Measuring orbital periods of white dwarf binary candidates using the Transiting Exoplanet Survey Satellite

Abstract

Over 130,000 candidate objects for compact white dwarf binaries are planned to be observed with the 4-metre Multi-Object Spectroscopic Telescope (4MOST). Following this, an analysis of periodic variabilities among these candidates is undertaken, coupled with the retrieval of public light curves from the Transiting Exoplanet Survey Satellite (TESS). After rigorous filtering to increase the likelihood of periodic variability, a total of 4464 sources are deemed suitable for further investigation. Utilising Lomb-Scargle periodograms, the periods of these candidates are determined, and subsequent modelling is performed using the lightkurve Python package. Through detailed visual inspection of 5% of the candidates, a preliminary period distribution is generated. Notably, it is found that 50% of the periods are below the 2-day threshold, with a significant 22.64% exhibiting periods shorter than half a day. This period distribution notably diverges from existing samples of accreting white dwarfs and detached white dwarf plus main sequence systems. This discrepancy is likely due to a considerable fraction of contaminants present in the catalogue.