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EXOSAT observations of clusters of galaxies - I. The X-ray data.
Edge, A. C.; Stewart, G. C.
X-ray observations of 45 clusters of galaxies made with the European X- ray Observatory Satellite, EXOSAT, are presented. The 0.1-20 keV spectra obtained constitute the largest homogeneous spectral sample presently available. Here the analysis of the spectral and imaging data is described. A significant scatter in the correlation between the X-ray…
EXOSAT observations of clusters of galaxies - II. X-ray to optical correlations.
Edge, A. C.; Stewart, G. C.
The results obtained for clusters of galaxies using X-ray data from the European X-ray Observatory Satellite, EXOSAT, are compared with the optical, infrared and radio properties of the clusters taken from the literature. A number of strong correlations are found. The ratios of the intracluster medium (ICM) temperature and the cluster velocity dis…
The EXOSAT High Galactic Latitude Survey
Tagliaferri, G.; Beuermann, K.; Branduardi-Raymont, G. +9 more
A survey of serendipitous sources performed in the very soft X-ray band (0.05-2.0 keV) using the EXOSAT imaging telescopes is presented. The survey covers 783 square degrees of high Galactic latitude sky and includes 210 serendipitous sources which define a complete (flux-limited) sample. An extensive program of optical and radio observations toge…
Compton reflection and the variable X-ray spectrum of NGC 5548.
Nandra, K.; George, I. M.; Hayashida, K. +4 more
Spectral analysis of EXOSAT and Ginga observations of the Seyfert galaxy NGC 5548 has revealed a complex spectral form. At least four components, a steep non-thermal power law, an iron line, a `hard tail' and a soft emission component, have been identified in the 0.05-20 keV range. The soft component arises from thermal emission by optically thick…
Optical and X-ray observations of AO PISCIUM and the origin of the spin pulse in intermediate polars.
Cropper, Mark; Hellier, Coel; Mason, Keith O.
Results are presented of three nights of time-resolved spectroscopic observations and of four Exosat X-ray observations of the AO Psc polar binary. It is found that the AO Psc has a magnetic field much weaker than that of the AM Her star and that it possesses an accretion disc extending inward to about 8 white-dwarf radii and outward to fill the R…
Accretion Mechanisms in the Be/X-Ray Transient System A0535+26
Stella, L.; Motch, C.; Janot-Pacheco, E. +1 more
We present four EXOSAT observations of the Be/X-ray transient pulsar HDE 245770/A0535+26 obtained at various phases of the 111d period. On all occasions, a faint X-ray flux is detected from the source (Fx = 1.5-3.0 × 10-10 ergs cm-2 s-1) which corresponds to Lx (1-20 keV) = 2.5 × 10…
Shot Model Parameters for Cygnus X-1 through Phase Portrait Fitting
Swank, J. H.; Szymkowiak, A. E.; Lochner, James C.
Shot models for systems having about 1/f power density spectrum are developed by utilizing a distribution of shot durations. Parameters of the distribution are determined by fitting the power spectrum either with analytic forms for the spectrum of a shot model with a given shot profile, or with the spectrum derived from numerical realizations of t…
Coordinated X-Ray, Ultraviolet, and Optical Observations of 3C 120
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +5 more
The results of 14 observations with EXOSAT and 10 quasi-simultaneous observations with IUE of the Seyfert galaxy 3C 120 are reported. On few epochs, quasi-simultaneous optical spectrophotometry was also obtained, allowing us to derive the energy distribution from the optical to the X-ray band in different intensity states. The X-ray spectra are we…
EXOSAT observations of Cygnus X-1 : study of the soft X-ray excess.
Hasinger, G.; Balucinska, M.
The paper presents results of a spectral analysis of the Cyg X-1 data collected during 1984-1985 by the Medium Energy instrument onboard the Exosat satellite. Emphasis is on two issues: the soft X-ray excess in the range below 3 keV and the iron-line intensity. The presence of a soft component in addition to the high-energy power-law component is …
The Orbital Ephemeris and Eclipse Transitions of the Low-Mass X-Ray Binary EXO 0748-676
Parmar, A. N.; Verbunt, F.; Corbet, R. H. D. +1 more
Using the eclipses as fiducial markers, an updated ephemeris for EXO 0748 - 676 is derived and evidence is found that between February 1985 and March 1989 the 3.82-h orbital period of EXO 0748 - 676 decreased with a time scale of -5 x 10 to the 6th yr. The sense of this change is the same as that predicted by simple models for the evolution of low…