Finding circumbinary planets: a semi-automated transit search of <i>TESS</i> eclipsing binaries

ABSTRACT The discovery of circumbinary planets (CBPs) has advanced our understanding of planet formation and dynamical evolution in complex environments. However, the population of such planets remains small, leading their underlying physical properties to be loosely constrained. In this work, we have developed a semi-automated framework to identify planetary transit events in light curves of eclipsing binaries observed by the Transiting Exoplanet Survey Satellite (TESS). Our search method, mono-cbp, removes stellar eclipses and applies a custom detrending procedure, searching for individual transit events and applying automated vetting procedures to filter false positive signals. We searched a sample of binaries from the TESS Eclipsing Binary Catalogue, yielding one candidate transit event. mono-cbp was also tested on the known population of transiting CBPs, using the Kepler long-cadence photometry for the Kepler transiting CBPs and the TESS Full Frame Image photometry for the TESS CBPs. Excluding transits that are shallower than the intrinsic noise of the Kepler/TESS data, mono-cbp achieved a recovery rate of $\ge 50$ per cent for each planet, reaching $\gt 75$ per cent for 9 of the 14 planets. To test the limits of our framework, we injected simulated transit profiles with varying depth and duration into our sample of TESS light curves, finding that our recovery rate is a strong function of transit duration and the metrics used to filter false positive signals. This framework may be applied to large samples of TESS eclipsing binaries with little computational burden and to photometry from future space-based photometric surveys.