Exploring Short-Term Optical Variability of Blazars Using $\textit{TESS}$

TL;DR

This study systematically analyzes short-term optical variability in 29 blazars observed by TESS, revealing significant flux variability, bimodal flux distributions, and power spectral slopes indicating complex emission processes.

Contribution

First comprehensive time series analysis of blazar optical variability using TESS data, including flux distribution modeling and power spectral density estimation.

Findings

Blazars show fractional variability between 1.41% and 53.84%.

Optical flux distributions are mostly bimodal and fit normal PDFs.

Power spectral slopes range from 1.7 to 3.2, indicating complex variability patterns.

Abstract

We present a first systematic time series study of a sample of blazars observed by the Transiting Exoplanet Survey Satellite $\textit{TESS}$ spacecraft. By cross matching the positions of the sources in the TESS observations with those from Roma-BZCAT, 29 blazars including both BL Lacerate objects and flat-spectrum radio quasars were identified. The observation lengths of the 79 light curves of the sources, across all sectors on which the targets of interest have been observed by $\textit{TESS}$, range between 21.25 and 28.2 days. The light curves were analyzed using various methods of time series analysis. The results show that the sources exhibit significant variability with fractional variability spanning between 1.41% and 53.84%. The blazar flux distributions were studied by applying normal and lognormal probability density function models. The results indicate that optical flux histogram of the sources are consistent with normal probability density function with most of them following bi-modal distribution as opposed to uni-modal distribution. This suggests that the days-timescale optical variability is contributed either by two different emission zones or two distinct states of short-term activity in blazars. Power spectral density analysis was performed by using the power spectral response method and the true power spectra of unevenly sampled light curves were estimated. The power spectral slopes of the light curves ranged from 1.7 to 3.2.