Gaia May Detect Hundreds of Well-characterized Stellar Black Holes

Abstract

Detection of black holes (BHs) with detached luminous companions (LCs) can be instrumental in connecting the BH properties with their progenitors since the latter can be inferred from the observable properties of the LC. Past studies showed the promise of Gaia astrometry in detecting BH–LC binaries. We build on these studies by (1) initializing the zero-age binary properties based on realistic, metallicity-dependent star formation history in the Milky Way (MW); (2) evolving these binaries to current epoch to generate realistic MW populations of BH–LC binaries; (3) distributing these binaries in the MW, preserving the complex age–metallicity-Galactic position correlations; (4) accounting for extinction and reddening using three-dimensional dust maps; and (5) examining the extended Gaia mission’s ability to resolve BH–LC binaries. We restrict ourselves to detached BH–LC binaries with orbital period P orb ≤ 10 yr such that Gaia can observe at least one full orbit. We find that (1) the extended Gaia mission can astrometrically resolve ∼30–300 detached BH–LC binaries depending on our assumptions of supernova physics and astrometric detection threshold; (2) Gaia’s astrometry alone can indicate BH candidates for ∼10–100 BH–LC binaries by constraining the dark primary mass ≥3 M ⊙; and (3) distributions of observables, including orbital periods, eccentricities, and component masses, are sensitive to the adopted binary evolution model and hence can directly inform binary evolution models. Finally, we comment on the potential to further characterize these BH binaries through radial velocity measurements and observation of X-ray counterparts.

No Peaks without Valleys: The Stable Mass Transfer Channel for Gravitational-wave Sources in Light of the Neutron Star–Black Hole Mass Gap

“…At the same time, many of these candidates are controversial (see El-Badry et al 2022, and references therein), and the existence of a gap in the remnant mass distribution remains an open question to this day. A large increase in BH mass measurements is expected from both GW observations (Abbott et al 2018), as well as from detections of BH+mainsequence systems in the Gaia Data Release 3 (e.g., Breivik et al 2017;Mashian & Loeb 2017;Andrews et al 2019;Langer et al 2020;Andrews et al 2021;Chawla et al 2022;Halbwachs et al 2022;Janssens et al 2022). Hence, we are hopeful that near-future detection surveys will provide evidence in favor of or against the existence of a NS-BH mass gap.…”

A red giant orbiting a black hole

“…The intrinsic period distribution of BH + normal star binaries is quite uncertain, but some models predict that it will rise steeply at 𝑃 orb 10 years, where the BH binaries will have formed without the BH progenitor ever having overflowed its Roche lobe (e.g. Breivik et al 2017;Chawla et al 2022). This prediction depends sensitively on the strength of BH natal kicks, which can easily unbind the widest binaries.…”

No peaks without valleys: The stable mass transfer channel for gravitational-wave sources in light of the neutron star-black hole mass gap

“…At the same time, many of these candidates are controversial (see El-Badry et al 2022, and references therein), and the existence of a gap in the remnant mass distribution remains an open question to this day. A large increase in BH mass measurements is expected from both GW observations (Abbott et al 2018), as well as from detections of BH + main sequence systems in the Gaia data release 3 (e.g., Breivik et al 2017;Mashian & Loeb 2017;Andrews et al 2019;Langer et al 2020;Andrews et al 2021;Chawla et al 2022;Janssens et al 2022;Halbwachs et al 2022). Hence we are hopeful that near future detection surveys will provide evidence in favour or against the existence of a NS-BH mass gap.…”