A Suzaku X-Ray Study of the Particle Acceleration Processes in the Relativistic Jet of Blazar Mrk 421

Abstract

We report on the findings of a 364 ksec observation of the BL LAC object Mrk 421 with the X-ray observatory Suzaku. The analysis in this paper uses fluxes and hardness ratios in the broad energy range from 0.5 keV to 30 keV. During the course of the observation, the 0.5 keV - 30 keV flux decreased by a factor of $\sim$2 and was accompanied by several large flares occurring on timescales of a few hours. We find that fitting a broken power model to spectra from isolated epochs during the observation describes the data well. Different flares exhibit different spectral and hardness ratio evolutions. The cumulative observational evidence indicates that the particle acceleration mechanism in the Mrk 421 jet produces electron energy distributions with a modest range of spectral indices and maximum energies. We argue that the short-timescale X-ray spectral variability in the flares can be attributed mostly to intrinsic changes in the acceleration process, dominating other influences such as fluctuations in the Doppler beaming factor, or radiative cooling in or outside the acceleration zone.

8 pages, 6 figures, apjgalley format, accepted for publication in The Astrophysical Journal

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• Multiwavelength Variability Signatures of Relativistic Shocks in Blazar Jets
• X-ray Intra-day Variability of the TeV Blazar Mrk 421 with Suzaku
• Particle Acceleration And Emission Processes In Mrk 421
• Systematic investigation of X-ray spectral variability of TeV blazars during flares in the $RXTE$ era
• Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53
• Extremely rapid x-ray flares of tev blazars in the rxte era
• Probing an X-ray flare pattern in Mrk 421 induced by multiple stationary shocks: a solution to the bulk Lorentz factor crisis
• Stochastic Gyroresonant Acceleration for Hard Electron Spectra of Blazars: Effect of Damping of Cascading Turbulence
• The polarization of the synchrotron radiation from a recollimated jet: application to high-energy BL Lacs
• X-ray variability patterns in blazars