Gaia DR3 variable white dwarfs vetted by ZTF

We cross-match this sample with the ZTF DR23 catalogue and apply a multiband Lomb-Scargle periodogram analysis to detect periodic variability. We then use the OPTICS unsupervised clustering algorithm to group and classify the confirmed periodic stars. We identify 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. Among these, 141 present significant periodicity. Using unsupervised clustering techniques, we classify 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, even though without detected periodicity. Finally, several variables show unusual properties and are highlighted for follow-up studies.

Our catalogue of candidate variable white dwarfs includes variability status, periodicity, and classification information for the 864 sources with ZTF time-series photometry, 519 of them newly identified, including 67 new periodic stars. It is publicly available through the VizieR database to support future investigations of white dwarf variability.