Search Publications
A comprehensive range of X-ray ionized-reflection models
Fabian, A. C.; Ross, R. R.
X-ray ionized reflection occurs when a surface is irradiated with X-rays so intense that its ionization state is determined by the ionization parameter ξ~F/n, where F is the incident flux and n the gas density. It occurs in accretion, on to compact objects including black holes in both active galaxies and stellar-mass binaries, and possibly in gam…
A Hubble Space Telescope lensing survey of X-ray luminous galaxy clusters - IV. Mass, structure and thermodynamics of cluster cores at z= 0.2
Smith, Graham P.; Smail, Ian; Kneib, Jean-Paul +3 more
We present a comprehensive space-based study of 10 X-ray luminous galaxy clusters (LX>= 8 × 1044 erg s-1, 0.1-2.4 keV) at z= 0.2. Hubble Space Telescope (HST) observations reveal numerous gravitationally lensed arcs for which we present four new spectroscopic redshifts, bringing the total to 13 confirmed arcs in…
What controls the CIV line profile in active galactic nuclei?
Laor, Ari; Baskin, Alexei
The high-ionization lines in active galactic nuclei (AGN), such as CIV, tend to be blueshifted with respect to the lower-ionization lines, such as Hβ, and often show a strong blue excess asymmetry not seen in the low-ionization lines. There is accumulating evidence that the Hβ profile is dominated by gravity, and thus provides a useful estimate of…
The unresolved hard X-ray background: the missing source population implied by the Chandra and XMM-Newton deep fields
Alexander, D. M.; Bauer, F. E.; Brandt, W. N. +6 more
We extend our earlier work on X-ray source stacking in the deep XMM-Newton observation of the Lockman Hole, to the 2-Ms Chandra Deep Field North (CDF-N) and the 1-Ms Chandra Deep Field South (CDF-S). The XMM-Newton work showed the resolved fraction of the X-ray background (XRB) to be ~80-100 per cent at <~ 2keV but this decreased to only ~50 pe…
Multicomponent decompositions for a sample of S0 galaxies
Salo, Heikki; Laurikainen, Eija; Buta, Ronald
We have estimated the bulge-to-total (B/T) light ratios in the Ks band for a sample of 24 S0, S0/a and Sa galaxies by applying a two-dimensional multicomponent decomposition method. For the disc an exponential function is used, the bulges are fitted by a Sérsic R1/n function and the bars and ovals are described either by a Sé…
How large are the bars in barred galaxies?
Erwin, Peter
I present a study of the sizes (semimajor axes) of bars in disc galaxies, combining a detailed R-band study of 65 S0-Sb galaxies with the B-band measurements of 70 Sb-Sd galaxies from Martin (1995). As has been noted before with smaller samples, bars in early-type (S0-Sb) galaxies are clearly larger than bars in late-type (Sc-Sd) galaxies; this is…
The initial conditions of isolated star formation - VI. SCUBA mappingof pre-stellar cores
Ward-Thompson, D.; André, P.; Kirk, J. M.
Observations have been carried out with the Submillimetre Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT) of regions of comparatively isolated star formation in molecular cloud cores. Some 52 starless cores were observed, which are molecular cloud cores that do not contain any sign of protostellar activity such as i…
The Hubble Deep Field North SCUBA Super-map - III. Optical and near-infrared properties of submillimetre galaxies
Dickinson, Mark; Mobasher, Bahram; Pope, Alexandra +3 more
We present a new submillimetre (submm) super-map in the Hubble Deep Field North (HDF-N) region (Great Observatories Origins Deep Survey North, GOODS-N, field), containing 40 statistically robust sources at 850µm. This map contains additional data, and several new sources, including one of the brightest blank-sky extragalactic submm sources e…
Transforming observational data and theoretical isochrones into the ACS/WFC Vega-mag system
Anderson, Jay; Salaris, Maurizio; Bedin, Luigi R. +5 more
We propose a zero-point photometric calibration of the data from the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) on board the Hubble Space Telescope, based on a spectrum of Vega and the most up-to-date in-flight transmission curves of the camera. This calibration is accurate at the level of a few hundredths of a magnitude. The main …
MCG-6-30-15: long time-scale X-ray variability, black hole mass and active galactic nuclei high states
Uttley, P.; Goad, M. R.; McHardy, I. M. +1 more
We present a detailed study of the long time-scale X-ray variability of the Seyfert 1 Galaxy MCG-6-30-15, based on eight years of frequent monitoring observations with the Rossi X-ray Timing Explorer. When combined with the published short-time-scale XMM-Newton observations, we derive the power-spectral density (PSD) covering six decades of freque…