Novel observing mode on XMM-Newton opens new perspectives on
galaxy clusters 31 May 2010 Surveying the sky, XMM-Newton has
discovered two massive galaxy clusters, confirming a previous
detection obtained through observations of the Sunyaev-
Zel'dovich effect, the 'shadow' they cast on the Cosmic
Microwave Background. The discovery, made possible thanks to a
novel mosaic observing mode recently introduced on ESA's X-ray
observatory, opens a new window to study the Universe's largest
bound structures in a multi-wavelength approach. Galaxy clusters
are the largest gravitationally bound objects in the Universe.
As such, they are extremely important probes of cosmic
properties on very large scales, since they form in the densest
knots of the large-scale structure, the cosmic web. Originally
discovered as an excess density (or cluster) of galaxies located
at the same redshift, hence the name, there is much more to
these enormous structures than mere galaxies: in fact, only
about one tenth of the entire mass of a gal