Search Publications
The EXOSAT spectral survey of AGN.
Turner, T. J.; Pounds, K. A.
Results are presented from EXOSAT Observations of 48 hard X-ray selected Seyfert type active galactic nuclei (AGN). These include all 30 of the emission line AGN in the Piccinotti sample. Combining EXOSAT LE and ME data has allowed us to obtain X-ray spectra over the broad energy range 0.1 - 10 keV spectra in the ~2-10 keV range are found to be we…
Spin modulated X-ray emission from intermediate polars.
Watson, M. G.; Norton, A. J.
This paper describes a comparative study of all the intermediate polars observed by Exosat. The X-ray pulse profiles of each source are presented, and it is shown that, in all cases, the modulation can be described in terms of an increasing depth with decreasing energy. By considering the pulse phase-resolved spectra, it is shown that the modulati…
Variable X-ray absorption in NGC 4151.
Warwick, R. S.; Yaqoob, T.; Pounds, K. A.
The Seyfert galaxy NGC 4151 was monitored over 20 times by EXOSAT in the period 1983 July-1986 March. The very soft spectral component detected by the EXOSAT low-energy telescope, which may be thermal emission from the narrow-line region of NGC 4151, remained constant over the observing period. In contrast, the medium-energy X-ray continuum emanat…
Iron features in the X-ray spectra of three Seyfert galaxies.
Nandra, K.; Pounds, K. A.; Stewart, G. C. +1 more
Ginga X-ray spectra are presented for three Seyfert type 1 galaxies, each one showing evidence for a significant iron K-emission line. This line is interpreted as fluorescence from cold material, apparently lying close to the plane of the host galaxy, for NGC 5548 (near face-on) and NGC 3227 (~60^deg^ inclination). The additional detection of a la…
EXOSAT observations of X 1822-371 : modelling of the accretion disc rim.
Hellier, Coel; Mason, Keith O.
Data from three Exosat observations have been used to model X1822-371 as an X-ray emitting accretion disk corona (ADC) which is partially obscured by an optically emitting disk whose height varies with azimuthal angle. Using a system inclination of 85 + or - 3 deg and a disk structure parameterized by as few as two straight lines, the model is abl…
Detection of iron features in the X-ray spectrum of the Seyfert I galaxy MCG -6-30-15.
Nandra, K.; Fabian, A. C.; Pounds, K. A. +2 more
The spectra analysis of an extended (~2 d) EXOSAT observation of the Seyfert l galaxy MCG-6-30-15 has revealed significant difference from the previous simple power-law description. In particular, evidence is found for both emission and absorption features from cold iron, indicating a large column density of material possibly located close to the …
The flux and spectral variability of NGC 6814 as observed with EXOSAT.
Branduardi-Raymont, G.; Mittaz, J. P. D.
We present five EXOSAT observations of the Seyfert galaxy NGC 6814 which were carried out over the period 1983 September to 1985 October at intervals of a few months to a year. Over these time-scales the soft X-ray (0.02-2.5 keV) flux of NGC 6814 varies by large factors, decreasing by over and order of magnitude in the first 9 months; this is foun…
Absorption dips and the properties of the accretion stream in polars.
Motch, C.; King, A. R.; Watson, M. G. +1 more
Simultaneous X-ray, optical and infrared observations of the absorption dips in the polar system EF Eri are presented. These observations are used to determine the properties of the dips and develop a simple model for the dips in which they are caused by absorption in the accretion stream as it crosses the line-of-sight to the X-ray/optical emissi…
On the nature of the old nova CP Puppis.
O'Donoghue, D.; Wargau, W.; Warner, B. +1 more
Results are reported from nearly 48 h of high-speed photometry of the ex-nova CP Pup, obtained at Sutherland or Mount Stromlo, and 23 h of spectroscopic coverage from Sutherland, during the period 1985-88. Analysis of the photometry and radial velocities derived from the spectroscopy gives a modulation period of 0.06143 d, free from the alias prob…
A 4.1 keV spectral feature in a type 1 X-ray burst from EXO 1747-214.
van Paradijs, J.; Lewin, W. H. G.; Magnier, E. +3 more
We present the results of a spectral analysis of two type 1 bursts from EXO 1747-214 detected during 9.4 h of observing with EXOSAT. The spectrum, during the rise of the strongest burst, shows a spectral feature, which can be well represented by an absorption line at 4.05 +/- 0.1 keV; the line has an equivalent width of 570 +/- 87 eV; the upper li…