Densely concentrated clusters of galaxies tend to have giant galaxies at their center and they are held together by their own gravity. Such clusters are filled with X-ray emitting gas at temperatures reaching temperatures of 10 million degrees. The key tool used to understand the physics of this gas and its role in the structure and evolution of the cluster is X-ray spectroscopy. XMM-Newton targets have included a number of galaxy clusters, including Abell S 1101(=Sérsic 159-03), Abell 1835 and Abell 1795.

Top left: X-ray image for Abell S 1101(=Sérsic 159-03) obtained by XMM-Newton's European Photon Imaging Camera (EPIC-MOS). Analysis has shown a sharp temperature drop near the outer part of the cluster, which might be associated with the transition from cluster to supercluster. Courtesy J. Kaastra, SRON, Utrecht, NL.

Middle right: Past studies have implied the presence of cool gas near the centers of clusters of galaxies. This, and other, characteristics have been studied in the Abell 1835 cluster of galaxies using the EPIC and RGS instruments on XMM-Newton. Observations have allowed the measurement of both the relative X-ray emission of the cold gas and a detailed study of the spectral properties of total gas distribution. The traditional model for cooling flows is not compatible with these observations, and new models will have to be sought. Courtesy J. Peterson, Columbia Univ., NY, USA.

Bottom left: XMM-Newton has observed the Abell 1795 cluster, one of the best targets for XMM-Newton to study the center of a cluster of galaxies. Its large-scale properties were measured with the EPIC spatially-resolved spectra and the high resolution Reflection Grating Spectrometers (RGS) were used to constrain the temperature structure of the cluster core. Courtesy T. Tamura, SRON, Utrecht, NL.

Shown are the EPIC-MOS X-ray contours of the Sérsic 159-03 cluster of galaxies, superimposed on an optical (Digitised Sky Survey) view of the corresponding region. The contours map the X-ray intensity distribution of the intra-cluster gas and the bottom graph illustrates the radial temperature profile of this X-ray emitting material. Courtesy J. Kaastra, SRON, Utrecht, NL.

Spectra extracted from the central regions of the rich galaxy clusters Abell S 1101(=Sérsic 159-03), Abell 1795 and Abell 1835 obtained with XMM-Newton's Reflection Grating Spectrometers (RGS). Courtesy T. Tamura, SRON, Utrecht, NL and J. Peterson, Columbia Univ. , NY, USA.

The luminous infrared-loud quasar IRAS 13349+2438, at a redshift of 0.10764, is a source extensively studied in the optical, infrared and X-ray bands. The spectrum obtained with XMM-Newton's Reflection Grating Spectrometer (RGS) shows the presence of a wide range of elements at different levels of ionisation. The most prominent features are the absorption lines of carbon, nitrogen, oxygen, neon and iron. These data, which are extremely rich in detail, can be used for highly precise studies of the warm absorber material thought to be present in our line of sight around the giant black holes in the center of such systems. The best-fit model spectrum is superimposed in red. Courtesy of M. Sako, Columbia Univ., NY, USA.

One of the brightest soft X-ray sources in the Large Magellanic Cloud is the supernova remnant N132D. Observations with XMM-Newton's Reflection Grating Spectrometers (RGS), complemented by images taken by the European Photon Imaging Camera (EPIC) have provided highly resolved X-ray spectra of this extended supernova remnant. In the narrow wavelength bands indicated, each EPIC-MOS image maps the distribution of nine different elements. Differences between more and less ionised regions can be noted. Oxygen rich gas is present in an area to the northeastern part of the remnant, where no other elements are emitting X-rays. This may either be relatively cold gas, or is the result of the supernova shockwave interacting with oxygen-rich stellar winds before the stellar explosion. Image courtesy of E. Behar, Columbia Univ., NY, USA.

The Coma Cluster, an aggregate thousands of galaxies. The picture is a mosaic of 12 partially overlapping pointings obtained with the EPIC-pn camera. The cluster was chosen during XMM-Newton's performance verification phase to prove the observatory's ability to map and analyse data from large extended X-ray sources.

Bottom, a close-up view of the temperature structure in the inner region of the Coma Cluster of galaxies, highlighting the X-ray hardness and corresponding temperatures around the giant elliptical galaxies NGC 4889 and NGC 4874 and the gas in the central part of the cluster. Courtesy U. Briel, Max-Planck Institut für extraterrestrische Physik, Garching, Germany.

XMM-Newton has provided detailed spectral analysis of the nucleus and jets of the giant elliptical galaxy M87. Observation of this relatively close bright X-ray and radio source situated at the center of the Virgo cluster of galaxies has allowed the first detailed study of the interactions between the thermal and radio emitting plasma in its central region.

Top left, EPIC-pn image of M87 in the energy range 0.5-2 keV. The galaxy's X-ray halo has an almost spherically symmetrical appearance, with the exception of two localised enhancements to the SW and E of the nucleus. Image courtesy of H. Böhringer, Max-Planck Institut für extraterrestrische Physik, Garching, Germany.

Top right, a combined view by both EPIC MOS cameras shows the asymmetric extended X-ray arms of M87. The galaxy's X-ray halo has been subtracted. Image courtesy of E. Belsole, Service d'Astrophysique, CEA Saclay, France.< /P>

Bottom, X-ray mean energy level map of M87 provided by the EPIC MOS camera superimposed on a radio map of the galaxy. Image courtesy of E. Belsole, Service d'Astrophysique, CEA Saclay, France.

Combining the images from all EPIC cameras, the Lockman Hole provides the deepest ever X-ray survey of this region where observation of the early Universe is facilitated by the relative absence of intervening, absorbing material. The view gives a "real colour" representation of all the sources, coded according to their X-ray hardness. More than 60 new sources are detected in the 5-10 keV band alone. Image courtesy of G. Hasinger, Astrophysikalisches Institute, Potsdam, Germany.