Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session N09: Numerical Simulations II |
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Sponsoring Units: DGRAV Chair: Francois Foucart, University of New Hampshire Room: Conrad B/C - 2nd Floor |
Monday, April 17, 2023 1:30PM - 1:42PM |
N09.00001: The Impact of Compactness in Black Hole - Neutron Star Mergers Bing-Jyun Tsao, Miguel Gracia-Linares, Pablo Laguna, Bhavesh Khamesra Recent gravitational wave observations have confirmed the mergers of black hole - neutron star binaries. In a previous study, we investigated how the mass ratio of the binary system has an impact on the disruption of the neutron star, and as a consequence, on the shape of the gravitational waves emitted. In present follow-up study, we extend the results to study the effects from varying the compactness of the neutron star. We consider two mass ratios: 1:3 and 1:4. For each case, we carry out numerical simulations with compactness in the range 0.12 to 0.20. As with the previous study, we use the generalized Bowen-York initial data method for black hole punctures with neutron star companions. |
Monday, April 17, 2023 1:42PM - 1:54PM |
N09.00002: Neutrino transport in magnetized collisions of compact objects Steven L Liebling We simulate binary mergers of either two neutron stars or a neutron star with a black hole using our open-source code MHDuet which evolves the fully nonlinear Einstein equations coupled to magnetohydrodynamics using Large Eddy Simulation techniques that help resolve the small scale magnetic turbulence that develops. The code also includes either a leakage scheme or a more advanced moment scheme (M1) for neutrino transport that allows for composition-dependent analysis of any ejected material. |
Monday, April 17, 2023 1:54PM - 2:06PM |
N09.00003: QCD Phase Transitions in Binary Neutron Star Mergers: Signatures from multi-modal GW Spectroscopy Aviral Prakash, Pedro Luis Espino, David Radice, Domenico Logoteta We report on multi-modal gravitational wave (GW) signatures of high-density phase transition to deconfined quarks in the context of binary neutron star (BNS) mergers. We employ state-of-the-art, general relativistic hydrodynamics simulations of BNS mergers in quasi-circular and nearly parabolic orbits and consider equations of state that model different treatments to both hadronic and quark matter. We find that such phase transitions robustly act to suppress the one-armed spiral instability in the postmerger remnant and lead to an anti-correlation between the energy carried by the l=2, m=1 GW mode and the energy density gap between the hadronic and quark phase. Consequently, this manifests as a reduced signal-to-noise ratio for the l=2, m=1 mode in the quark case and whose detection could potentially constrain the energy density gap between the phases. |
Monday, April 17, 2023 2:06PM - 2:18PM |
N09.00004: Electromagnetic precursor flares from the late inspiral of black hole - neutron star binaries Elias R Most, Alexander A Philippov Most neutron star – black hole gravitational wave events are thought to feature negligible remnant mass after the merger, suppressing potential electromagnetic counterpart production. There- fore, it is an essential question for current multi-messenger astronomy to understand what type of other electromagnetic transients can potentially be sourced by these merger events. In this work, we numerically investigate pre-merger interactions of the common magnetosphere of neutron star–black hole systems. Using general-relativistic force-free electrodynamics simulations, we demonstrate that this system can feature strong electromagnetic flaring activity. We quantify the energy released by these flaring events with a particular emphasis on GW200115-like gravitational wave events, including their ability to source fast-radio and X-ray transients. |
Monday, April 17, 2023 2:18PM - 2:30PM |
N09.00005: Behavior of dynamical ejecta from black hole-neutron star binaries near neutron star disruption limit Tia K Martineau, Francois V Foucart Black hole–neutron star (BHNS) binaries are important sources of gravitational waves (GWs) and are also a proposed mechanism for UV/optical/infrared kilonova signals. In order for a BHNS merger to produce a kilonova signal, the spin of the black hole must be sufficiently high, creating a tidal field strong enough to disrupt the neutron star. With spins above this threshold, a disrupting BHNS binary will usually eject a few percent of a solar mass of matter, leading to observable kilonovae driven by radioactive decays in the ejecta which may be used as a counterpart to GW observations of BHNS systems. Below this spin limit, the neutron star may plunge into the black hole in its entirety. In this talk, I summarize preliminary results from simulations of BHNS binaries with black hole spins just above and below the predicted spin limit. These simulations serve as an exploration into the behavior of dynamical ejecta close to this threshold and were run with the Spectral Einstein Code (SpEC). |
