Search

Total cross section for the double neutral pion photoproduction off the proton is presented in the incident photon energy range of 0.58 to 1.15 GeV. The data were accumulated in the years 2009–2010, recorded by a 4π EM calorimeter at ELPH, named FOREST. The number of recorded events obtained during this period is 1.6×109 for a hydrogen target. Two neutral pions are reconstructed via detecting their decay products, four gammas (2π0 → 4γ). Compared to the previous results obtained by other groups, our data are in good agreement with theirs within error bars.

We have studied positive-parity states of 28Si using antisymmetrized molecular dynamics and multiconfiguration mixing with constrained variation. Applying constraints to the cluster distance and the quadrupole deformation of the variational calculation, we have obtained basis wave functions that have various structures such as α-24Mg and 12C-16O cluster structures as well as deformed structures. Superposing those basis wave functions, we have obtained a oblate ground state band, a β vibration band, a normal-deformed prolate band, and a superdeformed band. It is found that the superdeformed bands contain large amounts of the α-24Mg cluster components. The results also suggest the presence of two excited bands with the developed α-24Mg cluster structure, where the inter-cluster motion and the 24Mg-cluster deformation play important roles.

We present Lyα and UV-nebular emission line properties of bright Lyα emitters (LAEs) at z = 6-7 with a luminosity of log LLyα/[erg s-1] = 43-44 identified in the 21 deg2 area of the SILVERRUSH early sample developed with the Subaru Hyper Suprime-Cam survey data. Our optical spectroscopy newly confirms 21 bright LAEs with clear Lyα emission, and contributes to making a spectroscopic sample of 96 LAEs at z = 6-7 in SILVERRUSH. From the spectroscopic sample, we select seven remarkable LAEs as bright as Himiko and CR7 objects, and perform deep Keck/MOSFIRE and Subaru/nuMOIRCS near-infrared spectroscopy reaching the 3 σ flux limit of ∼2 × 10-18 erg s-1 for the UV-nebular emission lines of He II λ1640, CIV λλ1548,1550, and OIII]λλ1661,1666. Except for one tentative detection of C IV, we find no strong UV-nebular lines down to the flux limit, placing the upper limits of the rest-frame equivalent widths (EW0) of ∼2-4 A for CIV, He II, and OIII] lines. We also investigate the VLT/X-SHOOTER spectrum of CR7 whose 6 σ detection of He II is claimed by Sobral et al. Although two individuals and the ESO archive service carefully reanalyzed the X-SHOOTER data that are used in the study of Sobral et al., no He II signal of CR7 is detected, supportive of weak UV-nebular lines of the bright LAEs even for CR7. The spectral properties of these bright LAEs are thus clearly different from those of faint dropouts at z ∼ 7 that have strong UV-nebular lines shown in the various studies. Comparing these bright LAEs and the faint dropouts, we find anti-correlations between the UV-nebular line EW0 and the UV-continuum luminosity, which are similar to those found at z ∼ 2-3.

We present the first observations of foreground Lyα forest absorption from high-redshift galaxies, targeting 24 star-forming galaxies (SFGs) with z ∼ 2.3-2.8 within a 5′ × 14′ region of the COSMOS field. The transverse sightline separation is ∼2 h-1 Mpc comoving, allowing us to create a tomographic reconstruction of the three-dimensional (3D) Lyα forest absorption field over the redshift range 2.20 ≤ z ≤ 2.45. The resulting map covers 6 h-1 Mpc × 14 h-1 Mpc in the transverse plane and 230 h-1 Mpc along the line of sight with a spatial resolution of ≈3.5 h-1 Mpc, and is the first high-fidelity map of a large-scale structure on ∼ Mpc scales at z > 2. Our map reveals significant structures with ≳10 h-1 Mpc extent, including several spanning the entire transverse breadth, providing qualitative evidence for the filamentary structures predicted to exist in the high-redshift cosmic web. Simulated reconstructions with the same sightline sampling, spectral resolution, and signal-to-noise ratio recover the salient structures present in the underlying 3D absorption fields. Using data from other surveys, we identified 18 galaxies with known redshifts coeval with our map volume, enabling a direct comparison with our tomographic map. This shows that galaxies preferentially occupy high-density regions, in qualitative agreement with the same comparison applied to simulations. Our results establish the feasibility of the CLAMATO survey, which aims to obtain Lyα forest spectra for ∼1000 SFGs over ∼1deg2 of the COSMOS field, in order to map out the intergalactic medium large-scale structure at 〈z〉 ∼ 2.3 over a large volume (100 h-1 Mpc)3.

