Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session B17: Black Holes and OrbitsRecordings Available
|
Hide Abstracts |
Sponsoring Units: DGRAV Chair: Alexandru Dima, University of Illinois at Urbana-Champaign Room: Sky Lobby |
Saturday, April 9, 2022 10:45AM - 10:57AM |
B17.00001: Paths to the Final Black Hole Pablo Laguna, Deirdre M Shoemaker, Miguel Gracia-Linares, Jacob A Lange, Galina Bouyer, Oriol Ricart Black hole uniqueness theorems ensure that, regardless of the details of the merging holes, the final black hole settles down to a Kerr black hole. As a consequence, the final state is characterized by two quantities: the mass and spin of the final black hole. This path-independence to the final state comes at the same time with a path-specificity: The gravitational waves emitted during the inspiral are strongly sensitive to the characteristics of the binary system. In other words, there is strong correlation between the emission of gravitational radiation and the path to the final black hole. We will present results of the degree of degeneracy of the path to approach the final state for non-processing binary black hole mergers and show LIGO's ability to disentangle this degeneracy. |
Saturday, April 9, 2022 10:57AM - 11:09AM |
B17.00002: Transition from inspiral to plunge in numerical relativity simulations Sergi Navarro Albalat We consider the evolution of the energy and angular momentum of quasicircular binaries during the transition to plunge in numerical simulations. By fitting the energy and angular momentum as functions of the frequency across mass ratios q=1 to q=20 we explore how well we can recover the small mass-ratio perturbative predictions. In particular we compare against two predictions for the binding energy: the prediction from the first law of binary mechanics (adiabatic) and the prediction from a two-timescale evolution (post-adiabatic). For frequencies close to the ISCO, fitting to an expansion in integer powers of the mass ratio becomes ineffective. When that is the case, we show that an expansion including fractional powers of the mass-ratio is more effective at recovering the leading small mass-ratio prediction. |
Saturday, April 9, 2022 11:09AM - 11:21AM |
B17.00003: Perturbation of Binary Orbits in Hierarchical Triple Systems to Dotriocontopole Order Landen Conway We analyze the secular evolution of hierarchical triple body systems in Newtonian gravity to dotriocontopole order. We expand the Newtonian equations of motion in powers of the semimajor axes a/A of the inner and outer orbits. The equations of motion take the effective form of two one-body Keplerian orbits that are perturbed by a series of multipolar perturbations that are labeled as (a/A)3 quadrupole, (a/A)4 octupole, (a/A)5 hexadecapole, (a/A)6 dotriocontopole and so on. We use the Lagrange Planetary equations and a two timescale method to obtain secular evolutions of the orbital elements. Effects of dotriocontopole order arise from two places; the (a/A)6 terms in the expansion of the equations of motion, and higher order, "quadrupole-squared" effects arising from quadrupole perturbations feeding back into quadrupole terms, and from corrections to the procedure for averaging over both orbital periods. |
Saturday, April 9, 2022 11:21AM - 11:33AM |
B17.00004: Motion of a hyperelastic sphere in Schwarzschild spacetime Nishita Jadoo, J D Brown We simulate the motion of a hyperelastic sphere in a background Schwarzschild spacetime using a finite element discretization and a Lagrangian formulation of the equations of motion. We set the initial spacetime coordinates and velocities of the nodes of the discretized sphere on a constant coordinate time hypersurface such that the tidal and elastic forces are balanced. We compute the coordinates and velocities of the center of mass in a Fermi normal frame (FNFnode) centered about a fiducial node. We then compute a geodesic that starts out with the same spacetime coordinates and velocities as the center of mass. Next, we construct a Fermi normal frame (FNFgeo) that is carried along the geodesic. The metric in each Fermi normal frame is nearly flat assuming that the size of the sphere is small compared to the curvature of spacetime. We simulate both a close encounter orbit as well as a radial plunge, and observe the sphere as it deforms, oscillates and rotates in the FNFgeo. The observed oscillation frequency agrees with the lowest-frequency ellipsoidal mode for small oscillations of a free solid elastic sphere. We integrate the stress-energy-momentum tensor in the FNFgeo to obtain the total momentum and total angular momentum about the geodesic and compute the spin. Finally, we observe how the spin and elastic energy change as the sphere interacts with the black hole. |
Saturday, April 9, 2022 11:33AM - 11:45AM |
