MPC-Scale, Low Surface Brightness Radio Emission in Cold Front Clusters
Abstract
Mpc-scale diffuse radio emission in clusters and the current key puzzle of how the relativistic particles are accelerated are likely tied to the motions induced through merging activity. Shear flows along cold fronts, e.g., may generate turbulence and amplify magnetic fields, and have also been proposed to be possible generators of small scale (<300 kpc) radio minihalos. We present results from a study of twelve clusters at 1.4 GHz with the 100-m Green Bank Telescope. After subtraction of point sources, we find low surface brightness (<1 microJy/arcsec^2 central), Mpc-scale halolike emission in five of the twelve clusters - including all four of the CF clusters. One interesting case is A2142, a sloshing cluster with two previously known Chandra CFs near the core, and a recently discovered peripheral CF at r 1 Mpc. We find a 2 Mpc synchrotron halo which extends to this peripheral cold front. All of the GBT halos are observed to be larger than typical giant radio halos of similar radio luminosity, implying relatively low volume averaged synchrotron emissivities. Our findings suggest a possible connection between the physics of sloshing cold fronts, minor mergers, and Mpc-scale CR acceleration.
- Publication:
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Cold fronts in Galaxy Clusters: Sloshing through the Dolomites
- Pub Date:
- January 2013
- Bibcode:
- 2013cfgc.confE..14F