NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-21 T11:13:39 PDT
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For refcode 1996ApJ...467..629K:
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Copyright by American Astronomical Society. Reproduced by permission
1996ApJ...467..629K ASCA OBSERVATIONS OF THE COMPOSITE WARM ABSORBER IN NGC 3516 G. A. KRISS, J. H. KROLIK, C. OTANI, B. R. ESPEY, T. J. TURNER, T. KII, Z. TSVETANOV, T. TAKAHASHI, A. F. DAVIDSEN, M. TASHIRO, W. ZHENG, S. MURAKAMI, R. PETRE, AND T. MIHARA Received 1996 January 4; accepted 1996 March 7 ABSTRACT We obtained X-ray spectra of the Seyfert 1 galaxy NGC 3516 in 1995 March using the Japanese X-ray satellite, ASCA. Simultaneous far-UV observations were obtained with the Hopkins Ultraviolet Telescope on the Astro-2 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 K{alpha} emission line from cold material is present as well as a broad Fe K{alpha} 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 x 10^22^ cm^-2^, adding a lower ionization absorber with U = 0.32 and a total column of 6.9 x 10^21^ cm^-2^ significantly improves the fit. The contribution of resonant line scattering to our warm absorber models limits the Doppler parameter to less than 160 km s^- 1^ at 90% confidence. Turbulence at the sound speed of the photoionized gas provides the best fit. None of the warm absorber models fitted to the X-ray spectrum can match the observed equivalent widths of all the UV absorption lines. Accounting for the X-ray and UV absorption simultaneously requires an absorbing region with a broad range of ionization parameters and column densities. Subject headings: galaxies: active - galaxies: individual (NGC 3516) - galaxies: nuclei - galaxies: Seyfert - X-ray: galaxies
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