Mining for Candidates of Galactic Stellar-mass Black Hole Binaries with LAMOST

TL;DR

This study predicts over 400 stellar-mass black hole binary candidates in the Milky Way using LAMOST spectroscopic data, aiding in understanding black hole populations and stellar evolution.

Contribution

It introduces a simulation-based method to identify potential black hole binaries in LAMOST data, estimating their numbers and characteristics.

Findings

Over 400 candidates from low-resolution surveys.

50-350 candidates from ongoing medium-resolution surveys.

Nearly half have a mass function exceeding 3 solar masses.

Abstract

We study the prospects of searching for black hole (BH) binary systems with a stellar-mass BH and a non-compact visible companion, by utilizing the spectroscopic data of Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). We simulate the Galactic BH binary population and determine its optical visibility by considering the stellar synthetic population model and the distributions of binary orbital parameters. By convolving the visibility of BH binaries with the LAMOST detection sensitivity, we predict that $\gtrsim$ 400 candidate BH binaries can be found by the low-resolution, non-time-domain survey, and $\sim$ 50-350 candidates by the LAMOST ongoing medium-resolution, time-domain spectroscopic survey. Most of the candidates are short-period (0.2-2 days) binaries with M-, K-, G-, or F-type companions, in which $\sim$ 47% have a mass function (the lower limit of the BH mass) larger than 3 $M_{\odot}$. By complementing the LAMOST spectroscopic data with other photometric/spectroscopic surveys or follow-up observations, these candidates could be confirmed. Therefore, by exploring the LAMOST data, we can enlarge the sample of dynamically confirmed BH binaries significantly, which can improve our understanding of the mass distribution of BHs and the stellar evolution model.