Eccentric Black Hole Mergers in Dense Star Clusters: The Role of Binary–Binary Encounters

By Michael Zevin, J. Samsing, C. Rodriguez, C. Haster, E. Ramirez-Ruiz. Astrophysical Journal, 2018

205 citations recorded by the source corpus.

We present the first systematic study of strong binary–single and binary–binary black hole (BH) interactions with the inclusion of general relativity. By including general relativistic effects in the equations of motion during strong encounters, the dissipation of orbital energy from the emission of gravitational waves (GWs) can lead to captures and subsequent inspirals with appreciable eccentricities when entering the sensitive frequency ranges of the LIGO and Virgo GW detectors. It has been shown that binary–single interactions significantly contribute to the rate of eccentric mergers, but no studies have looked exclusively into the contribution from binary–binary interactions. To this end, we perform binary–binary and binary–single scattering experiments with general relativistic dynamics up through the 2.5 post-Newtonian order included, both in a controlled setting to gauge the importance of non-dissipative post-Newtonian terms and derive scaling relations for the cross section of GW captures, as well as experiments tuned to the strong interactions from state-of-the art globular cluster (GC) models to assess the relative importance of the binary–binary channel in facilitating GW captures and the resultant eccentricity distributions of inspiral from channel. Although binary–binary interactions are 10–100 times less frequent in GCs than binary–single interactions, their longer lifetime and more complex dynamics leads to a higher probability for GW captures to occur during the encounter. We find that binary–binary interactions contribute 25%–45% of the eccentric mergers that occur during strong BH encounters in GCs, regardless of the properties of the cluster environment. The inclusion of higher multiplicity encounters in dense star clusters therefore have major implications on the predicted rates of highly eccentric binaries potentially detectable by the LIGO/Virgo network. Because gravitational waveforms of eccentric inspirals are distinct from those generated by merging binaries that have circularized, measurements of eccentricity in such systems would highly constrain their formation scenario.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/768991fe780efb63ceadaa799f9e9351141d37b8

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

GW190521: Orbital Eccentricity and Signatures of Dynamical Formation in a Binary Black Hole Merger Signal (2020, background): “…Bouffanais et al. 2019; Rodriguez et al. 2019; Fragione et al. 2020a, 2020b), isotropically distributed spin tilt angles (Rodriguez et al. 2016; Talbot & Thrane 2017), and nonzero orbital eccentricities (Zevin et al. 2017, 2019a; Rodriguez et al. 2018a; Gondán & Kocsis 2019; Samsing et al. 2018).”
GW231123: A Binary Black Hole Merger with Total Mass 190–265 M⊙ (2025, unknown): “…formed in dense environments may retain residual eccentricity in the sensitive band of current GW detectors (Samsing 2018; Rodriguez et al. 2018; Zevin et al. 2019; Chattopadhyay et al. 2023; Dall’Amico et al. 2024) or merge following a dynamical capture (Gold & Br¨ugmann 2013; East et al.…”
Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes (2017, background): “…Chatterjee et al. 2017; Mapelli 2016; Hurley et al. 2016; Rodriguez et al. 2016a; VanLandingham et al. 2016; Askar et al. 2017; Arca-Sedda & Capuzzo-Dolcetta 2019; Samsing 2018; Morawski et al. 2018; Banerjee 2018; Di Carlo et al. 2019; Zevin et al. 2019; Rodriguez et al. 2018; Perna et al. 2019).”
Tests of general relativity with the binary black hole signals from the LIGO-Virgo catalog GWTC-1 (2019, unknown): “[62] M.”