The Evolution of AGN Activity in Brightest Cluster Galaxies
Abstract
We present the results of an analysis of Wide-field Infrared Survey Explorer (WISE) observations on the full 2500 deg^2 South Pole Telescope (SPT)-SZ cluster sample. We describe a process for identifying active galactic nuclei (AGN) in brightest cluster galaxies (BCGs) based on WISE mid-infrared color and redshift. Applying this technique to the BCGs of the SPT-SZ sample, we calculate the AGN-hosting BCG fraction, which is defined as the fraction of BCGs hosting bright central AGNs over all possible BCGs. Assuming {\bf an evolving} single-burst stellar population model, we find statistically significant evidence (>99.9%) for a mid-IR excess at high redshift compared to low redshift, suggesting that the fraction of AGN-hosting BCGs increases with redshift over the range of 0 < z < 1.3. The best-fit redshift trend of the AGN-hosting BCG fraction has the form (1+z)^(4.1+/-1.0). These results are consistent with previous studies in galaxy clusters as well as field galaxies. One way to explain this result is that member galaxies at high redshift tend to have more cold gas. While BCGs in nearby galaxy clusters grow mostly by dry mergers with cluster members, leading to no increase in AGN activity, BCGs at high redshift could primarily merge with gas-rich satellites, providing fuel for feeding AGNs. If this observed increase in AGN activity is linked to gas-rich mergers, rather than ICM cooling, we would expect to see an increase in scatter in the P_cav vs L_cool relation at z > 1. Lastly, this work confirms that the runaway cooling phase, as predicted by the classical cooling flow model, in the Phoenix cluster is extremely rare and most BCGs have low (relative to Eddington) black hole accretion rates.
Keywords
Cite
@article{arxiv.2201.08398,
title = {The Evolution of AGN Activity in Brightest Cluster Galaxies},
author = {T. Somboonpanyakul and M. McDonald and A. Noble and M. Aguena and S. Allam and A. Amon and F. Andrade-Oliveira and D. Bacon and M. B. Bayliss and E. Bertin and S. Bhargava and D. Brooks and E. Buckley-Geer and D. L. Burke and M. Calzadilla and R. Canning and A. Carnero Rosell and M. Carrasco Kind and J. Carretero and M. Costanzi L. N. da Costa and M. E. S. Pereira J. De Vicente P. Doel P. Eisenhardt S. Everett A. E. Evrard and I. Ferrero and B. Flaugher and B. Floyd and J. García-Bellido and E. Gaztanaga and D. W. Gerdes and A. Gonzalez and D. Gruen and R. A. Gruendl and J. Gschwend and N. Gupta and G. Gutierrez and S. R. Hinton and D. L. Hollowood and K. Honscheid and B. Hoyle and D. J. James and T. Jeltema and G. Khullar and K. J. Kim and M. Klein and K. Kuehn and M. Lima and M. A. G. Maia and J. L. Marshall and P. Martini and P. Melchior and F. Menanteau and R. Miquel and J. J. Mohr and R. Morgan and R. L. C. Ogando and A. Palmese and F. Paz-Chinchón and A. Pieres and A. A. Plazas Malagón and K. Reil and A. K. Romer and F. Ruppin and E. Sanchez and A. Saro and V. Scarpine and M. Schubnell and S. Serrano and I. Sevilla-Noarbe and P. Singh and M. Smith and M. Soares-Santos and V. Strazzullo and E. Suchyta and M. E. C. Swanson and G. Tarle and C. To and D. L. Tucker and R. D. Wilkinson},
journal= {arXiv preprint arXiv:2201.08398},
year = {2022}
}
Comments
13 pages, 9 figures, Accepted for publication in ApJ