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ASCA Observations of the Composite Warm Absorber in NGC 3516 G. A. Kriss 1 , J. H. Krolik 1 , C. Otani 2 , B. R. Espey 1 , T. J. Turner 3;4 , T. Kii 5 , Z. Tsvetanov 1 , T.
 

Summary: ASCA Observations of the Composite Warm Absorber in NGC 3516
G. A. Kriss 1 , J. H. Krolik 1 , C. Otani 2 , B. R. Espey 1 , T. J. Turner 3;4 , T. Kii 5 , Z. Tsvetanov 1 , T.
Takahashi 2 , A. F. Davidsen 1 , M. Tashiro 6 , W. Zheng 1 , S. Murakami 7 , R. Petre 3 , and T. Mihara 2
ABSTRACT
We obtained X­ray spectra of the Seyfert 1 galaxy NGC 3516 in March 1995 using the
Japanese X­ray satellite ASCA. Simultaneous far­UV observations were obtained with
the Hopkins Ultraviolet Telescope on the Astro­2 shuttle mission. The ASCA spectrum
shows a lightly absorbed power law of energy index 0.78. The low energy absorbing
column is significantly less than previously seen. Prominent O vii and O viii absorption
edges are visible, but, consistent with the much lower total absorbing column, no Fe K
absorption edge is detectable. A weak, narrow Fe Kff emission line from cold material
is present as well as a broad Fe Kff line. These features are similar to those reported
in other Seyfert 1 galaxies. A single warm absorber model provides only an imperfect
description of the low energy absorption. In addition to a highly ionized absorber with
ionization parameter U = 1:66 and a total column density of 1:4 \Theta 10 22 cm \Gamma2 , adding
a lower ionization absorber with U = 0:32 and a total column of 6:9 \Theta 10 21 cm \Gamma2
significantly improves the fit. The contribution of resonant line scattering to our warm
absorber models limits the Doppler parameter to ! 160 km s \Gamma1 at 90% confidence.
Turbulence at the sound speed of the photoionized gas provides the best fit. None of
the warm absorber models fit to the X­ray spectrum can match the observed equivalent

  

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

 

Collections: Physics