Detection of a quasi-periodic oscillation in gamma-ray light curve of the high redshift blazar B2 1520+31

TL;DR

This paper reports the detection of a ~71-day quasi-periodic oscillation in the gamma-ray light curve of high-redshift blazar B2 1520+31, estimating the black hole mass and discussing possible emission models.

Contribution

First detection of a gamma-ray QPO in a high-redshift blazar, with black hole mass estimation and analysis of potential emission mechanisms.

Findings

Detected a ~71-day gamma-ray QPO in B2 1520+31

Estimated black hole mass between 5.4×10^9 and 6.0×10^10 solar masses

Discussed possible emission models for gamma-ray QPOs in blazars

Abstract

We detected a possible quasi-periodic oscillation (QPO) of ~ 71 days in the 0.1 -- 300 GeV gamma-ray Fermi-LAT light curve of the high redshift flat spectrum radio quasar B2 1520+31. We identify and confirm that quasi-period by Lomb Scargle periodogram (LSP), and weighted wavelet z-transform (WWZ) analyses. Using this QPO period, and assuming it originates from accretion-disc fluctuations at the innermost stable circular orbit, we estimate the central supermassive black hole mass to range between ~ 5.4 * 10$^{9}$ M$_{\odot}$ for a non-rotating black hole and ~ 6.0 * 10$^{10}$ M$_{\odot}$ for a maximally rotating black hole. We briefly discuss other possible radio-loud active galactic nuclei emission models capable of producing a gamma-ray QPO of such a period in a blazar.