Two complementary approaches of the periodicity detection in astronomical time series

Abstract

Estimation of the statistical significance of the peaks appearing in the spectra of various astronomical time series is essential for the detection of signals especially when they are contaminated by high levels of observational noise. In the present paper we consider a broader perspective which relies on two main aspects: (i) all the peaks have or may have significance and, therefore, (ii) we propose two complementary approaches to simultaneously supply estimates of the statistical significance of all the peaks of interest through Monte Carlo simulations. They are natural generalisations of the already used methods featured either by specificity in frequency or by specificity in amplitude/power of the peaks occurred in the spectrum. Three recently obtained radial velocity data on stars with orbiting exoplanets were used to illustrate these approaches: two G-type stars observed by the HARPS spectrograph (TOI-733, TOI-763) and an M-type star observed by the CARMENES spectrograph (Wolf 327). Some both interesting and useful features of the two considered statistical significances are also emphasised.