In this letter we present a morphological comparison between giant radio halos and radio mini-halos in galaxy clusters based on radio-X-ray luminosity, P1.4-L_X, and radio luminosity-size, P1.4-R_H, correlations. We report evidence that P1.4-LX and P1.4-RH trends may also exist for mini-halos: mini-halo clusters share the same region of giant halo clusters in the (P1.4,L_X) plane, whereas they are clearly separated in the (P1.4,R_H) plane. The synchrotron emissivity of mini-halos is found to be more than 50 times larger than that of giant halos, implying a very efficient process for their origins. By assuming a scenario of sporadical turbulent particle re-acceleration for both giant and mini halos, we discuss basic physical differences between these sources. Regardless of the origin of the turbulence, a more efficient source of injection of particles, which eventually takes part in the re-acceleration process, is required in mini-halos, and this may result from the central radio galaxy or from proton-proton collisions in the dense cool core regions.

A morphological comparison between giant radio halos and radio mini-halos in galaxy clusters

GITTI, MYRIAM;
2008

Abstract

In this letter we present a morphological comparison between giant radio halos and radio mini-halos in galaxy clusters based on radio-X-ray luminosity, P1.4-L_X, and radio luminosity-size, P1.4-R_H, correlations. We report evidence that P1.4-LX and P1.4-RH trends may also exist for mini-halos: mini-halo clusters share the same region of giant halo clusters in the (P1.4,L_X) plane, whereas they are clearly separated in the (P1.4,R_H) plane. The synchrotron emissivity of mini-halos is found to be more than 50 times larger than that of giant halos, implying a very efficient process for their origins. By assuming a scenario of sporadical turbulent particle re-acceleration for both giant and mini halos, we discuss basic physical differences between these sources. Regardless of the origin of the turbulence, a more efficient source of injection of particles, which eventually takes part in the re-acceleration process, is required in mini-halos, and this may result from the central radio galaxy or from proton-proton collisions in the dense cool core regions.
Cassano R.; Gitti M.; Brunetti G.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/101363
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