Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 1990
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990jhu..reptq....k&link_type=abstract
Final Technical Report Johns Hopkins Univ., Baltimore, MD. Dept. of Physics and Astronomy.
Astronomy and Astrophysics
Astronomy
Accretion Disks, Black Holes (Astronomy), Luminosity, Quasars, Seyfert Galaxies, Stellar Mass, Ultraviolet Spectra, X Rays, Exosat Satellite, Red Shift, Visual Observation, X Ray Spectra
Scientific paper
Nearly simultaneous optical, ultraviolet, and x ray observations of three low redshift quasars are presented. The EXOSAT x ray spectra span the range of observed spectral indices for quasars from the canonical 0.7 energy index typical of Seyfert galaxies for PG0923+129 (Mrk 705) to the steep spectral indices frequently seen in higher luminosity quasars with an index of 1.58 for PG0844+349 (Ton 951). None of the quasars exhibits any evidence for a soft x ray excess. This is consistent with accretion disk spectra fit to the IR through UV continua of the quasars -- the best fitting disk spectra peak at approximately 6 eV with black hole masses in the range 5 x 107 to 1 x 109 solar mass and mass accretion rates of approximately 0.1 times the Eddington-limited rate. These rather soft disk spectra are also compatible with the observed optical and ultraviolet line ratios.
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