Matsuoka, Y.Onoue, M.Iwasawa, KazushiStrauss, M.A.Kashikawa, N.Izumi, T.Nagao, T.Imanishi, M.Akiyama, M.Silverman, J.D.Asami, N.Bosch, J.Furusawa, H.Goto, T.Gunn, J.E.Harikane, Y.Ikeda, H.Inayoshi, K.Ishimoto, R.Kawaguchi, T.Kikuta, S.Kohno, K.Komiyama, Y.Lee C.-H.Lupton, R.H.Minezaki, T.Miyazaki, S.Murayama, H.Nishizawa, A.J.Oguri, M.Ono, Y.Oogi, T.Ouchi, M.Price, P.A.Sameshima, H.Sugiyama, N.Tait, P.J.Takada, M.Takahashi, A.Takata, T.Tanaka, M.Toba, Y.Wang, S.-Y.Yamashita, T.2025-01-312025-01-3120232041-8205https://hdl.handle.net/2445/218392We present the quasar luminosity function (LF) at z = 7, measured with 35 spectroscopically confirmed quasars at 6.55 < z < 7.15. The sample of 22 quasars from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, combined with 13 brighter quasars in the literature, covers an unprecedentedly wide range of rest-frame ultraviolet magnitudes over −28 < M1450 < −23. We found that the binned LF flattens significantly toward the faint end populated by the SHELLQs quasars. A maximum likelihood fit to a double power-law model has a break magnitude, a characteristic density Gpc−3 mag−1, and a bright-end slope, when the faint-end slope is fixed to α = −1.2 as observed at z ≤ 6. The overall LF shape remains remarkably similar from z = 4 to 7, while the amplitude decreases substantially toward higher redshifts, with a clear indication of an accelerating decline at z ≥ 6. The estimated ionizing photon density, 1048.2±0.1 s−1 Mpc−3, is less than 1% of the critical rate to keep the intergalactic medium ionized at z = 7, and thus indicates that quasars are not a major contributor to cosmic reionization.1 p.application/pdfeng(c) American Astronomical Society, 2023GalàxiesQuàsarsGalaxiesQuasarsinfo:eu-repo/semantics/article7538982025-01-31info:eu-repo/semantics/openAccess