J/A+A/420/61 X-ray clusters of galaxies (Schuecker+, 2004)
Detection of X-ray clusters of galaxies by matching RASS photons and
SDSS galaxies within GAVO.
Schuecker P., Boehringer H., Voges W.
<Astron. Astrophys., 420, 61-74 (2004)>
=2004A&A...420...61S 2004A&A...420...61S
ADC_Keywords: Clusters, galaxy ; X-ray sources ; Redshifts
Keywords: galaxies: clusters - galaxies: general - methods: statistical -
cosmology: large-scale structure of Universe
Abstract:
A new method for a simultaneous search for clusters of galaxies in
X-ray photon maps and optical galaxy maps is described. The method
appears ideally suited for the analysis of the recently proposed
wide-angle X-ray missions like DUO and ROSITA. As a first application,
clusters are extracted from the 3rd version of the ROSAT All-Sky
Survey (IX/10) and the Early Date Release of the Sloan Digital Sky
Survey (SDSS, J/AJ/123/567). The time-consuming computations are
performed within the German Astrophysical Virtual Observatory (GAVO).
On a test area of 140 square degrees, 75 X-ray clusters are detected
down to an X-ray flux limit of 3-5*10-13erg/s/cm2 in the ROSAT
energy band 0.1-2.4keV. The clusters have redshifts z<0.5.
Description:
Cluster parameters for 75 X-ray clusters of galaxies on a test area of
140 sq.deg. For each cluster the position, the galactic hydrogen
column density, the detection likelihoods, estimated and spectroscopic
redshifts, number of RASS3 photons, X-ray countrates, hardness ratios,
extent likelihood and further parameters and remarks on the clusters
are given.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 83 75 Cluster positions, detection significances etc.
table3.dat 92 75 Cluster countrates, hardness ratios etc.
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See also:
J/AJ/123/567 : SDSS quasar catalog, I: Early Data Release (Schneider+, 2002)
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Seq Cluster number
6- 12 F7.4 deg RAdeg Right ascension (J2000.0)
14- 20 F7.4 deg DEdeg Declination (J2000.0)
22- 26 F5.2 10+20cm-2 NH Neutral galactic hydrogen column density
28- 33 F6.2 10-16W/m2 S Unabsorbed X-ray flux in the ROSAT energy
band 0.1-2.4keV
35- 41 F7.3 --- ln(L/L0)R Detection likelihoods on RASS-3 photon maps
43- 50 F8.3 --- ln(L/L0)S Detection likelihoods on SDSS galaxy maps
53- 56 F4.2 --- zestR Estimated cluster redshift from RASS-3
59- 62 F4.2 --- zestS Estimated cluster redshift from SDSS
66- 71 F6.4 --- zspec Spectroscopic redshift
74- 75 I2 --- Nz Number of cluster galaxies used for zspec
78- 84 A7 --- Note Note whether the cluster in NOT found in a
catalogue (1)
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Note (1): Catalogs acronyms are:
V2 = ROSAT Faint Source Catalogue, Cat. IX/29
V3 = unscreened version of V2
G = Goto et al. (2002AJ....123.1807B 2002AJ....123.1807B)
B = Bahcall et al. (2003ApJS...148..243B).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Seq Cluster number
6- 12 F7.4 deg RAdeg Right ascension (J2000.0)
14- 20 F7.4 deg DEdeg Declination (J2000.0)
22- 26 F5.1 --- Nph Number of X-ray photons
28- 32 F5.3 s-1 Gamma Maximum likelihood X-ray countrate
35- 39 F5.3 s-1 e_Gamma rms uncertainty on Gamma
41- 45 F5.3 s-1 ctr(GCA) Growth Curve Analysis (GCA) X-ray count rate
48- 52 F5.3 s-1 e_ctr(GCA) rms uncertainty on ctr(GCA)
54- 58 F5.2 --- HR(GCA) GCA hardness ratio
60- 63 F4.1 --- EXT(GCA) GCA negative logarithmic KS-probability for a
point source
65- 69 F5.1 --- Rich Optical cluster richness from SDSS
71- 93 A23 --- Remarks Further remarks on the cluster (1)
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Note (1): Abbreviations in the remarks:
CONT = AGN within 1 arcmin from cluster position in NED
CUT = cluster only partially in test area of matched filter
zG = redshift in Goto et al. (2002AJ....123.1807B 2002AJ....123.1807B)
teff = effective exposure time in RASS3
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Acknowledgements: Peter Schuecker
References:
Bahcall, N.A., McKay, T.A., Annis, J., et al. 2003ApJS...148,..243B
A merged catalog of clusters from the Early Sloan Digital Sky Survey
Data
Goto, T., et al. 2002AJ....123.1807B 2002AJ....123.1807B
The Cut-and-Enhance method: Selecting clusters from the Sloan Digital
Sky Survey Commissioning Data
(End) Peter Schuecker [MPE, Germany], Patricia Bauer [CDS] 18-May-2004