EDP Sciences
Free Access
Volume 366, Number 1, January IV 2001
Page(s) 26 - 34
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361:20000198
Published online 15 January 2001

A&A 366, 26-34 (2001)
DOI: 10.1051/0004-6361:20000198

Reviving fossil radio plasma in clusters of galaxies by adiabatic compression in environmental shock waves

T. A. Enßlin1 and Gopal-Krishna2

1  Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str.1, 85741 Garching, Germany
2  National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune University Campus, Ganeshkhind, Pune 411007, India

(Received 30 March 2000 / Accepted 3 November 2000 )

We give for a plasma with a history of several expansion and contraction phases an analytical model of the evolution of a contained relativistic electron population under synchrotron, inverse Compton and adiabatic energy losses or gains. This is applied to different scenarios for evolution of radio plasma inside the cocoons of radio galaxies, after the activity of the central engine has ceased. It is demonstrated that fossil radio plasma with an age of even up to 2 Gyr can be revived by compression in a shock wave of large-scale structure formation, caused during the merging events of galaxy clusters, or by the accretion onto galaxy clusters. We argue, that this is a highly plausible explanation for the observed cluster radio relics, which are the regions of diffuse radio emission found in clusters of galaxies, without any likely parent radio galaxy seen nearby. An implication of this model is the existence of a population of diffuse, ultra-steep spectrum, very low frequency radio sources located inside and possibly outside of clusters of galaxies, tracing the revival of aged fossil radio plasma by the shock waves associated with large-scale structure formation.

Key words: acceleration of particles -- shock waves -- galaxies: intergalactic medium -- galaxies: active -- galaxies: clusters: general -- radio continuum: general

Offprint request: T. A. Enßlin ensslin@mpa-garching.mpg.de

SIMBAD Objects

© ESO 2001

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.