Search Publications
Energy-dependent variability and the origin of the soft X-ray excess in active galactic nuclei
Done, Chris; Gierliński, Marek
The origin of the soft excess seen in many active galactic nuclei (AGN) below ~1 keV is still an unsolved problem. It is unlikely to represent a true continuum component as its characteristic `temperature' shows a remarkable constancy over a wide range of AGN luminosity and black hole mass. This instead favours an association with atomic processes…
Probing the evolution of the near-infrared luminosity function of galaxies to z~= 3 in the Hubble Deep Field-South
Chincarini, G.; Fontana, A.; Vanzella, E. +6 more
We present the rest-frame Js- and Ks-band luminosity function (LF) of a sample of about 300 galaxies selected in the Hubble Deep Field-South (HDF-S) at Ks<= 23 (Vega). We use calibrated photometric redshift together with spectroscopic redshift for 25 per cent of the sample. The accuracy reached in the photometri…
First results of the XI Groups Project: studying an unbiased sample of galaxy groups
Raychaudhury, Somak; Mulchaey, John S.; Ponman, Trevor J. +2 more
X-ray observations of hot, intergalactic gas in galaxy groups provide a useful means of characterizing the global properties of groups. However, X-ray studies of large group samples have typically involved very shallow X-ray exposures or have been based on rather heterogeneous samples. Here we present the first results of the XI (XMM/IMACS) Groups…
High-redshift Faranoff-Riley type II radio galaxies: X-ray properties of the cores
Hardcastle, M. J.; Worrall, D. M.; Belsole, E.
We present an extensive X-ray spectral analysis of the cores of 19 Faranoff-Riley type II sources in the redshift range 0.5 < z < 1.0 which were selected to be matched in isotropic radio power. The sample consists of 10 radio galaxies (RGs) and nine quasars. We compare our results with the expectations from a unification model that ascribes …
Ages, metallicities and [α/Fe] ratios of globular clusters in NGC 147, 185 and 205
Afanasiev, V. L.; Sharina, M. E.; Puzia, T. H.
We present measurements of ages, metallicities and [α/Fe] ratios for 16 globular clusters (GCs) in NGC 147, 185 and 205 and of the central regions of the diffuse galaxy light in NGC 185 and 205. Our results are based on spectra obtained with the SCORPIO multislit spectrograph at the 6-m telescope of the Russian Academy of Sciences. We include in o…
The OB binary HD152219: a detached, double-lined, eclipsing system
Gosset, E.; Rauw, G.; Sana, H.
We present the results of an optical spectroscopic campaign on the massive binary HD152219 located near the core of the NGC6231 cluster. Though the primary to secondary optical brightness ratio is probably about 10, we clearly detect the secondary spectral signature and we derive the first reliable SB2 orbital solution for the system. The orbital …
Galaxy number counts - VI. An H-band survey of the Herschel Deep Field
McCracken, H. J.; Thompson, D.; Metcalfe, N. +3 more
We present H-band infrared (IR) galaxy data to a 3σ limit of H ~ 22.9 and optical-IR colours of galaxies on the William Herschel Deep Field (WHDF). These data were taken from a 7 × 7arcmin2 area observed for 14 h with the Ω Prime camera on the 3.5-m Calar Alto telescope. We also present counts derived from the Hubble Deep Field-South (H…
A new population of planetary nebulae discovered in the Large Magellanic Cloud - I. Preliminary sample
Parker, Quentin A.; Reid, Warren. A.
We report our initial discovery of 73 new planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) following confirmatory 2dF spectroscopy on the Anglo-Australian Telescope. Preliminary candidate sources come from a 10 per cent sub-area of our new deep, high-resolution Hα map of the central 25deg2 of the LMC obtained with the UK Schm…
An XMM-Newton observation of the young open cluster NGC 2547: coronal activity at 30 Myr
Briggs, K. R.; Jeffries, R. D.; Evans, P. A. +1 more
We report on XMM-Newton observations of the young open cluster NGC 2547 which allow us to characterize coronal activity in solar-type stars, and stars of lower mass, at an age of 30 Myr. X-ray emission is seen from stars at all spectral types, peaking among G stars at luminosities (0.3-3 keV) of Lx≃ 1030.5 erg s-1 …
The infrared Hourglass cluster in M8*†
Maíz Apellániz, J.; Barbá, R. H.; Rubio, M. +2 more
A detailed study of the Hourglass nebula in the M8 star-forming region is presented. The study is mainly based on recent subarcsec-resolution JHKs images taken at Las Campanas Observatory and complemented with archival Hubble Space Telescope (HST) images and long-slit spectroscopy retrieved from the European Southern Observatory Archive…