Program: GN-2025A-Q-205

The majority of white dwarf mergers have a combined mass below the Chandrasekhar limit. Recent observations demonstrate that hot/warm DQ white dwarfs with carbon atmospheres have high masses, high incidence of magnetism, and unusual kinematics for their age. All evidence points to a merger origin. Based on an analysis of warm DQ white dwarfs in the 100 pc sample, we demonstrate that a combination of GALEX FUV and Gaia photometry provides an efficient way to identify these merger remnants. We propose to take advantage of this unique opportunity to identify all warm DQ white dwarf merger remnants in the Gaia sample. We identify 107 targets, 82 of which are new. A pilot survey at Gemini had an 83% success rate. Here we propose to obtain GMOS low-resolution spectroscopy of 34 spring targets. Our proposed survey will nearly quadruple the sample of warm DQ white dwarfs, and will provide an unprecedented opportunity to constrain their nature, including their mass distribution, atmospheric composition, and kinematic properties.