Tracing Diffuse Emission in Galaxy Clusters at Low Frequencies
Abstract
We present detailed low frequency radio maps of the diffuse emission in the well known cluster Abell 2256 as well as the relatively obscure cluster Abell 2443. Our new data confirm our previously detected spectral gradient across the relic of Abell 2256 and further allow us to study the spectral curvature across the source. In the case of Abell 2443, we present multi-frequency radio images which reveal the first evidence of an ultra-steep spectrum radio relic.
The importance of these large scale ( Mpc) regions of steep spectrum emission is tied to the fact that they are only detected in the center and outskirts of clusters of galaxies which show evidence of current or recent merger activity. This diffuse emission is therefore a merging marker for cosmological studies using cluster samples. Detailed spectral studies of the systems are a key component to identifying and understanding the origin(s) of the emission as well as probing the details of cluster formation and evolution. We discuss the features seen in the low frequency spectral index maps of the diffuse emission and highlight the importance of the upcoming generation of low frequency instruments (e.g. LWA and LOFAR) to expand our knowledge of these types of systems. Finally, we outline a new study which uses the VLA Low Frequency Sky Survey to probe the shape of the radio spectrum for known clusters with diffuse emission. Basic research in radio astronomy at the Naval Research Laboratory is supported by 6.1 Base funding.- Publication:
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American Astronomical Society Meeting Abstracts #215
- Pub Date:
- January 2010
- Bibcode:
- 2010AAS...21543631C