Snowmass2021 Cosmic Frontier White Paper: Numerical relativity for next-generation gravitational-wave probes of fundamental physics

Abstract

The next generation of gravitational-wave detectors, conceived to begin operations in the 2030s, will probe fundamental physics with exquisite sensitivity. These observations will measure the equation of state of dense nuclear matter in the most extreme environments in the universe, reveal with exquisite fidelity the nonlinear dynamics of warped spacetime, put general relativity to the strictest test, and perhaps use black holes as cosmic particle detectors. Achieving each of these goals will require a new generation of numerical relativity simulations that will run at scale on the supercomputers of the 2030s to achieve the necessary accuracy, which far exceeds the capabilities of numerical relativity and high-performance computing infrastructures available today. Contents 1 Motivation 2 Gravitational waveform modeling 3 Nuclear physics and neutron stars 4 Modeling high-precision gravitational-wave observations 5 Testing gravity in the nonlinear regime 6 Black holes as cosmic particle detectors

General relativistic moving-mesh hydrodynamics simulations with AREPO and applications to neutron star mergers

“…Wilson & Mathews 2003;Font 2008;Alcubierre 2008;Baumgarte & Shapiro 2010;Rezzolla & Zanotti 2013;Rosswog 2015;Martí & Müller 2015;Shibata 2015, and references therein). Font (2008), Baiotti & Rezzolla (2017) and Foucart et al (2022) provide a survey of codes currently used to tackle general relativistic hydrodynamics (GRHD) problems mostly in the context of binary mergers; some recent relativistic SPH tools are presented in Liptai & Price (2019) (adopting a fixed metric) and in Rosswog & Diener (2021); Diener et al (2022) (including a dynamical evolution of the spacetime and applications to neutron star mergers).…”

What is the fate of Hawking evaporation in gravity theories with higher curvature terms?

“…Studying the evolution of BH Hawking evaporation beyond GR within an effective field theory approach is of limited interest, because deviations from the standard GR picture ought to be perturbative, while the most interesting effects are expected to occur in a nonperturbative regime. However, studying the nonlinear dynamics of gravity in the high-curvature regime beyond GR at nonperturbative level is very challenging [9].…”

Large eddy simulations of magnetized mergers of neutron stars with neutrinos

“…[4][5][6][7] and references within). Development of third generation gravitational wave detectors such as the Einstein Telescope and Cosmic Explorer promises to extend the usable bandwidth to observe the high frequency merger where the detailed high density physics affecting the structure of the stars may be better revealed [8,9].…”