2017ApJ...846...57I -
Astrophys. J., 846, 57-57 (2017/September-1)
An optically faint quasar Survey at z ∼ 5 in the CFHTLS wide field: estimates of the black hole masses and Eddington ratios.
IKEDA H., NAGAO T., MATSUOKA K., KAWAKATU N., KAJISAWA M., AKIYAMA M., MIYAJI T. and MOROKUMA T.
Abstract (from CDS):
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 (MBH) and Eddington ratios (L/LEdd). The inferred logMBH are 9.04 ± 0.14 and 8.53 ± 0.20, respectively. In addition, the inferred log(L/LEdd) are -1.00 ± 0.15 and -0.42 ± 0.22, respectively. If we adopt that L/LEdd=constant or∝(1+z)2, the seed black hole masses (Mseed) of our z ∼ 5 faint quasars are expected to be 105 M☉ in most cases. We also compare the observational results with a mass accretion model, where angular momentum is lost due to supernova explosions. Accordingly, MBH of the z ∼ 5 faint quasars in our sample can be explained even if Mseed is ∼103 M☉. 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 MBH of z ∼ 6 luminous quasars and our z ∼ 5 faint quasars even if their seed black holes are formed at z ∼ 7.
Abstract Copyright:
© 2017. The American Astronomical Society. All rights reserved.
Journal keyword(s):
cosmology: observations - quasars: supermassive black holes - surveys - surveys
Simbad objects:
11
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