SIMBAD references

2007ApJ...664L...9E - Astrophys. J., 664, L9-L12 (2007/July-3)

First measurement of a rapid increase in the AGN fraction in high-redshift clusters of galaxies.


Abstract (from CDS):

We present the first measurement of the AGN fraction in high-redshift clusters of galaxies (z∼0.6) with spectroscopy of one cluster and archival data for three additional clusters. We identify eight active galactic nuclei (AGNs) in these clusters from Chandra data that are sensitive to AGNs with hard X-ray (2-10 keV) luminosity LX,H>1043 ergs/s in host galaxies more luminous than a rest-frame MR←20 mag. This stands in sharp contrast to the one AGN with LX,H>1043 ergs/s that we discovered in our earlier study of eight low-redshift clusters with z=0.06-0.31 (z{d1}∼0.2). Three of the four high-redshift cluster data sets are sensitive to LX,H>1042 ergs/s, and we identify seven AGNs above this luminosity limit, compared to two AGNs in eight low-redshift clusters. Based on membership estimates for each cluster, we determine that the AGN fractions at z∼0.6 are fA(LX>1042;MR←20)=0.028+0.019–0.012 and fA(LX>1043;MR←20)=0.020+0.012–0.008. These values are approximately a factor of 20 greater than the AGN fractions in lower redshift (z{d1}∼0.2) clusters of galaxies. The cluster increase also represents substantially faster evolution than observed in the field over this redshift range (a factor of 1.3 and 3.3 for LX>1042 and LX>1043, respectively). The cluster AGN fraction increases more rapidly with redshift than the field, and the increase in cluster AGNs indicates the presence of an AGN Butcher-Oemler effect.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - galaxies: clusters: individual (Cl 0016+1609) - galaxies: clusters: individual (Cl 0542-4100 (read: ClG J0542-4100)) - galaxies: clusters: individual (Cl 0848.6+4453 (read: RX J0848.6+4453)) - Galaxies: Clusters: Individual: Alphanumeric: MS 2053-04 - Galaxies: Evolution

Nomenclature: Table 1: [EMS2007b] MS2053-XN (Nos X1 to X5).

CDS comments: Text: The cluster 0848.6+4453 (ClG 0848+4453 in SIMBAD) has a z = 1.273, and the cluster 0848.8+4456 (ClG J0848+4456 in SIMBAD) a z = 0.57. Table 2: CXOSEXSI sources seem to be in ClG 0848+4456. (See 1999AJ....118...76R, table 1)

Simbad objects: 21

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