Variability Properties of Southern TESS Blazars

An improved understanding of the physical mechanisms which produce optical variability in blazars necessitates the investigation of characteristic timescales in optical light curves. We present the variability characteristics of light curves from 26 BL Lacertae (BLL), 35 Flat Spectrum Radio Quasars (FSRQ), and 6 targets of unidentified activity type from the TESS spacecraft. Rapid cadence observations by TESS provide new insight into variability timescales in the optical comparable to observations in higher energy wavebands. We initially investigated our light curves to provide statistics describing the observed variability level, flux histograms, and the shortest timescales of variability. We deliver results of such variability descriptors for every object in our sample at the time resolution of the observation and in 6- and 12-hour bins. For those light curves which are sufficiently variable and do not contain systematics which limit power at low frequencies, by employing an adapted Power Spectral Response method, we test the goodness of fit of the power spectral density function (PSD) to 3 power-law variant models. From our best-fitting description of the PSD, we extract the high-frequency power-spectral slopes and determine the presence or absence of a significant bend or break in the model, which may indicate a characteristic timescale. We find that both subpopulations of blazars show power spectral slopes of α ∼2 in which 5 BLL & 6 FSRQ are best fit by a broken power-law and 1 BLL & 5 FSRQ by a bending power-law. Characteristic timescales exhibited by these objects range from ∼0.8-8 days.