EBL effect on the observation of multi-TeV flaring of 2009 from Markarian 501

TL;DR

This paper investigates how the extragalactic background light affects the observation of a significant TeV gamma-ray flare from Markarian 501 in 2009, using a photohadronic model to interpret the data.

Contribution

It introduces a detailed analysis of the EBL's impact on TeV gamma-ray observations of Markarian 501 during a major flare, highlighting the importance of EBL correction in such studies.

Findings

EBL significantly attenuates VHE gamma-ray flux from Markarian 501.

Photohadronic model effectively explains the observed high-energy flare.

EBL correction is crucial for accurate interpretation of TeV observations.

Abstract

Markarian 501 is a high-peaked BL Lacertae object and has undergone many major outburst since its discovery in 1996. As a part of the multiwavelength campaign, in the year 2009 this blazar was observed for 4.5 months from March 9 to August 1 and during the period April 17 to May 5 it was observed by both space and ground based observatories covering the entire electromagnetic spectrum. A very strong high energy $\gamma$-ray flare was observed on May 1 by Whipple telescope in the energy range 317 GeV to 5 TeV and the flux was about 10 times higher than the baseline flux. We use the photohadronic model complimented by the extragalactic background radiation (EBL) correction to this very high state flare and have shown that the EBL plays an important role in attenuating the very high energy flux even though Markarian 501 is in the local Universe.