Systematic evaluation of variability detection methods for eROSITA

Understand

The reliability of detecting source variability in sparsely and irregularly sampled X-ray light curves is investigated.

• This is motivated by the unprecedented survey capabilities of eROSITA onboard SRG, providing light curves for many thousand sources in its final-depth equatorial deep field survey.
• Four methods for detecting variability are evaluated: excess variance, amplitude maximum deviations, Bayesian blocks and a new Bayesian formulation of the excess variance.
• We judge the false detection rate of variability based on simulated Poisson light curves of constant sources, and calibrate significance thresholds.