Hisashi Kawai, Yu Taniguchi, Satoshi Seino, Ryota Sakurai, Yosuke Osuka, Shuichi Obuchi, Yutaka Watanabe, Hunkyung Kim, Hiroki Inagaki, Akihiko Kitamura, Shuichi Awata, Shoji ShinkaiTokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, JapanBackground: Gait measures such as gait speed, stride length, step width, and stance duration change with advanced age and are associated with adverse health outcomes among older adults. The stride-to-stride variabilities of gait measures are also related to falls and cognitive decline in older adults; however, reference values of these gait parameters in older Japanese adults do not exist. This study aimed to determine the reference values of gait parameters as measured by a plantar pressure platform in community-dwelling older Japanese adults.Methods: Community-dwelling adults (N=1,212) who were independent in basic activities of daily living and aged 70–96 years (491 men, 721 women) completed the gait performance measurement in a geriatric health assessment. We assessed 10 gait performance measures with a plantar pressure platform system (P-WALK, BTS Bioengineering) and calculated means and coefficient of variations (CVs) of the gait measures as well as quintiles for those gait parameters per age group among men and women.Results: Mean (SDs) of gait speed, stride length, step width, and stance durations were 1.26 (0.24) meters per second (m/s), 121.9 (19.8) cm, 24.0 (3.2) cm, and 552.4 (60.4) milliseconds (ms), respectively, in men, and 1.27 (0.21) m/s, 115.7 (16.3) cm, 17.9 (2.8) cm, and 517.6 (59.8) ms, respectively, in women. Mean of CVs (SD) of stride length, step width, and single-stance duration were 2.76 (1.35), 12.06 (3.98), and 5.74 (2.66), respectively, in men and 2.69 (1.24), 15.65 (4.53), and 5.77 (2.40), respectively, in women. Gait parameters (except CVs of step width) declined significantly with age regardless of gender (P< 0.01 for trends).Conclusion: This study determined age group dependent gait parameter reference values, presented as means with quintile ranges, in community-dwelling older Japanese adults. These reference values may be useful metrics for gait assessment in the elderly.Keywords: gait parameter, variation coefficient, community-dwelling, older adult, reference value

We have identified a very interesting Lyα emitter (LAE), whose Lyα emission line has an extremely large observed equivalent width of EW0 = 436+422 - 149 Å, which corresponds to an extraordinarily large intrinsic rest-frame equivalent width of EWint 0 = 872 +844 - 298 Å after the average intergalactic absorption correction. The object was spectroscopically confirmed to be a real LAE by its apparent asymmetric Lyα line profile detected at z = 6.538. The continuum emission of the object was definitely detected in our deep z′-band image; thus, its EW0 was reliably determined. Follow-up deep near-infrared spectroscopy revealed emission lines of neither He II λ1640 as an apparent signature of Population III (Pop III) nor C IV λ1549 as proof of an active nucleus. No detection of the short-lived He II λ1640 line is not necessarily inconsistent with the interpretation that the underlying stellar population of the object is dominated by Pop III. We found that the observed extremely large EW0 of the Lyα emission and the upper limit on the EW0 of the He II λ1640 emission can be explained by population synthesis models favoring a very young age less than 2-4 Myr and massive metal-poor (Z < 10 -5) or even metal-free stars. The observed large EW0 of Lyα is insufficiently explained by Population I/II synthesis models with Z ≥ 10 -3. However, we cannot conclusively rule out the possibility that this object is composed of a normal stellar population with a clumpy dust distribution, which could enhance the Lyα EW0, though its significance is still unclear. © 2012. The American Astronomical Society. All rights reserved..

