| 21st of November 2016 |
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| 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). |