Photon index and HR distribution of our selected transient candidates. Top panel: HR of each FXRT candidate (using the Bayesian BEHR code; Park et al. 2006). Middle panel: HR distributions of our final samples of nearby (hashed black histogram) and distant (hashed orange histogram) FXRTs, compared to the XRTs classified as “stars” according to Criterion 2 using Gaia (filled cyan histogram). Bottom panel: photon indices for FXRT candidates where the light curve was best fit by a BPL model, before (filled circles) and after (open squares) the break time (T_break) taken from Table 4. In all cases, errors bars are at the 90% confidence level.