We carried out extended spectroscopic confirmations of Lyα emitters (LAEs) at z = 6.5 and 5.7 in the Subaru Deep Field. Now, the total number of spectroscopically confirmed LAEs is 45 and 54 at z = 6.5 and 5.7, respectively, and at least 81% (70%) of our photometric candidates at z = 6.5 (5.7) have been spectroscopically identified as real LAEs. We made careful measurements of the Lyα luminosity, both photometrically and spectroscopically, to accurately determine the Lyα and rest-UV luminosity functions (LFs). The substantially improved evaluation of the Lyα LF at z = 6.5 shows an apparent deficit from z = 5.7 at least at the bright end, and a possible decline even at the faint end, though small uncertainties remain. The rest-UV LFs at z = 6.5 and 5.7 are in good agreement, at least at the bright end, in clear contrast to the differences seen in the Lyα LF. These results imply an increase in the neutral fraction of the intergalactic medium from z = 5.7 to 6.5. The rest-frame equivalent width (EW0) distribution at z = 6.5 seems to be systematically smaller than z = 5.7, and it shows an extended tail toward larger EW0. The bright end of the rest-UV LF can be reproduced from the observed Lyα LF and a reasonable EW0-UV luminosity relation. Integrating this rest-UV LF provides the first measurement of the contribution of LAEs to the photon budget required for reionization. The derived UV LF suggests that the fractional contribution of LAEs to the photon budget among Lyman break galaxies significantly increases toward faint magnitudes. Low-luminosity LAEs could dominate the ionizing photon budget, though this inference depends strongly on the uncertain faint-end slope of the Lyα LF. © 2011. The American Astronomical Society. All rights reserved.

We report new follow-up spectroscopy of i′-dropout galaxies with an NB921-band depression found in the Subaru Deep Field. The NB921-depressed 1′-dropout selection method is expected to select galaxies with large equivalent-width Lyα emission over a wide redshift range, 6.0 ≲ z ≲ 6.5. Two of four observed targets show a strong emission line with a clear asymmetric profile, identified as Lyα emitters at z = 6.11 and 6.00. Their rest-frame equivalent widths are 153 Å and 114 Å, which are lower limits on the intrinsic equivalent widths. Through our spectroscopic observations (including previous ones) of NB921 -depressed i′-dropout galaxies, we identified 5 galaxies in total with a rest-frame equivalent width larger than 100 Å at 6.0 ≲ z ≲ 6.5 out of 8 photometric candidates, which suggests that the NB921 -depressed i′-dropout selection method is possibly an efficient way to search for Lyα emitters with a large Lyα equivalent width, in a wider redshift range than with usual narrow-band excess techniques. By combining these findings with our previous observational results, we infer that the fraction of broad-band selected galaxies having a rest-frame equivalent width larger than 100 Å is significantly higher at z ∼ 6 (the cosmic age of ∼1 Gyr) than that at z ∼ 3 (∼2 Gyr), being consistent with the idea that the typical stellar population of galaxies is significantly younger at z ∼ 6 than that at z ∼ 3. The NB921-depressed i′-dropout galaxies may be interesting candidates for hosts of massive, zero-metallicity Population III stars. © ESO 2007.

We report an extensive search for Lyα emitters (LAEs) at z = 6.5 in the Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck identified eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs at z = 6.5. Based on this spectroscopic sample of 17, complemented by a photometric sample of 58 LAEs, we have derived a more accurate Lyα luminosity function of LAEs at z = 6.5, which reveals an apparent deficit at the bright end of ∼0.75 mag fainter L*, compared with that observed at z = 5.7. The difference in the LAE luminosity functions between z = 5.7 and 6.5 is significant at the 3 σ level, which is reduced to 2 σ when cosmic variance is taken into account. This result may imply that the reionization of the universe has not been completed at z = 6.5. We found that the spatial distribution of LAEs at z = 6.5 was homogeneous over the field. We discuss the implications of these results for the reionization of the universe. © 2006. The American Astronomical Society. All rights reserved.

