2015/03/25 by Ohad Shemmer, Sara Lieber · 1 citation
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics #Context (archaeology) #Eddington luminosity #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Physics #Quasar #Redshift #Rest frame #Spectral line #Supermassive black hole #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1088/0004-637x/805/2/124
7 pages (emulateapj), 2 figures. Accepted for publication in ApJ
arxiv created 2015/03/25 · openalex publication_date 2015/05/28 · arxiv updated 2015/06/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate the relationship between the rest-frame equivalent width (EW) of the C iv broad-emission line, monochromatic luminosity at rest-frame 5100 Å, and the H β -based Eddington ratio in a sample of 99 ordinary quasars across the widest possible ranges of redshift ( ) and bolometric luminosity ( ). We find that EW(C iv ) is primarily anti-correlated with the Eddington ratio, a relation we refer to as a modified Baldwin effect (MBE), an extension of the result previously obtained for quasars at . Based on the MBE, weak emission line quasars (WLQs), typically showing EW(C iv )≲10 Å, are expected to have extremely high Eddington ratios. By selecting all WLQs with archival H β and C iv spectroscopic data, nine sources in total, we find that their H β -based Eddington ratios are typical of ordinary quasars with similar redshifts and luminosities. Four of these WLQs can be accommodated by the MBE, but the other five deviate significantly from this relation, at the level, by exhibiting C iv lines much weaker than predicted from their H β -based Eddington ratios. Assuming the supermassive black hole masses in all quasars can be determined reliably using the single-epoch H β -method, our results indicate that EW(C iv ) cannot depend solely on the Eddington ratio. We briefly discuss a strategy for further investigation into the roles that basic physical properties play in controlling the relative strengths of broad-emission lines in quasars.