Lyman Alpha Emitters at z=7 in the Subaru/XMM-Newton Deep Survey Field: Photometric Candidates and Luminosity Function

We conducted a deep narrowband NB973 (FWHM = 200 A centered at 9755 A) survey of z=7 Lyman alpha emitters (LAEs) in the Subaru/XMM-Newton Deep Survey Field, using the fully depleted CCDs newly installed on the Subaru Telescope Suprime-Cam, which is twice more sensitive to z=7 Lyman alpha at ~ 1 micron than the previous CCDs. Reaching the depth 0.5 magnitude deeper than our previous survey in the Subaru Deep Field that led to the discovery of a z=6.96 LAE, we detected three probable z=7 LAE candidates. Even if all the candidates are real, the Lyman alpha luminosity function (LF) at z=7 shows a significant deficit from the LF at z=5.7 determined by previous surveys. The LAE number and Lyman alpha luminosity densities at z=7 is ~ 7.7-54% and ~5.5-39% of those at z=5.7 to the Lyman alpha line luminosity limit of L(Ly-alpha) >~ 9.2 x 10^{42} erg s^{-1}. This could be due to evolution of the LAE population at these epochs as a recent galaxy evolution model predicts that the LAE modestly evolves from z=5.7 to 7. However, even after correcting for this effect of galaxy evolution on the decrease in LAE number density, the z=7 Lyman alpha LF still shows a deficit from z=5.7 LF. This might reflect the attenuation of Lyman alpha emission by neutral hydrogen remaining at the epoch of reionization and suggests that reionization of the universe might not be complete yet at z=7. If we attribute the density deficit to reionization, the intergalactic medium (IGM) transmission for Lyman alpha photons at z=7 would be 0.4 <= T_{Ly-alpha}^{IGM} <= 1, supporting the possible higher neutral fraction at the earlier epochs at z > 6 suggested by the previous surveys of z=5.7-7 LAEs, z ~ 6 quasars and z > 6 gamma-ray bursts.Comment: Accepted to ApJ for publicatio

Development of a screening system for central visual field using the eye-tracking device\n

　Background: Visual field test with gaze movements do not require a subjective response because they are based on reflexive movements. In this study, we developed a visual field test system with gaze movements to perform a central visual field screening, and then examined the reproducibility of the measurements in healthy adult volunteers.　Methods: We examined 30 right eyes of 30 healthy volunteers (mean age, 22.7 ± 5.2 years) with a best-corrected visual acuity of at least 20/20. Gazefinder, an eye-tracking device, was used to measure gaze movements. Subjects with refractive correction were asked to follow a white target presented on a monitor. If a subject can accurately perform eye tracking with respect to the visual target, visual field with gaze movements measurements are theoretically possible in eight directions (horizontal/vertical to 15.3° and oblique to 21.5° ). After a total of three measurements, the data were quantified using analysis software (CreateChart). Finally, the intraclass correlation coefficients of the measurement values were obtained.　Results: The difference between theoretical and actual measurement values, which is thought to reflect gaze accuracy, were –0.1° ± 0.9° for upper, –0.6° ± 1.0° for upper right, –0.2° ± 1.0° for right, –0.8° ± 0.9° for lower right, –0.5° ± 0.7° for lower, –0.5° ± 0.9° for lower left, –0.6 ° ± 0.5 ° for left, and –0.6 ° ± 0.5 ° for upper left. No significant differences were found among the eight directions, and gaze accuracy was high, at within 1°. The intraclass correlation coefficients were 0.6 or higher in each direction (P < 0.01), indicating high repeatability.　Conclusions: In the traditional method for measuring visual field with gaze movements, the fixation point of view needs to be reset for each gaze movement. On the other hand, the system developed in this study has the advantage of not requiring eye movements to return to the fixation point. The present findings indicate that our newly developed system is a useful device when standard perimetry is difficult to measure

The exacerbation risk prediction by fractional exhaled nitric oxide in younger and elder children with bronchial asthma

The usefulness of the Fractional exhaled nitric oxide (FeNO) measurements for asthma exacerbation risk prediction in asthmatic children is controversial. Fifty-seven asthmatic children who were regularly treated and had previously been stable for at least 3 months were enrolled. The asthma excerbations risk prediction by the FeNO levels and age contribution on it were investigated. As analyzed all the patients, FeNO cut off value for the significant risk of asthma exacerbation was 36.9 ppb (risk odds was 5.1 [95% C.I., 1.8 to 15.0], chi square valve = 9.0, p=0.0028). However, sensitivity and specificity were not adequate for predicting asthma exacerbation (Sensitivity, 77.8%; Specificity, 59.9%; Area under the curve [AUC], 0.674). These parameters were improved only when 6-10 year old children were assessed (FeNO threshold=39.9 ppb, risk odds=10.2 [3.1 to 33.1], chi square valve 14.8, p=0.0001); Sensitivity, 80.8%; Specificity, 71.8%; AUC, 0.758). High value of FeNO is a risk factor for the asthma exacerbation, and FeNO measurement may be more useful for asthma control in younger children than elder asthmatic children

Subaru high-z exploration of low-luminosity quasars (SHELLQs). I. Discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9

We report the discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9. This is the initial result from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which exploits the exquisite multiband imaging data produced by the Subaru Hyper Suprime-Cam (HSC) Strategic Program survey. The candidate selection is performed by combining several photometric approaches including a Bayesian probabilistic algorithm to reject stars and dwarfs. The spectroscopic identification was carried out with the Gran Telescopio Canarias and the Subaru Telescope for the first 80 deg2 of the survey footprint. The success rate of our photometric selection is quite high, approaching 100 % at the brighter magnitudes (zAB < 23.5 mag). Our selection also recovered all the known high-z quasars on the HSC images. Among the 15 discovered objects, six are likely quasars, while the other six with interstellar absorption lines and in some cases narrow emission lines are likely bright Lyman-break galaxies. The remaining three objects have weak continua and very strong and narrow Ly alpha lines, which may be excited by ultraviolet light from both young stars and quasars. These results indicate that we are starting to see the steep rise of the luminosity function of z > 6 galaxies, compared with that of quasars, at magnitudes fainter than M1450 ~ -22 mag or zAB ~24 mag. Follow-up studies of the discovered objects as well as further survey observations are ongoing.Comment: Published in ApJ (828:26, 2016