Testing one-zone synchrotron-self-Compton models with spectral energy distributions of Mrk 421

TL;DR

This study evaluates one-zone SSC models against multiwavelength SED data of Mrk 421 using MCMC, finding the PLLP electron energy distribution best fits the data and deriving key physical parameters.

Contribution

It demonstrates that the one-zone SSC model with a PLLP electron energy distribution effectively explains Mrk 421's SEDs, highlighting the model's applicability during flares.

Findings

The PLLP EED provides successful fits to all SEDs.

LP and BPL EEDs fail to fit high-energy data in some states.

Derived magnetic field B'~0.01 G, Doppler factor ~30-50.

Abstract

We test one-zone synchrotron self-Compton (SSC) models with high-quality multiwavelength spectral energy distribution (SED) data of Mrk 421. We use Markov chain Monte Carlo (MCMC) technique to fit twelve day-scale SEDs of Mrk 421 with one-zone SSC models. Three types of electron energy distribution (EED), a log-parabola (LP) EED, a power-law log-parabola (PLLP) EED and a broken power-law (BPL) EED, are assumed in fits. We find that the one-zone SSC model with the PLLP EED provides successful fits to all the twelve SEDs. However, the one-zone SSC model with the LP and BPL EEDs fail to provide acceptable fits to the highest energy X-ray data or GeV data in several states. We therefore conclude that the one-zone SSC model works well in explaining the SEDs of Mrk 421, and the PLLP EED is preferred over the LP and BPL EEDs for Mrk 421 during the flare in March 2010. We derive magnetic field $B'\sim0.01$\ G, Doppler factor $\delta_{\rm D}\sim$30--50, and the curvature parameter of EED $r\sim1$--$10$ in the model with the PLLP EED. The evolutions of model parameters are explored. The physical implications of our results are discussed.