Environment and properties of emitting electrons in blazar jets: Mrk 421 as a laboratory

TL;DR

This study models the spectral energy distribution of Mrk 421 across different luminosity states using a chi2-minimization approach, revealing how magnetic field and electron energies influence emission properties in blazar jets.

Contribution

It introduces a comprehensive chi2-minimization method for SED modeling of blazars, providing new insights into electron and magnetic field behavior during different activity states.

Findings

Magnetic field decreases with increased source activity.

Electron break energy and Doppler factor increase with activity.

Total emission correlates with electron-photon scattering efficiency.

Abstract

Here we report our recent study on the spectral energy distribution (SED) of the high frequency BL Lac object Mrk 421 in different luminosity states. We used a full-fledged chi2-minimization procedure instead of more commonly used "eyeball" fit to model the observed flux of the source (from optical to very high energy), with a Synchrotron-Self-Compton (SSC) emission mechanism. Our study shows that the synchrotron power and peak frequency remain constant with varying source activity, and the magnetic field decreases with the source activity while the break energy of electron spectrum and the Doppler factor increase. Since a lower magnetic field and higher density of electrons result in increased electron-photon scattering efficiency, the Compton power increases, so does the total emission.