Search Publications
Shapelets - I. A method for image analysis
Refregier, Alexandre
We present a new method for the analysis of images, a fundamental task in observational astronomy. It is based on the linear decomposition of each object in the image into a series of localized basis functions of different shapes, which we call `shapelets'. A particularly useful set of complete and orthonormal shapelets is that consisting of weigh…
Surface brightness profiles and structural parameters for 53 rich stellar clusters in the Large Magellanic Cloud
Mackey, A. D.; Gilmore, G. F.
We have compiled a pseudo-snapshot data set of two-colour observations from the Hubble Space Telescope archive for a sample of 53 rich LMC clusters with ages of 106-1010 yr. We present surface brightness profiles for the entire sample, and derive structural parameters for each cluster, including core radii, and luminosity and…
Star cluster formation and disruption time-scales - I. An empirical determination of the disruption time of star clusters in four galaxies
Lamers, H. J. G. L. M.; Boutloukos, S. G.
We have derived the disruption times of star clusters from cluster samples of four galaxies, M51, M33, the Small Magellanic Cloud (SMC) and the solar neighbourhood. If the disruption time of clusters in a galaxy depends only on their initial mass as tdis(yr) =t4dis(Mcl/104 Msolar)
The iron line in MCG-6-30-15 from XMM-Newton: evidence for gravitational light bending?
Vaughan, S.; Fabian, A. C.
The lack of variability of the broad iron line seen in the Seyfert 1 galaxy MCG-6-30-15 is studied using the EPIC pn data obtained from a 2001 observation of 325 ks, during which the count rate from the source varied by a factor of 5. The spectrum of 80 ks of data from when the source was bright, using the lowest 10 ks as background, is well fitte…
Lyman break galaxies and the star formation rate of the Universe at z~ 6
Bunker, Andrew J.; McMahon, Richard G.; Stanway, Elizabeth R.
We determine the space density of UV-luminous starburst galaxies at z~ 6 using deep HST ACS SDSS-i' (F775W) and SDSS-z' (F850LP) and VLT ISAAC J and Ks band imaging of the Chandra Deep Field South. We find eight galaxies and one star with (i'-z') > 1.5 to a depth of z'AB= 25.6 (an 8σ detection in each of the 3 available AC…
Star cluster formation and evolution in nearby starburst galaxies - II. Initial conditions
Bastian, N.; de Grijs, R.; Anders, P. +3 more
We use the ages, masses and metallicities of the rich young star cluster systems in the nearby starburst galaxies NGC 3310 and 6745 to derive their cluster formation histories and subsequent evolution. We further expand our analysis of the systematic uncertainties involved in the use of broad-band observations to derive these parameters (Paper I) …
Evidence of a high-velocity ionized outflow in a second narrow-line quasar PG 0844+349
O'Brien, P. T.; King, A. R.; Page, K. L. +1 more
Following the discovery of X-ray absorption in a high-velocity outflow from the bright quasar PG 1211 + 143 we have searched for similar features in XMM-Newton archival data of a second (high accretion rate) quasar PG 0844+349. Evidence is found for several faint absorption lines in both the EPIC and RGS spectra, whose most likely identification w…
An XMM-Newton hard X-ray survey of ultraluminous infrared galaxies
Cappi, M.; Franceschini, A.; Bassani, L. +8 more
XMM-Newton observations of 10 ultraluminous infrared galaxies (ULIRGs) from a 200-ks mini-survey programme are reported. The aim is to investigate in hard X-rays a complete ULIRG sample selected from the bright IRAS 60-µm catalogue. All sources are detected in X-rays, five of which for the first time. These observations confirm that ULIRGs a…
X-ray continuum variability of MCG-6-30-15
Nandra, K.; Vaughan, S.; Fabian, A. C.
This paper presents a comprehensive examination of the X-ray continuum variability of the bright Seyfert 1 galaxy MCG-6-30-15. The source clearly shows the strong, linear correlation between rms variability amplitude and flux first seen in Galactic X-ray binaries. The high-frequency power spectral density (PSD) of MCG-6-30-15 is examined in detail…
A pulsational approach to near-infrared and visual magnitudes of RR Lyr stars
Degl'Innocenti, S.; Marconi, M.; Bono, G. +3 more
In this paper, we present an improved theoretical scenario concerning near-infrared and visual magnitudes of RR Lyr variables, as based on up-to-date pulsating models. New relations connecting V and K absolute magnitudes with periods, mass, luminosity and metal content are discussed separately for fundamental and first-overtone pulsators. We also …