Search Publications

A method to search for strong galaxy-galaxy lenses in optical imaging surveys

Dell'Antonio, Ian P.; Kubo, Jeffrey M.

We present a semi-automated method to search for strong galaxy-galaxy lenses in optical imaging surveys. Our search technique constrains the shape of strongly lensed galaxies (or arcs) in a multiparameter space, which includes the third-order (octopole) moments of objects. This method is applied to the Deep Lens Survey (DLS), a deep ground-based w…

Detectable signatures of cosmic radiative feedback

Salvaterra, R.; Burigana, C.; Schneider, R. +3 more

We use a semi-analytical model to study the impact of reionization, and the associated radiative feedback, on galaxy formation. Two feedback models have been considered: (i) a standard prescription, according to which star formation is totally suppressed in galaxies with circular velocity below a critical threshold (model CF06) and (ii) a characte…

A phenomenological model of galaxy clusters

Diego, J. M.; Ascasibar, Y.

We present a simple model to describe the dark matter density, the gas density and the gas temperature profiles of galaxy clusters. Analytical expressions for these quantities are given in terms of only five free parameters with a clear physical meaning: the mass M of the dark matter halo (or the characteristic temperature T₀), the char…

Optical spectroscopy of Arp220: the star formation history of the closest ULIRG

Tadhunter, C. N.; González Delgado, R. M.; Rodríguez Zaurín, J.

We present long-slit, optical spectra of the merging system Arp220, obtained using the William Herschel Telescope (WHT) on La Palma. These data were taken as a part of a large study of ultraluminous infrared galaxies (ULIRGs) with the aim of investigating the evolution and star formation histories of such objects. Spectral synthesis modelling has …

Constraining the mass of the GRB 030329 progenitor

Hayes, Matthew; Östlin, Göran; Sollerman, Jesper +2 more

The long-duration gamma-ray burst (GRB) GRB 030329, associated with the supernova (SN) SN 2003dh, occurred inside a star-forming dwarf galaxy at redshift z = 0.1685. The low redshift, and a rich set of archival Hubble Space Telescope (HST) images, makes this GRB well suited for a detailed study of the stellar population in the immediate vicinity o…

Observation and modelling of main-sequence stellar chromospheres - VII. Rotation and metallicity of dM1 stars

Houdebine, E. R.

We have measured v sini and metallicity from high-resolution spectroscopic observations of a selected sample of dM1-type stars.

To measure v sini, we first selected three template stars known for their slow rotation or their very low activity levels and then cross-correlated their spectra with those of our target stars. The excess broadening …

A limit on the number density of bright z ~ 7 galaxies

Lehnert, Matthew D.; Stanway, Elizabeth R.; Bremer, Malcolm N. +2 more

We present a survey of bright optical dropout sources in two deep, multiwavelength surveys comprising 11 widely separated fields, aimed at constraining the galaxy luminosity function at z ~ 7 for sources at 5-10L*(z = 6). Our combined survey area is 225arcmin² to a depth of J_AB = 24.2 (3σ) and 135arcmin² to J = 25.…

X-ray observations of the Large Magellanic Cloud pulsar PSR B0540-69 and its pulsar wind nebula

de Rosa, A.; Bassani, L.; Dean, A. J. +3 more

PSR B0540-69 is a young pulsar in the Large Magellanic Cloud that has similar properties with respect to the Crab Pulsar, and is embedded in a pulsar wind nebula (PWN). We have analysed the complete archival Rossi X-Ray Timing Explorer (RXTE) data set of observations of this source, together with new Swift/XRT (X-Ray Telescope) and International G…

Simulating anisotropic thermal conduction in supernova remnants - II. Implications for the interstellar medium

Howk, J. Christopher; Balsara, Dinshaw S.; Bendinelli, Anthony J. +2 more

We present a large number of 2.5D simulations of supernova remnants expanding into interstellar media having a range of densities, temperatures and magnetic field strengths. The simulations include equilibrium cooling and anisotropic, flux-limited thermal conduction along magnetic field lines. The volume of hot gas produced during the remnant's ev…

Swift captures the spectrally evolving prompt emission of GRB070616

Page, M. J.; Norris, J. P.; O'Brien, P. T. +14 more

The origins of gamma-ray burst (GRB) prompt emission are currently not well understood and in this context long, well-observed events are particularly important to study. We present the case of GRB070616, analysing the exceptionally long-duration multipeaked prompt emission, and later afterglow, captured by all the instruments on-board Swift and b…