Multi-TeV flaring from high energy blazars: An evidence of the photohadronic process

TL;DR

This paper demonstrates that the photohadronic process can effectively explain multi-TeV gamma-ray flaring in high-energy blazars, providing a simple relation between observed and intrinsic fluxes and constraining seed photon spectra.

Contribution

The study applies the photohadronic model to a large sample of blazar flaring events, deriving a relation between observed and intrinsic gamma-ray fluxes and constraining seed photon spectra.

Findings

Excellent fit to most observed spectra supports photohadronic origin.

Derived relation simplifies understanding of gamma-ray attenuation.

Constraints on seed photon spectra during flares.

Abstract

The high energy peaked blazars are known to undergo episodes of flaring in GeV-TeV gamma-rays involving different time scales and the flaring mechanism is not well understood despite long term simultaneous multiwavelength observations. These gamma-rays en route to Earth undergo attenuation by the extra galactic background light. Using the photohadronic model, where the seed photons follow a power-law spectrum and a template extragalactic background light model, we derive a simple relation between the observed multi-TeV gamma-ray flux and the intrinsic flux with a single parameter. We study 42 flaring epochs of 23 blazars and excellent fit to most of the observed spectra are obtained, strengthening the photohadronic origin of multi-TeV gamma-rays. We can also constrain the power spectrum of the seed photons during the flaring period. The blazars of unknown redshifts, whose multi-TeV flaring spectra are known, stringent bounds on the former can be placed using the photohadronic model.