Detection of Quasi-Periodic Oscillations in the Blazar S4 0954+658 with TESS

TL;DR

This study detects multiple quasi-periodic oscillations in the optical emission of blazar S4 0954+658 using TESS data, suggesting an origin near the black hole's accretion disk and estimating its mass.

Contribution

First detection of quasi-periodic oscillations in S4 0954+658 using TESS, with analysis supporting an accretion disk origin and black hole mass estimation.

Findings

Multiple QPOs around 0.6--2.5 days detected.

QPO of 1.52 days observed in several sectors.

Black hole mass estimated based on QPO analysis.

Abstract

We report the detection of several quasi-periodicities around 0.6--2.5 days in the optical emission of the blazar S4 0954+658. The source was observed by the Transiting Exoplanet Survey Satellite (TESS) in six sectors and it showed these features in all but one of them, with a QPO of 1.52 days apparently present in portions of four of them. We used the generalized Lomb-Scargle periodogram method to search for significant signals and we confirmed them using a weighted wavelet transform for time-frequency domain analyses. We discuss several possible explanations for these rapid quasi-periodic variations and suggest that an origin in the innermost part of the accretion disk is most likely. Within this framework, we provide estimates for the mass of the black hole at the core of this blazar.