Context. The publication of Gaia data releases DR2 and DR3 have brought major improvements in stellar astrometry and photometry, particularly regarding the description of the white dwarf sequence. In particular, Gaia DR2 enabled the detection of variability in white dwarfs based solely on averaged astrometric and photometric quantities; namely, the five astrometric parameters (positions, proper motion, and parallax) and general photometric properties in the G, BP, and RP bands (mean, standard deviation, and number of measurements).
Aims. We identify and classify variable white dwarfs using Gaia DR3 data and Zwicky Transient Facility (ZTF) DR23 observations. The objective is to construct a catalogue of pulsating white dwarf candidates with robust selection criteria.
Methods. We defined a new sample of candidate variable white dwarfs using Gaia DR3 astrometric and photometric data. We cross-matched this sample with the ZTF DR23 catalogue and applied a multi-band Lomb-Scargle periodogram analysis to detect periodic variability. We then used the OPTICS unsupervised clustering algorithm to group and classify the confirmed periodic stars.
Results. We identified 1423 variable white dwarf candidates from Gaia DR3 with an estimated false-positive rate of 32%. Of the 1423 candidates, 864 have ZTF time series available. Among these, 141 present significant periodicity. Using unsupervised clustering techniques, we classified these objects into known categories, including ZZ Ceti stars, V777 Her stars, and white dwarf–main sequence (WD–MS) binaries. Our analysis reveals several confirmed periodic stars, including three ZZ Ceti stars, one V777 Her, and 24 WD–MS binaries. Furthermore, our work reveals a significant population of potentially variable stars, although their periodicities have not yet been detected. Finally, we note that several variables displayed unusual properties and we highlighted these objects for follow-up studies.
Conclusions. Our catalogue of candidate variable white dwarfs includes variability status, periodicity, and classification information for the 864 sources in our sample with ZTF time-series photometry, with 519 of them being newly identified, including 67 new periodic stars. This catalogue is publicly available through the VizieR database to support future investigations of white dwarf variability.
