NOAO >   Observing Info >   Approved Programs >   2014A-0182

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Proposal Information for 2014A-0182


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

CoI: Scott Anderson, University of Washington
CoI: Niel Brandt, Pennsylvania State University
CoI: Aleksandar Diamond-Stanic, UC San Diego
CoI: Xiaohui Fan, University of Arizona
CoI: Pat Hall, York University
CoI: Paulina Lira, Universidad de Chile
CoI: Bin Luo, Pennsylvania State University
CoI: Hagai Netzer, Tel Aviv University
CoI: Richard Plotkin, University of Michigan
CoI: Gordon Richards, Drexel University
CoI: Don Schneider, Pennsylvania State University
CoI: Matthew Stein, University of North Texas
CoI: Michael Strauss, Princeton University
CoI: Benny Trakhtenbrot, Weizmann Institute of Science
CoI: Ran Wang, University of Arizona
CoI: Jianfeng Wu, Harvard-Smithsonian Center for Astrophysics

Title: Weak Line Quasars at High Redshift: Unusual Ionization Conditions 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 key to understanding WLQs lies in the properties of their rest-frame optical emission lines, accessible only with near-IR spectroscopy. We have successfully observed two WLQs in the near-IR with Gemini-N; we propose to extend this sample with GNIRS spectra of seven additional sources of this class in 2014A, and we will propose GNIRS spectra of six more such sources in 2014B. These spectra will provide H-beta equivalent widths and may provide virial, H-beta based black-hole mass and accretion rate determinations for a statistically meaningful sample of WLQs. The new observations will allow us to distinguish between two main competing scenarios for the physical properties of these sources: 1) unusual ionization conditions due to extremely high black-hole masses and/or 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. By comparing the rest-frame UV-optical spectra of WLQs with those of 'ordinary' quasars, in conjunction with photoionization modeling, we will obtain new insights about broad emission line formation in all active galactic nuclei.


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NOAO >   Observing Info >   Approved Programs >   2014A-0182

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