Program: GN-2016B-FT-7

The distribution of black hole (BH) masses are critical to constraining models of compact object formation and evolution. In all cases besides the recent gravitational wave detection, the mass of stellar-mass BHs comes from intensive spectroscopic and photometric campaigns. Thus, despite decades of research, the observational distributions of fundamental stellar-mass BH properties is still severely limited by small sample sizes. Moreover, the known sample may not accurately represent the larger population of so-far-undetected quiescent BHs, likely dominated by extremely low accretion rate systems. The goal of this proposal is the first confirmation and dynamical mass measurement of a stellar-mass BH candidate discovered in a quiescent low-mass X-ray binary. Using a novel approach, we have the opportunity to derive key binary parameters in a faint quiescent system using only properties of the strong H$\alpha$ emission line (i.e., at a fraction of the cost compared to past campaigns). With 1.4 hrs of total exposure time (including overheads), we propose to use GMOS-North OG515 band spectroscopy to detect the H$\alpha$ emission in this quiescent BH candidate. This detection will lead to a BH mass estimate for this system, which will have significant implications for our understanding of BH formation and evolution.