J/A+A/462/449 Chandra point-source counts in galaxy cluster (Branchesi+, 2007)
Chandra point-source counts in distant galaxy clusters.
Branchesi M., Gioia I.M., Fanti C., Fanti R., Cappelluti N.
<Astron. Astrophys., 462, 449-458 (2007)>
=2007A&A...462..449B 2007A&A...462..449B
ADC_Keywords: Clusters, galaxy ; X-ray sources
Keywords: galaxies: clusters: general - galaxies: active - X-rays: general -
X-rays: galaxies: clusters - galaxies: nuclei
Abstract:
With the superb angular resolution of the Chandra Observatory, it is
now possible to detect X-ray point sources, either embedded in galaxy
clusters or along the cluster line of sight, which could not be
resolved by previous instruments. This now allows studies of source
counts in distant cluster fields.
We want to analyze the inner region of clusters of galaxies to check
for the presence of any over-density of X-ray point sources embedded in
the gas diffuse emission. These point sources are possible AGN
belonging to the clusters and could contaminate the cluster emission.
We used a sample of 18 distant (0.25<z<1.01) galaxy clusters from
the Chandra archive to construct the logN-logS, in both the soft and
hard energy bands, for the X-ray point sources detected in the central
cluster region to be compared with the counts of point sources
detected in similarly deep fields without clusters.
Description:
The sample used in this study consists of 18 clusters of galaxies
observed by the Chandra observatory with redshift in the range
z=0.25-1.01.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 73 18 Cluster sample parameters and details of
Chandra observations
table2.dat 92 119 X-ray cluster region point sources
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Cluster Cluster name
19- 23 F5.3 --- z Spectroscopic redshift from literature
25- 26 I2 h RAh Right ascension (J2000)
28- 29 I2 min RAm Right ascension (J2000)
31- 32 I2 s RAs Right ascension (J2000)
34 A1 --- DE- Declination sign (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 42 I2 arcsec DEs Declination (J2000)
44- 47 I4 --- ObsID Identification number of the observation
49 A1 --- ACIS [IS] Detector where the aimpoint lies
(I=ACIS-I or S=ACIS-S)
51- 52 A2 --- Mode [VF ] Observation mode (F=FAINT or VF=VFAINT)
54- 58 F5.1 ks ExpTime Exposure time corresponding to the nominal
exposure filtered to exclude time periods
of high background
60- 63 F4.2 10+20cm-2 NH Galactic hydrogen density column
65- 68 F4.2 10+35W Lsoft X-ray luminosity in (0.5-2.0keV) band
70- 73 F4.2 10+35W Lhard X-ray luminosity in (2.0-10.0keV) band
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Cluster Cluster name
19- 21 I3 arcsec Rext Search radius
23- 24 I2 --- Seq Source identification number,
in the cluster (1)
26- 27 I2 h RAh Right ascension (J2000)
29- 30 I2 min RAm Right ascension (J2000)
32- 35 F4.1 s RAs Right ascension (J2000)
37 A1 --- DE- Declination sign (J2000)
38- 39 I2 deg DEd Declination (J2000)
41- 42 I2 arcmin DEm Declination (J2000)
44- 47 F4.1 arcsec DEs Declination (J2000)
49- 54 F6.2 ct Csoft ? Net counts in (0.5-2.0keV) energy band
55 A1 --- f_Csoft [*] Flag for non-used sources (2)
57- 62 F6.2 ct Chard ? Net counts in (2.0-7.0keV) energy band
63 A1 --- f_Chard [*] Flag for non-used sources (2)
65- 69 F5.2 aW/m2 Ssoft ? X-ray flux in (0.5-2.0keV) band (3)
71- 74 F4.2 aW/m2 e_Ssoft ? rms uncertainty on Ssoft
76- 80 F5.3 --- CNH Correction factor to be applied to the
observed soft X-ray flux to obtain the
Galactic absorption corrected X-ray flux
82- 86 F5.2 aW/m2 Shard ? X-ray flux in (2.0-10.0keV) band (3)
88- 92 F5.2 aW/m2 e_Shard ? rms uncertainty on S2.0-10.0keV
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Note (1): Sources identified as [BGF2007] Cluster NN in Simbad.
Note (2): source not used in Sect. 5 for the computation of the source
counts since their flux is smaller than the flux corresponding
to 20% of the sky coverage (see Appendix C).
Note (3): The conversion factors allowed us to convert the 0.5-2.0keV
band count rate to the observed X-ray fluxes in the same band and
the 2.0-7.0keV band count rate to the observed X-ray flux in the
2.0-10.0keV band. Units are 10-15cgs (aW/m2)
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History:
* 11-Sep-2007: From electronic version of the journal
* 24-Sep-2010: in table2, the "CNH" parameter was corrected from blank
to the value of the first galaxy in the cluster (the correction
is constant for the galaxies in a cluster)
(End) Patricia Vannier [CDS] 11-Sep-2007