Recollimation shocks and radiative losses in extragalactic relativistic jets

Journal
Date Issued
2018
Author(s)
•
DOI
Abstract
We present the results of state-of-the-art simulations of recollimation shocks induced by the interaction of a relativistic jet with an external medium, including the effect of radiative losses of the shocked gas. Our simulations confirm that - as suggested by earlier semi-analytical models - the post-shock pressure loss induced by radiative losses may lead to a stationary equilibrium state characterized by a very strong focusing of the flow, with the formation of quite narrow nozzles, with cross-sectional radii as small as 10-3 times the length scale of the jet. We also study the time-dependent evolution of the jet structure induced by a density perturbation injected at the flow base. The set-up and the results of the simulations are particularly relevant for the interpretation of the observed rapid variability of the γ-ray emission associated to flat spectrum radio quasars. In particular, the combined effects of jet focusing and Doppler beaming on the observed radiation make it possible to explain the sub-hour flaring events such as that observed in the flat specrum radio quasar PKS 1222+216 by MAGIC.
Volume
609
Start page
A122
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2018A&A...609A.122B
Rights
open.access
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