We present Lyα luminosity function (LF), clustering measurements, and Lyα line profiles based on the largest sample, to date, of 207 Lyα emitters (LAEs) at z = 6.6 on the 1-deg 2 sky of Subaru/XMM-Newton Deep Survey (SXDS) field. Our z = 6.6 Lyα LF including cosmic variance estimates yields the best-fit Schechter parameters of φ * = 8.5 +3.0 −2.2 × 10 −4 Mpc −3 and L * Lyα = 4.4 +0.6 −0.6 × 10 42 erg s −1 with a fixed α = −1.5, and indicates a decrease from z = 5.7 at the 90% confidence level. However, this decrease is not large, only ≃ 30% in Lyα luminosity, which is too small to be 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 −1 100 Mpc and 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 ⊙ , and duty cycle of LAE population is roughly ∼ 1% albeit with large uncertainties. The average of our high-quality Keck/DEIMOS spectra shows an FWHM velocity width of 251 ± 16km s −1 . We find no large evolution of Lyα line profile from z = 5.7 to 6.6, and no anti-correlation between Lyα 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 IGM's Lyα 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 7.

Subaru Deep Field line-emitting galaxies in four narrow-band filters (NB704, NB711, NB816, and NB921) at low and intermediate redshifts are presented. Broad-band colors, follow-up optical spectroscopy, and multiple narrow-band filters are used to distinguish Hα, [O ii], and [O iii] emitters between redshifts of 0.07 and 1.47 to construct their averaged rest-frame optical-to-UV spectral energy distributions and luminosity functions. These luminosity functions are derived down to faint magnitudes, which allows for a more accurate determination of the faint end slope. With a large (N ∼ 200 to 900) sample for each redshift interval, a Schechter profile is fitted to each luminosity function. Prior to dust extinction corrections, the [O iii] and [O ii] luminosity functions reported in this paper agree reasonably well with those of Hippelein et al. The z = 0.08 Hα LF, which reaches two orders of magnitude fainter than Gallego et al., is steeper by 25%. This indicates that there are more low luminosity star-forming galaxies for z < 0.1. The faint end slope α and φ ⋆ show a strong evolution with redshift while L ⋆ show little evolution. The evolution in α indicates that low-luminosity galaxies have a stronger evolution compared to brighter ones. These results can only be achieved with deep NB observations over a wide range in redshift. Integrated star formation rate densities are derived via Hα for 0.07 < z < 0.40, [O iii] for 0.40 < z < 0.84, and [O ii] for 0.89 < z < 1.47. A steep increase in the star-formation rate density, as a function of redshift, is seen for 0.4 z 0.9. For z 1, the star-formation rate densities are more or less constant. The latter is consistent with previous UV and [O ii] measurements. Below z 0.4, the SFR densities are consistent with several Hα, [O ii], and UV measurements, but other measurements are a factor of two higher. For example, the z = 0.066 − 0.092 Hα LF agrees with those of Jones & Bland-Hawthorn, but at z = 0.24 and 0.40, their number density is higher by a factor of two. This discrepancy can be explained by cosmic variance.

Using deep infrared observations conducted with the MOIRCS imager on the Subaru Telescope in the northern GOODS field combined with public surveys in GOODS-S, we investigate the dependence on stellar mass, M * , and galaxy type of the close pair fraction (5 h −1 kpc < r sep < 20 h −1 kpc) and implied merger rate. In terms of combined depth and survey area, our publicly available mass-limited sample represents a significant improvement over earlier infrared surveys used for this purpose. In common with some recent studies, we find that the fraction of paired systems that could result in major mergers is low (∼4%) and does not increase significantly with redshift to z ≈ 1.2, with ∝ (1 + z)1.6±1.6 . Our key finding is that massive galaxies with M * > 10 11 M are more likely to host merging companions than less massive systems (M * ∼ 10 10 M ). We find evidence for a higher pair fraction for red, spheroidal hosts compared to blue, late-type systems, in line with expectations based on clustering at small scales. The so-called "dry" mergers between early-type galaxies devoid of star formation (SF) represent nearly 50% of close pairs with M * > 3 × 10 10 M at z ∼ 0.5, but less than 30% at z ∼ 1. This result can be explained by the increasing abundance of red, early-type galaxies at these masses. We compare the volumetric merger rate of galaxies with different masses to mass-dependent trends in galaxy evolution. Our results reaffirm the conclusion of Bundy et al. that major mergers do not fully account for the formation of spheroidal galaxies since z ∼ 1. In terms of mass assembly, major mergers contribute little to galaxy growth below M * ∼ 3 × 10 10 M but play a more significant role among galaxies with M * 10 11 M ∼ 30% of which have undergone mostly dry mergers over the observed redshift range. Overall, the relatively rapid and recent coalescence of high-mass galaxies mirrors the expected hierarchical growth of halos and is consistent with recent model predictions, even if the topdown suppression of SF and morphological evolution (i.e., "downsizing") involves additional physical processes.

We report the discovery of primeval large-scale structures (LSSs) including two protoclusters in a forming phase at . We carried out extensive deep narrowband imaging in the 1 deg 2 sky of the Subaru/XMM-Newton Deep z p 5.7 Field and obtained a cosmic map of 515 Lya emitters (LAEs) in a volume with a transverse dimension of and a depth of ∼40 Mpc in comoving units. This cosmic map shows filamentary LSSs, including 180 Mpc # 180 Mpc clusters and surrounding 10-40 Mpc scale voids, similar to the present-day LSSs. Our spectroscopic follow-up observations identify overdense regions in which two dense clumps of LAEs with a sphere of 1 Mpc diameter in physical units are included. These clumps show about 130 times higher star formation rate density, mainly due to a large overdensity, ∼80, of LAEs. These clumps would be clusters in a formation phase involving a burst of galaxy formation.

