Census of Lyα Emission from ∼600 Galaxies at z = 5–14: Evolution of the Lyα Luminosity Function and a Late Sharp Cosmic Reionization
We present the statistical properties of Ly α emission in 586 galaxies at z = 4.5–14.2, observed by multiple JWST/NIRSpec spectroscopy projects, including the JADES, GLASS, CEERS, and GO/DDT programs. We obtain Ly α equivalent width (EW), Ly α escape fraction, and ionizing photon production efficie...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Supplement Series |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4365/adc690 |
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| Summary: | We present the statistical properties of Ly α emission in 586 galaxies at z = 4.5–14.2, observed by multiple JWST/NIRSpec spectroscopy projects, including the JADES, GLASS, CEERS, and GO/DDT programs. We obtain Ly α equivalent width (EW), Ly α escape fraction, and ionizing photon production efficiency measurements or upper limits for these galaxies, and confirm that the Ly α -emitting galaxy fraction decreases toward higher redshifts. We derive Ly α luminosity functions from z ∼ 5 to z ∼ 10–14 with the observed Ly α EW distributions and galaxy UV luminosity functions, and find an ∼3 dex decrease in number density at L _Ly _α = 10 ^42 –10 ^43 erg s ^−1 over the redshift range. Notably, this study presents the first constraints on the Ly α luminosity function at z ∼ 8–14. We obtain the neutral hydrogen fractions of ${x}_{{\rm{H}}\,{\rm\small{I}}}=0.1{7}_{-0.16}^{+0.23}$ , $0.6{3}_{-0.28}^{+0.18}$ , $0.7{9}_{-0.21}^{+0.13}$ , and $0.8{8}_{-0.13}^{+0.11}$ at z ∼ 6, 7, 8–9, and 10–14, respectively, via comparisons of the reionization models developed by seminumerical simulations with 21cmFAST explaining the observations of Ly α , UV continuum, and Planck electron optical depth. The high x _H I values over z ∼ 7–14 suggest a late and sharp reionization, with the primary reionization process occurring at z ∼ 6–7. Such a late and sharp reionization is not easily explained by either a clumpy intergalactic medium or sources of reionization in a classical faint-galaxy or a bright-galaxy/active galactic nucleus (AGN) scenario, unless a very high escape fraction or AGN duty cycle is assumed at z ∼ 6–7. |
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| ISSN: | 0067-0049 |