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The average X-ray/gamma-ray spectrum of radio-quiet Seyfert 1s
Zdziarski, Andrzej A.; George, Ian M.; Gondek, Dorota +5 more
We have obtained the average 1-500 keV spectrum of radio-quiet Seyfert 1s using data from EXOSAT, Ginga, HEAO-1 and GRO OSSE. The spectral fit to the combined average EXOSAT and OSSE data is fully consistent with that for Ginga and OSSE, confirming results from an earlier Ginga/OSSE sample. The average spectrum is well fitted by a power-law X-ray …
A Multiwavelength Catalog of Seyfert 2 Galaxies Observed in the 2--10 keV Energy Band
Malaguti, G.; Bassani, L.; Polletta, M. +2 more
This paper is a catalog of Seyfert 2 galaxies observed in the 2-10 keV band (339 flux entries). In total, it contains data on 150 objects; for 76 objects, a positive detection is reported, while for the remaining sources, 2 σ upper limits to the X-ray emission are given. Most of the data have been collected from the literature over a period starti…
Secular variations in the Z source CygnusX-2.
van der Klis, M.; Kuulkers, E.; Vaughan, B. A.
We analyzed the X-ray spectral variations of the low-mass X-ray binary CygX-2 on time scales longer than one day using EXOSAT data. We describe these variations in terms of the shifts and shape changes of the "Z" pattern in X-ray colour-colour and hardness-intensity diagrams. CygX-2 varies between three intensity "levels": "high", "medium" and "lo…
Periodic UV modulation of X1850-087: a double degenerate binary in the globular cluster NGC 6712?
van Paradijs, J.; Charles, P. A.; Naylor, T. +3 more
We report the discovery with the Hubble Space Telescope (HST) of a short-period (20.6 min) UV modulation in X1850-087, the luminous X-ray source in the globular cluster NGC 6712. The low-amplitude modulation (0.044+/-0.007 mag) is not detected in archival X-ray observations with EXOSAT. We compare the properties of X1850-087 with the 11-min binary…
Corona(e) of AR Lacertae. II. The Spatial Structure
White, N. E.; Singh, K. P.; Siarkowski, M. +2 more
The X-ray light curves in the 0.4-1.5 keV and 2-7 keV bands of the RS CVn binary AR Lacertae observed on 1993 June 1-3 over one full orbital cycle with the ASCA satellite have been used to map the spatial structure of AR Lac's coronae. We find that both stars are X-ray active, that the corona of the K-type secondary star appears to be hotter than …
The X-ray and EUV spectrum of the dwarf nova VW Hydri in outburst and quiescence.
Belloni, T.; Verbunt, F.; Watson, M. G. +5 more
We combine ROSAT, Ginga, and EXOSAT observations to investigate the X-ray and extreme-ultraviolet fluxes of VW Hyi in quiescence and throughout an ordinary dwarf-nova outburst. We show that the quiescent spectrum is consistent with emission from material heated to ~12keV and cooling through the X-ray band to temperatures below our sensitivity rang…
DA white dwarfs in pointed observations from the ROSAT archive.
Wolff, B.; Jordan, S.; Koester, D.
87 pointed PSPC (Position Sensitive Proportional Counter) observations of hot DA white dwarfs, available in the ROSAT public archive until the end of 1994, have been analyzed together with Wide Field Camera (WFC) and EXOSAT data. From the 57 objects with a significant count rate half of the objects have a temperature below 38,000K and a virtually …
Photometric and spectroscopic studies of cool stars discovered in EXOSAT X-ray images. III. Photometric properties.
Tagliaferri, G.; Pasquini, L.; Pallavicini, R. +2 more
We present high-precision UBV(RI)_c_ photometry for a sample of active stars detected serendipitously by the EXOSAT satellite. Fourteen objects, out of 47 likely optical counterparts, turned out to be clearly variable, with periods in the range 1-8 days, including a newly discovered eclipsing binary. For most of them the optical variability is con…
GX340+0 with EXOSAT: its correlated X-ray spectral and timing behaviour.
van der Klis, M.; Kuulkers, E.
We report on three observations of the Z source GX340+0 performed with EXOSAT during 1985 and 1986. In two observations the source was in the horizontal branch and the upper part of the normal branch of the Z pattern in the X-ray colour-colour diagram, while in the third observation it was in the normal and flaring branches. We found that the hori…
The canonical X-ray/gamma-ray spectrum of Seyfert 1s and low-state Galactic black hole candidates.
Zdziarski, A. A.; Magdziarz, P.; Gierlinski, M. +1 more
We review broad-band X-ray/γ-ray spectra of radio-quiet Seyfert 1s as well as of Galactic black hole candidates in the low state. The spectra share their basic components: an underlying power law, a Compton-reflection component with an Fe Kα line, low-energy absorption by cold matter, and a high-energy cutoff above ~200keV. The X-ray energy spectr…