AGN heating and ICM cooling in the HIFLUGCS sample of galaxy clusters

By R. Mittal, D. Hudson, T. Reiprich, T. Clarke. 2008

145 citations recorded by the source corpus.

Active galactic nuclei (AGN) at the center of galaxy clusters with gas cooling times that are much shorter than the Hubble time have emerged as heating agents powerful enough to prevent further cooling of the intracluster medium (ICM). We carried out an intensive study of the AGN heating−ICM cooling network by comparing various cluster parameters to the integrated radio luminosity of the central AGN, LR, defined as the total synchrotron power between 10 MHz and 15 G Hz. This study is based on the HIFLUGCSsample comprising the 64 X-ray brightest galaxy clusters. We adopted the central cooling time, tcool, as the diagnostic to ascertain cooling properties of the HIFLUGCSsample and classify clusters with tcool 7.7 Gyr as non-cool-core (NCC) clusters. We find 48 out of 64 clusters (7 5%) contain cluster center radio sources (CCRS) cospatial with or within 50 h −1 71 kpc of the X-ray peak emission. Furthermore, we find that the p robability of finding a CCRS increases from 45% to 67% to 100% for NCC, WCC, and SCC clusters, respectively. We use a total of∼ 140 independent radio flux-density measurements, with data at more than two frequencies for more than 54% of the sources extending below 500 MHz, enabling the determination of accurate estimates of LR. We find that LR in SCC clusters depends strongly on the cluster scale such that more massive clusters harbor more powerful radio AGN. The same trend is observed between LR and the classical mass deposition rate, ˙ Mclassical in SCC and partly also in WCC clusters, and can be quantified as LR∝ ˙ M 1.69±0.25 classical . We also perform correlations of the luminosity for the brightest cluster galaxy, LBCG, close to the X-ray peak in all 64 clusters with LR and cluster parameters, such as the virial mass, M500, and the bolometric X-ray luminosity, LX. To this end, we use the 2MASS K-band magnitudes and invoke the near-infrared bulge luminosity-black hole mass relation to convert LBCG to supermassive black hole mass, MBH. We find a weak correlation between MBH and LR for SCC clusters, LR∼ M 4.10±0.42 BH , although with a few outliers. We find an excellent correlati on of LBCG with M500 and LX for the entire sample, the SCC clusters showing a tighter trend in both the cases. We discuss the plausible reasons behind these scaling relations in the context of cooling flows and AGN feedback. Our results strongly suggest an AGN-feedback machinery in SCC clusters, which regulates the cooling in the central regions. Since the dispersion in these correlations, such a s that between LR and ˙ Mclassical or LR and MBH, increases in going from SCC to WCC clusters, we conclude there must be secondary processes that work either in conjunction with the AGN heating or independently to counteract the radiative losses in WCC clusters.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/8581a2367bda631d1b915b38b3c5e6c4ecc26faa

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. D. Eckert
2. Stéphane Paltani
3. S. Molendi
4. A. Mann
5. H. Ebeling
6. P. Nulsen
7. T. Reiprich
8. R. Mittal

In Instrumentation

1. D. Eckert
2. S. Molendi
3. Stéphane Paltani
4. A. Mann
5. T. Reiprich
6. H. Ebeling
7. P. Nulsen
8. G. Schellenberger

Citations in the corpus

• Scaling Properties of a Complete X-ray Selected Galaxy Group Sample (2014, background): “Mittal et al. (2009) showed that 75% of the galaxy clusters host a central radio source (CRS), with a higher probability to host an AGN for the CC objects and the lowest probability for the NCC.”
• The cool-core bias in X-ray galaxy cluster samples - I. Method and application to HIFLUGCS (2010, methodology): “More recently, studies have been carried out using Chandra data (Mittal et al. 2009; Hudson et al. 2010), which clearly demonstrate the existence of a class of intermediate objects.”
• What is a cool-core cluster? a detailed analysis of the cores of the X-ray flux-limited HIFLUGCS cluster sample (2009, background): “39 radio source, (Mittal et al. 2009).”
• X-ray–optical classification of cluster mergers and the evolution of the cluster merger fraction (2011, background): “…powerful evidence of a recent or ongoing merger (e.g. Smith et al. 2005; Shan et al. 2010); conversely, excellent alignment of the BCG with the intracluster gas distribution is typical of relaxed systems which often also exhibit significant radiative cooling in the core region (Mittal et al. 2009).”