Particle Acceleration And Emission Processes In Mrk 421

Abstract

We investigate the X-ray and $\gamma$-ray flares of Mrk 421 on 2008 June 6-15 using the synchrotron self- Compton(SSC) model with electron acceleration, in which an evident correlation between the X-ray and $\gamma$-ray bands appears, while no significant correlation between the optical and X-ray band is observed. We argue that the emission from Mrk 421 may originate from two different components. One is the steady component from the outer region that is mainly attributed to the optical band, in which the electrons are accelerated by first-order Fermi acceleration mechanism. We use a steady electron spectrum to produce the synchrotron self-Compton emission. The other is the variable component from the inner region, in which the electrons are accelerated by the stochastic acceleration process. We use the time-dependent SSC model to produce the emission from the variable component. We suggest that the flares are due to the hardening of the electron spectrum under the process of the stochastic acceleration, which leads to the hardening of the observed spectrum in the X-ray and $\gamma$-ray bands. Furthermore, we find that the energy densities of electrons and magnetic fields are near equipartition in both jet regions.

6 pages, 2 figures, accepted for publication in PASJ

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• Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009
• Time-Dependent Modeling of Gamma-ray Flares in Blazar PKS1510-089
• Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and $\gamma$-ray activity in 2015$-$2016
• On the origin of the hard X-Ray excess of high-synchrotron-peaked BL Lac object Mrk 421
• Connecting steady emission and Very High Energy flaring states in blazars: the case of Mrk 421
• Synchrotron Self-Compton Emission by Relativistic Electrons under Stochastic Acceleration: Application to Mrk 421 and Mrk 501
• Hadronuclear interactions in the jet of low TeV luminosity AGN: Implications for the low-state very-high-energy gamma-ray emission
• Understanding the X-ray spectral curvature of Mkn 421 using broadband AstroSat observations