Search Publications
The XMM-Newton/2dF survey - III. Comparison between optical and X-ray cluster detection methods
Georgakakis, A.; Georgantopoulos, I.; Plionis, M. +4 more
We directly compare X-ray and optical techniques of cluster detection by combining Sloan Digital Sky Survey photometric data with a wide-field (~1.6 deg2) XMM-Newton survey near the North Galactic Pole region. The optical cluster detection procedure is based on merging two independent selection methods: a smoothing + percolation techniq…
The Phoenix Deep Survey: the radio properties of the hard X-ray-selected sample
Georgakakis, A.; Sullivan, M.; Mobasher, B. +3 more
The radio properties of hard (2-8 keV) X-ray-selected sources are explored by combining a single 50-ks XMM-Newton pointing with the ultradeep and homogeneous Phoenix radio (1.4-GHz) survey. A total of 43 sources are detected above the X-ray flux limit fX(2-8 keV) = 7.7 × 10-15 erg s-1 cm-2, with 14 of th…
XMM-Newton observations of warm absorbers in PG quasars
Page, M. J.; Branduardi-Raymont, G.; Córdova, F. A. +5 more
We present XMM-Newton European Photon Imaging Camera observations of warm absorbers in the quasars PG 1114+445 and PG 1309+355, both of which exhibit evidence for absorption by warm material in the line of sight. We find the absorption in PG 1114+445 to be in two phases, a `hot' phase with a log ionization parameter, ξ, of 2.57, and a `cooler' pha…
Wolf-Rayet stars in M33 - I. Optical spectroscopy using CFHT-MOS
Drissen, Laurent; Crowther, Paul A.; Dessart, Luc +3 more
We have obtained spectroscopy of a large sample of Wolf-Rayet stars in M33 with the Canada-France-Hawaii Telescope Multi-Object Spectrograph (CFHT-MOS), including 26 WC stars, 15 WN stars and a WN/C star. In general, spectral types are merely refined, although the spectral type of X9 from Massey & Johnson is revised from WNL?+abs to WC4+abs, w…
On the observed disc temperature of accreting intermediate mass black holes
Fabian, A. C.; Miller, J. M.; Ross, R. R.
Some ultraluminous X-ray sources in nearby galaxies show soft components resembling thermal disc emission. Calculations based on blackbody emission then indicate that the accreting black holes at the centres of these discs have masses of hundreds to thousands solar mass. Establishing the existence of such intermediate mass black holes is of consid…
MERLIN observations of Stephan's Quintet
Muxlow, T. W. B.; Garrington, S. T.; Xanthopoulos, E. +1 more
We present MERLIN L-band images of the compact galaxy group, Stephan's Quintet (SQ). The Seyfert 2 galaxy, NGC 7319, the brightest member of the compact group, is seen to have a triple radio structure typical of many extra-galactic radio sources that have a flat spectrum core and two steep spectrum lobes with hot spots. The two lobes are asymmetri…
Large-scale structure in the ELAIS S1 Survey
Pozzi, F.; Vaccari, M.; Serjeant, S. +6 more
We present an analysis of the two-point angular correlation function of The European Large-Area Infrared Space Observatory (ELAIS) S1 survey. The survey covers 4 deg2 and contains 462 sources detected at 15 µm to a 5σ flux limit of 0.45 mJy. Using the 329 extragalactic sources not repeated in different observations, we detect a si…
Modelling of dust scattering toward the Coalsack
Shalima, P.; Murthy, Jayant
Murthy, Henry & Holberg discovered intense far-ultraviolet (FUV) (λλ912-1600) emission from the direction of the Coalsack molecular cloud 10 years ago. We have used their results in conjunction with a Monte Carlo model for the scattering in the region to show that the scattering is from dust in the foreground of the Coalsack. The albedo of the…
Continuous and burst-like accretion on to substellar companions in Mira winds
Struck, Curtis; Cohanim, Babak E.; Willson, Lee Anne
We present numerical hydrodynamical modelling of the effects of a giant planet or brown-dwarf companion orbiting within the extended atmosphere and wind formation zone of an approximately solar-mass Mira variable star. The large-scale, time-dependent accretion flows within the radially oscillating and outflowing circumstellar gas around Miras are …
Mid-infrared sources in the ELAIS Deep X-ray Survey
Franceschini, A.; Vaccari, M.; Serjeant, S. +9 more
We present a cross-correlation of the European Large Area Infrared Space Observatory (ISO) survey (ELAIS) with the ELAIS Deep X-ray Survey of the N1 and N2 fields. There are seven Chandra point sources with matches in the ELAIS Final Analysis 15-µm catalogue, out of a total of 28 extragalactic ISO sources present in the Chandra fields. Five …