Radio signature of cosmological structure formation shocks

By Matthias Hoeft, M. Brueggen. 2006

153 citations recorded by the source corpus.

In the course of the formation of cosmological structures, large shock waves are generated in the intracluster medium (ICM). In analogy to processes in supernova remnants, these shock waves may generate a significant population of relativistic electrons which, in turn, produce observable synchrotron emission. The extended radio relics found at the periphery of several clusters and possibly also a fraction of radio halo emission may have this origin. Here, we derive an analytic expression for (i) the total radio power in the downstream region of a cosmological shock wave, and (ii) the width of the radio-emitting region. These expressions predict a spectral slope close to -1 for strong shocks. Moderate shocks, such as those produced . in mergers between clusters of galaxies, lead to a somewhat steeper spectrum. Moreover, we predict an upper limit for the radio power of cosmological shocks. Comparing our results to the radio relics in Abell 115, 2256 and 3667, we conclude that the magnetic field in these relics is typically at a level of 0.1 μG. Magnetic fields in the ICM are presumably generated by the shocks themselves; this allows us to calculate the radio emission as a function of the cluster temperature. The resulting emissions agree very well with the radio power-temperature relation found for cluster haloes. Finally, we show that cosmic accretion shocks generate less radio emission than merger shock waves. The latter may, however, be detected with upcoming radio telescopes.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/1ace3dd80fff7f1637feb72b84b6a61e654ab45e

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

In Nuclear and High Energy Physics

Citations in the corpus

Cosmic ray transport in galaxy clusters: implications for radio halos, gamma-ray signatures, and cool core heating (2010, unknown): “…Enßlin et al. (1998); Roettiger et al. (1999a); Kassim et al. (2001); Miniati et al. (2001a); Bagchi et al. (2002); Berrington & Dermer (2003); Hoeft et al. (2004, 2008); Siemieniec-Ozieblo (2004); Keshet et al. (2004); Hoeft & Brüggen (2007); Giacintucci et al. (2008); Battaglia et al. (2009).”
Acceleration of primary and secondary particles in galaxy clusters by compressible MHD turbulence: from radio haloes to gamma-rays (2010, background): “…particles via shocks and turbulence (e.g. Ensslin et al 1998; Sarazin 1999; Blasi 2001; Brunetti et al. 2001, 2004; Petrosian 2001; Miniati et al. 2001; Fujita et al 2003; Gabici & Blasi 2003; Ryu et al. 2003; Cassano & Brunetti 2005; Hoeft & Bruggen 2007; Brunetti & Lazarian 2007; Pfrommer 2008).”