The impact of mass-transfer physics on the observable properties of field binary black hole populations

Abstract

We study the impact of mass-transfer physics on the observable properties of binary black hole populations that formed through isolated binary evolution. We used the POSYDON framework to combine detailed MESA binary simulations with the COSMIC population synthesis tool to obtain an accurate estimate of merging binary black hole observables with a specific focus on the spins of the black holes. We investigate the impact of mass-accretion efficiency onto compact objects and common-envelope efficiency on the observed distributions of the effective inspiral spin parameter χeff, chirp mass Mchirp, and binary mass ratio q. We find that low common envelope efficiency translates to tighter orbits following the common envelope and therefore more tidally spun up second-born black holes. However, these systems have short merger timescales and are only marginally detectable by current gravitational-wave detectors as they form and merge at high redshifts (z ∼ 2), outside current detector horizons. Assuming Eddington-limited accretion efficiency and that the first-born black hole is formed with a negligible spin, we find that all non-zero χeff systems in the detectable population can come only from the common envelope channel as the stable mass-transfer channel cannot shrink the orbits enough for efficient tidal spin-up to take place. We find that the local rate density (z ≃ 0.01) for the common envelope channel is in the range of ∼17–113 Gpc−3 yr−1, considering a range of αCE ∈ [0.2, 5.0], while for the stable mass transfer channel the rate density is ∼25 Gpc−3 yr−1. The latter drops by two orders of magnitude if the mass accretion onto the black hole is not Eddington limited because conservative mass transfer does not shrink the orbit as efficiently as non-conservative mass transfer does. Finally, using GWTC-2 events, we constrained the lower bound of branching fraction from other formation channels in the detected population to be ∼0.2. Assuming all remaining events to be formed through either stable mass transfer or common envelope channels, we find moderate to strong evidence in favour of models with inefficient common envelopes.

Joint constraints on the field-cluster mixing fraction, common envelope efficiency, and globular cluster radii from a population of binary hole mergers via deep learning

“…There are many valuable routes by which this present analysis may be expanded in the future. As features in the BBH spin distribution begin to be robustly resolved [4,[84][85][86][87][88], future analyses can incorporate spin measurements alongside mass and redshift. Future measurements of orbital eccentricity may additionally help to discriminate between formation scenarios [51,89,90].…”

The role of mass transfer and common envelope evolution in the formation of merging binary black holes

“…If the second phase of MT is stable, depending on the mass ratio of the system, a phase of nonconservative mass transfer can harden the binary without the need for CE evolution, as van den Heuvel et al (2017) argue, thus potentially allowing for the formation of compact object binaries that can merge within a Hubble time. Recent studies have claimed that the contribution from stable mass transfer to the observed sample of merging binary BHs can be comparable or even larger than those that formed through CE evolution (Neijssel et al 2019;Bavera et al 2021).…”

“…A large number of formation scenarios have been proposed to form the merging binary BHs observed by ground-based detectors. Scenarios that involve binary systems include evolution through a common-envelope (CE) phase (e.g., Paczynski 1976;van den Heuvel 1976;Tutukov & Yungelson 1993;Belczynski et al 2002;Dominik et al 2012;Stevenson et al 2017;Giacobbo & Mapelli 2018), chemically homogeneous evolution Marchant et al 2016;du Buisson et al 2020;Riley et al 2021), stable mass transfer (MT; van den Heuvel et al 2017;Neijssel et al 2019;Bavera et al 2021) and Population III stars (Belczynski et al 2004; Kinugawa et al 2014;Inayoshi et al 2017). Dynamical processes are also predicted to contribute to the observed sample, including isolated triple systems (Thompson 2011;Antonini et al 2017;Vigna-Gómez et al 2021) and interactions in globular (e.g., Kulkarni et al 1993;Sigurdsson & Hernquist 1993;Portegies Zwart & McMillan 2000;Rodriguez et al 2015;Di Carlo et al 2019) and nuclear clusters (Antonini & Perets 2012).…”

Probing the progenitors of spinning binary black-hole mergers with long gamma-ray bursts

“…Although several formation pathways of coalescing BBHs have been proposed in the literature, recent works suggest that the evolution of isolated binaries dominates the underlying, local merging BBH population (Zevin et al 2021;Franciolini et al 2021;Bavera et al 2021a) over dynamical formation in dense stellar environments (e.g., Rodriguez et al 2019;Antonini et al 2019) or primordial merging BBHs (e.g., Sasaki et al 2016;De Luca et al 2020). However, there is not yet enough observational evidence to make a definite conclusion regarding the origin of BBHs.…”