Search Publications
Multiwavelength spectral and high time resolution observations of SWIFTJ1753.5-0127: new activity?
Dhillon, V. S.; Gandhi, P.; Shahbaz, T. +2 more
We have conducted an extensive observational campaign of SWIFTJ1753.5-0127 during 2007 June after its bright outburst episode in 2005. We have performed multiband optical photometry, optical spectroscopy, X-ray spectroscopy and timing and ULTRACAM optical photometry simultaneously in three bands. Both the optical spectrum and the X-ray spectrum al…
X-ray spectra from magnetar candidates - III. Fitting SGR/AXP soft X-ray emission with non-relativistic Monte Carlo models
Rea, N.; Zane, S.; Nobili, L. +1 more
Within the magnetar scenario, the `twisted magnetosphere' model appears very promising in explaining the persistent X-ray emission from soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). In the first two papers of the series, we have presented a 3D Monte Carlo code for solving radiation transport as soft, thermal photons emitted by th…
On the formation of massive galaxies: a simultaneous study of number density, size and intrinsic colour evolution in GOODS
Lisker, Thorsten; Kaviraj, Sugata; Pasquali, Anna +2 more
The evolution of number density, size and intrinsic colour is determined for a volume-limited sample of visually classified early-type galaxies selected from the Hubble Space Telescope/Advanced Camera for Surveys images of the Great Observatories Origins Deep Survey (GOODS) North and South fields (version 2). The sample comprises 457 galaxies over…
Discovery of the orbital period in the supergiant fast X-ray transient IGR J17544-2619
Hill, A. B.; Bird, A. J.; Scaringi, S. +3 more
The supergiant fast X-ray transient (SFXT) system IGR J17544-2619 has displayed many large outbursts in the past and is considered an archetypal example of SFXTs. A search of the INTEGRAL/ISGRI data archive from MJD 52698-54354 has revealed 11 outbursts and timing analysis of the light curve identifies a period of 4.926 +/- 0.001d which we interpr…
The blazar S5 0014+813: a real or apparent monster?
Ghirlanda, G.; Ghisellini, G.; Tavecchio, F. +4 more
A strong hard X-ray luminosity from a blazar flags the presence of a very powerful jet. If the jet power is in turn related to the mass accretion rate, the most luminous, hard X-ray blazars should pinpoint the largest accretion rates, and thus the largest black hole masses. These ideas are confirmed by the Swift satellite observations of the blaza…
The Seyfert AGN RX J0136.9-3510 and the spectral state of super Eddington accretion flows
Done, Chris; Ward, Martin; Gierliński, Marek +2 more
We have carried out a survey of long 50 ks XMM-Newton observations of a sample of bright, variable active galactic nuclei (AGN). We found a distinctive energy dependence of the variability in RX J0136.9-3510 where the fractional variability increases from 0.3 to 2 keV, and then remains constant. This is in sharp contrast to other AGN where the X-r…
GEMINI 3D spectroscopy of BAL + IR + FeII QSOs - I. Decoupling the BAL, QSO, starburst, NLR, supergiant bubbles and galactic wind in Mrk 231
Taniguchi, Y.; Jahnke, K.; Zheng, W. +9 more
In this paper we present the first results of a study of BAL QSOs (at low and high redshift), based on very deep Gemini GMOS integral field spectroscopy. In particular, the results obtained for the nearest BAL IR-QSO Mrk 231 are presented.
For the nuclear region of Mrk 231, the QSO and host galaxy components were modelled, using a new techniq…Time-resolved optical observations of five cataclysmic variables detected by INTEGRAL
Pretorius, Magaretha L.
The European Space Agency γ-ray telescope, INTEGRAL, is detecting relatively more intrinsically rare cataclysmic variables (CVs) than were found by surveys at lower energies. Specifically, a large fraction of the CVs that are INTEGRAL sources consists of asynchronous polars and intermediate polars (IPs). IP classifications have been proposed for t…
LoCuSS: luminous infrared galaxies in the merging cluster Abell1758 at z = 0.28
Smith, G. P.; Okabe, N.; Egami, E. +5 more
We present the first galaxy evolution results from the Local Cluster Substructure Survey (LoCuSS), a multiwavelength survey of 100 X-ray selected galaxy clusters at 0.15 <= z <= 0.3. LoCuSS combines far-ultraviolet (UV) through far-infrared (IR) observations of cluster galaxies with gravitational lensing analysis and X-ray data to investigat…
An HST/ACS view of the inhomogeneous outer halo of M31
Mackey, A. D.; Chapman, S. C.; Tanvir, N. R. +6 more
We present a high precision photometric view of the stellar populations in the outer halo of M31, using data taken with the Hubble Space Telescope/Advanced Camera for Surveys. We analyse the field populations adjacent to 11 luminous globular clusters which sample the galactocentric radial range 18 <~ R <~ 100kpc and reach a photometric depth…