Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session X18: Dynamics and Observables of Curved Spacetime |
Hide Abstracts |
Sponsoring Units: GGR Chair: David Nichols, Cornell University Room: 251F |
Tuesday, April 19, 2016 10:45AM - 10:57AM |
X18.00001: Reduced-order surrogate models for Green's functions in black hole spacetimes Chad Galley, Barry Wardell The fundamental nature of linear wave propagation in curved spacetime is encoded in the retarded Green's function (or propagator). Green's functions are useful tools because almost any field quantity of interest can be computed via convolution integrals with a source. In addition, perturbation theories involving nonlinear wave propagation can be expressed in terms of multiple convolutions of the Green's function. Recently, numerical solutions for propagators in black hole spacetimes have been found that are globally valid and accurate for computing physical quantities. However, the data generated is too large for practical use because the propagator depends on two spacetime points that must be sampled finely to yield accurate convolutions. I describe how to build a reduced-order model that can be evaluated as a substitute, or surrogate, for solutions of the curved spacetime Green's function equation. The resulting surrogate accurately and quickly models the original and out-of-sample data. I discuss applications of the surrogate, including self-consistent evolutions and waveforms of extreme mass ratio binaries. Green's function surrogate models provide a new and practical way to handle many old problems involving wave propagation and motion in curved spacetimes. [Preview Abstract] |
Tuesday, April 19, 2016 10:57AM - 11:09AM |
X18.00002: ABSTRACT WITHDRAWN |
Tuesday, April 19, 2016 11:09AM - 11:21AM |
X18.00003: Constraining theories of gravity from Light Deviation Experiments Richard Bustos, Tirthabir Biswas ~Modifications of Einstein's theory of General Relativity (GR) are notorious for introducing ghosts and tachyons which renders these theories classically unstable and any attempts to quantize them doomed to fail. Over the last few years, concrete criteria on covariant modifications to GR have been derived that ensures that the gravitational theory is free from such instabilities, at least, around the Minkowski vacuum. The most general consistent action can be parameterized by two mass scales: the first one controls the scale of nonlocality in the graviton interaction, and the second characterizes the mass of a Brans-Dicke type scalar mode that can be present in the metric tensor. Our goal has been to develop techniques to directly constrain these mass parameters from experimental tests of GR. In particular, I will talk about the constraints from the light bending experiments. [Preview Abstract] |
Tuesday, April 19, 2016 11:21AM - 11:33AM |
X18.00004: To Collapse or not to Collapse: The Life of a Primordial Black Hole Robert Craig, Jolyon Bloomfield, Stephen Face Primordial black holes offer insights into topics ranging from cosmological questions about inflationary models to astrophysical questions regarding supermassive black holes. Such insights depend on being able to predict the number density of black holes that form from primordial fluctuations. Traditionally this has been done by means of a ``rule-of-thumb'' developed by Carr in the 1980s, but recent numerical studies have shown that this predictor is a coarse tool at best. We present a two-parameter predictor with much more discrimination power that can be straightforwardly used to compute number densities. We also discuss challenges that face this type of prediction strategy, both analytically and numerically, and possible ways to circumvent them. [Preview Abstract] |
Tuesday, April 19, 2016 11:33AM - 11:45AM |
X18.00005: Toroidal Event Horizons in Binary Black Hole Mergers Andy Bohn, Saul Teukolsky, Lawrence Kidder We find the first binary black hole (BBH) event horizon with a short-lived toroidal topology. The BBH mergers are produced using the Spectral Einstein Code (SpEC). It is expected that a toroidal topology should appear in space-like slicings of these $2+1$ dimensional event horizons, but this topology has not been found previously. While we do not see a toroidal phase in the generalized harmonic slicing used to simulate the BBHs, we do find a toroidal phase after using a motivated coordinate transformation to another space-like slicing. [Preview Abstract] |
Tuesday, April 19, 2016 11:45AM - 11:57AM |
X18.00006: Plasma-wave generation in a dynamic spacetime Fan Zhang, Huan Yang The studies on the electromagnetic counterparts to gravitational waves have largely been focusing on binary mergers containing at least one neutron star. Numerical studies have shown however, that binary black holes can also give off electromagnetic signals when immersed in magnetized plasma. I will present some analytical work that explore the underlying mechanism for generating such signals. [Preview Abstract] |
Tuesday, April 19, 2016 11:57AM - 12:09PM |
X18.00007: An analysis of explicit solutions to force-free electrodynamics in a Kerr background Govind Menon The talk will focus on two previously obtained exact solutions to force-free electrodynamics in a Kerr background. We will explicitly construct the kernel of the degenerate electromagnetic fields and explore the possibility of constructing combinations of solutions to the nonlinear equations. The goal of this analysis is to obtain non-trivial streaming surfaces of the theory that are astrophysically relevant. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700