Revisiting Quasi-Periodic modulation in $\gamma$-ray Blazar PKS 2155-304 with Fermi Pass 8 data

TL;DR

This study analyzes Fermi-LAT data of blazar PKS 2155-304, revealing a significant quasi-periodic gamma-ray variability of approximately 1.74 years, contributing to understanding blazar emission mechanisms.

Contribution

It provides the first detailed analysis of quasi-periodic variability in PKS 2155-304 using Pass 8 data with multiple analysis methods, confirming a 1.74-year period.

Findings

Detected a 1.74-year quasi-periodic signal with 4.9 sigma significance.

Used Lomb-Scargle Periodogram and Wavelet analysis for robust results.

Discussed implications for blazar emission models.

Abstract

We examine the gamma-ray quasi-periodic variability of PKS 2155-304 with the latest publicly available \emph{Fermi}-LAT Pass 8 data which covers the years from 2008 August to 2016 October. We produce the light curves in two ways, i.e., the exposure-weighted aperture photometry and the maximum likelihood optimization. The light curves are then analyzed by using Lomb-Scargle Periodogram (LSP) and Weighted Wavelet Z-transform (WWZ); and the results reveal a significant quasi-periodicity with a period of $1.74\pm0.13$ years and a significance of $\sim$ 4.9 $\sigma$. The constraint of multifrequencies quasi-periodic variabilities on blazar emission model is discussed.