Flaring gamma-ray emission from high redshift blazars

TL;DR

This paper reports the detection and analysis of gamma-ray flaring activity in high redshift blazars, highlighting their extreme luminosities and implications for understanding their energetics and the extragalactic background light.

Contribution

It presents the first detailed multi-band study of the highest redshift gamma-ray flaring blazar TXS 0536+145, revealing its extreme luminosity and comparing its properties with other high redshift blazars.

Findings

TXS 0536+145 reached a luminosity of 6.6x10^49 erg/s during flare

High redshift blazars are rare in gamma-ray observations

Preliminary results for PKS 2149-306 are discussed

Abstract

High redshift blazars are among the most powerful objects in the Universe. Although they represent a significant fraction of the extragalactic hard X-ray sky, they are not commonly detected in gamma-rays. High redshift (z>2) objects represent <10 per cent of the AGN population observed by Fermi so far, and gamma-ray flaring activity from these sources is even more uncommon. The characterization of the radio-to-gamma-ray properties of high redshift blazars represent a powerful tool for the study of both the energetics of such extreme objects and the Extragalactic Background Light. We present results of a multi-band campaign on TXS 0536+145, which is the highest redshift flaring gamma-ray blazar detected so far. At the peak of the flare the source reached an apparent isotropic gamma-ray luminosity of 6.6x10^49 erg/s, which is comparable with the luminosity observed from the most powerful blazars. The physical properties derived from the multi-wavelength observations are then compared with those shown by the high redshift population. In addition preliminary results from the high redshift flaring blazar PKS 2149-306 will be discussed.