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
astro-ph.CO
/ Authors
Planck Collaboration, N. Aghanim, M. Arnaud, M. Ashdown, F. Atrio-Barandela, J. Aumont, C. Baccigalupi, A. Balbi, A. J. Banday, R. B. Barreiro
and 182 more authors
J. G. Bartlett, E. Battaner, K. Benabed, A. Benoît, J. -P. Bernard, M. Bersanelli, R. Bhatia, H. Böhringer, A. Bonaldi, J. R. Bond, S. Borgani, J. Borrill, F. R. Bouchet, M. L. Brown, C. Burigana, P. Cabella, C. M. Cantalupo, B. Cappellini, P. Carvalho, A. Catalano, L. Cayón, L. -Y Chiang, C. Chiang, G. Chon
/ Abstract
We present first results on PLCK G266.6-27.3, 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 is a 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 M_500 = (7.8 +/- 0.8)e+14 solar masses. PLCK G266.6-27.3 is an exceptional system: its luminosity of L_X(0.5-2.0 keV)=(1.4 +/- 0.05)e+45 erg/s, 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, PLCK G266.6-27.3 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.