EDP Sciences
Free access
Issue
A&A
Volume 366, Number 1, January IV 2001
Page(s) 26 - 34
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20000198


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 )

Abstract
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

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.