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 G09: Effects of Eccentricity, Precession, and Multipoles in Compact Binary Waveforms |
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Sponsoring Units: DGRAV Chair: Leo Tsukada, Pennsylvania State University Room: Conrad B/C - 2nd Floor |
Sunday, April 16, 2023 10:45AM - 10:57AM |
G09.00001: When orbital eccentricity and spin precession are kind of the same Davide Gerosa, Isobel M Romero-Shaw, Nicholas P Loutrel Eccentricity and spin precession are key observables in gravitational-wave astronomy, encoding precious information about the astrophysical formation of compact binaries together with fine details of the relativistic two-body problem. However, the two effects can mimic each other in the emitted signals, raising issues around their distinguishability. Since inferring the existence of both eccentricity and spin precession simultaneously is -- at present -- not possible, current state-of-the-art analyses assume that either one of the effects may be present in the data. In such a setup, what are the conditions required for a confident identification of either effect? We present simulated parameter inference studies in realistic LIGO/Virgo noise, studying events consistent with either spin precessing or eccentric binary black hole coalescences and recovering under the assumption that either of the two effects may be at play. We quantify how the distinguishability of eccentricity and spin precession increases with the number of visible orbital cycles, confirming that the signal must be sufficiently long for the two effects to be separable. The threshold depends on the injected source, with inclination, eccentricity, and effective spin playing crucial roles. In particular, for injections similar to GW190521, we find that it is impossible to confidently distinguish eccentricity from spin precession. |
Sunday, April 16, 2023 10:57AM - 11:09AM |
G09.00002: Tracing the evolution of eccentric precessing binary black holes: A hybrid approach Amitesh Singh, Khun Sang Phukon, Nathan K Johnson-McDaniel, Anuradha Gupta To make astrophysical statements, it is important to evolve a generic binary black hole between formation and coalescence. There exist codes to do this for quasi-circular precessing binaries, but not yet any for eccentric precessing binaries. Evolving a binary back in time lets us obtain its properties at formation. Evolving it forward in time using its properties at formation and feeding our predictions to numerical relativity fits lets us predict the merger remnant’s properties (though these fits are currently only available for precessing binaries with negligible eccentricities near the merger). In this project, we develop a code for the hybrid evolution of an eccentric precessing binary black hole. Here, we evolve the binary using equations averaged over an orbital period close to the merger and transition to equations averaged over a precessional period for better computational efficiency when the binary has a large separation. We empirically determine the transition frequency between the two types of evolution to obtain a given accuracy. Applying this code, we study how the parameters of eccentric binaries near merger are mapped to their spin tilts at large separations, which are useful parameters for studying the formation channels of binary black holes. |
Sunday, April 16, 2023 11:09AM - 11:21AM |
G09.00003: Systematic bias away from GR due to missing physics of spin precession, eccentricity, and higher modes in gravitational waveforms Rohit S Chandramouli, Nicolas Yunes Theory-agnostic tests of general relativity (GR) are possible due to the development of gravitational waveforms with parameterized deviations, such as in the post-Einsteinian (ppE) framework. Most implementations of the theory-agnostic tests utilize base GR waveforms (on top of which parameterized corrections are added) that exclude some form of GR physics, such as spin precession, eccentricity, and higher modes, in order to simplify the GR base model. In our work, we study systematic errors that point to a bias away from GR due to the neglect of GR physics. We inject synthetic data using waveform models rooted in GR with either spin precession (IMRPhenomPv3), eccentricity (TaylorF2e), or higher modes (IMRPhenomXHM), and perform parameter estimation using a quasi-circular, non-precessing, fundamental mode waveform model IMRPhenomD with a single non-GR ppE parameter in our recovery model. We determine the bias away from GR for different injected waveforms. In this talk, I will highlight our results which indicate the importance of developing parameterized waveforms that include effects of spin, eccentricity, and higher modes |
Sunday, April 16, 2023 11:21AM - 11:33AM |
G09.00004: Reassessing candidate eccentric binary black holes: Results with a model including higher-order modes Hector L Iglesias, Jacob A Lange, Imre Bartos, Shubhagata Bhaumik, Rossella Gamba, Gayathri Vivekananthaswamy, Aasim Z Jan, Ryan Nowicki, Richard O'Shaughnessy, Deirdre M Shoemaker, Raghav Venkataramanan, Katelyn Wagner The detection of orbital eccentricity for a binary black hole system via gravitational waves is a key signature to distinguish between the possible binary origins. The identification of eccentricity has been difficult so far due to the limited availability of eccentric gravitational waveforms over the full range of black hole masses and eccentricities. For the first time using the TEOBResumSGeneral model, we have evaluated the eccentricity of 5 black hole mergers detected by the LIGO and Virgo observatories. This model accounts for large eccentricities and incorporates higher-order gravitational emission critical to model emission from highly eccentric orbits. The binaries have been selected due to previous hints of eccentricity or due to their unusual mass and spin. In this talk, we will present our findings and provide an update on recent work done on events from the O2 and O3 observing runs. |
