期刊
ASTRONOMY & ASTROPHYSICS
卷 536, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201116460
关键词
cosmology: observations; galaxies: clusters: general; galaxies: clusters: intracluster medium; cosmic background radiation; X-rays: galaxies: clusters
资金
- ESA
- NASA (USA)
- CNES
- CNRS/INSU-IN2P3-INP (France)
- ASI
- CNR
- INAF (Italy)
- NASA
- DoE (USA)
- STFC
- UKSA (UK)
- CSIC
- MICINN
- JA (Spain)
- Tekes
- AoF
- CSC (Finland)
- DLR
- MPG (Germany)
- CSA (Canada)
- DTU Space (Denmark)
- SER/SSO (Switzerland)
- RCN (Norway)
- SFI (Ireland)
- FCT/MCTES (Portugal)
- DEISA (EU)
- Science and Technology Facilities Council [ST/F01239X/1, ST/G002916/1, ST/F002998/1, ST/G00269X/1, ST/I005765/1, ST/H00243X/1, ST/I000976/1, ST/I002006/1, ST/F002858/1, ST/I005129/1, ST/G001901/1] Funding Source: researchfish
- UK Space Agency [ST/G003874/1, ST/H00002X/1] Funding Source: researchfish
We present the XMM-Newton follow-up for confirmation of Planck cluster candidates. Twenty-five candidates have been observed to date using snapshot (similar to 10 ks) exposures, ten as part of a pilot programme to sample a low range of signal-to-noise ratios (4 < S/N < 6), and a further 15 in a programme to observe a sample of S/N > 5 candidates. The sensitivity and spatial resolution of XMM-Newton allows unambiguous discrimination between clusters and false candidates. The 4 false candidates have S/N <= 4.1. A total of 21 candidates are confirmed as extended X-ray sources. Seventeen are single clusters, the majority of which are found to have highly irregular and disturbed morphologies (about similar to 70%). The remaining four sources are multiple systems, including the unexpected discovery of a supercluster at z = 0.45. For 20 sources we are able to derive a redshift estimate from the X-ray Fe K line (albeit of variable quality). The new clusters span the redshift range 0.09 less than or similar to z less than or similar to 0.54, with a median redshift of z similar to 0.37. A first determination is made of their X-ray properties including the characteristic size, which is used to improve the estimate of the SZ Compton parameter, Y-500. The follow-up validation programme has helped to optimise the Planck candidate selection process. It has also provided a preview of the X-ray properties of these newly-discovered clusters, allowing comparison with their SZ properties, and to the X-ray and SZ properties of known clusters observed in the Planck survey. Our results suggest that Planck may have started to reveal a non-negligible population of massive dynamically perturbed objects that is under-represented in X-ray surveys. However, despite their particular properties, these new clusters appear to follow the Y-500-Y-X relation established for X-ray selected objects, where Y-X is the product of the gas mass and temperature.
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