Planckearly results. XXVI. Detection withPlanckand confirmation byXMM-Newtonof PLCK G266.6–27.3, an exceptionally X-ray luminous and massive galaxy cluster atz ~ 1

E Saar,R B Barreiro,S R Hildebrandt,A Lasenby,J.-B Melin,F Perrotta,C Hernández-Monteagudo,J.-M Delouis,G Prézeau,L A Wade,D Munshi,P Carvalho,H Kurki-Suonio,T J Pearson,P Platania,E Martínez-González,D L Clements,K Ganga,B D Wandelt,T S Kisner,J P Rachen,J F Macías-Pérez,F Marleau,R Bhatia,S Fromenteau,M Tristram,T Poutanen,A Lähteenmäki,D Mortlock,C Dickinson,E Franceschi,G Morgante,A Mennella,S Colafrancesco,M Le Jeune,J Weller,P Natoli,H Dole,J Borrill,L Mendes,D Scott,F Pasian,S Masi,F Cuttaia,S Osborne,J M Diego,D Maino,G Polenta,L Toffolatti,G De Gasperis,A Zonca,J Démoclès,A J Banday,O Doré,H Dahle,P Cabella,M Reinecke,M Sandri,R Leonardi,D Sutton,P Heinämäki,E Pierpaoli,P Mazzotta,R Paladini,M Giard,C Baccigalupi,F Noviello,R Piffaretti,J Delabrouille,H K Eriksen,F Villa,J.-M Lamarre,M Juvela,T A Enßlin,M Bersanelli,H Böhringer,O D ’Arcangelo,X Dupac,P De Bernardis,J.-L Puget,E Hivon,A Gruppuso,I J O’Dwyer,M Frailis,S Borgani,K Benabed,G W Pratt,J R Bond,A Gregorio,R Rebolo,H U Nørgaard-Nielsen,P R Christensen,M Ashdown,S Leach,A Catalano,J G Bartlett,L Perotto,L Danese,N Ponthieu,G Chon,J A Rubiño-Martín,J.-F Sygnet,M Douspis,A Melchiorri,P Fosalba,M Hobson,A Zacchei,J.-P Bernard,L Terenzi,S Galeotta,L Cayón,C Leroy,A Moneti,B Cappellini,L Montier,S Ricciardi,C Chiang,P B Lilje,C Burigana,W C Jones,I Flores-Cacho,P Naselsky,B P Crill,G De Zotti,M.-A Miville-Deschênes,F Atrio-Barandela,G Patanchon,J Aumont,F Piacentini,N Aghanim,K M Górski,C R Lawrence,E Churazov,M Türler,R J Davis,C M Cantalupo,L Popa,G Savini,S Colombi,N Vittorio,G Luzzi,E Battaner,P Vielva,G Lagache,D Yvon,E Keihänen,M Arnaud,D Novikov,L Valenziano,J Nevalainen,I Ristorcelli,N Mandolesi,S Prunet,O Perdereau,S Matarrese,M Tomasi,T Riller,J A Tauber,O Forni,P R Meinhold,G Efstathiou,S Donzelli,C Renault,R T Génova-Santos,G Hurier,A H Jaffe,A Balbi,F R Bouchet,G Rocha,A Bonaldi,R Keskitalo,F K Hansen,Michael L Brown ,L.-Y Chiang ,A Benoı̂t ,Jean-Luc Starck ,M López‐Caniego ,Andrew R Liddle ,Martin White ,D L Harrison ,B Schaefer ,António Da Silva ,Simon D M White ,F.‐X Désert ,F Finelli⋆ ,George F Smoot ,R Kneißl ,И Д Новиков ,J González‐Nuevo ,É Pointecouteau ,R González‐Riestra

doi:10.1051/0004-6361/201117430

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.

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