We present first results on PLCKG266.6-27.3, a galaxy cluster candidate detected at a signal-to-noise ratio of 5 in the Planck All Sky survey. An XMM-Newton validation observation has allowed us to confirm that the candidate isa bona fide galaxy cluster. With these X-ray data we measure an accurate redshift, z = 0.94 ± 0.02, and estimate the cluster mass to be M500 = (7.8 ± 0.8) × 1014 Msun. PLCKG266.6-27.3 is an exceptional system: its luminosity of LX [0.5-2.0 keV] = (1.4 ± 0.05) × 1045 erg s-1 equals that of the two most luminous known clusters in the z > 0.5 universe, and it is one of the most massive clusters at z ~ 1. Moreover, unlike the majority of high-redshift clusters, PLCKG266.6-27.3 appears to be highly relaxed. This observation confirms Planck's capability of detecting high-redshift, high-mass clusters, and opens the way to the systematic study of population evolution in the exponential tail of the mass function.
Planck early results. XXVI. Detection with Planck and confirmation by XMM-Newton of PLCK G266.6–27.3, an exceptionally X-ray luminous and massive galaxy cluster at z ~ 1
BORGANI, STEFANO;GREGORIO, ANNA;
2011-01-01
Abstract
We present first results on PLCKG266.6-27.3, a galaxy cluster candidate detected at a signal-to-noise ratio of 5 in the Planck All Sky survey. An XMM-Newton validation observation has allowed us to confirm that the candidate isa bona fide galaxy cluster. With these X-ray data we measure an accurate redshift, z = 0.94 ± 0.02, and estimate the cluster mass to be M500 = (7.8 ± 0.8) × 1014 Msun. PLCKG266.6-27.3 is an exceptional system: its luminosity of LX [0.5-2.0 keV] = (1.4 ± 0.05) × 1045 erg s-1 equals that of the two most luminous known clusters in the z > 0.5 universe, and it is one of the most massive clusters at z ~ 1. Moreover, unlike the majority of high-redshift clusters, PLCKG266.6-27.3 appears to be highly relaxed. This observation confirms Planck's capability of detecting high-redshift, high-mass clusters, and opens the way to the systematic study of population evolution in the exponential tail of the mass function.Pubblicazioni consigliate
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