The End of the Reionization Epoch Probed by Lyα Emitters atz= 6.5 in the Subaru Deep Field

Abstract

We report an extensive search for Ly emitters (LAEs) at z ¼ 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 ¼ 6:5. Based on this spectroscopic sample of 17, complemented by a photometric sample of 58 LAEs, we have derived a more accurate Ly luminosity function of LAEs at z ¼ 6:5, which reveals an apparent deficit at the bright end of $0.75 mag fainter L Ã , compared with that observed at z ¼ 5:7. The difference in the LAE luminosity functions between z ¼ 5:7 and 6.5 is significant at the 3 level, which is reduced to 2 when cosmic variance is taken into account. This result may imply that the reionization of the universe has not been completed at z ¼ 6:5. We found that the spatial distribution of LAEs at z ¼ 6:5 was homogeneous over the field. We discuss the implications of these results for the reionization of the universe.

The Metal Abundances Across Cosmic Time (     ) Survey. I. Optical Spectroscopy in the Subaru Deep Field

“…The acquisition and reduction of these data have been discussed extensively in Kashikawa et al (2004Kashikawa et al ( , 2006, Ly et al (2007;hereafter Ly07), as well as in Ly et al (2012b) for the narrowband data, and in Nagao et al (2008) for the intermediate-band data. In brief, data were obtained mostly under photometric conditions with average seeing of 0 9-1 0 for all five narrowband and two intermediate-band filters.…”

“…The distribution of onsource integration times is illustrated in Figure 5. Kashikawa et al (2006) and Ly07, and the 2008-2009 data have been discussed in Kashikawa et al (2011). In brief, we constructed 22 slitmasks with 1″ slit widths, and used the 830 line mm −1 grating and GG495 order-cut filter.…”

Clustering and lifetime of Lyman Alpha Emitters in the Epoch of Reionization

“…For the χ HI value shown in Column 1, we summarise the fα/fc ratio required to best fit the simulated Lyα LF to observations (Kashikawa et al 2011) within 1σ limits in columns 2-4 with subscripts showing the fesc value used (Hutter et al 2014 to narrow the joint constraints on χHI , fesc and fα/fc. We start by describing our procedure for obtaining LAE ACFs, which depends both on the depth along the LOS (Peebles 1980) since all galaxies are projected to a plane perpendicular to the LOS, as well as the chosen field of view (FoV), which should be comparable to that observed (Kashikawa et al 2006). Indeed, while the measured ACF should be independent of the FoV if large enough areas are sampled, the restricted observational FoV leads to an ACF that is not independent of sample variance.…”

“…As seen from this equation, even a neutral hydrogen fraction as low as 10 −5 can lead to a significant attenuation of Lyα photons at high-z , making them extremely sensitive probes of H I in the IGM. As a result, a class of high-z galaxies called Lyman Alpha Emitters (LAEs), detected by means of their Lyα line (at 1216Å in the rest frame), have become popular probes of reionization, with statistically significant samples available in the reionization epoch, at z 5.7 and 6.6 (Malhotra et al 2005;Taniguchi et al 2005;Shimasaku et al 2006;Hu et al 2010;Kashikawa et al 2006;Ouchi et al 2010;Kashikawa et al 2011). Indeed, a number of theoretical papers have used semi-analytic (e.g.…”

Searching for Pop III stars and galaxies at high redshift

“…1 (right) show that these limits are already close to the maximum or slightly below the predicted values for metal-free populations with IMFs including very massive stars. Kashikawa et al (2006), andOta et al (2008) at z = 5.7, 6.5, and 7, as well as the z ∼ 8.5 to 10 lensed candidates of Stark et al (2007) are shown by the filled circles (observed fluxes, and crosses: intrinsic fluxes for lensed objects). The black line shows the flux limit from deep NIRSPEC/Keck spectroscopy of Richard et al (2008) from 0.95 to 1.1 μm.…”