We report fourteen and twenty-eight protocluster candidates at z = 5.7 and 6.6 over 14 and 19 deg2 areas, respectively, selected from 2,230 Lyα emitters (LAEs) photometrically identified with Subaru/Hyper Suprime-Cam (HSC) deep images. Six out of the 42 protocluster candidates include at least 1 spectroscopically confirmed LAEs at redshifts up to z = 6.574. By the comparisons with the cosmological Lyα radiative transfer (RT) model reproducing LAEs with the reionization effects, we find that more than a half of these protocluster candidates might be progenitors of the present-day clusters with a mass of ≳ 1014M⊙. We also investigate the correlation between LAE overdensity and Lya rest-frame equivalent width (EW), because the cosmological Lyα RT model suggests that a slope of EW-overdensity relation is steepened towards the epoch of cosmic reionization (EoR), due to the existence of the ionized bubbles around galaxy overdensities easing the escape of Lyα emission from the partly neutral intergalactic medium. The available HSC data suggest that the slope of the EW-overdensity correlation does not evolve from the post-reionization epoch z = 5.7 to the EoR z = 6.6 beyond the moderately large statistical errors.

Recently the bar model for our Galaxy has been an emerging consensus. Here, we investigate how a rotating bar-like bulge affects the global gas dynamics in a disk and compare the longitude-velocity (LV) maps from self-gravitating hydrodynamical simulations, which is based on Wada and Habe (1992), with observed maps of neutral hydrogen and carbon monoxide in the Galaxy. We found that the features on the numerical LV maps depend strongly on four factors: the pattern speed of the bar, the position angle of the Sun, the strength of the bar potential and the ratio of the gas mass to total dynamical mass. We conclude that our Galaxy has a rotating, weak, bar-like bulge (a/b ∼ 0.7) observed from nearly end on (θp < 20°). The allowed range of pattern speed of the bar is surprisingly narrow (19±5 km s−1 kpc−1) and is consistent with recent observations of bulge stars. Self-gravity of the interstellar matter is needed to account for the observed molecular ring at a radius of ∼ 4 kpc even if the gas mass fraction to the dynamical mass is small (about 5%).

Analyses of the distribution of far infrared point sources in the Galactic bulge have suggested that from a face-on perspective the bulge has a bar like shape. Here, we investigate how a rotating bar-like bulge affects the global gas dynamics in a disk and compare the longitude-velocity (LV) maps from selfgravitating hydrodynamical simulations with observed maps of neutral hydrogen and carbon monoxide in the Galaxy. We found that the features on the numerical LV maps depend strongly on four factors: the pattern speed of the bar, the position angle of the Sun, the strength of the bar potential and the ratio of the gas mass to total dynamical mass. We conclude that our Galaxy has a rotating, weak, bar-like bulge (a/b ∼ 0.8) observed from nearly end on (θp < 20°). The allowed range of pattern speed of the bar is surprisingly narrow (∼ 20 km s–1 kpc–1) and is consistent with recent observations of bulge stars. Selfgravity of the interstellar matter is needed to account for some of the observations.

AlGaAs/GaAs single-quantum-well (SQW) vertical-cavity surface-emitting laser diodes (VCSELDs) with 20 pairs of AlAs (71 nm)/GaAs (59 nm) distributed Bragg reflectors (DBRs) were grown on Si substrates by metalorganic chemical vapor deposition using the conventional two-step growth technique. The measured reflectivity of the 20 pairs of AlAs/GaAs DBRs was 93 % at the wavelength of 860 nm. The AlGaAs/GaAs SQW VCSELD on Si exhibited a threshold current of 79 mA and a threshold current density of 4.9 kA/cm2 under pulsed condition at room temperature. The emission wavelength was 840.3 nm with the full width at half maximum of 0.28 nm.

Conventional GaAs-based laser diodes grown on Si substrates suffer from rapid degradation, which results from the deteriorations of optical and electrical characteristics. Electroluminescence observation shows that the optical deterioration is caused by the formation of dark-line defects. The current-voltage (I-V) characteristic of the p-n junction is degraded with aging, and results in an ohmic-like under a higher ambient temperature and a larger forward current. The deterioration of the I-V characteristic is caused by defect-accelerated impurity diffusion because the growth of GaAs on Si substrates (GaAs/Si) involves the high dislocation density, the large tensile stress and the large amount of Si near the GaAs/Si interface. A significant improvement in reliability has been achieved in the strain-relieved AlGaAs/InGaAs laser diode on Si grown with the InGaAs intermediate layer. The stress relief by the InGaAs active layer and the reduction of the dark-line defect formation by the InGaAs intermediate layer are required to fabricate reliable GaAs-based laser diodes on Si substrates.

We have mapped the nuclear region of an Scd galaxy IC 342 in the CO (J = 1-0) emission with an angular resolution of 15″. This galaxy has a bright optical nucleus with a dark lane elongated in the north-south direction. A prominent molecular bar which has been discovered by Lo et al. (1984) using the Owens Valley Interferometer lies just on the dark lane. Their CO map was spatially limited by the primary beam pattern and the velocity coverage of their spectrometer was not sufficient. It is not known, therefore, whether the molecular bar is connected to the outer spiral arms or not. We made the highest resolution CO map accessible by a single-dish telescope with a sufficient velocity coverage.