1996/10/15 by Smita Mathur, B. J. Wilkes, Belinda J. Wilkes +2 · 4 citations
Physics and Astronomy · #Absorption (acoustics) #Absorption edge #Absorption spectroscopy #Astronomy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics #Atomic physics #Condensed matter physics #Galaxy #Line (geometry) #Optics #Physics #ROSAT #Reflection (computer programming) #Spectral line #Wavelength #X-ray #X-ray Spectroscopy and Fluorescence Analysis #astro-ph
paper · pdf · doi:10.1086/303761
24 pages with 5 figures. To appear in the Ap.J. Requires AAS macros
arxiv created 1996/10/15 · openalex publication_date 1997/03/20 · arxiv updated 2016/08/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The Seyfert 1 galaxy, NGC 3516 has been the subject of many absorption line studies at both ultraviolet and X-ray wavelengths. In the UV, strong, broad, variable associated metal line absorption with velocity width ~2000 km s -1 is thought to originate in gas with N H ≳ 10 19 cm -2 lying between 0.01 and 9 pc from the central active nucleus. The Ginga X-ray data are consistent with several possibilities: a warm absorber and a cold absorber combined either with partial covering or an unusually strong reflection spectrum. We present ROSAT observations of NGC 3516 which show a strong detection of a warm absorber dominated by a blend of O VII/O VIII edges at ~0.8 keV with N H ~ 7 × 10 21 cm -2 and U :8-12. We argue that NGC 3516 contains an outflowing "XUV" absorber showing the presence of X-ray absorption edges which are consistent with the presence of broad absorption lines in the old IUE spectra and their disappearance in the new UV observations. Our dynamical model suggests that the O VII absorption edge will continue to weaken compared to the O VIII edge, an easily testable prediction with future missions like AXAF. Eventually the source would be transparent to the X-rays unless a new absorption system is produced.