The properties of K-band selected galaxies (K_AB<24) in the z = 3.09 SSA22 protocluster field are studied. 430 galaxies at 2.6 < z_phot < 3.6 are selected as potential protocluster members in a 112 ...arcmin^2 area based on their photometric redshifts. We find that \approx 20% of the massive galaxies with stellar masses >10^11 M_sun at z_phot \sim 3.1 have colors consistent with those of quiescent galaxies with ages > 0.5 Gyr. This fraction increases to \approx 50% after correcting for unrelated foreground/background objects. We also find that 30% of the massive galaxies are heavily reddened dusty star-forming galaxies. Few such quiescent galaxies at similar redshifts are seen in typical survey fields. An excess surface density of 24\mu m sources at z_phot \sim 3.1 is also observed, implying the presence of dusty star-formation activity in the protocluster. Cross-correlation with the X-ray data indicates that the fraction of K-band selected protocluster galaxies hosting active galactic nuclei (AGN) is also high compared with the field. The sky distribution of the quiescent galaxies, the 24\mu m sources, and the X-ray AGNs show clustering around a density peak of z=3.1 Ly\alpha emitters (LAEs). A significant fraction of the massive galaxies have already become quiescent, while the dusty star-formation is still active in the SSA22 protocluster. These findings indicate that we are witnessing the formation epoch of massive early-type galaxies at the center of predecessors to present-day rich galaxy clusters.
A Seismic Exploration at Nango Valley, Aso Caldera TSUTSUI, Tomoki; SUDO, Yasuaki; YOSHIKAWA, Shin ...
BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN,
1997/08/31, Volume:
42, Issue:
4
Journal Article
Open access
Results of a seismic reflection survey in a southern valley of Aso caldera, central Kyushu, Japan are described in this paper. The survey includes two seismic lines, one along a radial direction and ...the another along a tangential direction of the caldera for a purpose to survey the depth to the caldera bottom. These lines are arranged to intersect with each other. A section of the radial line shows a dipping structure towards central cones of the caldera. The radial line is concluded as crossing over the intrinsic rim of caldera in its deeper portion and being laid through a transient structure between a fan and lake deposits in its shallower portion. In contrast with the radial section, the tangential section shows a simple and flat structure. Two well defined reflectors are obtained in these seismic sections. The lower reflector, which is estimated as a top face of the Pre-Aso volcanic rocks, declines steeply towards the central cones and becomes ambiguous in the central-cone side of the radial line. A depth of the lower reflector is estimated as more than 500 m below the surface in the central-cone side. The upper reflector underlies whole area of this survey in a depth about 100 m to 150 m, which is interpreted as the interface in caldera fill. The upper reflector implies a cycle of submergence and emergencies in this area.
We present the results of wide-field deep JHK imaging of the SSA22 field using MOIRCS instrument equipped with Subaru telescope. The observed field is 112 arcmin^2 in area, which covers the z=3.1 ...protocluster characterized by the overdensities of Ly Alpha emitters (LAEs) and Ly Alpha Blobs (LABs). The 5 sigma limiting magnitude is K_{AB} = 24.3. We extract the potential protocluster members from the K-selected sample by using the multi-band photometric-redshift selection as well as the simple color cut for distant red galaxies (DRGs; J-K_{AB}>1.4). The surface number density of DRGs in our observed fields shows clear excess compared with those in the blank fields, and the location of the densest area whose projected overdensity is twice the average coincides with the large-scale density peak of LAEs. We also found that K-band counterparts with z_{phot} = 3.1 are detected for 75% (15/20) of the LABs within their Ly Alpha halo, and the 40 % (8/20) of LABs have multiple components, which gives a direct evidence of the hierarchical multiple merging in galaxy formation. The stellar mass ofLABs correlates with their luminosity, isophotal area, and the Ly Alpha velocity widths, implying that the physical scale and the dynamical motion of Ly Alpha emission are closely related to their previous star-formation activities. Highly dust-obscured galaxies such as hyper extremely red objects (HEROs; J-K_{AB}>2.1) and plausible K-band counterparts of submillimeter sources are also populated in the high density region.
To develop a functional beverage from funori polysaccharide containing funoran, we investigated the removal of arsenic in funori and the optimal extraction condition to reduce the high viscosity. ...Among the various pre-treatment methods tested, the arsenic in funori material was removed the most effectively by ethanol washing. The viscosity of the polysaccharide extract by heating with citrate was remarkably reduced and resulted in a significant increase in the content of polysaccharide, funoran. From these results, a technology of processing the functional beverage containing funoran was established.
We present the results of deep near-infrared imaging observations of the z=3.1 proto-cluster region in the SSA22a field taken by MOIRCS mounted on the Subaru Telescope. We observed a 21.7 arcmin^2 ...field to the depths of J=24.5, H=24.3, and K=23.9 (5 sigma). We examine the distribution of the K-selected galaxies at z~3 by using the simple color cut for distant red galaxies (DRGs) as well as the photometric-redshift selection technique. The marginal density excess of DRGs and the photo-z selected objects are found around the two most luminous Ly alpha blobs (LABs). We investigate the correlation between the K-selected objects and the LABs, and find that several galaxies with stellar mass M_* = 10^9-10^11 M_solar exist in vicinity of LABs, especially around the two most luminous ones. We also find that 7 of the 8 LABs in the field have plausible K_s-band counterparts and the sum of the stellar mass possibly associated with LABs correlates with the luminosity and surface brightness of them, which implies that the origin of Ly alpha emission may be closely correlated with their stellar mass or their previous star formation phenomena.
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