Spectroscopic Identification and Population Properties of Cataclysmic Variables from DESI DR1

Abstract We present a systematic search for cataclysmic variables (CVs) using spectroscopic data from Data Release 1 of the Dark Energy Spectroscopic Instrument. Applying the Bagging-TopPush algorithm, we identified 433 CV candidates and related objects, of which 412 are confirmed CVs including 76 new systems. Subtypes were assigned through a combination of DESI spectra, Gaia data, and light curves from time-domain surveys, revealing populations of dwarf novae, novalike variables, magnetic CVs, and AM CVn binaries. Orbital periods were constrained from eclipsing light curves and DESI radial velocity curves for 14 systems. For 31 WZ Sge–type dwarf novae, we estimated white dwarf masses and radii by combining Galaxy Evolution Explorer ultraviolet photometry with DESI optical spectra, obtaining average values of 0.82 M ⊙ for mass and 13,452 K for effective temperature. We also calculated the strength of the magnetic field for three polars based on the cyclotron features. Furthermore, we derived subtype-dependent space densities and found values consistent, within uncertainties, with those inferred from Sloan Digital Sky Survey, Gaia, and other survey data, though remaining lower than theoretical predictions by 1–2 orders of magnitude. Besides, we highlight several notable objects, including newly identified AM CVn systems, eclipsing systems in the period gap, donor-dominated binaries, and other unusual systems of particular interest for follow-up observations.