Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Q16: Gravitational Waveform Modeling of Compact Binaries IILive
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Sponsoring Units: DGRAV Chair: Carl Rodriguez, Carnegie Mellon Univ. |
Monday, April 19, 2021 10:45AM - 10:57AM Live |
Q16.00001: Quasinormal Modes of deformed Black Holes with arbitrary spin Asad Hussain, Aaron Zimmerman The increasing precision of gravitational wave detectors has enabled even more precise tests of general relativity, including spectroscopic tests of black holes through the measurement of their quasinormal modes (QNMs). These spectroscopic tests ideally compare the QNM frequencies to predictions from theories beyond GR, where black holes may be described by deformations to the standard Kerr metric. I will present a framework to compute the leading shifts to QNM frequencies for perturbations around such deformed Kerr black holes, with arbitrary spin. To demonstrate this, we use the framework to find the scalar QNM shifts of the Johannsen–Psaltis (JP) metric, a starting point for generic parameterizations of beyond Kerr corrections. This method can aid in getting constraints on beyond Kerr models of black holes. [Preview Abstract] |
Monday, April 19, 2021 10:57AM - 11:09AM Live |
Q16.00002: Action integrals of eccentric, spinning black hole binaries at three-halves post-Newtonian order Sashwat Tanay, Gihyuk Cho, Leo Stein Accurate and efficient modeling of the dynamics of binary black holes (BBHs)is crucial for the detection of gravitational waves (GWs) emitted by them. General BBHs will have spinning black holes and a non-zero eccentricity. In arXiv:2012.06586, we evaluated four (out of five) action integrals of the system at 1.5 post-Newtonian (PN) order and showed that the system is integrable at 2PN (integrability implies the existence of action-angle variables). In this work, we compute the fifth action integral at 1.5PN which has been elusive until now. We also argue that the BBH system is a non-degenerate one in the context of canonical perturbation theory. This opens the door to computing action-angles at 2PN in the future using non-degenerate canonical perturbation theory and later add the 2.5PN radiation-reaction effects to the conservative and integrable 2PN system by applying the method of ‘variation of constants’ on the top of action-angle formalism, thus making the actions ‘vary in time’. This work can be seen as a stepping stone to obtaining closed-form solutions to the dynamics of spinning, eccentric BBHs which also shrink due to GW emission. [Preview Abstract] |
Monday, April 19, 2021 11:09AM - 11:21AM Live |
Q16.00003: Gravitational Waveforms from Compact Binary Systems in Einstein-Aether Gravity Fatemeh Taherasghari, Clifford Will Einstein-Aether gravity is an interesting alternative theory to general relativity. This theory has been constrained using solar system and binary pulsar observations, but we want to study strong-field constraints using gravitational waves. We analyze a three-parameter subset of the theory in which the gravitational and electromagnetic wave speeds are the same, as seen in the multimessenger merger GW170817. Our goal is to obtain gravitational waveforms suitable for GW pipelines to a suitably high post-Newtonian (PN) order. We study the PN expansion of Einstein-Aether gravity using direct integration of the relaxed Einstein equations, including the strong-field effects of compact bodies. We will report on the equations of motion of inspiralling compact binaries to 2.5 PN order.~ [Preview Abstract] |
Monday, April 19, 2021 11:21AM - 11:33AM Live |
Q16.00004: Detectibility of black hole modes from misaligned coalescences Halston Lim, Scott Hughes, Gaurav Khanna In recent work, we examined how different modes in the ringdown phase of a binary coalescence are excited as a function of the final plunge geometry. At least in the large mass-ratio limit, there is a clean mapping between angles describing the plunge and the amplitude of different quasi-normal modes which constitute the ringdown. In binaries where the black hole's spin and the orbital plane are misaligned, multiple harmonic modes can be significantly excited and imprinted on the observable waveform. In this talk, we discuss the prospect for inferring the plunge geometry from a spectrum of measured fundamental harmonic modes in various detection scenarios. [Preview Abstract] |
Monday, April 19, 2021 11:33AM - 11:45AM Live |
Q16.00005: Black Hole - Neutron Star Binary Mergers: The Imprint of Tidal Debris Pablo Laguna, Bhavesh Khamesra, Miguel Gracia The increase in the sensitivity of gravitational wave interferometers will bring more detections of binary black hole and double neutron star mergers. It will also very likely add many merger events of black hole - neutron star binaries. Distinguishing mixed binaries from binary black holes mergers for high mass ratios could be challenging because the neutron star coalesces with the black hole without experiencing significant disruption. To investigate the transition of the behavior of a mixed binary merger into one like a black hole binary, we present results from a series of merger simulations for different mass ratios. We show how the degree of disruption of the neutron star impacts the inspiral and merger dynamics, the properties of the final black hole, the accretion disk formed from the circularization of the tidal debris, the gravitational waves, and the strain spectrum and mismatches. The simulations use initial data constructed with a method that generalizes the Bowen-York initial data for black hole punctures to the case of neutron stars. [Preview Abstract] |
