THE FORMATION OF ECCENTRIC COMPACT BINARY INSPIRALS AND THE ROLE OF GRAVITATIONAL WAVE EMISSION IN BINARY–SINGLE STELLAR ENCOUNTERS

By J. Samsing, M. MacLeod, E. Ramirez-Ruiz. 2013

217 citations recorded by the source corpus.

The inspiral and merger of eccentric binaries leads to gravitational waveforms distinct from those generated by circularly merging binaries. Dynamical environments can assemble binaries with high eccentricity and peak frequencies within the LIGO band. In this paper, we study binary–single stellar scatterings occurring in dense stellar systems as a source of eccentrically inspiraling binaries. Many interactions between compact binaries and single objects are characterized by chaotic resonances in which the binary–single system undergoes many exchanges before reaching a final state. During these chaotic resonances, a pair of objects has a non-negligible probability of experiencing a very close passage. Significant orbital energy and angular momentum are carried away from the system by gravitational wave (GW) radiation in these close passages, and in some cases this implies an inspiral time shorter than the orbital period of the bound third body. We derive the cross section for such dynamical inspiral outcomes through analytical arguments and through numerical scattering experiments including GW losses. We show that the cross section for dynamical inspirals grows with increasing target binary semi-major axis a and that for equal-mass binaries it scales as a2/7. Thus, we expect wide target binaries to predominantly contribute to the production of these relativistic outcomes. We estimate that eccentric inspirals account for approximately 1% of dynamically assembled non-eccentric merging binaries. While these events are rare, we show that binary–single scatterings are a more effective formation channel than single–single captures for the production of eccentrically inspiraling binaries, even given modest binary fractions.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/88b44b1c6a0947f669479a938c09c7e58e699546

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In Astronomy and Astrophysics

1. Michela Mapelli
2. Ilya Mandel
3. F. Antonini
4. D. Holz
5. F. Rasio
6. Maya Fishbach
7. N. Giacobbo
8. Mario Spera

Citations in the corpus

• Black Hole Mergers From Globular Clusters Observable by LISA I: Eccentric Sources Originating From Relativistic N-body Dynamics (2018, methodology): “…argued by Samsing (2017), this population originates from GW capture mergers forming in chaotic threebody interactions (e.g., Gültekin et al. 2006; Samsing et al. 2014) during classical hardening, which explains why all recent Newtonian N-body studies have failed in resolving the correct fraction.”
• Constraining Stellar-mass Black Hole Mergers in AGN Disks Detectable with LIGO (2017, background): “…dynamical binary hardening (Antonini & Rasio 2016; Rodriguez et al. 2016b), or capture from single–single (O’Leary et al. 2009) and binary–single encounters (Samsing et al. 2014), a dense nuclear disk of gas can greatly accelerate the rate of BHB formation and merger (McKernan et al. 2012, 2014).”
• Eccentric Black Hole Mergers in Dense Star Clusters: The Role of Binary–Binary Encounters (2018, methodology): “• GW CAPTURE: Emission of GWs lead to a rapid inspiral and merger of two component BHs during the RI (Samsing et al. 2014).”
• Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo (2018, background): “Binary eccentricity is also a potentially observable quantity in BBH mergers, with several channels having imprints on eccentricity distributions (e.g.,Quinlan & Shapiro 1987; Kocsis & Levin 2012; Samsing et al. 2014; Fragione et al. 2018; Rodriguez et al. 2018a).”
• ASTROPHYSICAL IMPLICATIONS OF THE BINARY BLACK HOLE MERGER GW150914 (2016, background): “A small fraction of BBHs may form through triple stars in globular clusters and potentially maintain significant eccentricities until the merger (Samsing et al. 2014; Antonini et al. 2015).”
• Deep Learning for Real-time Gravitational Wave Detection and Parameter Estimation with Advanced LIGO Data (2017, methodology): “, the most sensitive search algorithm used by LIGO, targets only a 3D parameter space (spin-aligned binaries on quasi-circular orbits) [8, 9, 10]—a subset of the over 8D parameter space of GW signals [11, 12, 13, 14]. Extending these searches to target eccentric [15,13,16,17] or spin-precessing BBHs”
• DYNAMICAL FORMATION OF THE GW150914 BINARY BLACK HOLE (2016, background): “Note that we do not consider relativistic effects, such as post-Newtonian corrections to close dynamical encounters (Samsing et al. 2014) or long-term secular effects, such as Lidov–Kozai and gravitational-wave emission in BH triple systems (Antonini et al. 2014, 2016).”
• BLACK HOLE MERGERS AND BLUE STRAGGLERS FROM HIERARCHICAL TRIPLES FORMED IN GLOBULAR CLUSTERS (2015, methodology): “Assuming that 1% of these mergers will have a finite eccentricity within the aLIGO band (Samsing et al. 2014) results in a negligible contribution of binary-single encounters to the the population of eccentric inspirals when compared to the triple channel.”
• Eccentric Black Hole Gravitational-wave Capture Sources in Galactic Nuclei: Distribution of Binary Parameters (2017, background): “Finally, binary BHs forming in clusters through binary–single interactions may also produce LIGO/VIRGO sources with non-negligible eccentricities (Samsing et al. 2014; Samsing & Ramirez-Ruiz 2017; Samsing 2017; Samsing et al. 2018b).”