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Quasar X-ray spectra revisitedA sample of 45 quasars observed by the IPC on the Einstein satellite is used to reexamine the relationship of the soft X-ray energy index with radio properties and the optical Fe II emission. The tendency for radio-loud quasars to have systematically flatter X-ray energy indices than radio-quiet quasars is confirmed with the soft X-ray excess having negligible effect. There is a tendency for the flatness of the X-ray slope to correlate with radio core dominance for radio-loud quasars, suggesting that a component of the X-ray emission is relativistically beamed. For the radio-quiet quasars, the soft X-ray energy indices with a mean of about 1.0 are consistent with the indices found at higher energies, although steeper than those observed for Seyfert 1 galaxies where the reflection model gives a good fit to the data. The correlation of Fe II emission line strength with X-ray energy index is confirmed for radio-quiet quasars using a subset of 18 objects. The radio-loud quasars show no evidence for a correlation. This relation suggests a connection between the ionizing continuum and line emission from the broad emission-line region (BELR) of radio-quiet quasars, but in the opposite sense to that predicted by current photoionization models. The correlations of X-ray slope with radio core dominance and Fe II equivalent width within the radio-loud and radio-quiet subclasses, respectively, imply that the observed wide range of X-ray energy indices is real rather than due to the large measuring uncertainties for individual objects.
Document ID
19930057206
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Shastri, P.
(Texas Univ. Austin; California Univ., Berkeley, United States)
Wilkes, B. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Elvis, M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mcdowell, J.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Date Acquired
August 16, 2013
Publication Date
June 10, 1993
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 410
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
93A41203
Funding Number(s)
CONTRACT_GRANT: NAG5-1700
CONTRACT_GRANT: NAS8-30751
CONTRACT_GRANT: NAGW-52201
CONTRACT_GRANT: NAS5-30934
CONTRACT_GRANT: NSF AST-87-14937
Distribution Limits
Public
Copyright
Other

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