Growth of Structure Measurement from a Large Cluster Survey using Chandra and XMM-Newton
Abstract
We present a large X-ray selected seredipitous cluster survey based on a novel joint analysis of archival Chandra and XMM-Newton data. The survey provides enough depth to reach clusters of flux of ≈ 1014 ergs cm-2 s-1 near z ≈ 1 and simultaneously a large enough sample to find evidence for the strong evolution of clusters expected from structure formation theory. We detected a total of 723 clusters of which 462 are newly discovered clusters with greater than 6σ significance. In addition, we also detect and measure 261 previously-known clusters and groups that can be used to calibrate the survey. The survey exploits a technique which combines the exquisite Chandra imaging quality with the high throughput of the XMM-Newton telescopes using overlapping survey regions. A large fraction of the contamination from AGN point sources is mitigated by using this technique. This results in a higher sensitivity for finding clusters of galaxies with relatively few photons and a large part of our survey has a flux sensitivity between 10-14 and 10-15 ergs cm2 s-1. The survey covers 41.2 square degrees of overlapping Chandra and XMM-Newton fields and 122.2 square degrees of non-overlapping Chandra data. We measure the log N-log S distribution and fit it with a redshift-dependent model characterized by a luminosity distribution proportional to e-z/z0. We find that z0 to be in the range 0.7 to 1.3, indicative of rapid cluster evolution, as expected for cosmic structure formation using parameters appropriate to the concordance cosmological model.
- Publication:
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AAS/High Energy Astrophysics Division #11
- Pub Date:
- March 2010
- Bibcode:
- 2010HEAD...11.3412P