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ROSAT PSPC observations of NGC 7469 and Ark 120We present spatial, temporal and spectral analyses of ROSAT Position Sensitive Proportional Counter (PSPC) observations of the Seyfert 1 galaxies NGC 7469 and Ark 120. Both of these sources show evidence for excess emission and more complex 0.1- 2.5 keV spectra than are predicted by simple extrapolations of higher energy power laws. We find that the spectrum of NGC 7469 can be explained by models that have secondary power-law, secondary bremsstrahlung, secondary blackbody or emission-line components. We find evidence for 0.1-2.5 keV intensity variability of NGC 7469. The spectrum of Ark 120 is better described by models with secondary continuum components than by models with sharper spectral features. We discuss the agreement between X-ray and ultraviolet observations of these sources and examine the observations in the context of accretion disc reflection models. The inner parts of discs are likely to be reflective below approximately 0.24 keV, and this reflectivity complicates simple models of the soft excess.
Document ID
19990036508
Acquisition Source
Marshall Space Flight Center
Document Type
Other
Authors
Brandt, W. N.
(Institute of Astronomy Cambridge, United Kingdom)
Fabian, A. C.
(Institute of Astronomy Cambridge, United Kingdom)
Nandra, K.
(Institute of Astronomy Cambridge, United Kingdom)
Tsuruta, S.
(Montana State Univ. Bozeman, MT United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Monthly Notices: Royal Astronomical Society
Volume: 265
Subject Category
Astronomy
Funding Number(s)
CONTRACT_GRANT: NAG8-289
CONTRACT_GRANT: NAG5-1830
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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