X-ray/gamma-ray flux correlations in the BL Lacs Mrk 421 and 501 using HAWC data

TL;DR

This study analyzes 25 months of HAWC gamma-ray data and Swift-XRT X-ray data to investigate flux correlations in the BL Lac object Mrk 421, revealing a stronger-than-expected correlation between gamma-ray and X-ray emissions.

Contribution

It presents the first detailed correlation analysis between HAWC gamma-ray observations and Swift-XRT X-ray data for Mrk 421, demonstrating a significant flux correlation.

Findings

Strong correlation between gamma-ray and X-ray fluxes.

Correlation exceeds expectations for quasi-simultaneous observations.

Supports linked emission mechanisms in Mrk 421.

Abstract

The HAWC gamma ray observatory is located at the Sierra Negra Volcano in Puebla, Mexico, at an altitude of 4,100 meters. HAWC is a wide field of view array of 300 water Cherenkov detectors that are continuously surveying ~ 2sr of the sky, operating since March 2015. The large collected data sample allows HAWC to perform an unbiased monitoring of the BL Lac Mrk 421. This is the closest and brightest known extragalactic high-synchrotron-peaked BL Lac in the gamma-ray/X- ray bands and is extensively monitored by the Large Area Telescope (LAT) on-board the Fermi satellite, and the BAT and XRT instruments of the Swift satellite. In this work, we use 25 months of HAWC data together with Swift-XRT data to characterize potential correlations between both wavelengths. This analysis shows that HAWC and Swift-XRT data are correlated even stronger than expected for quasi-simultaneous observations.