Preprint Article Version 1 This version not peer reviewed

# Flaring γ-ray emission from high redshift blazars

Version 1 : Received: 14 July 2016 / Approved: 15 July 2016 / Online: 15 July 2016 (04:40:29 CEST)

A peer-reviewed article of this Preprint also exists.

Orienti, M.; D’Ammando, F.; Giroletti, M.; Finke, J.; Dallacasa, D. Flaring γ-Ray Emission from High Redshift Blazars. Galaxies 2016, 4, 26. Orienti, M.; D’Ammando, F.; Giroletti, M.; Finke, J.; Dallacasa, D. Flaring γ-Ray Emission from High Redshift Blazars. Galaxies 2016, 4, 26.

Journal reference: Galaxies 2016, 4, 26
DOI: 10.3390/galaxies4030026

## 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 represents a powerful tool for the study of the energetics of such extreme objects and the Extragalactic Background Light. This contribution will present results of multi-band campaigns, from radio to gamma-rays, on PKS 0836+710, PKS 2149-306, and TXS 0536+145. The latter is the highest redshift detection of a flaring gamma-ray blazar so far. At the peaks of their respective flares these sources reached an apparent isotropic gamma-ray luminosity of about 10^50 erg/s, which is comparable with the luminosity observed from the most powerful blazars. The physical properties derived from the multi-wavelength observations of these sources are then compared with those shown by the high redshift population.

## Subject Areas

galaxies: active; gamma-rays: general; radiation mechanisms: non-thermal