B17.00005: Residual eccentricity of inspiralling orbits at the gravitational-wave detection threshold: Accurate estimates using post-Newtonian theory Alexandria Tucker, Clifford M Will To date, gravitational wave detections have been predominantly from quasi-circular binary mergers. However, a significant percentage of mergers could have measurable residual eccentricities, resulting from external perturbations or short timescales between formation and merger. Understanding how the orbits of such binaries evolve could aid in creating eccentric gravitational waveform templates and provide astrophysical information about the environment and formation channels of these systems. We have used equations of motion containing gravitational radiation-reaction terms through 4.5 post-Newtonian and lowest order tail terms to calculate the late-time eccentricities of inspiralling binary systems of non-spinning compact bodies as they cross the detection threshold of ground-based gravitational-wave interferometers. We found that the final eccentricities are systematically smaller than those predicted by the leading quadrupole approximation and are independent of the ratio of the masses of the compact bodies. Additionally, we developed an analytic formula for the late-time eccentricity that accurately accounts for the higher-order post-Newtonian effects, generalizing a formula derived by Peters and Mathews. We will discuss these results. |
Saturday, April 9, 2022 11:45AM - 11:57AM |
B17.00006: Action-angle variables of a binary black-hole with arbitrary eccentricity, spins, and masses at 1.5 post-Newtonian order Sashwat Tanay, Leo C Stein, Jose T Galvez Ghersi, Gihyuk Cho Accurate and efficient modeling of the dynamics of binary black holes (BBHs) is crucial to their detection through gravitational waves (GWs), with LIGO/Virgo/KAGRA, and LISA in the future. Solving the dynamics of a BBH system with arbitrary parameters without simplifications (like orbit- or precession-averaging) in closed-form is one of the most challenging problems for the GW community. One potential approach is using canonical perturbation theory which constructs perturbed action-angle variables from the unperturbed ones of an integrable Hamiltonian system. Having action-angle variables of the integrable 1.5 post-Newtonian (PN) BBH system is therefore imperative. In this talk, we report on our latest results on the derivation of all five action variables and frequencies of a BBH system with arbitrary eccentricity, masses, and spins, at 1.5PN order. I also discuss how to construct closed-form solutions of such systems using action-angle variables at 1.5PN. All this is done using a novel method of extending the phase space by introducing unmeasurable phase space coordinates. This lays the groundwork to analytically solve the conservative dynamics of the BBH system with arbitrary masses, spins, and eccentricity, at higher PN order, by using canonical perturbation theory. |
Saturday, April 9, 2022 11:57AM - 12:09PM |
B17.00007: Spin precession and nutation of isolated stellar-mass black-hole binaries Nathan A Steinle, Michael Kesden The spins of binary black holes (BBHs) that originate from isolated binary stars are determined by the interplay of various phenomena. The possibility for these BBHs to experience spin precession, which modulates the gravitational waves (GWs) they emit, also depends on these phenomena. If isolated BBHs have negligible spins, then spin precession would be greatly suppressed. In previous work, we identified regions of the parameter space that may produce BBHs with large misalignments from natal kicks and high spin magnitudes from three mechanisms - tides, accretion, or inheritance via minimal core-envelope coupling. Here, we explore the precession and nutation of such BBHs. We find that precession is possible from natal kicks and that nutation depends on the spin-up mechanisms. Small spins from maximal core-envelope coupling ensure that BBHs only exhibit precession, except when tides synchronize both spins of the binary to allow for nutation. While accretion can produce high spin, it does not allow for nutation as it does not occur for both binary components in any of our pathways. Generally, nutation is difficult to achieve without minimal core-envelope coupling, implying that a measurement of nutation from GWs might suggest isolated origin with minimal core-envelope coupling. |
Saturday, April 9, 2022 12:09PM - 12:21PM |
B17.00008: The geometry of deformed isolated horizons and quasi-local perturbation theory Ariadna Ribes Metidieri, Béatrice P Bonga, Badri Krishnan It is generally believed that tidal deformations of a black hole in an external field, measured using the gravitational field multipoles, vanish. However, this does not mean that the black hole horizon is not deformed. In this talk, I shall discuss the deformations of a black hole horizon in the presence of an external field using a new method based on the characteristic initial value formulation. Unlike standard methods, the starting point here is the black hole horizon itself. The presence of the companion binary responsible for the tidal deformation is encoded on the geometry of the spacetime in the vicinity of the horizon, which is obtained by integrating the Einstein fields equations analytically outwards starting from the horizon. This method yields a powerful reformulation of black hole perturbation theory in a neighborhood of the horizon, which is quasi-local, geometrical, and completely general. For instance, by specializing the horizon geometry to be a perturbation of Kerr yields the metric for a tidally deformed Kerr black hole with arbitrary spin. In this talk, I will discuss the essential ideas in the application of the characteristic initial value formalism to black hole perturbation theory, and summarize the latest results. |
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