The January 2010 flare of Mrk421: Insights from a stochastic acceleration model

Abstract

Mrk421 displayed its highest flux state ever observed in February of 2010 with very high TeV fluxes and interesting cross-band correlations and a spectral energy distribution (SED) evolution not entirely consistent with the standard single zone leptonic synchrotron self-Compton model. The source was already in a high state in January 2010 and displayed strong variability in the days preceding the highest state. We study the temporal evolution of the spectra in January to extract information about the particle dynamics and the physical properties of the emission region. We build up on the temporal variability and correlations studied in the previous work (MAGIC collaboration - Abe et al. 2025) and attempt to improve the SED model fits with a physics oriented approach. The multi-wavelength data was processed and the SEDs were fit using JetSeT. The SED evolution and cross band correlations were modelled using leptonic log-parabola with a low energy power-law branch (LPPL) and pile-up distributions that are predicted in a stochastic acceleration scenario. A simplified temporal evolution model was developed and fit to the SEDs and the resulting trends and phenomenology were characterised in context of theoretical literature. An expanding emission region model was also tested. We find the spectral variability to be well in agreement with stochastic acceleration. Our analysis suggests that the standard LPPL distribution develops a Maxwellian pile-up component at the transition from acceleration to cooling dominated phase on 3 nights in the dataset, as also hinted by the very-high energy and X-ray light curves. The resulting phenomenology of our sequential snapshot evolution SED model agrees well with theoretical and numerical simulation studies on temporal evolution using the diffusion equation approach.

Accepted for publication in A&A. Corresponding Authors: : J. Abhir, A. Arbet-Engels, A. Tramacere

References in corpus (25)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The major upgrade of the MAGIC telescopes, Part II: A performance study using observations of the Crab Nebula
• Kinematics of Parsec-Scale Jets of Gamma-Ray Blazars at 43~GHz within the VLBA-BU-BLAZAR Program
• On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field
• Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010
• Time-Dependent Stochastic Particle Acceleration in Astrophysical Plasmas: Exact Solutions Including Momentum-Dependent Escape
• Signatures of synchrotron emission and of electron acceleration in the X-ray spectra of Mrk 421
• Modelling the spectral response of the Swift-XRT CCD camera: Experience learnt from in-flight calibration
• The Blazar sequence and its Physical Understanding
• The Relativistic Jet Dichotomy and the End of the Blazar Sequence
• Unravelling the complex behavior of Mrk 421 with simultaneous X-ray and VHE observations during an extreme flaring activity in April 2013
• Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017
• Study of the variable broadband emission of Markarian 501 during the most extreme Swift X-ray activity
• The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies
• Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars
• Connecting steady emission and Very High Energy flaring states in blazars: the case of Mrk 421
• Radio$-\gamma -$ray response in blazars as a signature of adiabatic blob expansion
• An expanding one-zone model for studying blazars emission
• The jet collimation profile at high resolution in BL Lacertae
• The relentless variability of Mrk 421 from the TeV to the radio
• Time dependent spectral modeling of Markarian 421 during a violent outburst in 2010
• VERITAS discovery of very high energy gamma-ray emission from S3 1227+25 and multiwavelength observations
• Looking into the Jet Cone of the Neutrino-Associated Very High Energy Blazar PKS 1424+240
• Time-Dependent Modeling of the Sub-Hour Spectral Evolution During the 2013 Outburst of Mrk 421
• Radiative signatures of electron-ion shocks in BL Lac type objects