NOAO >   Observing Info >   Approved Programs >   2011A-0241

Small NOAO Logo

Proposal Information for 2011A-0241


PI: Ohad Shemmer, University of North Texas, ohad@unt.edu
Address: Dept. of Physics, Denton, TX, 76203, USA

CoI: Scott Anderson, University of Washington
CoI: Niel Brandt, Pennsylvania State University
CoI: Aleksandar Diamond-Stanic, University of Arizona
CoI: Xiaohui Fan, University of Arizona
CoI: Pat Hall, York University
CoI: Ryan Lane, University of North Texas
CoI: Paulina Lira, Universidad de Chile
CoI: Hagai Netzer, Tel Aviv University
CoI: Richard Plotkin, University of Amsterdam
CoI: Gordon Richards, Drexel University
CoI: Don Schneider, Pennsylvania State University
CoI: Michael Strauss, Princeton University
CoI: Benny Trakhtenbrot, Tel Aviv University

Title: Weak Line Quasars at High Redshift: Extremely High Accretion Rates or Anemic Broad-Line Regions?

Abstract: Weak emission line quasars (WLQs) constitute a distinct population in the distributions of UV emission-line strengths in high-redshift quasars. The existence of a distinct WLQ population and the lack of a corresponding population of `strong-lined' quasars are not yet understood. We propose to extend our successful Gemini-N near-IR observations of two WLQs and obtain GNIRS H-band spectra of eight additional sources of this class at z 2.3. These spectra will provide virial, H_beta based accretion rate determinations and H_beta equivalent widths for a statistically meaningful sample of WLQs. The new observations will allow us to distinguish between two competing scenarios for the weakness of the UV lines in WLQs: 1) extremely high accretion rates, leading to suppressed high-ionization lines, such as C IV, with respect to low-ionization lines, such as H_beta, and 2) a significant gas deficit in the broad-line region of WLQs. Our spectra will also provide measurements of the [O III] lines in our targets, allowing investigation of the physical properties of the narrow-line regions in WLQs. The proposed Gemini-N observations, coupled with detailed photoionization modeling, may therefore lead to new insights about the accretion process and emission-line formation in all active galactic nuclei.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2011A-0241

noaoprop-help@noao.edu

Small NOAO Logo