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arXiv · 1009.2091

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

Ohad Shemmer·Benny Trakhtenbrot·Scott F. Anderson·W. N. Brandt·Aleksandar M. Diamond-Stanic·Xiaohui Fan·Paulina Lira·Hagai Netzer·Richard M. Plotkin·Gordon T. Richards·Donald P. Schneider·Michael A. Strauss
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Abstract

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), SDSS J114153.34+021924.3 at z=3.55 and SDSS J123743.08+630144.9 at z=3.49. In both sources we detect an unusually weak broad H_beta line and we place tight upper limits on the strengths of their [O III] lines. Virial, H_beta-based black-hole mass determinations indicate normalized accretion rates of L/L_Edd=0.4 for these sources, which is well within the range observed for typical quasars with similar luminosities and redshifts. We also present high-quality XMM-Newton imaging spectroscopy of SDSS J114153.34+021924.3 and find a hard-X-ray photon index of Gamma=1.91^{+0.24}_{-0.22} which supports the virial L/L_Edd determination in this source. Our results suggest that the weakness of the broad-emission lines in WLQs is not a consequence of an extreme continuum-emission source but instead due to abnormal broad-emission line region properties.

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Ohad Shemmer, Benny Trakhtenbrot, Scott F. Anderson, W. N. Brandt, Aleksandar M. Diamond-Stanic, Xiaohui Fan, Paulina Lira, Hagai Netzer, Richard M. Plotkin, Gordon T. Richards, Donald P. Schneider, Michael A. Strauss. 2010-09-10. Weak-Line Quasars at High Redshift: Extremely High Accretion Rates or Anemic Broad-Line Regions?. https://doi.org/10.1088/2041-8205%2F722%2F2%2Fl152

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