# A $\gamma$-ray Quasi-Periodic modulation in the Blazar PKS 0301$-$243?

## TL;DR

This paper reports a significant quasi-periodic gamma-ray signal in the blazar PKS 0301-243, suggesting possible evidence of a binary supermassive black hole based on analysis of Fermi-LAT data.

## Contribution

First detection of a high-confidence gamma-ray quasi-periodic modulation in PKS 0301-243 using multiple analysis techniques.

## Key findings

- Quasi-periodicity of 2.1±0.3 years detected at ~5σ significance.
- The periodicity is observed in a data set roughly four times longer than the period.
- Potential indication of a binary supermassive black hole in the blazar.

## Abstract

We report a nominally high-confidence $\gamma$-ray quasi-periodic modulation in the blazar PKS 0301$-$243. For this target, we analyze its \emph{Fermi}-LAT Pass 8 data covering from 2008 August to 2017 May. Two techniques, i.e., the maximum likelihood optimization and the exposure-weighted aperture photometry, are used to build the $\gamma$-ray light curves. Then both the Lomb-Scargle Periodogram and the Weighted Wavelet Z-transform are applied to the light curves to search for period signals. A quasi-periodicity with a period of $2.1\pm0.3$ yr appears at the significance level of $\sim5\sigma$, although it should be noted that this putative quasi-period variability is seen in a data set barely four times longer. We speculate that this $\gamma$-ray quasi-periodic modulation might be evidence of a binary supermassive black hole.