Constraints on the Physical Parameters of TeV Blazars

Abstract

We consider the constraints on the physical parameters of a homogeneous SSC model that can be derived from the spectral shape and variability of TeV blazars. Assuming that the relativistic electron spectrum is a broken power law, where the break energy $\gamma_b$ is a free parameter, we write the analytical formulae that allow to connect the physical parameters of the model to observable quantities. The constraints can be summarized in a plane where the coordinates are the Doppler factor and the magnetic field. The consistency between the break energy and the balance between cooling and escape and the interpretation of the soft photon lags measured in some sources as radiative cooling times are treated as additional independent constraints. We apply themethod to the case of three well known blazars, PKS 2155-304, Mrk 421 and Mrk 501.Comment: 36 pages, incl. 6 figures in PS format, AAS LaTeX, to be published in ApJ, Dec 199

The power of relativistic jets is larger than the luminosity of their accretion disks

“…We have the following two possibilities: 1) the SED could result from Synchrotron+SSC. In this case the parameters can be found univocally 46 . The synchrotron ν S and Compton ν C peak frequencies ratio gives γ 2 peak .…”

On the magnetization of BL Lac jets

“…Moreover, the absence of an important environmental radiation field around the jet implies that the high-energy bump in the SED of BL Lac is dominated by the inverse Compton scattering of the synchrotron photon themselves (synchrotron self Compton model, SSC). As demonstrated by Tavecchio et al (1998) in this case the relevant physical parameters (most notably for our purposes the magnetic field and the electron density) can be uniquely and robustly derived once the SED is relatively well sampled.…”

“…Specifically, we will apply the one-zone synchrotron-self Compton (SSC) model (e.g. Tavecchio et al 1998), from which we can derive the source size R, the Doppler factor δ, the jet comoving frame (primed symbols) magnetic field B ′ and the (jet frame) parameters describing the broken power law electron energy distribution N ′ (γ): the minimum, the break and the maximum Lorentz factors γmin, γ b and γmax, the two slopes n1 and n2 and the normalization, K ′ . The assumed phenomenological form of the electron energy distribution is generally valid to reproduce the typical blazar SED bumps, approximately characterized by two power laws with slopes α1 < 1 and α2 > 1, connected at the peak frequency.…”

“…Along the lines of the analytical treatment in Tavecchio et al (1998) for the one zone SSC model it is possible to derive a useful approximate analytical expression for the ratio U ′ B /U ′ e as a function of the observed SED quantities. We specialize the following treatment to the case -usually valid for high-energy emitting BL Lac -in which the SSC peak is produced by scatterings occurring in the Klein-Nishina limit (in any case the detailed numerical model include the full treatment of the IC kinematics and cross section).…”

“…An alternative and reliable way to estimate the magnetic fields associated to the emitting regions of the innermost ( 1 pc) part of jets is through the modeling of the relativistically beamed non-thermal continuum of blazars (e.g. c 0000 RAS Ghisellini et al 1998, Tavecchio et al 1998. Nalewajko, Sikora & Begelman (2014) noted that the large magnetic field flux derived through the core-shift effects by Zamaninasab et al (2014) seems to exceed the values suggested by the typical blazar spectral energy distribution (SED).…”