ar X iv : a st ro - p h / 96 03 05 7 v 1 1 3 M ar 1 99 6 ASCA Observations of the Composite Warm Absorber in NGC 3516

We obtained X-ray spectra of the Seyfert 1 galaxy NGC 3516 in March 1995 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 Kα emission line from cold material is present as well as a broad Fe Kα 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 × 10 cm, adding a lower ionization absorber with U = 0.32 and a total column of 6.9 × 10 cm significantly improves the fit. The contribution of resonant line scattering to our warm absorber models limits the Doppler parameter to < 160 km s 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 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 Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218. The Institute of Physical and Chemical Research (RIKEN), Hirosawa, Wako, Saitama 351-01, Japan. Laboratory for High Energy Astrophysics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771. Universities Space Research Association. Institute of Space and Astronautical Sciences, Yoshinodai, Sagamihara, Kanagawa 229, Japan. Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan. Department of Physics, Osaka City University, 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka, 558, Japan.