Spectral analysis of the blazars Markarian 421 and Markarian 501 with the HAWC Gamma-Ray Observatory

TL;DR

This paper presents a detailed spectral analysis of two blazars, Markarian 421 and 501, using HAWC data, revealing differences in their intrinsic spectra above 1 TeV, with implications for understanding their emission mechanisms.

Contribution

The study provides the first detailed time-average spectral analysis of these blazars with HAWC, highlighting differences in their intrinsic spectral properties above 1 TeV.

Findings

Mrk 421's spectrum fits a power-law with an exponential cutoff at 5.24 TeV.

Mrk 501's spectrum is a simple power-law without a cutoff.

Differences in intrinsic spectra suggest different emission characteristics.

Abstract

The High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory surveys the very high energy sky in the $\sim300$ to 100 TeV energy range and has detected two high-synchrotron-peaked BL Lacertae objects, Markarian 421 and Markarian 501 in a period of time of 837 days between June 2015 and December 2017. In this work, we present the detailed time-average spectral analysis. Using an extragalactic background light model, we address the difference in the intrinsic spectral properties between the two blazars above 1 TeV, preliminary results show that the intrinsic spectrum of Mrk 421 is better described by a power-law with an exponential energy cut-off function with photon index $\alpha_{421}=2.22\pm0.10$ and energy cut-off $Ec_{421}=5.24\pm1.02$ TeV, and for Mrk 501 the intrinsic spectrum is well described by a power-law with spectral index $\alpha_{501}=2.40\pm0.06$, without requiring an energy cut-off.