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

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.

Authors: Tuan Yi, Mouyuan Sun, and Wei-Min Gu

(accepted for publication in Astrophysical Journal)

Figure caption:

The number of detectable candidates as a function of distance. Upper panel: low-resolution, non-time-domain survey; lower panel: medium-resolution, time-domain survey.