A search for hot subdwarf binaries in data from the Transiting Exoplanet Survey Satellite

Abstract

ABSTRACT We present the results of a search for binary hot subdwarf stars in photometric data from the Transiting Exoplanet Survey Satellite (TESS). The sample of objects used in this work was a byproduct of another search for pulsating hot subdwarfs, which resulted in the discovery of nearly 400 non-pulsating variable candidates. The periodogram for each object was calculated and a frequency signal with one or more harmonics above the 4 σ detection threshold was used to consider the candidate as a possible binary system. The type of variability was subsequently confirmed by visual inspection. We present a list of 46 binary system candidates that were not previously known as binaries. We also analysed a few example light curves to demonstrate the importance of double checking the variability of the source in the TESS light curves corrected for instrumental signatures. Four objects, TIC 55753808, TIC 118412596, TIC 4999380, and TIC 68834079, which show variations in the TESS-calibrated fluxes, were actually found to be constant. We also found that it might be more appropriate to increase the commonly used  4σ detection threshold in order to avoid the detection of multiple spurious peaks in the periodograms or Fourier transform of the TESS light curves.