The origin of multi-TeV flares from the nearest blazar Markarian 421

TL;DR

This paper explains the multi-TeV flares of the blazar Markarian 421 using a photohadronic model, emphasizing the importance of multiwavelength data and accounting for extragalactic background light attenuation.

Contribution

It introduces a model that accounts for variable intrinsic spectra during flares by analyzing the low-energy tail of SSC photons, improving understanding of high-energy blazar emissions.

Findings

Different intrinsic spectra during flares due to changes in SSC photon tail

Successful explanation of 2004 and 2010 flares with the photohadronic model

Highlighting the role of multiwavelength observations in flare analysis

Abstract

Markarian 421 is a high-peaked BL Lac object and it has undergone many strong outbursts since its discovery as a TeV source in 1992. Markarian 421 has been stud- ied intensively and was observed by various Cherenkov tele- scope arrays ever since. The outbursts of April 2004 observed by the Whipple telescope and of February 2010 by the HESS telescopes are explained well in this work by using the photohadronic model. To account for the attenuation of these high- energy gamma-rays by the extragalactic background light (EBL), we use template EBL models. The intrinsic spectrum of each epoch is different even though the high-energy protons have almost the same spectral index. We observe that this difference in intrinsic spectra is due to the change in the spectral index of the low-energy tail of the synchrotron self Compton (SSC) photons during different epochs of flaring. Our results show that the contemporaneous multiwavelength observations, particularly in the low-energy tail region of the SSC emission of the source, are important in explaining the flaring phenomenon.