We discuss the environmental dependence of galaxy evolution based on deep panoramic imaging of two distant clusters, RX J0152.7–1357 at z= 0.83 and CL0016+1609 at z= 0.55, taken with the Subaru Prime Focus Camera on the Subaru Telescope as part of the Panoramic Imaging and Spectroscopy of Cluster Evolution with Subaru project. By combining with the Sloan Digital Sky Survey data as a local counterpart for comparison, we construct a large sample of galaxies that spans wide ranges in environment, time and stellar mass (or luminosity). This allows us to conduct systematic and statistical analyses of the photometric properties of galaxies based on the colour–density diagrams, colour–magnitude relations, and luminosity functions. We find that colours of galaxies, especially those of faint galaxies (MV > M*V+ 1), change from blue to red at a break density as we go to denser regions. This trend is observed at all redshifts in our sample. Based on local and global densities of galaxies, we classify three environments – field, groups and clusters – and look into the environmental dependence of galaxies in detail. In particular, we quantify how the colour–magnitude relation is built up as a function of environment. We show that the bright end of the cluster colour–magnitude relation is already built at z= 0.83, while the faint end is possibly still in the process of build‐up. In contrast to this, the bright end of the field colour–magnitude relation has been vigorously built all the way down to the present‐day and the build‐up at the faint end has not started yet. A possible interpretation of these results is that galaxies evolve in a ‘down‐sizing’ fashion. That is, massive galaxies complete their star formation first and the truncation of star formation is propagated to smaller objects as time progresses. This trend is likely to depend on environment since the build‐up of the colour–magnitude relation is delayed in lower density environments. Therefore, we may suggest that the evolution of galaxies took place earliest in massive galaxies and in high‐density regions, and it is delayed in less massive galaxies and in lower density regions. Further studies are, however, obviously needed to confirm the observed trends and establish the ‘down‐sizing’ picture.

We present luminosity functions (LFs) and various properties of Ly emitters (LAEs) at z ¼ 3:1, 3.7, and 5.7, in a 1 deg 2 sky of the Subaru /XMMÀNewton Deep Survey (SXDS) Field. We obtain a photometric sample of 858 LAE candidates based on deep Subaru Suprime-Cam imaging data and a spectroscopic sample of 84 confirmed LAEs from Subaru FOCAS and VLT VIMOS spectroscopy in a survey volume of $106 Mpc 3 with a limiting Ly luminosity of $3 ; 10 42 ergs s À1. We derive the LFs of the Ly and UV continuum ('1500 8) for each redshift, taking into account the statistical error and the field-to-field variation. We find that the apparent Ly LF shows no significant evolution between z ¼ 3:1 and 5.7 within factors of 1.8 and 2.7 in L à and à , respectively. On the other hand, the UV LF of LAEs increases from z ¼ 3:1 to 5.7, indicating that galaxies with Ly emission are more common at earlier epochs. We identify six LAEs with AGN activities from our spectra combined with VLA, Spitzer, and XMM-Newton data. Among the photometrically selected LAEs at z ¼ 3:1 and 3.7, only '1% show AGN activities, while the brightest LAEs with log L(Ly) k 43:4 43:6 ergs s À1 appear to always host AGNs. Our LAEs are bluer in UV-continuum color than dropout galaxies, suggesting lower extinction and/or younger stellar populations. Our stacking analyses provide upper limits to the radio luminosity and the f He ii /f Ly line fraction and constrain the hidden star formation (+low-luminosity AGN ) and the primordial population in LAEs.

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We report on an analysis of the gas and dust budget in the interstellar medium (ISM) of the Large Magellanic Cloud (LMC). Recent observations from the Spitzer Space Telescope enable us to study the mid‐infrared dust excess of asymptotic giant branch (AGB) stars in the LMC. This is the first time we can quantitatively assess the gas and dust input from AGB stars over a complete galaxy, fully based on observations. The integrated mass‐loss rate over all intermediate and high mass‐loss rate carbon‐rich AGB candidates in the LMC is 8.5 × 10−3 M⊙ yr−1, up to 2.1 × 10−2 M⊙ yr−1. This number could be increased up to 2.7 × 10−2 M⊙ yr−1 if oxygen‐rich stars are included. This is overall consistent with theoretical expectations, considering the star formation rate (SFR) when these low‐ and intermediate‐mass stars where formed, and the initial mass functions. AGB stars are one of the most important gas sources in the LMC, with supernovae (SNe), which produces about 2–4 × 10−2 M⊙ yr−1. At the moment, the SFR exceeds the gas feedback from AGB stars and SNe in the LMC, and the current star formation depends on gas already present in the ISM. This suggests that as the gas in the ISM is exhausted, the SFR will eventually decline in the LMC, unless gas is supplied externally. Our estimates suggest ‘a missing dust‐mass problem’ in the LMC, which is similarly found in high‐z galaxies: the accumulated dust mass from AGB stars and possibly SNe over the dust lifetime (400–800 Myr) is significant less than the dust mass in the ISM. Another dust source is required, possibly related to star‐forming regions.