Rates of compact object coalescences

Abstract

Gravitational-wave detections are enabling measurements of the rate of coalescences of binaries composed of two compact objects—neutron stars and/or black holes. The coalescence rate of binaries containing neutron stars is further constrained by electromagnetic observations, including Galactic radio binary pulsars and short gamma-ray bursts. Meanwhile, increasingly sophisticated models of compact objects merging through a variety of evolutionary channels produce a range of theoretically predicted rates. Rapid improvements in instrument sensitivity, along with plans for new and improved surveys, make this an opportune time to summarise the existing observational and theoretical knowledge of compact-binary coalescence rates.

Stable Mass Transfer Can Explain Massive Binary Black Hole Mergers with a High-spin Component

“…Since the discovery of the first gravitational-wave source GW150914 (Abbott et al 2016), there have been about 90 binary black hole (BBH) mergers reported to date (Abbott et al 2019(Abbott et al , 2021a(Abbott et al , 2021bNitz et al 2021). A number of formation channels have been put forward to explain the origin of BBH mergers (see Mandel & Broekgaarden 2022 for a review). In the isolated binary evolution channel, compact BH binaries are formed either through common-envelope evolution (e.g., Tutukov & Yungelson 1993;Lipunov et al 1997;Voss & Tauris 2003;Belczynski et al 2016;Eldridge & Stanway 2016;Stevenson et al 2017;Khokhlov et al 2018;Kruckow et al 2018;Spera et al 2019;Breivik et al 2020;Zevin et al 2020;Broekgaarden et al 2021) or through stable mass transfer between the BH and its companion (e.g., van den Heuvel et al 2017;Neijssel et al 2019;Bavera et al 2021;Gallegos-Garcia et al 2021;Shao & Li 2021).…”

The Redshift Evolution of the Binary Black Hole Merger Rate: A Weighty Matter

“…Our estimate of the total intrinsic BBH merger rate is R 0 = 73 Gpc −3 yr −1 at redshift zero, and R 0.2 = 94 Gpc −3 yr −1 at z = 0.2. Although this rate prediction is not an outlier in the recent review of local BBH merger rate predictions for isolated binaries from Mandel & Broekgaarden (2022), it is a factor of 2-5 higher than the most recent estimates from the LIGO/ Virgo/Kagra collaboration (R 0.2 = 17.3-45 Gpc −3 yr −1 ; see Abbott et al 2021b). Our setup and binary physics assumptions are similar to those in Neijssel et al (2019), who predict a local rate of R 0 ≈ 22 Gpc −3 yr −1 .…”

“…The variety of physics involved is vast, and hence the span of predictions for merging BBH properties is equally large. See also Mapelli et al (2021) and Mandel & Farmer (2022) for reviews of proposed formation channels, and Mandel & Broekgaarden (2022) for a review of predictions for the merger rates from said formation channels. Below, we summarize findings for other formation channels, with an emphasis on delay-time predictions, the slope of R BBH (z), and the predicted mass distribution (see also Fishbach & Kalogera 2021 for an overview of delay-time predictions from several different formation channels).…”

Establishing the Nonprimordial Origin of Black Hole–Neutron Star Mergers

“…The vast majority of these events are binary black holes (BH-BH) with components in the ∼10-100 M e mass range (Abbott et al 2021a). While a variety of conventional astrophysical stellar evolution channels could contribute to such events (see, e.g., Mandel & Farmer 2022;Mandel & Broekgaarden 2022 for reviews), comprehensive understanding of their origin is still lacking and could be connected with central puzzles of modern physics, such as the nature of dark matter (DM).…”