Search Publications
Where are the X-ray quasi-periodic oscillations in active galaxies?
Vaughan, S.; Uttley, P.
In this paper, we address the question of whether existing X-ray observations of Seyfert galaxies are sufficiently sensitive to detect quasi-periodic oscillations (QPOs) similar to those observed in the X-ray variations of Galactic black holes (GBHs). We use data from XMM-Newton and simulated data based on the best Rossi X-ray Timing Explorer (RXT…
The X-ray emission properties and the dichotomy in the central stellar cusp shapes of early-type galaxies
Pellegrini, S.
The Hubble Space Telescope has revealed a dichotomy in the central surface brightness profiles of early-type galaxies, which have subsequently been grouped into two families: core, boxy, anisotropic systems; and cuspy (`power-law'), discy, rotating ones. Here we investigate whether a dichotomy is also present in the X-ray properties of the two fam…
Stellar populations and Lyα emission in two lensed z>~ 6 galaxies
Schaerer, Daniel; Pelló, Roser
We present an analysis of two strongly lensed galaxies at z= 6.56 and z~ 7 for which multi-band photometric and spectroscopic observations are available. For one source, the data include recent Hubble Space Telescope (HST) and Spitzer observations. Using a spectral energy distribution (SED) fitting technique considering a number of parameters (var…
Dust in spiral galaxies: global properties
Stevens, J. A.; Gear, W. K.; Amure, M.
We present and analyse high-quality Submillimetre Common-User Bolometer Array (SCUBA) 850- and 450-µm images of 14 local spiral galaxies, including the detection of dust well out into the extended disc in many cases. We use these data in conjunction with published far-infrared flux densities from IRAS and ISO, and millimetre-wave measurement…
Systematic uncertainties in the analysis of star cluster parameters based on broad-band imaging observations
Bastian, N.; de Grijs, R.; Anders, P. +5 more
High-resolution Hubble Space Telescope (HST) imaging observations of star cluster systems provide a very interesting and useful alternative to spectroscopic studies for stellar population analyses with 8-m class telescopes. Here, we assess the systematic uncertainties in (young) cluster age, mass and (to a lesser extent) extinction and metallicity…
What a local sample of spectroscopic binaries can tell us about the field binary population
Schröder, Klaus-Peter; Fisher, James; Smith, Robert Connon
We study a sample of spectroscopic binaries (SBs) in the local solar neighbourhood (d<= 100 pc and MV<= 4) in an attempt to find the distributions of the period, P, the primary mass, m1, and the mass ratio q(=m2/m1), as well as the initial mass function (IMF) of the local population of field binari…
The XMM-Newton/2dF Survey - VI. Clustering and bias of the soft X-ray point sources
Georgakakis, A.; Georgantopoulos, I.; Plionis, M. +1 more
We study the clustering properties of X-ray sources detected in the wide area (~2deg2) bright, contiguous XMM-Newton/2dF survey. We detect 432 objects to a flux limit of 5 × 10-15ergcm-2s-1 in the soft 0.5-2keV band. Performing the standard angular correlation function analysis, a ~3σ correlation signal …
Unusual X-ray transients in the Galactic Centre
Decourchelle, A.; Warwick, R. S.; Wang, Q. D. +1 more
We report the discovery in the Galactic Centre region of two hard X-ray sources, designated as XMM J174457-2850.3 and XMM J174544-2913.0, which exhibit flux variations in the 2-10 keV band in excess of a factor of 100 in observations spanning roughly a year. In both cases the observed hydrogen column density is consistent with a location near to t…
Wind-wind collision in the η Carinae binary system: a shell-like event near periastron
Falceta-Gonçalves, D.; Jatenco-Pereira, V.; Abraham, Z.
The exact nature of η Carinae is still an open issue. Strict periodicity in the light curves at several wavelengths seem to point to a binary system, but the observed radial velocities, measured from space with high spatial resolution, are in conflict with the ground-based observations used to calculate the binary orbit. Also, the observed 2-10 ke…
Optical and near-infrared integral field spectroscopy of the SCUBA galaxy N2 850.4
Ivison, R. J.; Smail, Ian; Swinbank, A. M. +7 more
We present optical and near-infrared integral field spectroscopy of the SCUBA galaxy SMMJ163650.43+405734.5 (ELAIS N2 850.4) at z= 2.385. We combine Lyα and Hα emission line maps and velocity structure with high-resolution HST ACS and NICMOS imaging to probe the complex dynamics of this vigorous starburst galaxy. The imaging data show a complex mo…