Journal article
DETECTION OF REST-FRAME OPTICAL LINES FROM X-SHOOTER SPECTROSCOPY OF WEAK EMISSION-LINE QUASARS
The Astrophysical journal, v 805(2), pp 1-18
01 Jun 2015
Abstract
Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4-1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C IV) to low-ionization lines (e.g., Mg II, H beta, H alpha) in individual objects. We detect broad Ha and Ha emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., H beta has rest-frame equivalent widths ranging from 15-40 angstrom). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe II emission, H beta FWHM less than or similar to 4000 km s(-1), and significant C IV blueshifts (approximate to 1000-5500 km s(-1)) relative to the systemic redshift; two spectra also show elevated UV Fe II emission, and an outflowing component to their (weak) Mg II emission lines. These properties suggest that WLQs are exotic versions of "wind-dominated" quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum.
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Details
- Title
- DETECTION OF REST-FRAME OPTICAL LINES FROM X-SHOOTER SPECTROSCOPY OF WEAK EMISSION-LINE QUASARS
- Creators
- Richard M. Plotkin - University of Michigan–Ann ArborOhad Shemmer - University of North TexasBenny Trakhtenbrot - École Polytechnique Fédérale de LausanneScott F. Anderson - University of WashingtonW. N. Brandt - Pennsylvania State UniversityXiaohui Fan - University of ArizonaElena Gallo - University of Michigan–Ann ArborPaulina Lira - University of ChileBin Luo - Pennsylvania State UniversityGordon T. Richards - Drexel UniversityDonald P. Schneider - Pennsylvania State UniversityMichael A. Strauss - Princeton UniversityJianfeng Wu - Harvard University ,
- Publication Details
- The Astrophysical journal, v 805(2), pp 1-18
- Publisher
- Iop Publishing Ltd
- Number of pages
- 18
- Grant note
- GO3-14100X / Chandra X-ray Center AST 11-07862 / NSF; National Science Foundation (NSF) 1107682 / Division Of Astronomical Sciences; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) NNX10AC99G / NASA ADP; National Aeronautics & Space Administration (NASA) National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000356715400038
- Scopus ID
- 2-s2.0-84934880990
- Other Identifier
- 991019169802604721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics