Search Publications
X-ray observations of the galaxy cluster PKS0745-191: to the virial radius, and beyond
Young, A. J.; Fabian, A. C.; Russell, H. R. +2 more
We measure X-ray emission from the outskirts of the cluster of galaxies PKS0745-191 with Suzaku, determining radial profiles of density, temperature, entropy, gas fraction and mass. These measurements extend beyond the virial radius for the first time, providing new information about cluster assembly and the diffuse intracluster medium out to ~1.5…
Two-dimensional kinematics of SLACS lenses - II. Combined lensing and dynamics analysis of early-type galaxies at z = 0.08-0.33
Treu, Tommaso; Gavazzi, Raphaël; Czoske, Oliver +3 more
We present the first detailed analysis of the mass and dynamical structure of a sample of six early-type lens galaxies, selected from the Sloan Lens ACS Survey, in the redshift range 0.08 <~ z <~ 0.33. Both Hubble Space Telescope/Advanced Camera for Surveys (ACS) high-resolution imaging and Very Large Telescope Visible Multi-Object Spectrogr…
Host galaxy morphologies of X-ray selected AGN: assessing the significance of different black hole fuelling mechanisms to the accretion density of the Universe at z ~ 1.
Cooper, M. C.; Georgakakis, A.; Nandra, K. +7 more
We use morphological information of X-ray selected active galactic nuclei (AGN) hosts to set limits on the fraction of the accretion density of the Universe at z ~ 1 that is not likely to be associated with major mergers. Deep X-ray observations are combined with high-resolution optical data from the Hubble Space Telescope in the All-wavelength Ex…
Gamma-ray emission from SNR RX J1713.7-3946 and the origin of galactic cosmic rays
Morlino, G.; Amato, E.; Blasi, P.
We calculate the flux of non-thermal radiations from the supernova remnant (SNR) RX J1713.7-3946 in the context of the non-linear theory of particle acceleration at shocks, which allows us to take into account self-consistently the dynamical reaction of the accelerated particles, the generation of magnetic fields in the shock proximity and the dyn…
Determining the spin of two stellar-mass black holes from disc reflection signatures
Fabian, A. C.; Miller, J. M.; Reis, R. C. +1 more
We present measurements of the dimensionless spin parameters and inner-disc inclination of two stellar-mass black holes. The spin parameter of SWIFT J1753.5-0127 and GRO J1655-40 is estimated by modelling the strong reflection signatures present in their XMM-Newton observations. Using a newly developed, self-consistent reflection model which inclu…
Constraints on turbulent pressure in the X-ray haloes of giant elliptical galaxies from resonant scattering
Simionescu, A.; Kaastra, J. S.; Churazov, E. +5 more
The dense cores of X-ray emitting gaseous haloes of large elliptical galaxies with temperatures kT <~ 0.8 keV show two prominent FeXVII emission features, which provide a sensitive diagnostic tool to measure the effects of resonant scattering. We present here high-resolution spectra of five bright nearby elliptical galaxies, obtained with the r…
Kinematics of OB-associations and the new reduction of the Hipparcos data
Dambis, A. K.; Mel'Nik, A. M.
The proper motions of OB-associations computed using the old and new reductions of the Hipparcos data are in good agreement with each other. The Galactic rotation curve derived from an analysis of the line-of-sight velocities and proper motions of OB-associations is almost flat in the 3-kpc neighbourhood of the Sun. The angular rotation velocity a…
The first outburst of the new magnetar candidate SGR0501+4516
Campana, S.; Tiengo, A.; Hurley, K. +17 more
We report here on the outburst onset and evolution of the new soft gamma-ray repeater SGR0501+4516. We monitored the new SGR with XMM-Newton starting on 2008 August 23, 1 day after the source became burst active, and continuing with four more observations in the following month, with the last one on 2008 September 30. Combining the data with the S…
The fraction of Compton-thick sources in an INTEGRAL complete AGN sample
Bird, A. J.; Ubertini, P.; Malizia, A. +3 more
We study the NH distribution in a complete sample of 88 active galactic nuclei (AGN) selected in the 20-40 keV band from INTEGRAL/Imager on Board the Integral Satellite (IBIS) observations. We find that the fraction of absorbed (NH >= 1022cm2) sources is 43 per cent while the Compton thick AGN compris…
Long-term optical and X-ray variability of the Seyfert galaxy Markarian 79
Gaskell, C. M.; Breedt, E.; Horne, K. +8 more
We present the results of concurrent X-ray and optical monitoring of the Seyfert 1 galaxy Mrk 79 over a period of more than 5yr. We find that on short to medium time-scales (days to a few tens of days) the 2-10 keV X-ray and optical u- and V-band fluxes are significantly correlated, with a delay between the bands consistent with 0d. We show that m…