Probing Reionization & Galaxy Evolution by High-z Lyα Emitters z=6.96 LAE Kazuaki Ota Cosmic Radiation Lab. RIKEN Institute of Physical and Chemical Research

Outline When did reionization end? I. Goal: to address the question, II. Approach: Lyα Emitters III. Result IV. Conclusion V. Upcoming Projects

Outline When did reionization end? I. Goal: to address the question, II. Approach: Lyα Emitters III. Result IV. Conclusion V. Upcoming Projects

When did reionization end? GP trough quasars Fan et al. 2006 neutral fraction XHI ~ 1 – 4% z=6.3 WMAP (CMB) Dunkley et al. 2008 zreion=11.0±1.4 zreion　> 6.7 (3σ limit) γ-ray burst Totani et al. 2006 neutral fraction 0< XHI < 17 – 60%

Reionization Scenario: Late vs. Early Neutral Fraction XHI Redshift z Fan et al.2006 ARAA

Reionization might have ended at z~6. Our Result: LAEs support late reionization Neutral Fraction XHI z=7 z=6.6 Lyα Emitters (LAEs) Reionization might have ended at z~6. Redshift z Fan et al.2006 ARAA

Outline When did reionization end? I. Goal: to address the question, II. Approach: Lyα Emitters III. Result IV. Conclusion V. Upcoming Projects

Reionization Probe： z~6 Quasars Neutral Fraction1 – 4% Fan et al. 2002 Reionization Probe：　 z~6 Quasars Neutral Fraction1 – 4% GP trough z=5.7 z=6.6 z=7 Lyα emitters (LAEs) If NF increases beyond z~6, observed LAE number density could decrease beyond z~6. Iye et al. 2006

Narrowband Filters to Detect Lyα Filter Response z=5.7Lyα z=6.6 z=7 LAE Skylines z=7 　　　Wavelength (A)

Sample Selection: NB excess Taniguchi et al.2005 Kashikawa et al.2006 z=5.7 LAEs z=6.6 LAEs Shimasaku et al.2006 Taniguchi et al.2005 Kashikawa et al.2006

Sample Selection of z=7LAEs i’ – z’ [mag] z’ – NB973 [mag] 3:z=6.6LAE 1 Detected in only NB973 2 Model z=7 LAE Ota et al.2008

Spectroscopic confirmation Kashikawa et al.2006 z=6.6 LAEs 89% complete Shimasaku et al.2006 z=5.7 LAEs 86% complete Iye, Ota et al.2006 z=7 LAE

Target Sky Region & Samples 3σ, 2” aper. Limit. Mag. B ≤ 28.45 V ≤ 27.74 　 　 R ≤ 27.80 i’ ≤ 27.43 z’ ≤ 26.62 NB816 ≤ 26.63 (z=5.7) NB921 ≤ 26.54 (z=6.6) NB973 ≤ 25.47 (z=7.0) 876 arcmin2 Subaru Deep Field Suprime-Cam SDF Latest LAE Samples 　　　　 Image　Spec.　 z=5.7 89 34 Shimasaku et al. 2006 z=6.6 58 17 Kashikawa et al. 2006 z=7.0 2 1　 Ota et al. 2008

Outline When did reionization end? I. Goal: to address the question, II. Approach: Lyα Emitters III. Result IV. Conclusion V. Upcoming Projrcts

Comparison of z<6 & z>6 LAE’s Lyα Luminosity Function (LF) Did reionization end at z~6? Does HI increase beyond z=6? Comparison of z<6 & z>6 LAE’s Lyα Luminosity Function (LF) Increase in HI galaxy evolution LAE evolution model

Lyα LF（Observed） Number density log[n(>L) Mpc-3] z=5.7Phot■ z=6.6Phot● z=6.6Spec▲ z=7.0Spec◆ z=7LAE detection limit Number density log[n(>L) Mpc-3] Decline in n(>L) ・galaxy evolution? ・increase in HI? ・both? Lyα Luminosity log[L(Lyα) erg/s]

IGM transmission to Lyα photons A LAE Evolution Model (Kobayashi et al.2007) Observed Lyα luminosity IGM transmission to Lyα photons 0 ≤ TLyα ≤ 1 IGM Lyα luminosity emitted from a galaxy fesc =0 Lyc Lyα emitters Quiescent galaxy Starburst galaxy Lyα escape fraction 0.8 outflow + dust model

Lyα LF（Model vs. Observation） 　LAE evolution model 　　 (Kobayashi et al.2007) TLyα=1 IGM galaxy evol. Number density log[n(>L) Mpc-3] Increase in HI TLyα z=6.6: 0.62–0.78 IGM Lyα Luminosity log[L(Lyα) erg/s]

Lyα LF（Model vs. Observation） 　LAE evolution model 　　 (Kobayashi et al.2007) TLyα=1 IGM galaxy evol. Number density log[n(>L) Mpc-3] Increase in HI TLyα z=7.0: 0.40–0.64 IGM Lyα Luminosity log[L(Lyα) erg/s]

Neutral Fraction z=6.6 24–36% z=7.0 32–64% IGM transmission to Lyα photons: TLyα z=6.6: 0.62–0.78 z=7.0: 0.40–0.64 Neutral Fraction z=6.6 24–36% z=7.0 32–64% IGM Lyα line attenuation: Model of Santos（2004） Neutral Fraction wavelength(A) Flux IGM TLyα

z~3-5 z=5.7 z=6.5 z=7 Gal. evol. reionization Model prediction Kobayashi 07 reionization z=6.5 z=7 Ouchi 08 Shimasaku 06 Dawson 07 Kashikawa 06 van Breukelen 05 Ota 08

Reionization History Neutral Fraction XHI Redshift z z=7 z=6.6 Lyα Emitters Redshift z Fan et al.2006 ARAA

LAEs support late reionization. Reionization might have ended at z~6. Conclusion When did reionization end? NOTE: Estimation of XHI is model dependent. z=7 LAE survey is shallow. We surveyed only one sky field. LAEs support late reionization. Reionization might have ended at z~6.

Outline When did reionization complete? I. Goal: to address the question, When did reionization complete? II. Approach: Lyα Emitters III. Result IV. Conclusion V. Upcoming Projects

Upcoming Projects New Filter + New CCDs Filter Response Wavelength (A) NB1005 filter z~7.3 LAE center=10050A FWHM=210A NB1005 34’x27’ Suprime-Cam Red-sensitive CCDs for Suprime-Cam QE @ 1μm ~ 0.422

876 arcmin2 Suprime-Cam 1 pointing Upcoming Project (1) Deepen z=7 Image NB973=24.9  25.4 Obtain z=7.3 Image NB1005=25.0 or deeper Improved samples z=7 LAEs z=7.3 LAEs Subaru Deep Field 876 arcmin2 Suprime-Cam 1 pointing

Upcoming Project (2) Subaru/XMM-Newton Deep Survey（SXDS） ~1.3 degree2 (Suprime-Cam 5 pointings) Samples: z=5.7 LAEs 5 fields z=6.6 LAEs 5 fields (Ouchi et al.) z=7 LAEs 1 field z=7.3 LAEs 1 field (Observation in this Oct. & Nov.)

UV LF of LAEs at z=5.7 – 7