X-ray and γ-ray variability of Mrk 421

Abstract

We present an ordinary case in the momentum diffusion equation for the electron spectrum evolution and investigate the energy spectra and time dependent properties of flare in Mrk 421 in the frame of a time-dependent one-zone synchrotron self-Compton model. In this model, electrons are accelerated to extra-relativistic energy through the strong magnetic turbulence and evolve with time, and non-thermal photons are produced by both synchrotron and inverse Comtpon scattering off synchrotron photons. Moreover, non-thermal photons during a preflare are produced by the relativistic electrons in the steady state and those during a flare are produced by the electrons whose injection rate is changed during some time interval. We apply the model to the energy spectra and time-dependent properties of flares in Mrk 421 by reproducing the pre-burst spectrum of the source and varying the injection rate in the Bohm diffusion (q=1) and the hard sphere approximation (q=2) case, respectively. Our results show that Bohm diffusion case leads to hard photon spectra, and hard sphere case approximation seems to reproduce the energy spectra and the time dependent properties of flare still better.

INVERSE COMPTON X-RAY EMISSION FROM TeV BLAZAR MRK 421 DURING A HISTORICAL LOW-FLUX STATE OBSERVED WITH NuSTAR

“…The source of the seed photons for the IC process can be either the synchrotron emission of the jet itself ("Synchrotron self-Compton" model, or SSC for short; e.g., Jones et al 1974;Marscher 1980;Band & Grindlay 1985), or the thermal emissions of circumnuclear gas and dust (e.g., Dermer & Schlickeiser 1993;Sikora et al 1994;Inoue & Takahara 1996). There is an ongoing debate on the exact localization of the dominant blazar emission zone, with current estimates ranging from hundreds of gravitational radii from central supermassive black holes up to parsec-scale distances, as well as on the dominant particle acceleration processes involved, with different scenarios including mildly relativistic internal shocks (e.g., Böttcher & Dermer 2010;Mimica & Aloy 2012;Saito et al email: kataoka.jun@waseda Yan et al 2013;Asano et al 2014;Zheng et al 2014;Kakuwa et al 2015), or even relativistic magnetic reconnection (e.g., Narayan & Piran 2012;Biteau & Giebels 2012;Sironi et al 2015).…”

Modelling the multi-wavelength emission of flat-spectrum radio quasar 3C 279

“…More recently, the time-dependent models were proposed to reproduce the multi-wavelength spectrum of blazar during flaring state (e.g. Kirk et al 1998;Böttcher & Chiang 2002;Li & Kusunose 2000;Tsang & Kirk 2007;Zheng & Zhang 2011;Zheng et al 2013;Zheng et al 2014). In these models, The authors argue that multi-wavelength emission comes from a small spherical region of jet plasma.…”

Time-Dependent Modeling of Gamma-Ray Flares in Blazar Pks1510–089

“…Yet the jet magnetization emerging in our modeling is very low, so a self-consistency of the internal shock scenario explored in this paper would require in addition a very efficient conversion of the magnetic energy flux to the particle flux (accompanied by an efficient proton loading) between the jet base and the blazar emission zone (located at ∼ pc distances from the core). It may be that other energy dissipation processes are involved instead in the production of blazar flares, including turbulent acceleration (e.g., Ushio et al 2010;Lefa et al 2011;Tramacere et al 2011;Cao & Wang 2013;Yan et al 2013;Asano et al 2014;Zheng et al 2014;Kakuwa et al 2015;Chen et al 2015), or relativistic magnetic reconnection (see, e.g., Narayan & Piran 2012;Giannios 2013;Sironi et al 2015, and references therein). These interesting alternatives have been analyzed so far more quantitatively only in the context of low-power blazars of the BL Lac type, and not FSRQs, for which the internal shock scenario is still the most appealing possibility (though see in this context also the discussion in Nalewajko et al 2012b).…”