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J/MNRAS/392/1509    Distribution of AGNs in galaxy clusters    (Gilmour+, 2009)

The distribution of active galactic nuclei in a large sample of galaxy clusters. Gilmour R., Best P., Almaini O. <Mon. Not. R. Astron. Soc., 392, 1509-1531 (2009)> =2009MNRAS.392.1509G
ADC_Keywords: Clusters, galaxy ; Active gal. nuclei ; X-ray sources Keywords: galaxies: active - galaxies: clusters: general - X-rays: galaxies - X-rays: galaxies: clusters Abstract: We present an analysis of the X-ray point source populations in 182 Chandra images of galaxy clusters at z>0.1 with exposure time >10ks, as well as 44 non-cluster fields. The analysis of the number and flux of these sources, using a detailed pipeline to predict the distribution of non-cluster sources in each field, reveals an excess of X-ray point sources associated with the galaxy clusters. A sample of 148 galaxy clusters at 0.1<z<0.9 , with no other nearby clusters, shows an excess of 230 cluster sources in total, an average of ∼1.5 sources per cluster. The lack of optical data for these clusters limits the physical interpretation of this result, as we cannot calculate the fraction of cluster galaxies hosting X-ray sources. However, the fluxes of the excess sources indicate that over half of them are very likely to be active galactic nuclei (AGN), and the radial distribution shows that they are quite evenly distributed over the central 1Mpc of the cluster, with almost no sources found beyond this radius. We also use this pipeline to successfully reproduce the results of previous studies, particularly the higher density of sources in the central 0.5Mpc of a few cluster fields, but show that these conclusions are not generally valid for this larger sample of clusters. We conclude that some of these differences may be due to the sample properties, such as the size and redshift of the clusters studied, or a lack of publications for cluster fields with no excess sources. This paper also presents the basic X-ray properties of the galaxy clusters, and in subsequent papers in this series the dependence of the AGN population on these cluster properties will be evaluated. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 136 182 Final cluster sample split by morphological class table4.dat 105 9833 Properties of sources detected in the cluster fields refs.dat 54 81 References
See also: B/chandra : The Chandra Archive Log (CXC, 1999-) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 A2 --- Mcl Morphological class code (1) 4- 27 A24 --- Cluster Cluster name (2) 29- 42 A14 --- ObsID Chandra observation identification number(s) 44- 45 I2 h RAh Right ascension (J2000) 47- 48 I2 min RAm Right ascension (J2000) 50- 53 F4.1 s RAs Right ascension (J2000) 55 A1 --- DE- Declination sign (J2000) 56- 57 I2 deg DEd Declination (J2000) 59- 60 I2 arcmin DEm Declination (J2000) 62- 65 F4.1 arcsec DEs Declination (J2000) 67- 70 A4 --- CCD ACIS detector or CCDs used 71- 75 F5.1 ks Exp Good exposure time, after filtering (average over the selected chips) 77- 81 F5.2 fW/m2 FX ?=- Observed X-ray flux in 0.5-8keV band (4) 83- 87 F5.2 10+37W LX1 ?=- Rest frame 0.5-8keV luminosity (4) 89- 93 F5.2 10+37W LX2 ?=- Rest frame 0.1-2.4keV luminosity (4) 95- 98 F4.2 --- rchi2 ?=- Reduced chi2 value 100-104 F5.3 --- z Redshift 106-110 A5 --- r_z References for redshift, in refs.dat file 112 A1 --- n_z [1/3] Note on z (3) 114-118 F5.2 --- Excess Excess number of sources in the central 1Mpc (compared to the prediction) 120-123 F4.2 --- E_Excess Error on Excess (upper value) 125-128 F4.2 --- e_Excess Error on Excess (lower value) 130-134 F5.2 [10-7W] Centre ? log luminosity of any source detected within 25 kpc of the cluster centre 136 I1 --- n_Centre [2]? Note on Centre (3)
Note (1): Morphological classes code explained in section 3.2.1: 0 = no cluster emission visible 1 = relaxed cluster (may be elliptical or have edges) 2 = disturbed cluster (disturbance must be joined to the cluster by visible emission) 3 = merging cluster (double-peaked system with sub-cluster > 20% of the main cluster) 4 = two clusters (a second cluster but not clearly associated) 1c = morphology 1 (relaxed cluster) with a small contamination (<20%) 2c = morphology 2 (disturbed cluster) with a small contamination (<20%) hz = High redshift (proto)clusters Note (2): Name of cluster in the NED. If more than one cluster name exists, then the nearest is given. If there is no cluster within 2 arcmin, then the nearest object name at the cluster redshift is given. Note (3): Notes as follows: 1 = NED gives z=0.35, but the X-ray spectral data have a far better fit with z=0.38 2 = this cluster has two X-ray point sources within 25kpc, which overlap slightly. The second, at 10kpc, has log luminosity ∼43.72 3 = NED gives two redshifts, but only one is given in the paper which NED refers to Note (4): X-ray flux in 10-12erg/cm2/s, and luminosities in 1044erg/s
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 24 A24 --- Cluster Cluster name 26- 31 A6 --- --- [CXOGBA] 33- 48 A16 --- CXOGBA Source name (JHHMMSS.s+DDMMSS) 50- 51 I2 h RAh Right ascension (J2000) 53- 54 I2 min RAm Right ascension (J2000) 56- 59 F4.1 s RAs Right ascension (J2000) 61 A1 --- DE- Declination sign (J2000) 62- 63 I2 deg DEd Declination (J2000) 65- 66 I2 arcmin DEm Declination (J2000) 68- 71 F4.1 arcsec DEs Declination (J2000) 73- 79 F7.1 ct Ct Net Counts 81- 87 F7.2 aW/m2 FX X-ray flux (1) 89- 94 F6.1 --- Sig Source significance (2) 96-100 F5.2 --- HR ?=-1.00 Hardness ratio (3) 102-105 F4.2 --- e_HR ?=0.00 rms uncertainty on HR
Note (1): assuming a spectrum with Γ=1.7; expressed in 10-15erg/cm2/s Note (2): Sig=Counts/σbg, where σbg is he error on the calculated background counts in the annulus Note (3): Hardness ratio, (H-S)/(H+S), where H(2-8keV) and S(0.5-2keV) are set to 0 for detections with significance <3 in that band.
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Ref Reference code 4- 22 A19 --- BibCode BibCode 24- 54 A31 --- Aut Author's name
History: * 06-Oct-2009 : From electronic version of the journal * 06-May-2010 : Some names corrected in table2
(End) Patricia Vannier [CDS] 21-Aug-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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