Abstract
We present luminosity functions (LFs) and angular correlation functions (ACFs) derived from 18,960 Lyα emitters (LAEs) at z = 2.2−7.3 over a wide survey area of ≲24 deg2 that are identified in the narrowband data of the HSC-SSP and CHORUS surveys. Confirming the large sample with 241 spectroscopically identified LAEs, we determine Lyα LFs and ACFs in the brighter luminosity range down to 0.5L⋆, and confirm that our measurements are consistent with previous studies but offer significantly reduced statistical uncertainties. The improved precision of our ACFs allows us to clearly detect one-halo terms at some redshifts, and provides large-scale bias measurements that indicate host halo masses of ∼1011M⊙ over z ≃ 2−7. By comparing our Lyα LF (ACF) measurements with reionization models, we estimate the neutral hydrogen fractions in the intergalactic medium to be xH i < 0.05 (= 0.06 − 0.03 + 0.12 ) at z = 5.7 and xH i = 0.1 5 − 0.08 + 0.10 ( 0.21 − 0.14 + 0.19 ), 0.1 8 − 0.12 + 0.14 , and 0.7 5 − 0.13 + 0.09 at z = 6.6, 7.0, and 7.3, respectively. Our findings suggest that the neutral hydrogen fraction remains relatively low, xH i ≲ 0.2, at z = 5−7, but increases sharply at z > 7, reaching xH i ∼ 0.9 by z ≃ 8−9, as indicated by recent JWST studies. The combination of our results from LAE observations with recent JWST observations suggests that the major epoch of reionization occurred at z ∼ 7−8, likely driven by the emergence of massive sources emitting significant ionizing photons.
Recommended Citation
H. Umeda and M. Ouchi and S. Kikuta and Y. Harikane and Y. Ono and T. Shibuya and A. K. Inoue and K. Shimasaku and Y. Liang and A. Matsumoto and S. Saito and H. Kusakabe and Y. Kageura, "SILVERRUSH. XIV. Lyα Luminosity Functions and Angular Correlation Functions from 20,000 Lyα Emitters at Z ∼ 2.2-7.3 from up to 24 Deg2 HSC-SSP and CHORUS Surveys: Linking the Postreionization Epoch to the Heart of Reionization," Astrophysical Journal Supplement Series, vol. 277, no. 2, article no. 37, American Astronomical Society; IOP Publishing, Apr 2025.
The definitive version is available at https://doi.org/10.3847/1538-4365/adb1c0
Department(s)
Physics
Publication Status
Open Access
International Standard Serial Number (ISSN)
0067-0049
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2025 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
01 Apr 2025
Comments
National Astronomical Observatory of Japan, Grant 21H04467