An Optically Faint Quasar Survey at z ∼ 5 in the CFHTLS Wide Field: Estimates of the Black Hole Masses and Eddington Ratios

Journal Article · Fri Sep 01 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA83AE· OSTI ID:22875851

Ikeda, H. ^[1]; Nagao, T.; Kajisawa, M. ^[2]; Matsuoka, K. ^[3]; Kawakatu, N. ^[4]; Akiyama, M. ^[5]; Miyaji, T. ^[6]

---

1. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
2. Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan)
3. Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)
4. Faculty of Natural Sciences, National Institute of Technology, Kure College, 2-2-11 Agaminami, Kure, Hiroshima 737-8506 (Japan)
5. Astronomical Institute, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai 980-8578 (Japan)
6. Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada, Baja California (Mexico)

We present the result of our spectroscopic follow-up observation for faint quasar candidates at z ∼ 5 in part of the Canada–France–Hawaii Telescope Legacy Survey wide field. We select nine photometric candidates and identify three z ∼ 5 faint quasars, one z ∼ 4 faint quasar, and a late-type star. Since two faint quasar spectra show the C iv emission line without suffering from a heavy atmospheric absorption, we estimate their black hole masses (M{sub BH}) and Eddington ratios (L/L{sub Edd}). The inferred logM{sub BH} are 9.04 ± 0.14 and 8.53 ± 0.20, respectively. In addition, the inferred log(L/L{sub Edd}) are −1.00 ± 0.15 and −0.42 ± 0.22, respectively. If we adopt that L/L{sub Edd}=constant or∝(1+z){sup 2}, the seed black hole masses (M{sub seed}) of our z ∼ 5 faint quasars are expected to be >10{sup 5} M{sub ⊙} in most cases. We also compare the observational results with a mass accretion model, where angular momentum is lost due to supernova explosions. Accordingly, M{sub BH} of the z ∼ 5 faint quasars in our sample can be explained even if M{sub seed} is ∼10{sup 3} M{sub ⊙}. Since z ∼ 6 luminous qusars and our z ∼ 5 faint quasars are not on the same evolutionary track, z ∼ 6 luminous quasars and our z ∼ 5 quasars are not the same populations but different populations, due to the difference of a period of the mass supply from host galaxies. Furthermore, we confirm that one can explain M{sub BH} of z ∼ 6 luminous quasars and our z ∼ 5 faint quasars even if their seed black holes are formed at z ∼ 7.

• OSTI ID: 22875851
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 846; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ANGULAR MOMENTUM
BLACK HOLES
COMPARATIVE EVALUATIONS
COSMOLOGY
EMISSION
GALAXIES
MASS
QUASARS
SPECTRA
STARS
TELESCOPES