Eclipse timing variation analysis of OGLE-IV eclipsing binaries towards the Galactic Bulge - II. Short periodic triple stellar systems

Abstract

We report an eclipse timing variations (ETV) study to identify close, stellar mass companions to the eclipsing binaries monitored during the photometric survey Optical Gravitational Lensing Experiment-IV. We also present an alternative automatic way to determine the first and last contacts of an eclipse. Applying the phase dispersion minimization method to identify potential triples, we find close third components with outer periods in less than 1500 d in 23 systems. We present outer orbit solution for 21 of 23 systems. For the 10 tightest triples, we find that the ETV can only be modelled with the combination of the light-travel-time effect (LTTE) and third-body perturbations, while in case of another 11 systems, pure LTTE solutions are found to be satisfactory. In the remaining two systems, we identify extra eclipses connected to the outer component, but for the incomplete and noisy ETV curves, we are unable to find realistic three-body solutions. Therefore, in these cases we give only the outer period.