The Reionization and Galaxy Evolution Probed by z=7 Ly Emitters Ota, 2007, PhD Thesis, Univ. TokyoIye, Ota, Kashikawa et al. 2006, Nature, 443, 186Ota et al. 2007, submitted to ApJ (arXiv:0707.1561)

Kazuaki Ota Cosmic Radiation Laboratory, RIKENMasanori Iye, Nobunari Kashikawa, Kazuhiro Shimasaku, Masakazu Kobayashi, Tomonori Totani, Masahiro Nagashima, Tomoki Morokuma, Hisanori Furusawa, Takashi Hattori, Yuichi Matsuda, Tetsuya Hashimoto, Masami Ouchi

z~6z~14

Subaru Deep FieldSuprime-CamNarrowband filter NB973 to detect z=6.9-7 Lya (c=9755, FWHM=200) B 28.45 V 27.74 R 27.80, NB816 26.63 i 27.43, NB921 26.54 z 26.62, NB973 24.90 (5) 876 arcmin23427 Field of View16,17 March 2005 Seeing 0.4-0.9 15 hours integration Volume: 3.2105 Mpc3

Two z=7 LAE Candidates< 3 NB973 < 24.9 (5)

SubaruFOCASMay, June 2005, April 2006slits W0.8 L8 15175 lines mm-1 + z filter R ~ 1600 Dispersion = 0.98pixel-1Spectroscopy

5.5hr exp. S/N=5.5SFR(Ly)10Myr-1A Galaxy was forming just 750Myr after the Big Bang!ID of Candidate1: z=6.96LAERed linez=6.96 LAEBlue lineComposite of 12 z=6.6 LAEs

IOK-ID of Candidate2: Noise?

11 hours integration time Spectroscopic limit reaches Lya line flux estimated from NB973 photometry

However, no signal was detected. Maybe, it is noise.

z=5.7z=6.6z=7Quasar GP trough neutral fraction 1-4%z>6 If HI increases rapidly, it attenuates Lya photons. Observed LAE number density decreases?3 Lya emitter samples

5.7Redshift6.67.0Galaxy evolution reionizationGalaxy evolution reionizationSemi-analytic model (kobayashi et al.2006)

neutral fraction @z=7.0: 32-64%@z=6.6: 24-36%L(Lya)observed L(Lya)intrinsic

Fan et al.2006 ARAANeutral Fraction

Fan et al.2006 ARAALy Emitters This StudyNeutral Fraction

ConclusionQ1. Can we still find objects at z>6.6 YES. At least one galaxy at z=7. We do not know about z>7. Q2. How was the reionization at z>6? Probably YES. Our result is consistent with theory and other observations.YES. At least one galaxy at z=7.We do not know about z>7.Neutral fraction rapidly increases, being consistent with theory and other observations.

12Detected in only NB9733:z=6.6LAEModel z=7 LAE

12Detected in only NB9733:z=6.6LAEModel z=7 LAE

Lya line Luminosity Function Shimasaku+06 Kashikawa+06Kobayashi+07