Sunday, April 16, 2023 11:33AM - 11:45AM |
G09.00005: Astrophysical Implications of Eccentric Black Hole Mergers Michael J Zevin Eccentricity in binary black hole mergers is a clear sign that some kind of dynamical processes were responsible for the coalescence of the binary. In this talk, I will overview eccentricity predictions from various dynamical formation channels, and what an eccentric gravitational-wave detection would imply for binary black hole formation channels. Given the robust predictions for the eccentricity distribution in dense star clusters, I will show how a single confident eccentric detection (or lack thereof) in the upcoming observing run of the LIGO—Virgo—KAGRA network will allow for stringent constraints on the fraction of merging systems that have a dynamical origin. I will also discuss the redshift evolution of the eccentricity distribution, which will be apparent with next-generation gravitational-wave detectors, and the astrophysical quandaries the quantification of this effect will answer. |
Sunday, April 16, 2023 11:45AM - 11:57AM |
G09.00006: Multitimescale dynamics of precessing binary black holes: faster, more accurate, and including more physics Giulia Fumagalli, Davide Gerosa Understanding the dynamics of binary black holes is crucial to extract information from gravitational-wave data. By now, a consistent amount of effort has been put into exploring the phenomenology of black-hole binaries in the Post-Newtonian regime that evolve on quasi-circular orbits and undergo spin precession. We present substantial advances in this area using a multi-timescale approach to the binary dynamics. In particular, this includes a reparametrization of spin precession that is regular across the entire parameter space, an innovative numerical implementation that is orders of magnitude faster, and an initial exploration of the interplay between spin precession and eccentricity. |
Sunday, April 16, 2023 11:57AM - 12:09PM |
G09.00007: On the effective action of compact objects from full GR Neev Khera, Eric Poisson Calculations involving compact objects, such as post-Newtonian (PN) or self-force calculations, are greatly simplified by treating the body as point particles. Going to higher orders in compactness introduces successively higher order multipolar structure to the compact object. Effective field theory methods provide a systematic tool to account for these finite size effects, by using an effective world-line action to describe the objects. This effective action has proven to work very effectively, but is a postulate that has not been derived from first principles. In this talk, we present such an effective action for compact objects in from first principles in General Relativity. For a spherically symmetric body, we show how a multipolar decomposition of the action recovers the traditional effective field theory action. In particular, this derivation provides a geometrical understanding of the effective action. Moreover, it shows us how the nature of the horizon leads to the vanishing of the Love number for Schwarzschild black holes. Additionally, it clarifies the relation between the Love numbers that enter PN calculations (via the effective action) and the Love numbers computed from the metric of a tidally deformed object.
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Sunday, April 16, 2023 12:09PM - 12:21PM |
G09.00008: Surrogate model for gravitational waveforms from spinning binary black hole coalescences using perturbation theory Ritesh Bachhar, Gaurav Khanna, Katie Rink, Kevin Gonzalez-Quesada, Nur-E-Mohammad Rifat, Scott E Field, Scott A Hughes, Tousif Islam, Vijay Varma Accurate inspiral-merger-ringdown waveform models are crucial for the detection and characterization of gravitational wave sources such as binary black hole (BBH) mergers. Surrogate models for gravitational waveforms from non-spinning BBH mergers trained with point-particle blackhole perturbation theory (ppBHPT) waveform (BHPTNRSur1dq1e4) have proved to be efficient for comparable and large mass ratio configurations. In this work, we extend the BHPTNRSur1dq1e4 surrogate model to include spin on the primary black hole, aligned or anti-aligned with the orbital angular momentum of the binary. Our model is trained with ppBHPT waveforms covering mass ratios from q=3 to q=1000, spin magnitudes on the primary black hole up to 0.8, and includes a total of $11$ positive $m$ modes up to $ell=5$. Similar to the BHPTNRSur1dq1e4 model, we find that our model works surprisingly well in the comparable mass ratio limit after we perform a simple calibration against the spin-aligned numerical relativity waveforms. Finally, we discuss challenges and possible modeling strategies to handle precessing binary systems. |
Sunday, April 16, 2023 12:21PM - 12:33PM |
G09.00009: Motion of a spinning particle under the conservative piece of the self-force is Hamiltonian to first order in mass and spin Francisco M Blanco, Eanna E Flanagan The two body body problem in general relativity is of great theoretical and observational interest, and can be studied in the post-Newtonian, post-Minkowskian and small mass ratio approximations, as well as with effective one body and fully numerical techniques. When gravitational wave dissipation is turned off, the motion is expected to form a Hamiltonian dynamical system. This had been established to various order in the post-Newtonian and post-Minkowskian approximations. In a previous work, we showed that the motion of a point particle under the conservative (time even) piece of the first-order self force is Hamiltonian in any stationary spacetime, and found an explicit expression for the Hamiltonian in terms of a Greens function. In this work we extend this result for spinning particles, to first order in mass and spin. We also show progress towards developing a new formalism to extend this result to second order in mass. |
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