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52 records were found.

Comment: 17 pages, LATeX (paspconf.sty), 4 encapsulated postscript figures. To appear in proceedings of "Quasars and Cosmology" (1998 May 18-22, La Serena, Chile), ASP Conference Series, ed. G. Ferland
Comment: 11 pages, LATeX (paspconf.sty), no figures. To appear in proceedings of "Quasars and Cosmology" (1998 May 18-22, La Serena, Chile), ASP Conference Series, ed. G. Ferland
Comment: 15 pages, LATeX (AASTeX aaspp4.sty), 5 postscript figures, accepted for publication in The Astrophysical Journal
Using a realistic model for line emission from the broad emission line regions of quasars, we are able to reproduce the previously observed correlations of emission-line ratios with the shape of the spectral energy distribution (SED). In agreement with previous studies, we find that the primary driving force behind the Baldwin Effect (EW ~ L^beta, beta < 0) is a global change in the SED with quasar luminosity, in that more luminous quasars must have characteristically softer ionizing continua. This is completely consistent with observations that show correlations between L_uv, alpha_ox, alpha_uvx, line ratios and EWs. However, to explain the complete lack of a correlation in the EW(NV)--L_uv diagram we propose that the more luminous quasars have characteristically larger gas metallicities (Z). As a secondary element, nitrogen's rapid...
Comment: 24 pages (AASTeX, v5.02), 8 separate figures, in press with the Astrophysical Journal
Comment: Latex, 8 postscript figures. Astrophysical Journal, 536, June 10, in press
Comment: 22 pages, plus 14 Postscript figures. Accepted for publication in the Astrophysical Journal
We investigate the effect of a global change in the ionizing continuum level on the behavior of the strong optical broad emission-lines seen in spectra of the nuclear emission-line regions of active galactic nuclei (AGN), including the Balmer lines, HeI 5876, and HeII 4686. Unlike most of the prominent heavy element lines found in the UV, the optical hydrogen and helium recombination lines' emissivities are strongly dependent upon the incident continuum flux, since these lines arise out of excited states whose optical depths depend upon the incident flux of photons. Using photoionization calculations we determine the luminosity-dependent responsivities of these lines for a general model of the broad emission line region (BLR), with the purpose of establishing them as important probes of the physical conditions within the BLR of AGNs....
Our research program is designed to carry out state-of-the-art atomic physics calculations crucial to advancing our understanding of fundamental astrophysical problems. We redress the present inadequacies in the atomic data base along two important areas: dielectronic recombination and inner-shell photoionization and multiple electron ejection/Auger fluorescence therefrom. All of these data are disseminated to the astrophysical community in the proper format for implementation in spectral simulation code.
Comment: 11 pages AAS-LATeX aaspp4.sty format, including 1 figure; accepted for publication in ApJ
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