White Dwarfs with Infrared Excess from DESI Early Data Release

Abstract Infrared (IR) excess emission around white dwarfs (WDs) is commonly attributed to circumstellar debris disks and/or low-mass companions, providing a unique window into the evolution of planetary systems and binary evolution after the main-sequence stage. Based on a spectroscopically confirmed WD sample from the Dark Energy Spectroscopic Instrument (DESI) Early Data Release, we performed a systematic search for IR excess by combining multi-band photometry from SDSS, Pan-STARRS, UKIDSS, 2MASS, and WISE. Using spectral energy distribution (SED) fitting, we initially identified 72 IR-excess candidates and conducted a stringent contamination assessment based on higher-resolution imaging within 6 ″ of each target. After removing sources affected by blending or source confusion, we obtained a final sample of 62 reliable IR excess candidates. Among them, we identify three candidate WD+M dwarf binaries (two new systems), five candidate WD+brown dwarf (BD) binaries (all new), 38 candidate WD+dust disks (28 new), and 16 ambiguous systems that could be either WD+BD or WD+dust (15 new). Compared with previous samples, our catalog extends the parameter space of known dusty WDs toward older cooling ages. Due to the limited spatial resolution of WISE, follow-up high-resolution imaging and/or infrared spectroscopy is required to confirm the physical nature of all candidate systems and to further expand the parameter space of dust disks in terms of cooling age and other properties.