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Surprises from a Deep ASCA Spectrum of the Broad Absorption Line Quasar PHL 5200
Author and Affiliation:
Mathur, Smita(Ohio State Univ., Dept. of Astronomy, Columbus, OH United States)
Matt, G.(Rome Univ., Dept. di Fisica, 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, Dept. of Astronomy and Astrophysics, Mumbai, India)
Abstract: We 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.
Publication Date: Apr 10, 2002
Document ID:
(Acquired Jan 17, 2003)
Subject Category: ASTRONOMY
Document Type: Reprint
Publication Information: Astrophysical Journal; Volume 55; L13-L16
Publisher Information: American Astronomical Society, United States
Contract/Grant/Task Num: NAG5-9270; NAG5-8913
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD United States
Organization Source: Ohio State Univ.; Dept. of Astronomy; Columbus, OH United States
Description: 5p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
Availability Source: Other Sources
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