The quasar luminosity function at redshift 4 with the Hyper Suprime-Cam Wide Survey

PASJ: Publications of the Astronomical Society of Japan

He, Wanqiu¹  Akiyama, Masayuki¹  Ono, Yoshiaki²  Terashima, Yuichi²  Lee, Chien-Hsiu²  Coupon, Jean³  Bosch, James⁴  Kawaguchi, Toshihiro⁵  Niida, Mana⁶  Schulze, Andreas⁷  Enoki, Motohiro⁸  Onoue, Masafusa⁹  Tanaka, Manobu M^1,10  Ueda, Yoshihiro^1,10  Toba, Yoshiki^1,11  Silverman, John D^1,11  Miyazaki, Satoshi^1,12  Tanaka, Masayuki^1,12  Kashikawa, Nobunari^1,12  Oguri, Masamune^1,12  Imanishi, Masatoshi^1,12  Komiyama, Yutaka^1,12  Ikeda, Hiroyuki^1,12  Nishizawa, Atsushi J^1,13  Nagao, Tohru^1,13  Ouchi, Masami^1,14  Matsuoka, Yoshiki^1,15 

[1] Astronomical Institute, Tohoku University, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan;Department of Astronomical Science, Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;Department of Astronomy, University of Geneva, ch. dÉcogia 16, 1290 Versoix, Switzerland;Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA;Department of Economics, Management and Information Science, Onomichi City University, Hisayamada 1600-2, Onomichi, Hiroshima 722-8506, Japan;Department of Physics, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan;Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033;Faculty of Business Administration, Tokyo Keizai University, 1-7-34 Minami-cho, Kokubunji, Tokyo 185-8502, Japan;Institute for Advanced Research, Nagoya University, Furocho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan;Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582;Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan;National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;Research Center for Space and Cosmic Evolution, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan;Research Center for the Early Universe, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan;Subaru Telescope, National Astronomical Observatory of Japan, 650 N. A’ohoku Pl., Hilo, HI 96720, USA

关键词: galaxies: active;    (galaxies:) quasars: general;    surveys;   

DOI  :  10.1093/pasj/psx091

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We present the luminosity function of z ∼ 4 quasars based on the Hyper Suprime-Cam Subaru Strategic Program Wide layer imaging data in the g, r, i, z, and y bands covering 339.8 deg2. From stellar objects, 1666 z ∼ 4 quasar candidates are selected via the g-dropout selection down to i = 24.0 mag. Their photometric redshifts cover the redshift range between 3.6 and 4.3, with an average of 3.9. In combination with the quasar sample from the Sloan Digital Sky Survey in the same redshift range, a quasar luminosity function covering the wide luminosity range of M1450 = −22 to −29 mag is constructed. The quasar luminosity function is well described by a double power-law model with a knee at M1450 = −25.36 ± 0.13 mag and a flat faint-end slope with a power-law index of −1.30 ± 0.05. The knee and faint-end slope show no clear evidence of redshift evolution from those seen at z ∼ 2. The flat slope implies that the UV luminosity density of the quasar population is dominated by the quasars around the knee, and does not support the steeper faint-end slope at higher redshifts reported at z > 5. If we convert the M1450 luminosity function to the hard X-ray 2–10 keV luminosity function using the relation between the UV and X-ray luminosity of quasars and its scatter, the number density of UV-selected quasars matches well with that of the X-ray-selected active galactic nuclei (AGNs) above the knee of the luminosity function. Below the knee, the UV-selected quasars show a deficiency compared to the hard X-ray luminosity function. The deficiency can be explained by the lack of obscured AGNs among the UV-selected quasars.

【 授权许可】

CC BY