Statistical properties of SZ and X-ray cluster detections

F. Pace, M. Maturi, M. Bartelmann, N. Cappelluti, K. Dolag, M. Meneghetti, L. Moscardini

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Aims. We calibrate the number density, completeness, reliability, and the lower mass limit of galaxy-cluster detections through their thermal SZ signal and compare them to X-ray cluster detections.Methods. We simulate maps of the thermal SZ effect and the X-ray emission from light cones constructed in a large, hydrodynamical, cosmological simulation volume, including realistic noise contributions. The maps are convolved with linear, optimised, single- and multi-band filters to identify local peaks and their signal-to-noise ratios. The resulting peak catalogues are then compared to the halo population in the simulation volume to identify true and spurious detections. Results. Multi-band filtering improves the statistics of SZ cluster detections considerably compared to single-band filtering. Observations with the characteristics of ACT detect clusters with masses M ≥ 6-9 × 1013 MȮ/h, quite independent of redshift, reach 50% completeness at ∼ 1014 MȮ/h and 100% completeness at ∼2×. 1014 MȮ/h Samples are contaminated by a few spurious detections, but they are only a small percentage of all detections. This is broadly comparable to X-ray cluster detections with XMM-Newton with 100 ks exposure time in the soft band, except that the mass limit for X-ray detections increases much more steeply with redshift than for SZ detections. A comparison of true and filtered signals in the SZ and X-ray maps confirms that the filters introduce at most a negligible bias.

Original languageEnglish (US)
Pages (from-to)389-400
Number of pages12
JournalAstronomy and Astrophysics
Issue number2
StatePublished - May 2008
Externally publishedYes


  • Cosmology: cosmic microwave background
  • Cosmology: theory
  • Galaxies: clusters: general
  • Methods: N-body simulations
  • X-rays: galaxies: clusters

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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