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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
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z~6z~14
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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
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Two z=7 LAE Candidates< 3 NB973 < 24.9 (5)
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SubaruFOCASMay, June 2005, April 2006slits W0.8 L8 15175 lines
mm-1 + z filter R ~ 1600 Dispersion = 0.98pixel-1Spectroscopy
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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
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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.
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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
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5.7Redshift6.67.0Galaxy evolution reionizationGalaxy evolution
reionizationSemi-analytic model (kobayashi et al.2006)
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neutral fraction @z=7.0: 32-64%@z=6.6: 24-36%L(Lya)observed
L(Lya)intrinsic
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Fan et al.2006 ARAANeutral Fraction
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Fan et al.2006 ARAALy Emitters This StudyNeutral Fraction
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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.
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12Detected in only NB9733:z=6.6LAEModel z=7 LAE
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12Detected in only NB9733:z=6.6LAEModel z=7 LAE
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Lya line Luminosity Function Shimasaku+06
Kashikawa+06Kobayashi+07