Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XVI. 69 New Quasars at 5.8 < z < 7.0
Yoshiki Matsuoka, K. Iwasawa, Masafusa Onoue, Takuma Izumi, Nobunari Kashikawa, Michael A. Strauss, Masatoshi Imanishi, Tohru Nagao, Masayuki Akiyama, J. D. Silverman, Naoko Asami, James Bosch, Hisanori Furusawa, Tomotsugu Goto, James E. Gunn, Yuichi Harikane, Hiroyuki Ikeda, Rikako Ishimoto, Toshihiro Kawaguchi, N. Kato, Satoshi Kikuta, Kotaro Kohno, Yutaka Komiyama, Chien‐Hsiu Lee, Robert H. Lupton, Takeo Minezaki, Satoshi Miyazaki, Hitoshi Murayama, Atsushi J. Nishizawa, Masamune Oguri, Yoshiaki Ono, Masami Ouchi, P. A. Price, Hiroaki Sameshima, Naoshi Sugiyama, Philip J. Tait, Masahiro Takada, Ayumi Takahashi, Tadafumi Takata, Masayuki Tanaka, Yoshiki Toba, Yousuke Utsumi, Shiang‐Yu Wang, Takuji Yamashita
Abstract
Abstract We present the spectroscopic discovery of 69 quasars at 5.8 < z < 7.0, drawn from the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) imaging survey data. This is the 16th publication from the Subaru High- z Exploration of Low-Luminosity Quasars (SHELLQs) project, and it completes identification of all but the faintest candidates (i.e., i -band dropouts with z AB < 24 and y -band detections, and z -band dropouts with y AB < 24) with Bayesian quasar probability <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>P</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Q</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>></mml:mo> <mml:mn>0.1</mml:mn> </mml:math> in the HSC-SSP third public data release (PDR3). The sample reported here also includes three quasars with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>P</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Q</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo><</mml:mo> <mml:mn>0.1</mml:mn> </mml:math> at z ∼ 6.6, which we selected in an effort to completely cover the reddest point sources with simple color cuts. The number of high- z quasars discovered in SHELLQs has now grown to 162, including 23 type II quasar candidates. This paper also presents identification of seven galaxies at 5.6 < z < 6.7, an [O iii ] emitter at z = 0.954, and 31 Galactic cool stars and brown dwarfs. High- z quasars and galaxies compose 75% and 16%, respectively, of all the spectroscopic SHELLQs objects that pass our latest selection algorithm with the PDR3 photometry. That is, a total of 91% of the objects lie at z > 5.6. This demonstrates that the algorithm has very high efficiency, even though we are probing an unprecedentedly low luminosity population down to M 1450 ∼ −21 mag.