Mergers of double white dwarfs (DWDs) are considered significant potential progenitors of type Ia supernovae (SNe Ia), which serve as "standard candles" in cosmology to measure the expansion rate of the Universe and explore the nature of dark energy. Although there is no direct observational evidence to definitively determine the formation pathways of SNe Ia, studying the physical properties of DWDs provides valuable insights into their evolutionary processes, interaction modes, and merger mechanisms, which are essential for understanding the explosion mechanisms of SNe Ia. This study aims to identify DWD candidates through spectroscopic radial velocity (RV) measurements and analyze their physical properties based on DESI EDR. We crossmatched DESI EDR with Gaia EDR3 WD catalog to select DA spectra. Spectroscopic RV was measured using the cross-correlation function (CCF), with RV variability assessed via a chi-squared method. We derived spectroscopic Teff and log g by fitting hydrogen Balmer lines, applying 3D convection corrections. Orbital periods and semi-amplitudes came from Lomb-Scargle analysis of RV time series. WD cooling models and Monte Carlo simulations were used to calculate masses, cooling ages, radii, and uncertainties. We also analyzed photometric and SED properties to derive temperatures and radii, comparing them with spectroscopic parameters. We identified 33 DA DWD candidates with significant RV variability, including 28 new discoveries. Among them, an extremely low mass (ELM) DWD candidate and a potential triple system were found. We measured key parameters like Teff, logg, mass, and radius for these candidates and estimated their orbital periods from the data. Of these, 17 showed clear periodic RV variability, and we reported their best-fitting periods and RV semi-amplitudes.

Cone search capability for table J/A+A/699/A212/tableb2 (Parameters for 33 DWD candidates)