Near-IR spectroscopy of luminous LoBAL quasars at 1<z<2.5

Abstract

We present near-IR spectroscopy of 22 luminous low-ionization broad absorption line quasars (LoBAL QSOs) at redshift 1.3<z<2.5, with 12 objects at z~1.5 and 10 at z~2.3. The spectra cover the rest-frame H$\alpha$ and H$\beta$ line regions, allowing us to obtain robust black hole mass estimates based on the broad H$\alpha$ line. We use these data, augmented by a lower-redshift sample from the Sloan Digital Sky Survey, to test the proposed youth scenario for LoBALs, which suggests that LoBALs constitute an early short-lived evolutionary stage of quasar activity, by probing for any difference in their masses, Eddington ratios, or rest-frame optical spectroscopic properties compared to normal quasars. In addition, we construct the UV to mid-IR spectral energy distributions (SEDs) for the LoBAL sample and a matched non-BAL quasar sample. We do not find any statistically significant difference between LoBAL QSOs and non-BAL QSOs in their black hole mass or Eddington ratio distributions. The mean UV to mid-IR SED of the LoBAL QSOs is consistent with non-BAL QSOs, apart from their stronger reddening. At z>1 there is no clear difference in their optical emission line properties. We do not see particularly weak [OIII] or strong FeII emission. The LoBAL QSOs do not show a stronger prevalence of ionized gas outflows as traced by the [OIII] line, compared to normal QSOs of similar luminosity. We conclude that the optical-MIR properties of LoBAL QSOs are consistent with the general quasar population and do not support them to constitute a special phase of active galactic nucleus evolution.

13 pages, 12 figures, accepted for publication in ApJ

References in corpus (15)

• A Catalog of Quasar Properties from SDSS DR7
• Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population
• The Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release
• A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5
• The WISSH Quasars Project I. Powerful ionised outflows in hyper-luminous quasars
• Correcting CIV-Based Virial Black Hole Masses
• X-shooter reveals powerful outflows in z~1.5 X-ray selected obscured quasi stellar objects
• Spitzer Observations of Young Red Quasars
• Rest-frame Optical Spectra and Black Hole Masses of 3<z<6 Quasars
• Radio Through X-ray Spectral Energy Distributions of 38 Broad Absorption Line Quasars
• Evidence that FeLoBALs may signify the transition between an ultraluminous infrared galaxy and a quasar
• The Dependence of C IV Broad Absorption Line Properties on Accompanying Si IV and Al III Absorption: Relating Quasar-Wind Ionization Levels, Kinematics, and Column Densities
• A Balmer-line Broad Absorption Line Quasar
• Black Hole Mass Estimates and Rapid Growth of Supermassive Black Holes in Luminous $z\sim$ 3.5 Quasars
• Discovery of H alpha absorption in the unusual broad absorption line quasar SDSS J083942.11+380526.3

Cited by in corpus (3)

• No signs of star formation being regulated in the most luminous quasars at z~2 with ALMA
• Variability of Low-ionization Broad Absorption Line Quasars Based on Multi-epoch Spectra from The Sloan Digital Sky Survey
• Star Formation in Luminous LoBAL Quasars at 2.0<z<2.5