of their post-merger remnants and of their gravitational and electromagnetic emission. [Preview Abstract] |
Tuesday, January 31, 2017 10:57AM - 11:09AM |
X3.00002: Binary neutron star mergers as engines of short gamma-ray bursts: delayed vs. prompt collapse Milton Ruiz, Vasileios Paschalidis, Stuart Shapiro Inspiralling and merging binary neutron stars (NSNSs) are not only promising sources of detectable gravitational waves, but they are also possible progenitors of short gamma-ray bursts. We have recently performed magnetohydrodynamic simulations in full general relativity which show that a jet is launched from the poles of the spinning black hole formed following magnetized NSNS mergers. For the cases we explored the black hole-disk remnant arises from the ``delayed" collapse of a hypermassive NSNS that forms following an equal-mass merger. Now we have varied both the initial NS compaction and binary mass ratio to explore the formation of jets for cases in which the merger leads to ``prompt'' collapse. [Preview Abstract] |
Tuesday, January 31, 2017 11:09AM - 11:21AM |
X3.00003: Binary neutron star initial data and single, rotating neutron stars as gravitational wave emitters Antonios Tsokaros, Koji Uryu, Luca Baiotti, Filippo Galeazzi, Bruno Mundim, Luciano Rezzolla, Noriyuki Sugiyama, Keisuke Taniguchi, Shin'ichirou Yoshida In the first part of this talk, we compare gravitational waveforms for the same irrotational binary configuration computed with two different initial-data codes, but evolved with the same evolution code. The impact of the difference on the estimation of physical parameters will be addressed. In the second part we present quasiequilibrium solutions of triaxially deformed rotating compact stars (generalization of Jacobi ellipsoids under relativistic gravity and compressible equations of state). We show that supramassive equilibrium solutions exist and a new scenario to probe the EOS of high density nuclear matter through gravitational wave detection will be discussed. [Preview Abstract] |
Tuesday, January 31, 2017 11:21AM - 11:33AM |
X3.00004: Magnetorotatioal Collapse of Supermassive Stars: Black Hole Formation and Jets Lunan Sun, Vasileios Paschalidis, Milton Ruiz, Stuart Shapiro We perform magnetohydrodynamic simulations in full general relativity of the collapse of radially unstable, uniformly rotating, massive stars to black holes. The stars spin at the mass-shedding limit, account for magnetic fields and obey a $\Gamma$ = 4/3 EOS. The calculations lift the restriction of axisymmetry imposed in previous simulations. Our simulations model the direct collapse of supermassive stars to supermassive BHs ($\geq 10^4 \text{M}_{\odot}$) at high cosmological redshifts, which may explain the appearance of supermassive BHs and quasars by z $\sim$ 7. They also crudely model the collapse of massive Pop III stars to massive BHs, which could power some of the long gamma-ray bursts observed by FERMI and SWIFT at z $\sim$ 6-8. We analyze the properties of the electromagnetic and gravitational wave signatures of these events and discuss the detectability of such multimessenger sources. [Preview Abstract] |
Tuesday, January 31, 2017 11:33AM - 11:45AM |
X3.00005: White Holes in Einstein-Aether Theory David Garfinkle, Ratindranath Akhoury, Nishant Gupta Numerical simulations are performed of gravitational collapse in Einstein-aether theory. We find that under certain circumstances the collapse results in the temporary formation of a white hole horizon. [Preview Abstract] |
Tuesday, January 31, 2017 11:45AM - 11:57AM |
X3.00006: Critical Collapse of Perfect Fluids with Angular Momentum Thomas Baumgarte, Carsten Gundlach We study critical phenomena in the gravitational collapse of rotating perfect fluids. We perform numerical simulations and observe critical scaling in both supercritical evolutions, which lead to the formation of a black hole, and subcritical evolutions, in which case the fluid disperses to infinity and leaves behind flat space. We also develop a theoretical model of mass and angular momentum scaling for critical collapse with rotation, and compare the predictions of this model with the numerical data. [Preview Abstract] |
Tuesday, January 31, 2017 11:57AM - 12:09PM |
X3.00007: ABSTRACT WITHDRAWN |
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