The Wide Angle ROSAT Pointed Survey
The WARPS cluster survey is an international collaboration to compile and investigate the properties of an x-ray selected sample of galaxy clusters out to high redshifts and down to low x-ray luminosities.
Since galaxy clusters are the largest gravitationally bound aggregates to have decoupled from the Hubble expansion, they offer a unique probe of cosmologically interesting quantities. In particular, the abundance and evolutionary properties of clusters reveal important clues to understanding the formation of structures in the Universe and the values of fundamental cosmological parameters.
Large samples of clusters are essential to studying the evolution of large-scale structure in the universe. Until recently, such studies were based on optically selected samples which (while large) have the disadvantage of being biased by projection effects. X-ray surveys are a much less biased way to select large samples of clusters, as x-ray emission originates from diffuse gas at T ~ 107-108 K trapped in a deep potential well. Searching for clusters with x-ray observations is therefore very efficient and also provides information about the cluster gravitational potential.
The Wide Angle ROSAT Pointed Survey (WARPS) is based entirely on serendipitous source detections in ROSAT pointed observations archived at the HEASARC at the Laboratory for High Energy Astrophysics at Goddard Space Flight Center. The cluster sample is compiled from PSPC pointed observations of non-cluster targets at |b| > 20° with texp > 8ks. Our detection algorithm, VTP, detects sources of arbitrary shape with equal efficiency, and is particularly sensitive to low-surface brightness emission. WARPS is the only x-ray cluster survey which has tested the efficacy of its approach by optically imaging all x-ray sources in our initial sample lacking counterparts on sky survey plates. This test is crucial to the completeness of any x-ray selected cluster sample.
More information on clusters of galaxies is available from the High-Energy Astrophysics Learning Center.Status of WARPS
- Catalog paper for the WARPS-II sample of ~300 fields has been published by ApJS.
On-Line Resources
- WARPS-I catalog with downloadable finder charts.
- WARPS-II catalog with downloadable finder charts.
WARPS Publications
- The WARPS Survey. VII. The WARPS-II Cluster Catalog, Horner, Donald J.; Perlman, Eric S.; Ebeling, Harald; Jones, Laurence R.; Scharf, Caleb A.; Wegner, Gary; Malkan, Matthew; Maughan, Ben, 2008, ApJS, 176, 374
- The WARPS
Survey: VI. Galaxy Cluster and Source Identifications from Phase
I, E. S. Perlman (University of Maryland, Baltimore County),
D.J. Horner (University of Maryland, College Park), L. R. Jones
(University of Birmingham), C. A. Scharf (Columbia University),
H. Ebeling (University of Hawaii), G. Wegner (Dartmouth University),
M. Malkan (UCLA) 2002, ApJS, 140, 265.
Errata
Below is list of errata for the paper. If you spot any more mistakes, please let us know. The version on astro-ph has been updated to reflect the changes
- The redshift of J0210.4-3929 has been established to be z=0.165 (well, at least for the BCG) by spectroscopic follow-up of the CfA 160 sq. deg. survey. Our redshift (noted as uncertain in the paper) was based on best guess from two ratty spectra taken at the AAT and CTIO 1.5m. Thanks to Chris Mullis for the correction.
- The caption of Figure 1 is incorrect. The images are adaptively smoothed no smoothed with a Gaussian. Thanks to Stefano Ettori for pointing this out.
- The flux values in Table 2 and Table 3 (which list all the sources detected and other sources that did not make it into the final catalog) were not calculated as specified in the text (an old value of the table was published by mistake). The differences are typically only 1-2%. The cluster tables are not affected. The version on astro-ph has been updated with the correct version of the tables.
- Discovery of a very X-ray luminous galaxy cluster at z=0.89 in the WARPS survey, H. Ebeling, L.R. Jones, B.W. Fairley, E. Perlman, C. Scharf, D. Horner 2002, ApJL, 548,23.
- The WARPS Survey. IV. The X-ray Luminosity - Temperature Relation of High Redshift Galaxy Clusters, B.W. Fairley, L.R. Jones, C.A. Scharf, H. Ebeling, E. Perlman, D. Horner, G. Wegner & M. Malkan 2000, MNRAS, 315, 669.
- The WARPS Survey. III. The Discovery of an X-Ray Luminous Galaxy Cluster at z=0.833 and the Impact of X-Ray Substructure on Cluster Abundance Measurements, H. Ebeling, L.R. Jones, C.A. Scharf, E. Perlman, D. Horner, G. Wegner & M. Malkan 1999, 2000, ApJ, 534, 133.
- The WARPS Survey. II. The log N-- log S Relation and the X-Ray Evolution of Low-Luminosity Clusters of Galaxies, L.R. Jones, C.A. Scharf, H. Ebeling, E. Perlman, G. Wegner, M. Malkan & D. Horner 1998, ApJ, 495, 100.
- The Wide-Angle ROSAT Pointed X-Ray Survey of Galaxies, Groups, and Clusters. I. Method and First Results, C.A. Scharf, L.R. Jones, H. Ebeling, E. Perlman, G. Wegner, & M. Malkan 1997, ApJ, 477, 79.
The WARPS cluster collaboration (in alphabetical order)
- Harald Ebeling (Institute for Astronomy)
- Don Horner (EUD)
- Laurence Jones ( University of Birmingham)
- Matt Malkan (UCLA)
- Ben Maughan (Bristol)
- Eric Perlman ( UMBC)
- Caleb Scharf (Columbia)
- Gary Wegner ( Dartmouth)
Last modified: Thu Jun 19 15:20:43 EDT 2008
