The SPT-Chandra BCG Spectroscopic Survey. I. Evolution of the Entropy Threshold for ICM Cooling and AGN Feedback in Galaxy Clusters over the Last 10 Gyr

Calzadilla, Michael S.; McDonald, Michael; Benson, Bradford A.; Bleem, Lindsey E.; Croston, Judith H.; Donahue, Megan; Edge, Alastair C.; Floyd, Benjamin; Garmire, Gordon P.; Hlavacek-Larrondo, Julie; Huynh, Minh T.; Khullar, Gourav; Kraft, Ralph P.; McNamara, Brian R.; Noble, Allison G.; Romero, Charles E.; Ruppin, Florian; Somboonpanyakul, Taweewat; Voit, G. Mark

Abstract

We present a multiwavelength study of the brightest cluster galaxies (BCGs) in a sample of the 95 most massive galaxy clusters selected from the South Pole Telescope Sunyaev–Zeldovich (SZ) survey. Our sample spans a redshift range of 0.3 < z < 1.7, and is complete with optical spectroscopy from various ground-based observatories, as well as ground and space-based imaging from optical, X-ray, and radio wave bands. At z ∼ 0, previous studies have shown a strong correlation between the presence of a low-entropy cool core and the presence of both star formation and radio-loud active galactic nuclei in the central BCG. We show for the first time that the central entropy threshold for triggering star formation, which is universally seen in nearby systems, persists out to z ∼ 1, with only marginal (∼1σ) evidence for evolution in the threshold entropy value itself. In contrast, we do not find a similar high-z analog for an entropy threshold for feedback, but instead measure a strong evolution in the fraction of radio-loud BCGs in high-entropy cores, decreasing with increasing redshift. This could imply that the cooling-feedback loop was not as tight in the past, or that some other fuel source like mergers are fueling the radio sources more often with increasing redshift, making the radio luminosity an increasingly unreliable proxy for radio jet power. We also find that our SZ-based sample is missing a small (∼4%) population of the most luminous radio sources (ν L ν > 1042 erg s−1), likely due to radio contamination suppressing the SZ signal with which these clusters are detected.

Citation

Calzadilla, M. S., McDonald, M., Benson, B. A., Bleem, L. E., Croston, J. H., Donahue, M., Edge, A. C., Floyd, B., Garmire, G. P., Hlavacek-Larrondo, J., Huynh, M. T., Khullar, G., Kraft, R. P., McNamara, B. R., Noble, A. G., Romero, C. E., Ruppin, F., Somboonpanyakul, T., & Voit, G. M. (2024). The SPT-Chandra BCG Spectroscopic Survey. I. Evolution of the Entropy Threshold for ICM Cooling and AGN Feedback in Galaxy Clusters over the Last 10 Gyr. The Astrophysical Journal, 976(2), Article 169. https://doi.org/10.3847/1538-4357/ad8916

• Journal Article Type: Article
• Acceptance Date: Oct 19, 2024
• Online Publication Date: Nov 21, 2024
• Publication Date: Dec 1, 2024
• Deposit Date: Nov 25, 2024
• Publicly Available Date: Nov 25, 2024
• Journal: The Astrophysical Journal
• Electronic ISSN: 1538-4357
• Peer Reviewed: Peer Reviewed
• Volume: 976
• Issue: 2
• Article Number: 169
• DOI: https://doi.org/10.3847/1538-4357/ad8916
• Keywords: Intracluster medium, Star formation, Active galactic nuclei, High-redshift galaxy clusters, Cooling flows
• Public URL: https://durham-repository.worktribe.com/output/3105043