Search Publications
Evidence for radio-source heating of groups
Hardcastle, M. J.; Croston, J. H.; Birkinshaw, M.
We report evidence that the gas properties of X-ray groups containing radio galaxies differ from those of radio-quiet groups. For a well-studied sample of ROSAT-observed groups, we found that more than half of the elliptical-dominated groups can be considered `radio-loud', and that radio-loud groups are likely to be hotter at a given X-ray luminos…
The Chandra view of extended X-ray emission from Pictor A
Hardcastle, M. J.; Croston, J. H.
We discuss the extended X-ray emission seen in three archival Chandra observations, and one archival XMM-Newton observation, of the Fanaroff-Riley type II radio galaxy, Pictor A. The overall properties of the X-ray lobes are consistent with the conclusions of earlier works that the extended X-ray emission is largely due to the inverse-Compton proc…
The exceptional X-ray variability of the dwarf Seyfert nucleus NGC 4395
Iwasawa, K.; Vaughan, S.; Fabian, A. C. +1 more
An analysis of the X-ray variability of the low-luminosity Seyfert nucleus NGC 4395, based on a long XMM-Newton observation, is presented. The power spectrum shows a clear break from a flat spectrum (α~ 1) to a steeper spectrum (α~ 2) at a frequency fbr= 0.5-3.0 × 10-3 Hz, comparable to the highest characteristic frequency fo…
The first detection of [OIII] emission from high-redshift damped Lyman-α galaxies
Fall, S. M.; Møller, P.; Weatherley, S. J. +3 more
We present the detection of [OIII] emission lines from the galaxies responsible for two high-redshift z > 1.75 damped Lyman-α (DLA) absorption lines. We find two sources of [OIII] emission corresponding to the z= 1.92 DLA absorber towards the quasar Q2206-1958, and we also detect [OIII] emission from the galaxy responsible for the z= 3.10 DLA a…
Pushing the ground-based limit: 14-µmag photometric precision with the definitive Whole Earth Telescope asteroseismic data set for the rapidly oscillating Ap star HR1217
Kepler, S. O.; Kawaler, S. D.; Winget, D. E. +43 more
HR1217 is one of the best-studied rapidly oscillating Ap (roAp) stars, with a frequency spectrum of alternating even- and odd-l modes that are distorted by the presence of a strong, global magnetic field. Several recent theoretical studies have found that within the observable atmospheres of roAp stars the pulsation modes are magneto-acoustic with…
Non-parametric mass reconstruction of A1689 from strong lensing data with the Strong Lensing Analysis Package
Diego, J. M.; Broadhurst, T.; Benítez, N. +3 more
We present the mass distribution in the central area of the cluster A1689 by fitting over 100 multiply lensed images with the non-parametric Strong Lensing Analysis Package. The surface mass distribution is obtained in a robust way, finding a total mass of 0.25 × 1015h-1 Msolar within a 70-arcsec circle radius from…
Post-glitch variability in the anomalous X-ray pulsar 1RXSJ170849.0-400910
Haberl, F.; Stella, L.; Rea, N. +5 more
Here we report on the first XMM-Newton observation of the anomalous X-ray pulsar 1RXSJ170849.0-400910. The source was observed in 2003 August, and was found at a flux level factor of about 2 lower than previous observations. Moreover, a significant spectral evolution appears to be present, the source exhibiting a much softer spectrum than in the p…
Chandra and XMM-Newton observations of NGC 6251
Hardcastle, M. J.; Croston, J. H.; Birkinshaw, M. +2 more
We present new X-ray observations of the nucleus, jet and extended emission of the nearby radio galaxy NGC 6251 using the Chandra/ACIS-S camera, together with a reanalysis of archival Chandra/ACIS-I and XMM-Newton/EPIC data. We find that the nuclear X-ray spectrum is well fitted with an absorbed power law, and that there is tentative, but not high…
XMM-Newton EPIC observations of the ultraluminous X-ray source NGC 5204 X-1
Warwick, R. S.; Roberts, T. P.; Ward, M. J. +2 more
We present the results of two XMM-Newton observations of the ultraluminous X-ray source NGC 5204 X-1. The EPIC spectra are well fitted by the standard spectral model of a black hole X-ray binary, comprising a soft multicolour disc blackbody component plus a harder power-law continuum. The cool (kTin~ 0.2 keV) inner-disc temperature requ…
The giant Hα/X-ray filament in the cluster of galaxies A1795
Fabian, A. C.; Sanders, J. S.; Crawford, C. S.
The cluster of galaxies A1795 hosts a 46 kpc long filament at its core, which is clearly visible in the light of Hα and X-ray emission. We present optical slit spectroscopy and deeper Chandra X-ray data of the filament. The optical spectra reveal that the bulk of the filament is quiescent (with σ < 130 km s-1), although considerable …