Evidence for AGN-regulated Cooling in Clusters at z ∼ 1.4: A Multiwavelength View of SPT-CL J0607-4448

• Published in: The Astrophysical Journal
• Main Authors: Megan Masterson, Michael McDonald, Behzad Ansarinejad, Matthew Bayliss, Bradford A. Benson, Lindsey E. Bleem, Michael S. Calzadilla, Alastair C. Edge, Benjamin Floyd, Keunho J. Kim, Gourav Khullar, Taweewat Somboonpanyakul
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2023
• Subjects: Brightest cluster galaxies; Galaxy clusters; Intracluster medium; Radio galaxies; High-redshift galaxy clusters; Astrophysics; QB460-466; South Pole; South pole
• Online Access: https://doi.org/10.3847/1538-4357/acae9e; https://doaj.org/article/43a3ed7fb69d400dbfbd03fa18d00080

We present a multiwavelength analysis of the galaxy cluster SPT-CL J0607-4448 (SPT0607), which is one of the most distant clusters discovered by the South Pole Telescope at z = 1.4010 ± 0.0028. The high-redshift cluster shows clear signs of being relaxed with well-regulated feedback from the active galactic nucleus (AGN) in the brightest cluster galaxy (BCG). Using Chandra X-ray data, we 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 ( ${K}_{0}={18}_{-9}^{+11}$ keV cm ^2 ), which we estimate assuming an isothermal temperature profile due to the limited spectral information given the distance to the cluster. Using the density profile and gas cooling time inferred from the X-ray data, we find a mass-cooling rate ${\dot{M}}_{\mathrm{cool}}={100}_{-60}^{+90}\,{M}_{\odot }$ yr ^−1 . From optical spectroscopy and photometry around the [O ii ] emission line, we estimate that the BCG star formation rate is ${\mathrm{SFR}}_{[{\rm{O}}\,{\rm\small{II}}]}={1.7}_{-0.6}^{+1.0}\,{M}_{\odot }$ yr ^−1 , roughly two orders of magnitude lower than the predicted mass-cooling rate. In addition, using ATCA radio data at 2.1 GHz, we measure a radio jet power ${P}_{\mathrm{cav}}={3.2}_{-1.3}^{+2.1}\times {10}^{44}$ erg s ^−1 , which is consistent with the X-ray cooling luminosity ( ${L}_{\mathrm{cool}}={1.9}_{-0.5}^{+0.2}\times {10}^{44}$ erg s ^−1 within r _cool = 43 kpc). These 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. We discuss the implications for these findings on the evolution of AGN feedback in galaxy clusters.