J/MNRAS/446/2709 X-ray bright AGN in massive galaxy clusters (Ehlert+, 2015)
X-ray bright active galactic nuclei in massive galaxy clusters.
III. New insights into the triggering mechanisms of cluster AGN.
Ehlert S., Allen S.W., Brandt W.N., Canning R.E.A., Luo B., Mantz A.,
Morris R.G., von der Linden A., Xue Y.Q.
<Mon. Not. R. Astron. Soc., 446, 2709-2729 (2015)>
=2015MNRAS.446.2709E 2015MNRAS.446.2709E (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; X-ray sources ; Active gal. nuclei ; Morphology
Keywords: galaxies: active - galaxies: clusters: general - X-rays: galaxies -
X-rays: galaxies: clusters
Abstract:
We present the results of a new analysis of the X-ray selected active
galactic nuclei (AGN) population residing in and behind 135 of the
most massive galaxy clusters in the redshift range of 0.2<z<0.9
observed with Chandra. With a sample of more than 11000 X-ray point
sources, we are able to measure, for the first time, evidence for
evolution in the cluster AGN population beyond the expected evolution
of field AGN. Our analysis shows that overall number density of
cluster AGN scales with the cluster mass as ∼M500-1.2. There is no
evidence for the overall number density of cluster member X-ray AGN
depending on the cluster redshift in a manner different than field
AGN, nor is there any evidence that the spatial distribution of
cluster AGN (given in units of the cluster overdensity radius r500)
strongly depends on the cluster mass or redshift. The M-1.2±0.7
scaling relation we measure is consistent with theoretical predictions
of the galaxy merger rate in clusters, which is expected to scale with
the cluster velocity dispersion, σ, as ~σ-3 or ∼M-1.
This consistency suggests that galaxy mergers may be an important
contributor to the cluster AGN population, a result that is further
corroborated by visual inspection of Hubble images for 23
spectroscopically confirmed cluster member AGN in our sample. A
merger-driven scenario for the triggering of X-ray AGN is not strongly
favoured by studies of field galaxies, however, suggesting that
different mechanisms may be primarily responsible for the triggering
of cluster and field X-ray AGN.
Description:
The clusters included in our study have been drawn from wide-area
cluster surveys derived from the ROSAT All Sky Survey (Truemper,
1993Sci...260.1769T 1993Sci...260.1769T, See Cat. IX/29): the ROSAT Brightest Cluster
Sample (BCS; Ebeling et al., 1998, Cat. J/MNRAS/301/881); the
ROSAT-ESO Flux-Limited X-ray Sample (REFLEX; Bohringer et al., 2004,
Cat. J/A+A/425/367); and the Massive Cluster Survey (MACS; Ebeling et
al., 2007ApJ...661L..13T 2007ApJ...661L..13T, 2010MNRAS.407...83E 2010MNRAS.407...83E). We also included
clusters from the 400deg2 ROSAT PSPC Galaxy Cluster Survey (Burenin
et al., 2007, Cat. J/ApJS/172/561).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 102 225 *Summary of the cluster sample and Chandra
observations (either ACIS-I or ACIS-S) listed
in order of cluster redshift
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Note on table1.dat: A total of 135 clusters of galaxies and 224 independent
Chandra observations were used.
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See also:
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
J/MNRAS/301/881 : The ROSAT brightest cluster sample - I. (Ebeling+, 1998)
J/A+A/425/367 : REFLEX Galaxy Cluster Survey catalogue (Boehringer+, 2004)
J/ApJS/172/561 : The 400d cluster Survey (Burenin+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Cluster Cluster name
21 A1 --- n_Cluster [a] a: Clusters included in Paper I
(Ehlert et al., 2013MNRAS.428.3509E 2013MNRAS.428.3509E)
23- 27 F5.3 --- z Redshift
29- 30 I2 h RAh Right ascension (J2000)
32- 33 I2 min RAm Right ascension (J2000)
35- 39 F5.2 s RAs Right ascension (J2000)
41 A1 --- DE- Declination sign (J2000)
42- 43 I2 deg DEd Declination (J2000)
45- 46 I2 arcmin DEm Declination (J2000)
48- 52 F5.2 arcsec DEs Declination (J2000)
54- 58 I5 --- ObsID Chandra observation number
60- 69 A10 "date" ObsDate Observation date
71- 76 A6 --- Det Primary detector array used
78- 83 F6.2 ks Texp Exposure time, after cleaning
85- 88 F4.1 10+14Msun M500 M500 for the cluster
90- 92 F3.1 Mpc r500 r500
94- 98 F5.2 10+20cm-2 NH Equivalent Galactic hydrogen column density
in the direction of the cluster
100-102 F3.1 --- r12' Equivalent radius of 12 arcmin for each
cluster in units of r500, which denotes the
maximum radius sampled
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History:
From electronic version of the journal
References:
Ehlert et al., Paper I 2013MNRAS.428.3509E 2013MNRAS.428.3509E
Ehlert et al., Paper II 2014MNRAS.437.1942E 2014MNRAS.437.1942E
(End) Patricia Vannier [CDS] 15-Jun-2015