Search Publications
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…
Wide-field HST/ACS images of M81: the population of compact star clusters
Mayya, Y. D.; Rosa-González, D.; Santiago-Cortés, M.
We study the population of compact star clusters (CSCs) in M81, using the Hubble Space Telescope/Advanced Camera for Surveys (ACS) images in the filters F435W, F606W and F814W covering, for the first time, the entire optical extent of the galaxy. Our sample contains 435 clusters of full width at half-maximum less than 10 ACS pixels (9pc). The samp…
Determining the extragalactic extinction law with SALT - II. Additional sample
O'Donoghue, Darragh; Buckley, David A. H.; Sefako, Ramotholo +8 more
We present new results from an ongoing programme to study the dust extragalactic extinction law in E/S0 galaxies with dust lanes with the Southern African Large Telescope (SALT) during its performance verification phase. The wavelength dependence of the dust extinction for seven galaxies is derived in six spectral bands ranging from the near-ultra…
Central galaxy growth and feedback in the most massive nearby cool core cluster
Böhringer, H.; Simionescu, A.; Fabian, A. C. +4 more
We present multiwavelength observations of the centre of RXCJ1504.1 - 0248 - the galaxy cluster with the most luminous and relatively nearby cool core at z ~ 0.2. Although there are several galaxies within 100kpc of the cluster core, only the brightest cluster galaxy (BCG), which lies at the peak of the X-ray emission, has blue colours and strong …