Search Publications
The UV colours of high-redshift early-type galaxies: evidence for recent star formation and stellar mass assembly over the last 8 billion years
van Dokkum, P. G.; Gawiser, E.; Urry, C. M. +7 more
We combine deep optical and NIR (UBVRIzJK) photometry from the Multiwavelength Survey by Yale-Chile (MUSYC) with redshifts from the COMBO-17 survey to perform a large-scale study of the rest-frame ultraviolet (UV) properties of 674 high-redshift (0.5 < z < 1) early-type galaxies, drawn from the Extended Chandra Deep Field-South (E-CDFS). Gal…
Multidimensional modelling of X-ray spectra for AGN accretion disc outflows
Turner, T. J.; Long, K. S.; Sim, S. A. +1 more
We use a multidimensional Monte Carlo code to compute X-ray spectra for a variety of active galactic nucleus (AGN) disc-wind outflow geometries. We focus on the formation of blueshifted absorption features in the Fe K band and show that line features similar to those which have been reported in observations are often produced for lines of sight th…
Large Einstein radii: a problem for ΛCDM
Barkana, Rennan; Broadhurst, Tom J.
The Einstein radius of a cluster provides a relatively model-independent measure of the mass density of a cluster within a projected radius of ~150kpc, large enough to be relatively unaffected by gas physics. We show that the observed Einstein radii of four well-studied massive clusters, for which reliable virial masses are measured, lie well beyo…
The role of AGN in the colour transformation of galaxies at redshifts z ~ 1
Barmby, P.; Cooper, M. C.; Georgakakis, A. +10 more
We explore the role of active galactic nuclei (AGN) in establishing and/or maintaining the bimodal colour distribution of galaxies by quenching their star formation and hence, causing their transition from the blue to the red cloud. Important tests for this scenario include (i) the X-ray properties of galaxies in the transition zone between the tw…
The shape of the dark matter halo in the early-type galaxy NGC 2974
Krajnović, Davor; van de Ven, Glenn; Morganti, Raffaella +3 more
We present HI observations of the elliptical galaxy NGC 2974, obtained with the Very Large Array. These observations reveal that the previously detected HI disc in this galaxy is in fact a ring. By studying the harmonic expansion of the velocity field along the ring, we constrain the elongation of the halo and find that the underlying gravitationa…
Galaxy evolution in Hickson compact groups: the role of ram-pressure stripping and strangulation
Yun, Min S.; Ponman, Trevor J.; Verdes-Montenegro, Lourdes +2 more
Galaxies in compact groups tend to be deficient in neutral hydrogen compared to isolated galaxies of similar optical properties. In order to investigate the role played by a hot intragroup medium (IGM) for the removal and destruction of HI in these systems, we have performed a Chandra and XMM-Newton study of eight of the most HI deficient Hickson …
The weak magnetic field of the O9.7 supergiant ζOrionisA
Bouret, J. -C.; Martins, F.; Donati, J. -F. +4 more
We report here the detection of a weak magnetic field of 50-100G on the O9.7 supergiant ζOrionisA (ζOriA), using spectropolarimetric observations obtained with NARVAL at the 2-m Télescope Bernard Lyot atop Pic du Midi (France). ζOriA is the third O star known to host a magnetic field (along with θ1OriC and HD191612), and the first detec…
A deep X-ray observation of M82 with XMM-Newton
Maiolino, R.; Ranalli, P.; Comastri, A. +1 more
We report on the analysis of a deep (100-ks) observation of the starburst galaxy M82 with the EPIC and RGS instruments onboard the X-ray telescope XMM-Newton. The broad-band (0.5-10 keV) emission is due to at least three spectral components: (i) continuum emission from point sources; (ii) thermal plasma emission from hot gas; and (iii) charge-exch…
Globular clusters in the outer halo of M31: the survey
Tanvir, N. R.; Ferguson, A. M. N.; Lewis, G. F. +4 more
We report the discovery of 40 new globular clusters (GCs) that have been found in surveys of the halo of M31 based on the Isaac Newton Telescope/Wide-Field Camera and Canada-France-Hawaii Telescope/Megacam imagery. A subset of these new GCs are of an extended, diffuse nature and include those already found in Huxor et al. The search strategy is de…
Cool X-ray emitting gas in the core of the Centaurus cluster of galaxies
Fabian, A. C.; Allen, S. W.; Sanders, J. S. +3 more
We use a deep XMM-Newton Reflection Grating Spectrometer observation to examine the X-ray emission from the core of the Centaurus cluster of galaxies. We clearly detect FeXVII emission at four separate wavelengths, indicating the presence of cool X-ray emitting gas in the core of the cluster. Fe ions from FeXVII toXXIV are observed. The ratio of t…