Near-IR Spectroscopy of Luminous LoBAL Quasars at 1 < z < 2.5
- National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)
- Shanghai Astronomical Observatory, Shanghai 200030 (China)
- Department of Astronomy, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China)
- Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)
- Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Piikkiö (Finland)
- Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Väisäläntie 20, FI-21500 Piikkiö (Finland)
- Department of Physics, Ehime University, Bunkyo-cho, 2–5, Matsuyama, 790-8577 (Japan)
- Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho 2–5, Matsuyama, 790-8577 (Japan)
- Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 3037-5 Honjo, Kamogata, Asakuchi, Okayama 719-0232 (Japan)
We present near-IR spectroscopy of 22 luminous low-ionization broad absorption line quasars (LoBAL QSOs) at redshift 1.3<2.5, with 12 objects at z ∼ 1.5 and 10 at z ∼ 2.3. The spectra cover the rest-frame Hα and Hβ line regions, allowing us to obtain robust black hole mass estimates based on the broad Hα 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 [O iii] or strong Fe ii emission. The LoBAL QSOs do not show a stronger prevalence of ionized gas outflows as traced by the [O iii] 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.
- OSTI ID:
- 22875678
- Journal Information:
- Astrophysical Journal, Vol. 848, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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