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Abstract We present luminosity functions (LFs) and angular correlation functions (ACFs) derived from 18,960 Lyαemitters (LAEs) atz = 2.2−7.3 over a wide survey area of ≲24 deg²that are identified in the narrowband data of the HSC-SSP and CHORUS surveys. Confirming the large sample with 241 spectroscopically identified LAEs, we determine LyαLFs 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_⊙overz ≃ 2−7. By comparing our LyαLF (ACF) measurements with reionization models, we estimate the neutral hydrogen fractions in the intergalactic medium to bex_Hi < 0.05 (= ${0.06}_{-0.03}^{+0.12}$) atz= 5.7 andx_Hi= $0.15_{-0.08}^{+0.10}$( ${0.21}_{-0.14}^{+0.19}$), $0.18_{-0.12}^{+0.14}$, and $0.75_{-0.13}^{+0.09}$atz= 6.6, 7.0, and 7.3, respectively. Our findings suggest that the neutral hydrogen fraction remains relatively low,x_Hi ≲ 0.2, atz = 5−7, but increases sharply atz > 7, reachingx_Hi ∼ 0.9 byz ≃ 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 atz ∼ 7−8, likely driven by the emergence of massive sources emitting significant ionizing photons. 

Abstract We present spatially resolved morphological properties of [CII] 158μm, [OIII] 88μm, dust, and rest-frame ultraviolet (UV) continuum emission for A1689-zD1, a strongly lensed, sub-L* galaxy atz= 7.13, by utilizing deep Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope (HST) observations. While the [OIII] line and UV continuum are compact, the [CII] line is extended up to a radius ofr∼ 12 kpc. Using multi-band rest-frame far-infrared continuum data ranging from 52 to 400μm, we find an average dust temperature and emissivity index of $T_{\mathrm{dust}}={41}_{-14}^{+17}$K and $\beta ={1.7}_{-0.7}^{+1.1}$, respectively, across the galaxy. We find slight differences in the dust continuum profiles at different wavelengths, which may indicate that the dust temperature decreases with distance. We map the star formation rate (SFR) via IR and UV luminosities and determine a total SFR of 37 ± 1M_⊙yr⁻¹with an obscured fraction of 87%. While the [OIII] line is a good tracer of the SFR, the [CII] line shows deviation from the localL_[CII]-SFR relations in the outskirts of the galaxy. Finally, we observe a clear difference in the line profile between [CII] and [OIII], with significant residuals (∼5σ) in the [OIII] line spectrum after subtracting a single Gaussian model. This suggests a possible origin of the extended [CII] structure from the cooling of hot ionized outflows. The extended [CII] and high-velocity [OIII] emission may both contribute in part to the highL_[OIII]/L_[CII]ratios recently reported inz> 6 galaxies. 

Abstract We  present the demography of the dynamics and gas mass fraction of 33 extremely metal-poor galaxies (EMPGs) with metallicities of 0.015–0.195Z_⊙and low stellar masses of 10⁴–10⁸M_⊙in the local universe. We conduct deep optical integral field spectroscopy (IFS) for the low-mass EMPGs with the medium-high resolution (R= 7500) grism of the 8 m Subaru FOCAS IFU instrument by the EMPRESS 3D survey, and investigate the Hαemission of the EMPGs. Exploiting the resolution high enough for the low-mass galaxies, we derive gas dynamics with the Hαlines by the fitting of three-dimensional disk models. We obtain an average maximum rotation velocity (v_rot) of 15 ± 3 km s⁻¹and an average intrinsic velocity dispersion (σ₀) of 27 ± 10 km s⁻¹for 15 spatially resolved EMPGs out of 33 EMPGs, and find that all 15 EMPGs havev_rot/σ₀< 1 suggesting dispersion-dominated systems. There is a clear decreasing trend ofv_rot/σ₀with the decreasing stellar mass and metallicity. We derive the gas mass fraction (f_gas) for all 33 EMPGs, and find no clear dependence on stellar mass and metallicity. Thesev_rot/σ₀andf_gastrends should be compared with young high-zgalaxies observed by the forthcoming JWST IFS programs to understand the physical origins of the EMPGs in the local universe. 

Abstract We present kinematics of six local extremely metal-poor galaxies (EMPGs) with low metallicities (0.016–0.098Z_⊙) and low stellar masses (10^4.7–10^7.6M_⊙). Taking deep medium/high-resolution (R∼ 7500) integral-field spectra with 8.2 m Subaru, we resolve the small inner velocity gradients and dispersions of the EMPGs with Hαemission. Carefully masking out substructures originating by inflow and/or outflow, we fit three-dimensional disk models to the observed Hαflux, velocity, and velocity dispersion maps. All the EMPGs show rotational velocities (v_rot) of 5–23 km s⁻¹smaller than the velocity dispersions (σ₀) of 17–31 km s⁻¹, indicating dispersion-dominated (v_rot/σ₀= 0.29–0.80 < 1) systems affected by inflow and/or outflow. Except for two EMPGs with large uncertainties, we find that the EMPGs have very large gas-mass fractions off_gas≃ 0.9–1.0. Comparing our results with other Hαkinematics studies, we find thatv_rot/σ₀decreases andf_gasincreases with decreasing metallicity, decreasing stellar mass, and increasing specific star formation rate. We also find that simulated high-z(z∼ 7) forming galaxies have gas fractions and dynamics similar to the observed EMPGs. Our EMPG observations and the simulations suggest that primordial galaxies are gas-rich dispersion-dominated systems, which would be identified by the forthcoming James Webb Space Telescope observations atz∼ 7.