Monday, April 17, 2023 2:30PM - 2:42PM |
N09.00006: Self-gravitating disks around rapidly spinning, tilted black holes: General-relativistic simulations Antonios Tsokaros, Milton Ruiz, Stuart L Shapiro, Vasileios Paschalidis We present general-relativistic simulations of self-gravitating black hole disks in which the spin of the black hole is significantly tilted with respect to the angular momentum of the disk. Such systems lead to black hole and disk precession, as well as to gravitational-wave emission via various modes beyond, but as strong as, the typical (2,2) mode. Our simulations suggest that any electromagnetic luminosity from our models may power relativistic jets, such as those characterizing short gamma-ray bursts. Depending on the black-hole-disk system scale the gravitational waves may be detected by LIGO/Virgo, LISA and/or other laser interferometers. |
Monday, April 17, 2023 2:42PM - 2:54PM |
N09.00007: Impact of viscosity on the perturbations of neutron stars Justin L Ripley, Abhishek Hegade K R, Nicolas Yunes Viscous dissipation may play an important role in the late inspiral, merger, and ringdown of neutron star binaries. As a step towards determining how important these effects may be, we compute the quasinormal modes and tidal Love numbers of compact stars that are made up of a ``BDNK'' fluid. The BDNK (Bemfica, Disconzi, Noronha, and Kovtun) fluid model is a relativistic generalization of Navier-Stokes theory that is hyperbolic, has stable equilibrium solutions, and incorporates all possible leading-order dissipative effects (bulk viscosity, shear viscosity, and heat conduction), which arguably makes it the most physically realistic model of relativistic viscous fluids currently available. Making use of a covariant framework to consider spherical perturbations, we demonstrate how viscous effects can couple axial (odd-parity) fluid and gravitational perturbations, and discuss how sensitive our results are on different equations of state.
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Monday, April 17, 2023 2:54PM - 3:06PM |
N09.00008: Minidisk Influence on Flow Variability in Accreting Spinning Black Hole Binaries: Simulations in Full General Relativity Jane Bright, Vasileios Paschalidis We perform magnetohydrodynamic simulations of accreting, equal-mass binary black holes in full general relativity focusing on the effect of spin and minidisks on the accretion rate and Poynting luminosity variability. We report on the structure of the minidisks and periodicities in the mass of the minidisks, mass accretion rates, and Poynting luminosity. The accretion rate exhibits a quasi-periodic behavior related to the orbital frequency of the binary in all systems that we study, but the amplitude of this modulation is dependent on the existence of persistent minidisks. In particular, systems that are found to produce persistent minidisks have a much weaker modulation of the mass accretion rate, indicating that minidisks can increase the inflow time of matter onto the black holes, and dampen out the quasi-periodic behavior. This finding has potential consequences for binaries at greater separations where minidisks can be much larger and may dampen out the periodicities significantly. |
Monday, April 17, 2023 3:06PM - 3:18PM |
N09.00009: GRMHD simulations of gas accretion onto merging supermassive black hole binaries Lorenzo Ennoggi, Manuela Campanelli, Yosef Zlochower, Federico G Lopez Armengol, Vassilios Mewes, Liwei Ji, Scott C Noble The merger of two galaxies is expected to result in a supermassive binary black hole ('SMBBH') system surrounded by gas. SMBBH emit gravitational radiation, which could be detected by next-generation gravitational wave ('GW') detectors (LISA, PTAs). However, SMBBH could also emit electromagnetic ('EM') radiation through accretion of gas onto the binary; detecting such radiation and predicting its signatures by means of numerical simulations is key to telling SMBBH and regular AGNs apart and to direct GW detectors to the correct location in the sky. |
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