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Date and Time of the Query: 2019-08-20 T16:52:43 PDT
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For refcode 1993ApJ...403..592K:
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1993ApJ...403..592K SIMULTANEOUS GINGA AND IUE OBSERVATIONS OF THE SEYFERT GALAXY NGC 3516 MICHIEL KOLMAN, JULES P. HALPERN, AND CHRISTOPHER MARTIN Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY 10027 HISAMITSU AWAKI Department of Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-01, Japan AND KATSUJI KOYAMA Department of Astrophysics, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606, Japan Received 1992 January 7; accepted 1992 August 7 ABSTRACT Simultaneous X-ray and UV observations of the Seyfert 1 galaxy NGC 3516 were carried out to investigate the connection between the variable X-ray and ultraviolet absorption features. Over a 2 week period, X-ray spectra Were obtained with Ginga, simultaneously with UV spectra from IUE. The X-ray spectrum was complex and could be fitted satisfactorily with a warm absorber model, a partial covering model, or a cold reflector model, in addition to an overlying column density of NH ~4 x 10^22^ cm^-2^. The X-ray absorption remained unchanged (in all the spectral models), while the spectral index a changed significantly. The Fe K{alpha} line was generally found to be strong (EW ~ 250-400 eV). The UV spectra displayed a significant variation in the continuum flux, while the absorption features in the C IV {lambda}1550, N V {lambda}1240, and Si IV {lambda}1400 lines stayed constant. A common origin of the UV and X-ray absorption could not be established due to the absence of variability in either the X-ray or the UV absorption. A lower limit on the column densities of the UV absorber is ~2 x 10^19^ cm^-2^. Assuming that the variability in the C IV {lambda}1550 absorption (as detected in the archival data) is due to changes in the ionization level, the UV absorbers should be located closer than 9 Pc from the ionizing source for log N_H_~20, and at smaller distances for higher column densities. Based on estimates of the absorbing properties of a low-luminosity AGN in the framework of broad absorption line (BAL) theories, we suggest that NGC 3516 is consistent with a low-luminosity equivalent of a BAL QSO. Finally, we discuss the likely location of the UV absorbers in optically thin clouds in the broad line region. A common origin of the UV and X-ray absorption in such clouds is probably ruled out. Subject headings: galaxies: individual (NGC 3516) - galaxies: nuclei - galaxies: Seyfert - ultraviolet: galaxies - X-ray: galaxies
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