Showing papers by "Nabila Aghanim published in 2000"
TL;DR: In this article, the first analysis of the XMM Newton EPIC-MOS data of the galaxy group around NGC4839, which lies at a projected distance to the Coma cluster center of 1.6Mpc, was presented.
Abstract: We present here the first analysis of the XMM Newton EPIC-MOS data of the galaxy group around NGC4839, which lies at a projected distance to the Coma cluster center of 1.6Mpc. In our analysis, which includes imaging, spectro-imaging and spectroscopy we find compelling evidence for the sub group being on its first infall onto the Coma cluster. The complex temperature structure around NGC 4839 is consistent with simulations of galaxies falling into a cluster environment. We see indications of a bow shock and of ram pressure stripping around NGC4839. Furthermore our data reveal a displacement between NGC4839 and the center of the hot gas in the group of about 300kpc. With a simple approximation we can explain this displacement by the pressure force originating from the infall, which acts much stronger on the group gas than on the galaxies.
124 citations
TL;DR: In this paper, a methodology for spatially resolved spectroscopy of extended sources, adapted to XMM background and vignetting characteristics, was proposed to correct for particle induced background.
Abstract: Using the PV observation of A1795, we illustrate the capability of XMM-EPIC to measure cluster temperature profiles, a key ingredient for the determination of cluster mass profiles through the equation of hydrostatic equilibrium. We develop a methodology for spatially resolved spectroscopy of extended sources, adapted to XMM background and vignetting characteristics. The effect of the particle induced background is discussed. A simple unbiased method is proposed to correct for vignetting effects, in which every photon is weighted according to its energy and location on the detector. We were able to derive the temperature profile of A1795 up to 0.4 times the virial radius. A significant and spatially resolved drop in temperature towards the center (r<200 kpc) is observed, which corresponds to the cooling flow region of the cluster. Beyond that region, the temperature is constant with no indication of a fall-off at large radii out to 1.2 Mpc.
118 citations
TL;DR: The Coma cluster of galaxies was observed with XMM-Newton in 12 partially overlapping pointings as mentioned in this paper, and the resulting X-ray map in different energy bands and discuss the large scale structure of this cluster.
Abstract: The Coma cluster of galaxies was observed with XMM-Newton in 12 partially overlapping pointings. We present here the resulting X-ray map in different energy bands and discuss the large scale structure of this cluster. Many point sources were found throughout the observed area, at least 11 of them are coincident with bright galaxies. We also give a hardness ratio map at the so far highest angular resolution obtained for a cluster of galaxies. In this map we found soft regions at the position of bright galaxies, little variation in the central 15 arcmin, but some harder regions north of the line NGC 4874 - NGC 4889.
87 citations
Posted Content•
TL;DR: In this article, the cosmological effects of this scenario in terms of the thermal and kinetic Sunyaev-Zel'dovich distortions induced on galactic scales by a population of proto-galaxies are predicted.
Abstract: Recent studies of galactic nuclei suggest that most galaxies are seeded by super-massive black holes which power the central nucleus. In this picture, the proto-galactic object is likely to have undergone a very active phase during which the surrounding medium was shocked and heated up to very high temperatures. We predict the cosmological effects of this scenario in terms of the thermal and kinetic Sunyaev-Zel'dovich distortions induced on galactic scales by a population of proto-galaxies. These predictions are compared to the observational limit on the mean Compton distortion set by the COBE-FIRAS instrument. This enables us to derive tight constraints on the fraction of proto-galaxies seeded by super-massive black holes as well as on the black hole-to-spheroid mass ratio. Finally, we estimate the contribution of such a population to the angular power spectrum of the Cosmic Microwave Background temperature anisotropies on very small angular scales ($l\simeq 10^4-10^5$).
4 citations
17 Mar 2000
TL;DR: In this article, the cosmological effects of super-massive black hole seeded galaxies were predicted in terms of the thermal and kinetic Sunyaev-Zel'dovich distortions induced on galactic scales by a population of proto-galactic objects.
Abstract: Recent studies of galactic nuclei suggest that most galaxies are seeded by super-massive black holes which power the central nucleus. In this picture, the proto-galactic object is likely to have undergone a very active phase during which the surrounding medium was shocked and heated up to very high temperatures. We predict the cosmological effects of this sce- nario in terms of the thermal and kinetic Sunyaev-Zel'dovich distortions induced on galactic scales by a population of proto- galaxies. These predictions are compared to the observational limit on the mean Compton distortion set by the COBE-FIRAS instrument. This enables us to derive tight constraints on the fraction of proto-galaxies seeded by super-massive black holes as well as on the black hole-to-spheroid mass ratio. Finally, we estimate the contribution of such a population to the angular power spectrum of the Cosmic Microwave Background temper- ature anisotropies on very small angular scales (l ' 10 4 10 5 ).
3 citations
01 Jan 2000
2 citations