Journal
ASTROPHYSICAL JOURNAL
Volume 723, Issue 1, Pages 869-894Publisher
IOP Publishing Ltd
DOI: 10.1088/0004-637X/723/1/869
Keywords
cosmology: observations; dark ages, reionization, first stars; galaxies: formation; galaxies: high-redshift; galaxies: luminosity function, mass function
Categories
Funding
- Carnegie Fellowship
- Science and Technology Facilities Council [PP/E001149/1, ST/H002391/1] Funding Source: researchfish
- STFC [ST/H002391/1, PP/E001149/1] Funding Source: UKRI
- Grants-in-Aid for Scientific Research [19104004] Funding Source: KAKEN
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We present the Ly alpha luminosity function (LF), clustering measurements, and Ly alpha line profiles based on the largest sample to date of 207 Ly alpha emitters (LAEs) at z = 6.6 on the 1 deg(2) sky of Subaru/XMM-Newton Deep Survey field. Our z = 6.6 Ly alpha LF including cosmic variance estimates yields the best-fit Schechter parameters of phi* = 8.5(-2.2)(+3.0) x 10(-4) Mpc(-3) and L*(Ly alpha) = 4.4(-0.6)(+0.6) x 10(42) erg s(-1) with a fixed alpha = -1.5, and indicates a decrease from z = 5.7 at the greater than or similar to 90% confidence level. However, this decrease is not large, only similar or equal to 30% in Ly alpha luminosity, which is too small to have been identified in the previous studies. A clustering signal of z = 6.6 LAEs is detected for the first time. We obtain the correlation length of r(0) = 2-5 h(100)(-1) Mpc and a bias of b = 3-6, and find no significant boost of clustering amplitude by reionization at z = 6.6. The average hosting dark halo mass inferred from clustering is 10(10)-10(11) M-circle dot, and a duty cycle of LAE population is roughly similar to 1%, albeit with large uncertainties. The average of our high-quality Keck/DEIMOS spectra shows an FWHM velocity width of 251 +/- 16 km s(-1). We find no large evolution of the Ly alpha line profile from z = 5.7 to 6.6, and no anti-correlation between Ly alpha luminosity and line width at z = 6.6. The combination of various reionization models and our observational results about the LF, clustering, and line profile indicates that there would exist a small decrease of the intergalactic medium's (IGM's) Ly alpha transmission owing to reionization, but that the hydrogen IGM is not highly neutral at z = 6.6. Our neutral-hydrogen fraction constraint implies that the major reionization process took place at z greater than or similar to 7.
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