Title: The survey of DA double white dwarf candidates based on DESI EDR Show Chinese title

Title: 基于DESI EDR的DA型白矮星双星候选体的调查

Abstract: Mergers of double white dwarfs are considered significant potential progenitors of type Ia supernovae. 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 measurements and analyze their physical properties based on DESI EDR. We crossmatched DESI EDR with the Gaia EDR3 to select DA. We measured the spectroscopic RV using the cross-correlation function and assessed the significance of RV variability using a chi-squared-based variability method. Spectroscopic Teff and log g were derived by fitting the hydrogen Balmer lines, with 3D convection corrections applied. Orbital periods and semi-amplitudes were obtained through a Lomb-Scargle analysis of the RV time series. We interpolated WD cooling models and applied Monte Carlo simulations to calculate masses, cooling ages, radii, and their associated uncertainties. We also analyzed their photometric and spectral energy distribution properties to derive photometric temperatures and radii, which were then compared with the corresponding spectroscopic parameters. We identified 33 DA DWD candidates with significant RV variability, including 28 new discoveries. Among them, we found an extremely low-mass DWD candidate and a potential triple system. For these candidates, we measured key physical parameters including Teff, log g, mass, and radius, and estimated the orbital periods based on the available data. Of these, 17 candidates exhibit relatively clear periodic RV variability in the current data, and we report their best-fitting periods and RV semi-amplitudes. Show Chinese abstract

Abstract: 双白矮星的合并被认为是I型超新星的重要潜在前身星。 尽管没有直接的观测证据可以确定I型超新星的形成途径，但研究DWD的物理特性为理解其演化过程、相互作用模式和合并机制提供了有价值的见解，这对于理解I型超新星的爆炸机制至关重要。 本研究旨在通过光谱径向速度测量识别DWD候选体，并基于DESI EDR分析其物理特性。 我们将DESI EDR与Gaia EDR3进行了交叉匹配，以选择DA型天体。 我们使用交叉相关函数测量了光谱径向速度，并通过基于卡方的变异性方法评估了径向速度变异性的重要性。 通过拟合氢巴尔末线得到了光谱有效温度和log g，并应用了三维对流修正。 通过径向速度时间序列的Lomb-Scargle分析获得了轨道周期和半振幅。 我们插值了白矮星冷却模型，并应用蒙特卡罗模拟计算了质量、冷却年龄、半径及其相关不确定性。 我们还分析了它们的测光和光谱能量分布特性，以推导测光温度和半径，并将其与相应的光谱参数进行比较。 我们识别出33个具有显著径向速度变异性DA DWD候选体，其中包括28个新的发现。 其中，我们发现了一个极低质量的DWD候选体和一个潜在的三重系统。 对于这些候选体，我们测量了包括有效温度、log g、质量和半径在内的关键物理参数，并根据现有数据估计了轨道周期。 其中，17个候选体在当前数据中表现出相对清晰的周期性径向速度变异性，我们报告了它们的最佳拟合周期和径向速度半振幅。