An international team, including scientists from the Astrophysics Department-AIM and the Particle Physics Department of CEA-Irfu, has just used the Planck satellite to discover galaxy clusters with characteristics that were previously unknown. These clusters, which contain up to a thousand galaxies, are the largest structures in the Universe. Many of them are located very far away from us, and we still know relatively little about them. Astrophysicists were able to detect the new clusters thanks to the imprint left in the background radiation of the universe by the hot gas from the clusters. Of the 189 clusters detected by Planck at distances from 1 to 5 billion light-years, 20 were previously unknown. Thanks to a joint program with the XMMNewton x-ray satellite, some of these new clusters could be observed, revealing weaker luminosity and a highly perturbed gas distribution. These must therefore be clusters with different characteristics.
These results were presented at a scientific colloquium on results from the Planck satellite, held from 10th to 14th January 2011 in Paris. They were published in a special issue of Astronomy & Astrophysics.
For a more detailed account, see also the French version.
 « Planck early results: XMM-Newton follow-up for validation of Planck cluster candidates »
submitted to Astronomy & Astrophysics (2011), pour une version electronique ficher PDF
 « Planck early results : Statistical analysis of S-Z scaling relations for X-ray galaxy clusters »
soumis à Astronomy & Astrophysics (2011), for an electronic document ficher PDF
 « Planck early results : Calibration of the local galaxy cluster Sunyaev-Zeldovich scaling relations »
submitted to Astronomy & Astrophysics (2011), for an electronic document ficher PDF
 « The MCXC: a Meta-Catalogue of X-ray detected Clusters of galaxies »
R. Piffaretti (1), M. Arnaud (1), G.W. Pratt (1), E. Pointecouteau (2), J.-B. Melin (3)
(1) Service d'Astrophysique CEA-Saclay (2) CESR, France, (3) Service de Physique des Particules CEA-Saclay
soumis à Astronomy & Astrophysics (2011), pour une version electronique ficher PDF
voir : - "Le communiqué de presse CNES-CEA-CNRS" (12 janvier 2011)
: - "Le communiqué de presse de l'Agence Spatiale Européenne" (11 janvier 2011)
voir aussi : - "Découverte d’un superamas grâce au rayonnement fossile" (16 septembre 2010)
- "Le satellite européen Planck achève son premier tour de ciel " (24 mars 2010)
Redaction: J.M. Bonnet-Bidaud
last update : 04-21 00:00:00-2011 (3029)