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To appear in the Astrophy. J., Lett, November 20, 1995 issue FarUltraviolet Spectrum of Fairall 9

Summary: To appear in the Astrophy. J., Lett, November 20, 1995 issue
Far­Ultraviolet Spectrum of Fairall 9
with the Hopkins Ultraviolet Telescope
Wei Zheng, Gerard A. Kriss, Arthur F. Davidsen and Jeffrey W. Kruk
Center for Astrophysical Sciences, The Johns Hopkins University
Baltimore, MD 21218--2695
We observed the Seyfert 1 galaxy Fairall 9 with the Hopkins Ultraviolet Telescope
(HUT) for ¸ 3500 s during the Astro­2 mission. The spectrum covers 820--1840 š A with
a resolution of ¸ 3 š A. The intrinsic far--UV continuum is unattenuated to wavelengths
as short as 920 š A (¸ 880 š A in the galaxy's rest frame) and can be fitted with a power law
with f š / š \Gamma1:0 after a reddening correction corresponding to EB \GammaV = 0:03 magnitudes.
The power--law fit to the far--UV continuum of Fairall 9 may be extrapolated to
connect to the soft X--ray component measured with ROSAT, forming a weak UV
bump. Photoionization by such an energy distribution would produce relatively weak
high­ionization lines. The intensity ratio of O vi –1034+Lyfi emission to that of C iv
–1549 is ¸ 0:36. While this is typical for high--redshift quasars, it is one of the lowest
among the low--luminosity, low--redshift AGN observed by HUT. A correlation between
the strength of O vi emission and the soft X--ray excess is supported by the observations
of Fairall 9 and other AGN.


Source: Henry, Richard C.- Department of Physics and Astronomy, Johns Hopkins University


Collections: Physics