The Faint End of the Quasar Luminosity Function at z ∼ 5 from the Subaru Hyper Suprime-Cam Survey

Mana Niida, Tohru Nagao, Hiroyuki Ikeda, Masayuki Akiyama, Yoshiki Matsuoka, Wanqiu He, Kenta Matsuoka, Yoshiki Toba, Masafusa Onoue, Masakazu A.R. Kobayashi, Yoshiaki Taniguchi, Hisanori Furusawa, Yuichi Harikane, Masatoshi Imanishi, Nobunari Kashikawa, Toshihiro Kawaguchi, Yutaka Komiyama, Hikari Shirakata, Yuichi Terashima, Yoshihiro Ueda

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1 Citation (Scopus)

Abstract

We present the quasar luminosity function at z ∼ 5 derived from the optical wide-field survey data obtained as a part of the Subaru strategic program (SSP) with the Hyper Suprime-Cam (HSC). From a ∼81.8 deg2 area in the Wide layer of the HSC-SSP survey, we selected 224 candidates of low-luminosity quasars at z ∼ 5 by adopting the Lyman-break method down to i = 24.1 mag. Based on our candidates and spectroscopically confirmed quasars from the Sloan Digital Sky Survey (SDSS), we derived the quasar luminosity function at z ∼ 5, covering a wide luminosity range of-28.76 < M 1450 <-22.32 mag. We found that the quasar luminosity function is fitted by a double power-law model with a break magnitude of mag. The inferred number density of low-luminosity quasars is lower, and the derived faint-end slope, is flatter than those of previous studies at z ∼ 5. A compilation of the quasar luminosity function at 4 ≤ z ≤ 6 from the HSC-SSP suggests that there is little redshift evolution in the break magnitude and in the faint-end slope within this redshift range, although previous studies suggest that the faint-end slope becomes steeper at higher redshifts. The number density of low-luminosity quasars decreases more rapidly from z ∼ 5 to z ∼ 6 than from z ∼ 4 to z ∼ 5.

Original languageEnglish
Article number89
JournalAstrophysical Journal
Volume904
Issue number2
DOIs
Publication statusPublished - 2020 Dec 1

Keywords

  • Active galaxies (17)
  • Luminosity function (942)
  • Quasars (1319)
  • Supermassive black holes (1663)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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