Shedding New Light on Weak Emission-line Quasars in the C iv-H β Parameter Space

Trung Ha, Cooper Dix, Brandon M. Matthews, Ohad Shemmer, Michael S. Brotherton, Adam D. Myers, Gordon T. Richards, Jaya Maithil, Scott F. Anderson, W. N. Brandt, Aleksandar M. Diamond-Stanic, Xiaohui Fan, S. C. Gallagher, Richard Green, Paulina Lira, Bin Luo, Hagai Netzer, Richard M. Plotkin, Jessie C. Runnoe, Donald P. SchneiderMichael A. Strauss, Benny Trakhtenbrot, Jianfeng Wu

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Weak emission-line quasars (WLQs) are a subset of type 1 quasars that exhibit extremely weak Lyα + N v λ1240 and/or C iv λ1549 emission lines. We investigate the relationship between emission-line properties and accretion rate for a sample of 230 "ordinary"type 1 quasars and 18 WLQs at z < 0.5 and 1.5 < z < 3.5 that have rest-frame ultraviolet and optical spectral measurements. We apply a correction to the Hβ-based black hole mass (M BH) estimates of these quasars using the strength of the optical Fe ii emission. We confirm previous findings that WLQs' M BH values are overestimated by up to an order of magnitude using the traditional broad-emission-line region size-luminosity relation. With this M BH correction, we find a significant correlation between Hβ-based Eddington luminosity ratios and a combination of the rest-frame C iv equivalent width and C iv blueshift with respect to the systemic redshift. This correlation holds for both ordinary quasars and WLQs, which suggests that the two-dimensional C iv parameter space can serve as an indicator of accretion rate in all type 1 quasars across a wide range of spectral properties.

Original languageEnglish (US)
Article number97
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 1 2023

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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