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HST Spectral Observations near the He II Ly-alpha Break: Implications for He II Reionization
David Syphers, Scott F. Anderson, Wei Zheng +4
Quasars that allow the study of IGM He II are very rare, since they must be at high redshift along sightlines free of substantial hydrogen absorption, but recent work has dramatica…
Weak-Line Quasars at High Redshift: Extremely High Accretion Rates or Anemic Broad-Line Regions?
Ohad Shemmer, Benny Trakhtenbrot, Scott F. Anderson +9
We present Gemini-North K-band spectra of two representative members of the class of high-redshift quasars with exceptionally weak rest-frame ultraviolet emission lines (WLQs), SDS…
Multiwavelength Observations of Radio-quiet Quasars with Weak Emission Lines
Richard M. Plotkin, Scott F. Anderson, W. N. Brandt +5
We present radio and X-ray observations, as well as optical light curves, for a subset of 26 BL Lac candidates from the Sloan Digital Sky Survey (SDSS) lacking strong radio emissio…
Chandra X-Ray Observations of Two Unusual BAL Quasars
Jesse A. Rogerson, Patrick B. Hall, Stephanie A. Snedden +2
We report sensitive Chandra X-ray non-detections of two unusual, luminous Iron Low-Ionization Broad Absorption Line Quasars (FeLoBALs). The observations do detect a non-BAL, wide-b…
The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
Donald P. Schneider, Gordon T. Richards, Patrick B. Hall +45
We present the fifth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog, which is based upon the SDSS Seventh Data Release. The catalog, which contains 105,783 spectrosc…
The Field X-ray AGN Fraction to z=0.7 from the Chandra Multiwavelength Project and the Sloan Digital Sky Survey
Daryl Haggard, Paul J. Green, Scott F. Anderson +4
We employ the Chandra Multiwavelength Project (ChaMP) and the Sloan Digital Sky Survey (SDSS) to study the fraction of X-ray-active galaxies in the field out to z = 0.7. We utilize…