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 signiicantly 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 emission line from cold material is present as well as a broad Fe K 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 22 cm ?2 , adding a lower ionization absorber with U = 0:32 and a total column of 6:9 10 21 cm ?2 signiicantly improves the t. The contribution of resonant line scattering to our warm absorber models limits the Doppler parameter to < 160 km s ?1 at 90% conndence. Turbulence at the sound speed of the photoionized gas provides the best t. None of the warm absorber models t 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.