White Dwarfs with Infrared Excess from DESI EDR

TL;DR

This study systematically identifies infrared excess in white dwarfs from DESI data, revealing new candidate systems with debris disks and companions, thereby expanding understanding of planetary system evolution post-main sequence.

Contribution

It provides a new catalog of IR excess white dwarf candidates with improved contamination assessment, including many newly identified systems and extended parameter space.

Findings

62 reliable IR excess candidates identified after contamination removal.

Discovery of 28 new dusty white dwarf systems.

Detection of new white dwarf+brown dwarf and white dwarf+M dwarf binaries.

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 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 arcseconds 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.