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Surprises from a Deep ASCA Spectrum of the Broad Absorption Line Quasar PHL 5200We present a deep (approx. 85 ks) ASCA observation of the prototype broad absorption line quasar (BALQSO) PHL 5200. This is the best X-ray spectrum of a BALQSO yet. We find the following: (1) The source is not intrinsically X-ray weak. (2) The line-of-sight absorption is very strong, with N(sub H) = 5 x 10(exp 23)/sq cm. (3) The absorber does not cover the source completely; the covering fraction is approx. 90%. This is consistent with the large optical polarization observed in this source, implying multiple lines of sight. The most surprising result of this observation is that (4) the spectrum of this BALQSO is not exactly similar to other radio-quiet quasars. The hard X-ray spectrum of PHL 5200 is steep, with the power-law spectral index alpha approx. 1.5. This is similar to the steepest hard X-ray slopes observed so far. At low redshifts, such steep slopes are observed in narrow-line Seyfert 1 (NLS1) galaxies, believed to be accreting at a high Eddington rate. This observation strengthens the analogy between BALQSOs and NLS1 galaxies and supports the hypothesis that BALQSOs represent an early evolutionary state of quasars. It is well accepted that the orientation to the line of sight determines the appearance of a quasar: age seems to play a significant role as well.
Document ID
20030004012
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Mathur, Smita
(Ohio State Univ. Columbus, OH United States)
Matt, G.
(Rome Univ. Rome, Italy)
Green, P. J.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA United States)
Elvis, M.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA United States)
Singh, K. P.
(Tata Inst. of Fundamental Research Mumbai, India)
Date Acquired
August 21, 2013
Publication Date
April 10, 2002
Publication Information
Publication: Astrophysical Journal
Publisher: American Astronomical Society
Volume: 55
Subject Category
Astronomy
Funding Number(s)
CONTRACT_GRANT: NAG5-9270
CONTRACT_GRANT: NAG5-8913
Distribution Limits
Public
Copyright
Other

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