Quasar Luminosity Function at z = 7

Yoshiki Matsuoka; Masafusa Onoue; Kazushi Iwasawa; Michael A. Strauss; Nobunari Kashikawa; Takuma Izumi; Tohru Nagao; Masatoshi Imanishi; Masayuki Akiyama; John D. Silverman; Naoko Asami; James Bosch; Hisanori Furusawa; Tomotsugu Goto; James E. Gunn; Yuichi Harikane; Hiroyuki Ikeda; Kohei Inayoshi; Rikako Ishimoto; Toshihiro Kawaguchi; 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; Taira Oogi; Masami Ouchi; Paul A. Price; Hiroaki Sameshima; Naoshi Sugiyama; Philip J. Tait; Masahiro Takada; Ayumi Takahashi; Tadafumi Takata; Masayuki Tanaka; Yoshiki Toba; Shiang Yu Wang; Takuji Yamashita

doi:10.3847/2041-8213/acd69f

Quasar Luminosity Function at z = 7

Yoshiki Matsuoka, Masafusa Onoue, Kazushi Iwasawa, Michael A. Strauss, Nobunari Kashikawa, Takuma Izumi, Tohru Nagao, Masatoshi Imanishi, Masayuki Akiyama, John D. Silverman, Naoko Asami, James Bosch, Hisanori Furusawa, Tomotsugu Goto, James E. Gunn, Yuichi Harikane, Hiroyuki Ikeda, Kohei Inayoshi, Rikako Ishimoto, Toshihiro KawaguchiSatoshi Kikuta, Kotaro Kohno, Yutaka Komiyama, Chien Hsiu Lee, Robert H. Lupton, Takeo Minezaki, Satoshi Miyazaki, Hitoshi Murayama, Atsushi J. Nishizawa, Masamune Oguri, Yoshiaki Ono, Taira Oogi, Masami Ouchi, Paul A. Price, Hiroaki Sameshima, Naoshi Sugiyama, Philip J. Tait, Masahiro Takada, Ayumi Takahashi, Tadafumi Takata, Masayuki Tanaka, Yoshiki Toba, Shiang Yu Wang, Takuji Yamashita

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Abstract

We 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 < M 1450 < -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 M1450∗=-25.60-0.30+0.40, a characteristic density φ∗=1.35-0.30+0.47 Gpc-3 mag-1, and a bright-end slope β=-3.34-0.57+0.49, 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.

Original language	English (US)
Article number	L42
Journal	Astrophysical Journal Letters
Volume	949
Issue number	2
DOIs	https://doi.org/10.3847/2041-8213/acd69f
State	Published - Jun 1 2023

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/2041-8213/acd69f

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Matsuoka, Y., Onoue, M., Iwasawa, K., Strauss, 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., ... Yamashita, T. (2023). Quasar Luminosity Function at z = 7. Astrophysical Journal Letters, 949(2), Article L42. https://doi.org/10.3847/2041-8213/acd69f

@article{7d67c9138be5451f914d7b93865994c5,

title = "Quasar Luminosity Function at z = 7",

abstract = "We 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 < M 1450 < -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 M1450∗=-25.60-0.30+0.40, a characteristic density φ∗=1.35-0.30+0.47 Gpc-3 mag-1, and a bright-end slope β=-3.34-0.57+0.49, 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.",

author = "Yoshiki Matsuoka and Masafusa Onoue and Kazushi Iwasawa and Strauss, {Michael A.} and Nobunari Kashikawa and Takuma Izumi and Tohru Nagao and Masatoshi Imanishi and Masayuki Akiyama and Silverman, {John D.} and Naoko Asami and James Bosch and Hisanori Furusawa and Tomotsugu Goto and Gunn, {James E.} and Yuichi Harikane and Hiroyuki Ikeda and Kohei Inayoshi and Rikako Ishimoto and Toshihiro Kawaguchi and Satoshi Kikuta and Kotaro Kohno and Yutaka Komiyama and Lee, {Chien Hsiu} and Lupton, {Robert H.} and Takeo Minezaki and Satoshi Miyazaki and Hitoshi Murayama and Nishizawa, {Atsushi J.} and Masamune Oguri and Yoshiaki Ono and Taira Oogi and Masami Ouchi and Price, {Paul A.} and Hiroaki Sameshima and Naoshi Sugiyama and Tait, {Philip J.} and Masahiro Takada and Ayumi Takahashi and Tadafumi Takata and Masayuki Tanaka and Yoshiki Toba and Wang, {Shiang Yu} and Takuji Yamashita",

