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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/218392
Quasar Luminosity Function at z = 7
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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 < 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.
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MATSUOKA, Y., et al. Quasar Luminosity Function at z = 7. Astrophysical Journal Letters. 2023. ISSN 2041-8205. [consulted: 9 of October of 2026]. Available at: https://hdl.handle.net/2445/218392