Search Publications
The OGLE view of microlensing towards the Magellanic Clouds - II. OGLE-II Small Magellanic Cloud data
Soszyński, I.; Udalski, A.; Szymański, M. K. +8 more
The primary goal of this paper is to provide evidence that can prove true or false the hypothesis that dark matter in the Galactic halo can clump into stellar-mass compact objects. If such objects exist, they would act as lenses to external sources in the Magellanic Clouds, giving rise to an observable effect of microlensing. We present the result…
Host galaxy colour gradients and accretion disc obscuration in AEGIS z ~ 1 X-ray-selected active galactic nuclei
Faber, S. M.; Lotz, J. M.; Coil, A. L. +7 more
We describe the effect of active galactic nucleus (AGN) light on host galaxy optical and UV-optical colours, as determined from X-ray-selected AGN host galaxies at z ~ 1, and compare the AGN host galaxy colours to those of a control sample matched to the AGN sample in both redshift and stellar mass. We identify as X-ray-selected AGNs 8.7+4
A systematic study of low-mass X-ray binaries in the M31 globular cluster system
Kundu, Arunav; Zepf, Stephen E.; Maccarone, Thomas J. +1 more
We investigate low-mass X-ray binaries (LMXBs) in the M31 globular cluster (GC) system using data from the 2XMMi catalogue. These X-ray data are based on all publicly available XMM-Newton observations of the galaxy. This new survey provides the most complete and homogeneous X-ray survey of M31's GCs to date, covering >80 per cent of the confirm…
A Very Large Telescope imaging and spectroscopic survey of the Wolf-Rayet population in NGC7793
Crowther, P. A.; Bibby, J. L.
We present a Very Large Telescope/Focal Reducer and Low Dispersion Spectrograph #1 (VLT/FORS1) imaging and spectroscopic survey of the Wolf-Rayet (WR) population in the Sculptor group spiral galaxy NGC7793. We identify 74 emission-line candidates from archival narrow-band imaging, from which 39 were observed with the Multi Object Spectroscopy mode…
Radio weak gravitational lensing with VLA and MERLIN
Muxlow, T. W. B.; Beswick, R. J.; Hoyle, B. +2 more
We carry out an exploratory weak gravitational lensing analysis on a combined Very Large Array and Multi-Element Radio-Linked Interferometer Network radio data set: a deep (3.3µJybeam-1 rms noise) 1.4GHz image of the Hubble Deep Field-North. We measure the shear estimator distribution at this radio sensitivity for the first time, …
Direct observation of cosmic strings via their strong gravitational lensing effect - II. Results from the HST/ACS image archive
Treu, Tommaso; Schrabback, Tim; Blandford, Roger D. +2 more
We have searched 4.5deg2 of archival Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) images for cosmic strings, identifying close pairs of similar, faint galaxies and selecting groups whose alignment is consistent with gravitational lensing by a long, straight string. We find no evidence for cosmic strings in five large-are…
Observational constraints on supermassive dark stars
Östlin, Göran; Rydberg, Claes-Erik; Zackrisson, Erik +6 more
Some of the first stars could be cooler and more massive than standard stellar models would suggest, due to the effects of dark matter annihilation in their cores. It has recently been argued that such objects may attain masses in the 104-107Msolar range and that such supermassive dark stars should be within reach …
The central region of M83: massive star formation, kinematics, and the location and origin of the nucleus
Knapen, J. H.; Sharp, R. G.; Ryder, S. D. +3 more
We report new near-IR integral field spectroscopy of the central starburst region of the barred spiral galaxy M83 obtained with Cambridge Infra-Red Panoramic Survey Spectrograph (CIRPASS) on Gemini-South, which we analyse in conjunction with GHαFaS Fabry-Perot data, an Anglo-Australian Telescope (AAT) IRIS2 Ks-band image, and near- and …
A relativistically broadened OVIII Lyα line in the ultracompact X-ray binary 4U 0614+091
de Plaa, J.; Fabian, A. C.; Pinto, C. +3 more
Ultracompact X-ray binaries consist of a neutron star or black hole that accretes material from a white dwarf donor star. The ultracompact nature is expressed in very short orbital periods of less than 1 h. In the case of 4U 0614+091 oxygen-rich material from a CO or ONe white dwarf is flowing to the neutron star. This oxygen-rich disc can reflect…
The circumnuclear environment of the peculiar galaxy NGC3310
Terlevich, Roberto; Terlevich, Elena; Díaz, Ángeles I. +2 more
Gas and star velocity dispersions have been derived for eight circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC3310 using high-resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the CaII triplet in the near-IR, using cross-correlation techniques, while gas veloci…