Multiwavelength Observations of Mrk 501 in 2008

TL;DR

This paper reports multiwavelength observations of the blazar Mrk 501 in 2008, revealing flux variability across the spectrum and modeling its spectral energy distribution with a one-zone synchrotron self-Compton model.

Contribution

It provides a comprehensive multiwavelength dataset and demonstrates how changes in electron populations explain different emission states.

Findings

Detected flux variability in X-ray and gamma-ray bands.

Spectral energy distribution modeled successfully with a one-zone SSC model.

High emission states linked to increased high-energy electron populations.

Abstract

The well-studied VHE (E >100 GeV) blazar Mrk 501 was observed between March and May 2008 as part of an extensive multiwavelength observation campaign including radio, optical, X-ray and VHE gamma-ray instruments. Mrk 501 was in a low state of activity during the campaign, with a low VHE flux of about 20% the Crab Nebula flux. Nevertheless, significant flux variations could be observed in X-rays as well as $\gamma$-rays. Overall Mrk 501 showed increased variability when going from radio to gamma-ray energies. The broadband spectral energy distribution during the two different emission states of the campaign was well described by a homogeneous one-zone synchrotron self-Compton model. The high emission state was satisfactorily modeled by increasing the amount of high energy electrons with respect to the low emission state. This parameterization is consistent with the energy-dependent variability trend observed during the campaign.