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21st of November 2016
Separation of ICM components in the high-redshift cluster MACS J0025.4-1222
by Chris Riseley (CASS)
The image shows the separation of bulk components in the intracluster medium (ICM) of the merging cluster system, MACS J0025.4-1222. The background image is from the Hubble Space Telescope (HST). Cyan denotes the total mass distribution (dominated by dark matter) traced by gravitational lensing, purple denotes the baryonic mass distribution (the hot ICM gas) traced by X-ray emission, and red denotes the non-thermal components (synchrotron emission) detected at radio wavelengths with the Giant Metrewave Radio Telescope (GMRT). The diffuse radio emission here takes the form of a pair of radio relics: Mpc-scale sources of diffuse synchrotron emission, associated with merger shocks, toward the periphery on opposite sides of the cluster. At redshift 0.5857, MACS J0025.4-1222 joins the small (but growing) population of high-redshift clusters where diffuse radio emission is detected; this parameter space is set to be unveiled with future highly-sensitive observations with the SKA.

The HST image and lensing mass reconstruction are from Bradac et al. (2008); radio and X-ray data (from Chandra) are from Riseley et al. (2016).

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