Detection of a Transient Quasi-periodic Oscillation in $\gamma$-Rays from Blazar PKS 2255-282

TL;DR

This study reports the detection of a transient 93-day quasi-periodic oscillation in gamma-ray emissions from blazar PKS 2255-282, using multiple analysis methods over four years of Fermi-LAT data.

Contribution

The paper presents the first detection of a transient QPO in gamma-ray data from this blazar, employing diverse Fourier and time domain analysis techniques for confirmation.

Findings

QPO detected at 93 days with >3.96σ significance

QPO observed consistently across multiple analysis methods

Possible physical origin involves jet precession or plasma motion

Abstract

We conducted a comprehensive variability analysis of the blazar PKS 2255-282 using Fermi-LAT observations spanning over four years, from MJD 57783.5 to 59358.5. Our analysis revealed a transient quasi-periodic oscillation (QPO) with a period of 93$\pm$2.6 days. We employed a variety of Fourier-based methods, including the Lomb-Scargle Periodogram (LSP) and Weighted Wavelet Z-Transform (WWZ), as well as time domain analysis techniques such as Seasonal and Non-Seasonal Autoregressive Integrated Moving Average (ARIMA) models and the Stochastic modeling with Stochastically Driven Damped Harmonic Oscillator (SHO) models. Consistently, the QPO with a period of 93 days was detected across all methods used. The observed peak in LSP and time-averaged WWZ plots has a significance level of 4.06$\sigma$ and 3.96$\sigma$, respectively. To understand the source of flux modulations in the light curve, we explored various physical models. A plausible scenario involves the precession of the jet with a high Lorentz factor or the movement of a plasma blob along a helical trajectory within the relativistic jet.