Search Publications
Spatially resolved STIS spectra of the gravitationally lensed broad absorption line quasar APM08279+5255: the nature of component C and evidence for microlensing
Lewis, Geraint F.; Pettini, Max; Ellison, Sara L. +4 more
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While gravitationally lensed quasars are expected to display an odd number of images, invariably systems are observed with an even number of quasars. For this, lensing galaxies must have very small core radii; this provides strong demagnification of one of the images. High-resolution imaging of the gravitationally lensed broad absorption…The Sunyaev-Zel'dovich effect as a cosmological discriminator
Diego, J. M.; Martínez-González, E.; Benitez, N. +2 more
We show how future measurements of the Sunyaev-Zel'dovich effect (SZE) can be used to constrain the cosmological parameters. We combine the SZ information expected from the Planck full-sky survey, N (S ), where no redshift information is included, with the N (z ) obtained from an optically identified SZ-selected survey covering less than 1 per cen…
µJy radio sources in the cluster MS1054-03
Franx, M.; van Dokkum, P. G.; Röttgering, H. J. A. +1 more
An extremely deep 5-GHz radio observation is presented of the rich cluster MS1054-03 at redshift 34 radio sources are detected down to a 6σ level of 32µJy, compared with about 25 expected from previous blank-field radio source count determinations; the sources giving rise to these excess counts lie predominantly within 2arcmin (~700kpc) of t…
Extreme X-ray variability in the luminous quasar PDS 456
O'Brien, P. T.; Reeves, J. N.; Pounds, K. A. +1 more
We present evidence from BeppoSAX and XMM-Newton of extreme X-ray variability in the high-luminosity radio-quiet quasar PDS 456, the most luminous known active galactic nucleus (AGN) at z < 0.3. Repeated X-ray flaring is found in PDS 456, over the duration of the 340-ks long BeppoSAX observation. The X-ray flux doubles in just 30 ks, whilst the…
Luminosity-metallicity relation for stars on the lower main sequence
Jimenez, Raul; Flynn, Chris; Kotoneva, Eira
We present a comparison of the predictions of stellar models with the luminosity of the lower main sequence (5.5 < MV < 7.3) using K dwarfs in the Hipparcos catalogue. The parallaxes of our comparison stars are known to better than 15 per cent and metallicities have been recently determined from photometry. A major advantage of ou…
Gamma-ray bursts in normal and extreme star-forming galaxies
Ramirez-Ruiz, Enrico; Blain, A. W.; Trentham, Neil
We discuss how gamma-ray burst (GRB) optical afterglows and multiwavelength observations of their host galaxies can be used to obtain information about the relative amounts of star formation happening in optical and submillimetre galaxies. That such an analysis will be possible follows from the currently favoured idea that GRBs are closely linked …
First XMM-Newton observations of strongly magnetic cataclysmic variables - II. Timing studies of DP Leo and WW Hor
Cropper, Mark; Ramsay, Gavin; Much, Rudi +5 more
XMM-Newton was used to observe two eclipsing, magnetic cataclysmic variables, DP Leo and WW Hor, continuously for three orbital cycles each. Both systems were in an intermediate state of accretion. For WW Hor we also obtained optical light curves with the XMM-Newton Optical Monitor and from ground-based observations. Our analysis of the X-ray and …
The radio galaxy 3C 356 and clues to the trigger mechanisms for powerful radio sources
Simpson, Chris; Rawlings, Steve
We present deep near-infrared images, taken with the Subaru Telescope, of the region around the z=1.08 radio source 3C 356 which show it to be associated with a poor cluster of galaxies. We discuss evidence that this cluster comprises two subclusters traced by the two galaxies previously proposed as identifications for 3C 356, which both seem to h…
Restrictions to the galaxy evolutionary models from the Hawaiian Deep Fields SSA13 and SSA22
Aguerri, J. A. L.; Trujillo, I.
Quantitative structural analysis of the galaxies present in the Hawaiian Deep Fields SSA13 and SSA22 is reported. The structural parameters of the galaxies have been obtained automatically by fitting a two-component model (Sérsic r1/n bulge and exponential disc) to the surface brightness of the galaxies. The galaxies were classified on …
Old elliptical galaxies at z ~= 1.5 and the Kormendy relation
Stern, D.; McLure, R. J.; Dunlop, J. S. +8 more
Deep spectroscopy of the two Leiden-Berkeley Deep Survey mJy radio galaxies LBDS 53W069 and 53W091 has previously shown them to have old (>~3 Gyr) stellar populations at z~= 1.5. Here we present the results of Hubble Space Telescope (HST) observations with the Wide Field and Planetary Camera 2 (WFPC2) in F814W and with the Near-Infrared Camera …