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Probing Reionization & Galaxy Evolution by High-z Lyα Emitters

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

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Probing Reionization & Galaxy Evolution by High-z Lyα Emitters

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

  2. Outline I. Goal: to address the question, When did reionizationend? II. Approach: LyαEmitters III. Result IV. Conclusion V. Upcoming Projects

  3. Outline I. Goal: to address the question, When did reionizationend? II. Approach: LyαEmitters III. Result IV. Conclusion V. Upcoming Projects

  4. When did reionization end? quasars Fan et al. 2006 neutral fraction XHI ~ 1 – 4% z~6.2 WMAP (CMB) Dunkley et al. 2008 zreion=11.0±1.4 zreion> 6.7 (3σ limit) z=6.3 γ-ray burst Totani et al. 2006 neutral fraction 0< XHI < 17 – 60% GP trough

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

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

  7. Outline I. Goal: to address the question, When did reionizationend? II. Approach: LyαEmitters III. Result IV. Conclusion V. Upcoming Projects

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

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

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

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

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

  13. Target Sky Region & Samples 3σ, 2” aper. Limit. Mag.B ≤ 28.45 V ≤ 27.74 R ≤ 27.80i’ ≤ 27.43z’ ≤ 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 SDFLatest LAE Samples ImageSpec.z=5.789 34 Shimasaku et al. 2006z=6.658 17 Kashikawa et al. 2006z=7.0 2 1Ota et al. 2008

  14. Outline I. Goal: to address the question, When did reionizationend? II. Approach: LyαEmitters III. Result IV. Conclusion V. Upcoming Projrcts

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

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

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

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

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

  20. Flux wavelength(A) Neutral Fraction Lyαline attenuation: Model of Santos（2004） IGM transmission to Lyα photons: TLyα z=6.6: 0.62–0.78 z=7.0: 0.40–0.64 IGM Neutral Fraction z=6.624–36% z=7.032–64% IGM TLyα

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

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

  23. Conclusion • When did reionizationend? • 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.

  24. Outline I. Goal: to address the question, When did reionizationcomplete? II. Approach: LyαEmitters III. Result IV. Conclusion V. Upcoming Projects

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

  26. Upcoming Project (1) Deepen z=7 ImageNB973=24.9  25.4 Obtain z=7.3 ImageNB1005=25.0 or deeper Improved samples z=7 LAEs z=7.3 LAEs Subaru Deep Field 876 arcmin2Suprime-Cam 1 pointing

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

  28. UV LF of LAEs at z=5.7 – 7

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