The influence of the magnetic field on the spectral properties of blazars

Дата и время публикации : 2013-10-21T07:18:32Z

Авторы публикации и институты :
J. M. Rueda-Becerril
P. Mimica
M. A. Aloy

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: Accepted for publication in MNRAS, 14 pages, 13 figures
Первичная категория: astro-ph.HE

Все категории : astro-ph.HE

Краткий обзор статьи: We explore the signature imprinted by dynamically relevant magnetic fields on the spectral energy distribution (SED) of blazars. It is assumed that the emission from these sources originates from the collision of cold plasma shells, whose magnetohydrodynamic evolution we compute by numerically solving Riemann problems. We compute the SEDs including the most relevant radiative processes and scan a broad parameter space that encompasses a significant fraction of the commonly accepted values of not directly measurable physical properties. We reproduce the standard double hump SED found in blazar observations for unmagnetized shells, but show that the prototype double hump structure of blazars can also be reproduced if the dynamical source of the radiation field is very ultrarelativistic both, in a kinematically sense (namely, if it has Lorentz factors gtrsim 50) and regarding its magnetization (e.g., with flow magnetizations sigma simeq 0.1). A fair fraction of the {em blazar sequence} could be explained as a consequence of shell magnetization: negligible magnetization in FSRQs, and moderate or large (and uniform) magnetization in BL Lacs. The predicted photon spectral indices (gph) in the gamma-ray band are above the observed values (Gamma_{rm ph, obs} lesssim 2.6 for sources with redshifts 0.4le z le 0.6) if the magnetization of the sources is moderate (sigma simeq 10^{-2}).

Category: Physics