Monday, April 19, 2021 11:45AM - 11:57AM Live |
Q16.00006: Importance of mirror modes in binary black hole ringdown waveform Arnab Dhani The post-merger signal in binary black hole merger is described by linear, black-hole perturbation theory. Historically, this has been modeled using the dominant positive-frequency (corotating) fundamental mode. Recently, there has been a renewed effort in modeling the post-merger waveform using higher, positive-frequency overtones in an attempt to achieve greater accuracy in describing the waveform at earlier times using linear perturbation theory. It has been shown that the inclusion of higher overtones can shift the linear regime to the peak of (l,m)=(2,2) spherical harmonic mode. In this work, we show that the inclusion of negative-frequency (counterrotating) modes, called 'mirror' modes, extends the validity of linear perturbation theory to even earlier times, with far lower systematic uncertainties in the model in recovering the remnant parameters at these early times. A good description of the signal at early times also enables for a greater signal-to-noise ratio to be accumulated in the ringdown phase, thereby, allowing for a more accurate measurement of remnant parameters and tests of general relativity. [Preview Abstract] |
Monday, April 19, 2021 11:57AM - 12:09PM Live |
Q16.00007: Highly Eccentric EMRI Confusion Noise in LISA Aaron Johnson, Daniel Oliver, Daniel Kennefick Subthreshold extreme mass ratio inspirals (EMRIs), while not individually resolvable, collectively will constitute a noise source for LISA, the future space-based gravitational wave detector. Previous characterizations of this noise source have used a Newtonian order approximation. We seek to improve this estimate by using a frequency domain, Teukolsky based code which is available on GitHub (https://github.com/AaronDJohnson/fbtpoint) and is currently under active development. Additionally, we use the semi-relativistic approximation, sometimes called the numerical kludge. EMRI formation may lead to highly eccentric orbits, where a gravitational wave burst is emitted only upon closest approach to the black hole and will not be seen again in LISA’s lifetime. This type of subthreshold signal requires the computation of a large number of radial modes, some of which are negligible. Here we discuss strategies for skipping the negligible modes and the methods available to compute gravitational waves from highly eccentric EMRIs. [Preview Abstract] |
Monday, April 19, 2021 12:09PM - 12:21PM Live |
Q16.00008: Do external tidal perturbations induce chaos in EMRIs? David Bronicki, Leo Stein, Alejandro Cárdenas-Avendaño One of the important classes of targets for the LISA is extreme mass ratio inspirals (EMRIs), where long and accurate waveform modeling is necessary for detection and characterization. In particular, in modeling the dynamics of an EMRI, even small effects may need to be included, such as an external tidal field. The effects of such perturbations may manifest themselves as chaotic behavior at resonances. In this talk, we use a Newtonian analogue of a Kerr black hole to study the effect of an external tidal field on the dynamics and the gravitational waveform. We have developed a numerical framework that takes advantage of the separability of the system to evolve it with a symplectic splitting integrator that produces kludge waveforms to estimate the time scale over which the perturbation affects the dynamics. We compare this time scale with the inspiral time to gauge whether or not tidal effects will be relevant to the modeling of EMRI gravitational waves. [Preview Abstract] |
Monday, April 19, 2021 12:21PM - 12:33PM Live |
Q16.00009: High mass-ratio binary black hole simulations in numerical relativity Matthew Giesler, Mark Scheel, Vijay Varma, Saul Teukolsky We present high accuracy, fully nonlinear, numerical simulations of binary black holes up to a mass ratio of $q=30$. Using improved methods, we extend the capabilities of the numerical relativity code, SpEC, to simulate binary black holes with mass ratios beyond its previous limit of $q=10$. Such systems are potential sources for current gravitational wave detectors (i.e. LIGO) and are expected to be even more promising for future space-based detectors (e.g. LISA). The binaries are evolved through a minimum of $14$ orbits, providing a sufficient number of gravitational wave cycles to compare with predictions from approximate models. We present comparisons of our numerical waveforms with self-force predictions, the most promising perturbative scheme for extreme mass ratio inspirals. Additionally, we compare our waveforms with effective-one-body (EOB) approximants, which model the full waveform and are presumed to be valid at any mass ratio. [Preview Abstract] |
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