Search Publications
Ram pressure stripping and the formation of cold fronts
Churazov, E.; Forman, W.; Heinz, S. +2 more
Chandra and XMM-Newton observations of many clusters reveal sharp discontinuities in the surface brightness, which, unlike shocks, have lower gas temperature on the X-ray brighter side of the discontinuity. For this reason, these features are called `cold fronts'. It is believed that some cold fronts are formed when a subcluster merges with anothe…
A deep Chandra observation of the cluster environment of the z= 1.786 radio galaxy 3C 294
Fabian, A. C.; Ettori, S.; Sanders, J. S. +1 more
We report the results from a 200-ks Chandra observation of the z= 1.786 radio galaxy 3C 294 and its cluster environment, increasing by ten-fold our earlier observation. The diffuse emission, extending about 100 kpc around the nucleus, has a roughly hourglass shape in the north-south (N-S) direction with surprisingly sharp edges to the N and S. The…
Star cluster formation and disruption time-scales - II. Evolution of the star cluster system in the fossil starburst of M82
de Grijs, Richard; Bastian, Nate; Lamers, Henny J. G. L. M.
We obtain new age and mass estimates for the star clusters in the fossil starburst region B of M82, based on improved fitting methods. Our new age estimates confirm the peak in the age histogram attributed to the last tidal encounter with M81; we find a peak formation epoch at slightly older ages than previously published, log(tpeak yr<…
First-look XMM-Newton EPIC observations of the prototypical starburst galaxy M82
Stevens, Ian R.; Bravo-Guerrero, Jimena; Read, Andrew M.
We present initial XMM-Newton EPIC observations of the prototypical starburst galaxy M82. The superwind is seen to extend continuously from the starburst region to the X-ray emission associated with the Hα`cap'. We also find evidence for a ridge feature, probably associated with the superwind interacting with an HI streamer. Narrow-band images, ce…
Fe K emission and absorption features in XMM-Newton spectra of Markarian 766: evidence for reprocessing in flare ejecta
O'Brien, P. T.; Reeves, J. N.; Page, K. L. +2 more
We report on the analysis of a long XMM-Newton European Photon Imaging Camera (EPIC) observation in 2001 May of the narrow-line Seyfert 1 galaxy Markarian 766 (Mrk 766). The 3-11 keV spectrum exhibits a moderately steep power-law continuum, with a broad emission line at ~6.7 keV, probably blended with a narrow line at ~6.4 keV, and a broad absorpt…
Multiwavelength cosmological simulations of elliptical galaxies
Kawata, D.; Gibson, B. K.
We study the chemodynamical evolution of elliptical galaxies and their X-ray and optical properties using high-resolution cosmological simulations. Our tree N-body/smoothed particle hydrodynamics (SPH) code includes a self-consistent treatment of radiative cooling, star formation, supernovae feedback and chemical enrichment. We present a series of…
The Fundamental Plane and the evolution of the M/L ratio of early-type field galaxies up to z~ 1
Franx, M.; van Dokkum, P. G.; van de Ven, G.
We analyse the Fundamental Plane (FP) of 26 strong gravitational lens galaxies with redshifts up to z~ 1, using tabulated data from Kochanek et al. and Rusin et al. The lens galaxies effectively form a mass-selected sample of early-type galaxies in environments of relatively low density. We analyse the FP and its evolution in the rest-frame Johnso…
Extreme galactic wind and Wolf-Rayet features in infrared mergers and infrared quasi-stellar objects
Taniguchi, Y.; Zheng, W.; Terlevich, R. +5 more
We report, as a part of a long-term study of infrared (IR) mergers and IR quasi-stellar objects (QSOs), detailed spectroscopic evidence for outflow (OF) and Wolf-Rayet (WR) features in the nearby mergers NGC4038/39 and IRAS 23128-5919 (with low-velocity OF); and the nearby QSOs IRAS 01003-2238 and 13218+0552 (with extreme velocity OF, EVOF). We al…
Near-infrared spectroscopy of (proto)-planetary nebulae: molecular hydrogen excitation as an evolutionary tracer
Smith, Michael D.; Davis, Christopher J.; Stern, Luke +2 more
We present an in-depth analysis of molecular excitation in 11 H2-bright planetary and protoplanetary nebulae (PN and PPN). From newly acquired K-band observations, we extract a number of spectra at positions across each source. H2 line intensities are plotted on `column density ratio' diagrams so that we may examine the excit…
RR Lyrae stars in four globular clusters in the Fornax dwarf galaxy
Mackey, A. D.; Gilmore, G. F.
We have surveyed four of the globular clusters in the Fornax dwarf galaxy (clusters 1, 2, 3 and 5) for RR Lyrae stars, using archival F555W and F814W Hubble Space Telescope observations. We identify 197 new RR Lyrae stars in these four clusters, and 13 additional candidate horizontal-branch variable stars. Although somewhat restricted by our short…