Search Publications
Bias in the estimation of global luminosity functions
Maccagni, D.; Ilbert, O.; Adami, C. +13 more
We discuss a bias present in the calculation of the global luminosity function (LF) which occurs when analysing faint galaxy samples. This effect exists as a result of the different spectral energy distributions of galaxies, which are in turn quantified by the k corrections. We demonstrate that this bias occurs because not all galaxy types are vis…
Quantitative morphological analysis of the Hubble Deep Field North and Hubble Deep Field South - I. Early- and late-type luminosity-size relations of galaxies out to z~ 1
Aguerri, J. A. L.; Trujillo, I.
Based on drizzled F606W and F814W images, we present quantitative structural parameters in the V-band rest-frame for all galaxies with z < 1 and I814(AB) < 24.5 mag in the Hubble Deep Fields North and South. Our structural parameters are based on a two-component surface brightness distribution using a Sérsic bulge and an exponenti…
XMM-Newton observations of the binary cluster system Abell 399/401
Sakelliou, Irini; Ponman, Trevor J.
Both Abell 399 and Abell 401 are rich clusters of galaxies, with global temperatures of 7.2 (Abell 399) and 8.5 keV (Abell 401), respectively. They lie at a projected separation of ~3 Mpc, forming a close pair. We have observed the system with the XMM-Newton satellite. The data of each cluster show significant departures from our idealized picture…
Image simulation with shapelets
Refregier, Alexandre; Conselice, Christopher J.; Massey, Richard +2 more
We present a method to simulate deep sky images, including realistic galaxy morphologies and telescope characteristics. To achieve a wide diversity of simulated galaxy morphologies, we first use the shapelets formalism to parametrize the shapes of all objects in the Hubble Deep Fields. We measure this distribution of real galaxy morphologies in sh…
Period and light variations for the cool, overcontact binary BX Pegasi
Han, Wonyong; Kim, Ho-Il; Lee, Jae Woo +2 more
New charge-coupled device photometric observations of the W UMa-type binary BX Pegasi (BX Peg) were collected on four nights from 1999 October to 2000 September. The light curve was covered completely in each season. Seven new times of minimum light were determined. It was found that the orbital period of the system has varied recently in a sinuso…
Physical conditions in the planetary nebula NGC 6543
Liu, X. -W.; Wesson, R.
We present analysis of spectra and Hubble Space Telescope (HST) images of NGC 6543, the Cat's Eye Nebula. Using HST WFPC2 images taken in narrow-band filters isolating Hα and Hβ, we have produced an extinction map towards the nebula, and find that c(Hβ) is low, at ~0.1, and exhibits only very small spatial variations across the surface of the nebu…
Powerful, obscured active galactic nuclei among X-ray hard, optically dim serendipitous Chandra sources
Fabian, A. C.; Gandhi, P.; Johnstone, R. M. +1 more
We present a small sample of Chandra X-ray sources selected from the fields of ACIS observations which probe fluxes around the break in the hard band source counts. The targets of these fields include nine nearby galaxy clusters, one distant cluster and two powerful radio galaxy fields. The follow-up of this serendipitous sample was biased towards…
The nature of a gravitationally lensed submillimetre arc in MS0451.6-0305: two interacting galaxies at z~ 2.9?
Donahue, Megan; Smith, Graham P.; Kneib, Jean-Paul +6 more
We present a new SCUBA image of the cluster MS 0451.6-0305, which exhibits strong, extended submillimetre flux at 850 µm. The most striking feature in the map is an elongated region of bright submillimetre emission, with a flux density of ~10 mJy over several beam sizes. This region is apparently coincident with a previously known optical ar…
XMM-Newton observations of Sagittarius A East
Decourchelle, A.; Warwick, R. S.; Predehl, P. +1 more
We present an analysis of a recent XMM-Newton observation of Sgr A East, a supernova remnant located close to the Galactic Centre. Very high-quality X-ray spectra reveal many emission lines from highly ionized atoms consistent with a multitemperature thin thermal plasma in ionization equilibrium. We use a two-temperature model to fit the spectra a…
The soft X-ray absorption lines of the Seyfert 1 galaxy MCG-6-30-15
Vaughan, S.; Fabian, A. C.; Lee, J. C. +1 more
The absorption lines in the soft X-ray spectrum of MCG-6-30-15 are studied using the reflection grating spectrometer data from the 2001 XMM-Newton 320-ks observation. A line search of the full time-averaged spectrum reveals 51 absorption lines and one emission line. The equivalent widths of the lines are measured and the majority of the lines iden…