note = "Publisher Copyright: {\textcopyright} 2023. The Author(s). Published by the American Astronomical Society.",

year = "2023",

month = jun,

day = "1",

doi = "10.3847/2041-8213/acd69f",

language = "English (US)",

volume = "949",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "IOP Publishing Ltd.",

number = "2",

}

Matsuoka, Y, Onoue, M, Iwasawa, K, Strauss, MA, Kashikawa, N, Izumi, T, Nagao, T, Imanishi, M, Akiyama, M, Silverman, JD, Asami, N, Bosch, J, Furusawa, H, Goto, T, Gunn, JE, Harikane, Y, Ikeda, H, Inayoshi, K, Ishimoto, R, Kawaguchi, T, Kikuta, S, Kohno, K, Komiyama, Y, Lee, CH, Lupton, RH, Minezaki, T, Miyazaki, S, Murayama, H, Nishizawa, AJ, Oguri, M, Ono, Y, Oogi, T, Ouchi, M, Price, PA, Sameshima, H, Sugiyama, N, Tait, PJ, Takada, M, Takahashi, A, Takata, T, Tanaka, M, Toba, Y, Wang, SY & Yamashita, T 2023, 'Quasar Luminosity Function at z = 7', Astrophysical Journal Letters, vol. 949, no. 2, L42. https://doi.org/10.3847/2041-8213/acd69f

TY - JOUR

T1 - Quasar Luminosity Function at z = 7

AU - Matsuoka, Yoshiki

AU - Onoue, Masafusa

AU - Iwasawa, Kazushi

AU - Strauss, Michael A.

AU - Kashikawa, Nobunari

AU - Izumi, Takuma

AU - Nagao, Tohru

AU - Imanishi, Masatoshi

AU - Akiyama, Masayuki

AU - Silverman, John D.

AU - Asami, Naoko

AU - Bosch, James

AU - Furusawa, Hisanori

AU - Goto, Tomotsugu

AU - Gunn, James E.

AU - Harikane, Yuichi

AU - Ikeda, Hiroyuki

AU - Inayoshi, Kohei

AU - Ishimoto, Rikako

AU - Kawaguchi, Toshihiro

AU - Kikuta, Satoshi

AU - Kohno, Kotaro

AU - Komiyama, Yutaka

AU - Lee, Chien Hsiu

AU - Lupton, Robert H.

AU - Minezaki, Takeo

AU - Miyazaki, Satoshi

AU - Murayama, Hitoshi

AU - Nishizawa, Atsushi J.

AU - Oguri, Masamune

AU - Ono, Yoshiaki

AU - Oogi, Taira

AU - Ouchi, Masami

AU - Price, Paul A.

AU - Sameshima, Hiroaki

AU - Sugiyama, Naoshi

AU - Tait, Philip J.

AU - Takada, Masahiro

AU - Takahashi, Ayumi

AU - Takata, Tadafumi

AU - Tanaka, Masayuki

AU - Toba, Yoshiki

AU - Wang, Shiang Yu

AU - Yamashita, Takuji

PY - 2023/6/1

Y1 - 2023/6/1

N2 - We 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 < M 1450 < -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 M1450∗=-25.60-0.30+0.40, a characteristic density φ∗=1.35-0.30+0.47 Gpc-3 mag-1, and a bright-end slope β=-3.34-0.57+0.49, 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.

AB - We 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 < M 1450 < -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 M1450∗=-25.60-0.30+0.40, a characteristic density φ∗=1.35-0.30+0.47 Gpc-3 mag-1, and a bright-end slope β=-3.34-0.57+0.49, 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.

UR - http://www.scopus.com/inward/record.url?scp=85164014496&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85164014496&partnerID=8YFLogxK

U2 - 10.3847/2041-8213/acd69f

DO - 10.3847/2041-8213/acd69f

M3 - Article

AN - SCOPUS:85164014496

SN - 2041-8205

VL - 949

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L42

ER -

Quasar Luminosity Function at z = 7

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