Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session B11: Invited Session: Innovative Computing in Relativity |
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Sponsoring Units: GGR DCOMP Chair: Evan O'Connor, University of Toronto Room: Key 7 |
Saturday, April 11, 2015 10:45AM - 11:21AM |
B11.00001: Novel Numerical Approaches to Loop Quantum Cosmology Invited Speaker: Peter Diener Loop Quantum Gravity (LQG) is an (as yet incomplete) approach to the quantization of gravity. When applied to symmetry reduced cosmological spacetimes (Loop Quantum Cosmology or LQC) one of the predictions of the theory is that the Big Bang is replaced by a Big Bounce, i.e.\ a previously existing contracting universe underwent a bounce at finite volume before becoming our expanding universe. The evolution equations of LQC take the form of difference equations (with the discretization given by the theory) that in the large volume limit can be approximated by partial differential equations (PDEs). In this talk I will first discuss some of the unique challenges encountered when trying to numerically solve these difference equations. I will then present some of the novel approaches that have been employed to overcome the challenges. I will here focus primarily on the Chimera scheme that takes advantage of the fact that the LQC difference equations can be approximated by PDEs in the large volume limit. I will finally also briefly discuss some of the results that have been obtained using these numerical techniques by performing simulations in regions of parameter space that were previously unreachable. [Preview Abstract] |
Saturday, April 11, 2015 11:21AM - 11:57AM |
B11.00002: Numerical Relativity's Contributions to Theoretical Astrophysics, and Its Path Forward Invited Speaker: Zachariah Etienne In the extreme violence of merger and mass accretion, compact objects like black holes, neutron stars, and white dwarfs are thought to launch some of the most luminous outbursts of electromagnetic, neutrino, and gravitational wave energy in the Universe. Modeling these systems realistically remains a central problem in theoretical astrophysics, due to two key challenges. First, the emission mechanisms often stem from magnetized flows and dynamical gravitational fields spanning many orders of magnitude in lengthscale and timescale, from the strong-field region near compact objects, to the often magnetically-dominated, weak-field regions far away. Second, the equations governing the dynamics are highly complex and nonlinear, including the full general relativistic field equations as coupled to the equations of radiation general relativistic magnetohydrodynamics. I will review some of the current progress in developing numerical relativity codes that robustly and efficiently solve these equations (or some subset thereof) on non-uniform numerical grids to capture the multi-scale nature of compact object merger and mass accretion. Some key results from such codes will also be explored, providing examples of how numerical relativity has advanced theoretical astrophysics. Though these results are highly interesting, they often rely on extremely computationally expensive simulations that lack the accuracy and physical realism required for complete theoretical models. Thus, although numerical relativity simulations have begun to address key astrophysical questions, large gaps in our understanding remain. Bridging these gaps will require a continued focus on adding more physics to our simulations, as well as development of more computationally-efficient formulations of the equations and the algorithms for solving them. [Preview Abstract] |
Saturday, April 11, 2015 11:57AM - 12:33PM |
B11.00003: Computational approaches in gravitational wave data analysis Invited Speaker: Tyson Littenberg The potential for gravitational wave observations to revolutionize our understanding of the universe is made possible in part by innovative data analysis strategies.This talk focuses on novel computational approaches used to squeeze every last drop of information out of the coming flood of data. Topics include mining through data to identify candidate signals, source characterization using optimization algorithms and Bayesian inference, and advances in modeling gravitational wave signals and detector noise. [Preview Abstract] |
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