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13th of March 2023
A multi-wavelength view of the galaxy cluster SPT-CL J0607-4448
by Masterson et al.
A galaxy cluster contains tens to hundreds of member galaxies surrounded by hot, ionized plasma called the intracluster medium (ICM). The ICM is the dominant baryonic component of clusters, and it is visible at X-ray wavelengths via bremsstrahlung radiation caused by the motion of charged particles. Masterson et al. present a multiwavelength analysis of the galaxy cluster SPT-CL J0607-4448 (SPT0607) which, at a redshift of z=1.4, is one of the most distant clusters discovered by the South Pole Telescope. Chandra X-ray data is used to construct thermodynamic profiles and determine the properties of the intracluster medium. The cool-core nature of the cluster is supported by a centrally peaked density profile and low central entropy. Optical spectroscopy and photometry are used to infer that the BCG star formation rate is roughly two orders of magnitude lower than the predicted mass-cooling rate. Finally, ATCA 2.1 GHz radio data are used to measure a radio jet power which is consistent with the X-ray cooling luminosity. These multi-wavelength findings suggest that SPT0607 is a relaxed, cool-core cluster with AGN-regulated cooling at an epoch shortly after cluster formation, implying that the balance between cooling and feedback can be reached quickly.

The image at left Chandra X-ray counts in the broadband range 0.5–7 keV. The middle image shows SPT0607 using Hubble Space Telescope data from the F140W (red), F110W (green), and F814W (blue) filters. The green x shows the location of the X-ray peak and the magenta + shows the location of the radio peak, both of which are coincident with the BCG of SPT0607. The immage at right is the ATCA 2.1 GHz radio image with the synthesized beam in orange in the lower right corner. The magenta + shows the location of the radio peak.

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