We explored the clustering properties of Lyman break galaxies at z = 4 and 5 with an angular two-point correlation function on the basis of the very deep and wide Subaru Deep Field data. We confirmed the previous result that the clustering strength of LBGs depends on the UV luminosity in the sense that brighter LBGs are more strongly clustered. In addition, we found an apparent dependence of the correlation function slope on UV luminosity for LBGs at both z = 4 and 5. More luminous LBGs have a steeper correlation function. The bias parameter was found to be a scale-dependent function for bright LBGs, whereas it appears to be almost scale-independent for faint LBGs. Luminous LBGs have a higher bias at smaller angular scales, which decreases as the scale increases. To compare these observational results, we constructed numerical mock LBG catalogs based on a semianalytic model of hierarchical clustering combined with high-resolution N-body simulation, carefully mimicking the observational selection effects. The luminosity functions and the overall correlation functions for LBGs at z = 4 and 5 predicted by this mock catalog were found to be almost consistent with the observation. The observed dependence of the clustering on UV luminosity was not reproduced by the model, unless subsamples of distinct halo mass were considered. That is, LBGs belonging to more massive dark halos had steeper and larger amplitude correlation functions. With this model, we found that LBG multiplicity in massive dark halos amplifies the clustering strength at small scales, which steepens the correlation function. The hierarchical clustering model could therefore be reconciled with the observed luminosity dependence of the correlation function if there is a tight correlation between UV luminosity and halo mass. Our finding that the slope of the correlation function depends on luminosity could be an indication that massive dark halos hosted multiple bright LBGs. © 2006. The American Astronomical Society. All rights reserved.

We report new spectroscopy of two star-forming galaxies with strong Lyα emission at z = 6.03 and 6.04 in the Subaru Deep Field. These two objects are originally selected as i′-dropouts (i′ -z′ > 1.5) showing an interesting photometric property, the "NB921 depression." The NB921-band (centered at 9196 Å) magnitude is significantly depressed with respect to the z′-band magnitude. The optical spectra of these two objects exhibit asymmetric emission lines at λobs ∼ 8540 and ∼8560 Å, suggesting that these objects are Lyα emitters at z ∼ 6. The rest-frame equivalent widths of the Lyα emission of the two objects are 94 and 236 Å; the latter is the Lyα emitter with the largest Lyα equivalent width at z ≳ 6 ever spectroscopically confirmed. The spectroscopically measured Lyα fluxes of these two objects are consistent with the interpretation that the NB921 depression is caused by the contribution of the strong Lyα emission to the z′-band flux. Most of the NB921-depressed i′-dropout objects are thought to be strong Lyα emitters at 6.0 ≲ z ≲ 6.5; Galactic L and T dwarfs and NB921-dropout galaxies at z > 6.6 do not dominate the NB921-depressed i′-dropout sample. Thus, the NB921 -depression method is very useful for finding high-z Lyα emitters with a large Lyα equivalent width over a large redshift range, 6.0 ≲ z ≲ 6.5. Although the broadband-selected sample at z ∼ 3 contains only a small fraction of objects with a Lyα equivalent width larger than 100 Å, the i′-dropout sample of the Subaru Deep Field contains a much larger fraction of such strong Lyα emitters. This may imply a strong evolution of the Lyα equivalent width from z ≳ 6 to z ∼ 3. © 2005. The American Astronomical Society. All rights reserved.

We have applied an absorbing boundary condition (ABC) method to calculations of the level density (LD) and the continuum level density (CLD). The results of LD and CLD in the ABC calculation are compared with those calculated by the complex scaling method (CSM). The energy dependences of LD in ABC show similar behavior to those in CSM around the resonance energy but they are prominently different, especially at the lower-energy region, due to the different sequence of the energy eigenvalues in the complex plane. The phase shift for two-body scattering problems is also derived from CLD. The phase shift obtained by ABC is almost the same as that calculated from CSM although the ABC method seems to be slightly inferior to the CSM calculation in the numerical precision. The improvement of the numerical precision in ABC is also discussed. [ABSTRACT FROM AUTHOR]