Physical Sciences and Mathematics Commons^™

Broad Ne Viii Λ744 Emission From The Quasar Pg 1148+549, Fred Hamann, Joseph C. Shields, Gary J. Ferland, Kirk T. Korista

Physics and Astronomy Faculty Publications

We discuss the probable detection of broad Ne VIII λ774 emission from the z_ɛ = 0.978 quasar PG 1148+549, and we use spectral synthesis calculations to study the physical conditions in the line-forming gas. The theoretical predictions and the measured line wavelength both support Ne VIII λ774 as the most likely identification.

Our calculations show that Ne VIII λ774 forms in hotter and more highly ionized gas than previously recognized in the broad emission line region. If the gas is photoionized by a standard active galactic nucleus continuum, the observed Ne VIII equivalent width, the Ne VIII/O VI flux …

The Geometry And Kinematics Of The Broad-Line Region In Ngc 5548 From Hst And Iue Observations, Ignaz Wanders, Mike R. Goad, Kirk T. Korista, Bradley M. Peterson, Keith Horne, Gary J. Ferland, Anuradha P. Koratkar, Richard W. Pogge, Joseph C. Sheilds

Physics and Astronomy Faculty Publications

The spatial and radial velocity distribution of broad-line-emitting gas in the Seyfert 1 galaxy NGC 5548 is examined through the process of reverberation mapping, which is done by detailed comparison of continuum and emission-line variations. Recent spectroscopic monitoring of NGC 5548 with HST and IUE allows us to resolve the "transfer function" (TF) that relates the continuum and emission-line variability. We also examine the radial velocity-resolved TFs, and confirm that predominantly radial motions of the line-emitting clouds can be excluded. We find that a broad-line region comprised of clouds that are orbiting a central source of mass ~10⁸ M …

The Hubble Space Telescope Sample Of Radio-Loud Quasars: The LyΑ/HΒ Ratio, Hagai Netzer, M. S. Brotherton, Beverley J. Wills, Mingsheng Han, D. Wills, J. A. Baldwin, Gary J. Ferland, I. W. A. Browne

Physics and Astronomy Faculty Publications

We have used the first Hubble Space Telescope Faint Object Spectrograph spectra of our sample of radio- loud quasars, and quasi-simultaneous ground-based spectrophotometry, to investigate the intensity ratio Lyα/Hβ, whose small observed values are one of the outstanding problems of active galactic nuclei research. The present sample of 20 quasars with complete flux and profile data shows the first significant correlations of this ratio with other observed properties. The strongest correlations are with various continuum slope indicators: we find smaller Lyα/Hβ ratios in quasars whose continua rise more steeply into the red. The …

The Hubble Space Telescope Sample Of Radio-Loud Quasars: Ultraviolet Spectra Of The First 31 Quasars, Beverley J. Wills, Keith L. Thompson, Mingsheng Han, H. Netzer, D. Wills, J. A. Baldwin, Gary J. Ferland, I W. A. Browne, M. S. Brotherton

Physics and Astronomy Faculty Publications

We report the first results from a continuing program to investigate the multifrequency spectrophotometric and other properties of a sample of about 50 radio-loud quasars in the redshift range ˜0.3-1.3. Here we present spectrophotometric data of high signal-to-noise ratio (≳20 in the continuum) of the first 31 radio-loud quasars, over the wavelength range from below Lyα to an observed wavelength of 3250 or 4800 Å, obtained using the Faint Object Spectrograph on the Hubble Space Telescope. We have also made quasi-simultaneous observations to extend these spectra beyond the Balmer lines -- either Hβ or Hα -- …