Distant cluster hunting: A comparison between the optical and X-ray luminosity functions from an optical/X-ray joint survey

被引:50
作者
Donahue, M
Mack, J
Scharf, C
Lee, P
Postman, M
Rosati, P
Dickinson, M
Voit, GM
Stocke, JT
机构
[1] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[2] Columbia Univ, Dept Astron, New York, NY 10027 USA
[3] European So Observ, D-85748 Garching, Germany
[4] Univ Colorado, CASA, Boulder, CO 80309 USA
关键词
cosmology : observations; dark matter; galaxies : clusters : general; intergalactic medium; surveys; X-rays : galaxies;
D O I
10.1086/320334
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present a comparison of X-ray and optical luminosities and luminosity functions of cluster candidates from a joint optical/X-ray survey, the ROSAT Optical X-Ray Survey. Completely independent X-ray and optical catalogs of 23 ROSAT fields (4.8 deg(2)) were created by a matched-filter optical algorithm and by a wavelet technique in the X-ray. We directly compare the results of the optical and X-ray selection techniques. The matched-filter technique detected 74% (26 out of 35) of the most reliable cluster candidates in the X-ray-selected sample; the remainder could be either constellations of X-ray point sources or z > 1 clusters. The matched-filter technique identified approximately 3 times the number of candidates (152 candidates) found in the X-ray survey of nearly the same sky (57 candidates). While the estimated optical and X-ray luminosities of clusters of galaxies are correlated, the intrinsic scatter in this relationship is very large. We can reproduce the number and distribution of optical clusters with a model defined by the X-ray luminosity function and by an L-X-Lambda (cl) relation if H-0 = 75 km s(-1) Mpc(-1) and if the L-X-Lambda (cl) relation is steeper than the expected L-X proportional to Lambda (2)(cl). On statistical grounds, a bimodal distribution of X-ray luminous and X-ray faint clusters is unnecessary to explain our observations. Follow-up work is required to confirm whether the clusters without bright X-ray counterparts are simply X-ray faint for their optical luminosity because of their low mass or youth or are a distinct population of clusters that do not, for some reason, have dense intracluster media. We suspect that these optical clusters are low-mass systems, with correspondingly low X-ray temperatures and luminosities, or that they are not yet completely virialized systems.
引用
收藏
页码:L93 / L96
页数:4
相关论文
共 35 条
[1]   The Canada-France-Hawaii telescope optical PDCS survey (COP). I. The data [J].
Adami, C ;
Holden, BP ;
Castander, FJ ;
Nichol, RC ;
Mazure, A ;
Ulmer, MP ;
Postman, M ;
Lubin, LM .
ASTRONOMICAL JOURNAL, 2000, 120 (01) :1-22
[2]   Linear regression for astronomical data with measurement errors and intrinsic scatter [J].
Akritas, MG ;
Bershady, MA .
ASTROPHYSICAL JOURNAL, 1996, 470 (02) :706-714
[3]   A test for partial correlation with censored astronomical data [J].
Akritas, MG ;
Siebert, J .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1996, 278 (04) :919-924
[4]  
ARNAUD M, 1992, ASTRON ASTROPHYS, V254, P49
[6]   X-RAY CLUSTERS OF GALAXIES - CORRELATIONS WITH OPTICAL MORPHOLOGY AND GALAXY DENSITY [J].
BAHCALL, NA .
ASTROPHYSICAL JOURNAL, 1977, 217 (02) :L77-L82
[7]   Cosmological constraints from the ROSAT Deep Cluster Survey [J].
Borgani, S ;
Rosati, P ;
Tozzi, P ;
Norman, C .
ASTROPHYSICAL JOURNAL, 1999, 517 (01) :40-53
[8]   A UNIFORMLY SELECTED CATALOG OF DISTANT GALAXY CLUSTERS [J].
COUCH, WJ ;
ELLIS, RS ;
MALIN, DF ;
MACLAREN, I .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1991, 249 (04) :606-628
[9]   A CATALOG OF INTRACLUSTER GAS TEMPERATURES [J].
DAVID, LP ;
SLYZ, A ;
JONES, C ;
FORMAN, W ;
VRTILEK, SD ;
ARNAUD, KA .
ASTROPHYSICAL JOURNAL, 1993, 412 (02) :479-488
[10]   The ROSAT Brightest Cluster sample (BCS): The cluster X-ray luminosity function within z=0.3 [J].
Ebeling, H ;
Edge, AC ;
Fabian, AC ;
Allen, SW ;
Crawford, CS ;
Bohringer, H .
ASTROPHYSICAL JOURNAL, 1997, 479 (02) :L101-L104