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Deep Survey of z=7 Lyα Emitters with the new red-sensitive CCDs on Subaru / Suprime-Cam

Deep Survey of z=7 Lyα Emitters with the new red-sensitive CCDs on Subaru / Suprime-Cam. Kazuaki Ota Cosmic Radiation Laboratory RIKEN M. Iye, N. Kashikawa (NAOJ), M. Ouchi (Carnegie), K. Shimasaku (Univ. of Tokyo), T. Totani (Kyoto Univ.), M.A.R. Kobayashi, T. Morokuma (NAOJ),

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Deep Survey of z=7 Lyα Emitters with the new red-sensitive CCDs on Subaru / Suprime-Cam

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  1. Deep Survey of z=7 Lyα Emitters with the new red-sensitive CCDs on Subaru / Suprime-Cam Kazuaki OtaCosmic Radiation LaboratoryRIKEN M. Iye, N. Kashikawa (NAOJ), M. Ouchi (Carnegie), K. Shimasaku (Univ. of Tokyo), T. Totani (Kyoto Univ.), M.A.R. Kobayashi, T. Morokuma (NAOJ), M. Nagashima (Nagasaki Univ.), H. Furusawa, T. Hattori (SubaruTelescope), N. Kodaka, A. Harayama (Saitama Univ.) Reionization @ Ringberg

  2. Outline I. Background & Motivation (1) Reionization probed by Lyα emitters at z ≿ 6 (2) Weaknesses in the previous z=7 Lyα emitter survey II. Solution: - New deeper z=7 survey in SXDS Field III. Result: - Deeper Lyα LF and Constraint on XHI IV. Conclusion

  3. Outline I. Background & Motivation (1) Reionization probed by Lyα emitters at z ≿ 6 (2) Weaknesses in the previous z=7 Lyα emitter survey II. Solution: - New deeper z=7 survey in SXDS Field III. Result: - Deeper Lyα LF and Constraint on XHI IV. Conclusion

  4. Neutral Fraction vs Redshift Neutral Fraction XHI z=6.3, 6.7 z=7z=6.6Lyα Emitters Redshift z Fan et al.2006

  5. Reionization Probed by Lyα emitters: Lyα LF LyαLFdeclines. Number & Lyα luminosity density decrease. n(z=6.6)/n(z=5.7)=0.24 n(z=7.0)/n(z=6.6)=0.17 to L(Lya) > 1043 erg/s Subaru Deep Field Project Subaru Telescope Suprime-Cam

  6. 3 weakneses in the previous z=7 survey (1) Depth was shallow. (2) Sample is small. (3) Only one sky field was surveyed. Subaru Deep Field876 arcmin2 L(Lyα) > 1043 erg/s Only 1 Lyα emitter

  7. Outline I. Background & Motivation (1) Reionization probed by Lyα emitters at z ≿ 6 (2) Weaknesses in the previous z=7 Lyα emitter survey II. Solution: - New deeper z=7 survey in SXDS Field III. Result: - Deeper Lyα LF and Constraint on XHI IV. Conclusion

  8. New fully depleted CCDs on Subaru / Suprime-CamMore sensitive to 0.9 – 1 μm light Transmission, QE, flux Wavelenght (A) >2 x more sensitive to z=7 Lyα

  9. Target Sky Region Subaru/XMM-NewtonDeep Survey Field（SXDS） Spitzer 13 hours imagingNB973 = 25.4 (5σ)(previously, 24.9) UKIDSS-UDS Oct, Nov 2008SubaruThis Work

  10. Narrowband filter to detect z=7 Lyα emitters Filter Response z=7Lyα NB973 Wavelength(Å) λc=9755Å⊿λ=200Å

  11. New z=7 Lyα emitter candidates B V R i’ NB816 z’ NB921 NB973 No detection (< 3σ) NB973 ≤ 25.4 (5σ) Equivalently, z’ – NB973 > 1 ~

  12. Color Selection Visual Inspection 10z=7 Lyα emittercandidates （tentative) Remove spurious & transient objects using images taken in different months #Candidates ≤ 10

  13. Outline I. Background & Motivation (1) Reionization probed by Lyα emitters at z ≿ 6 (2) Weaknesses in the previous z=7 Lyα emitter survey II. Solution: - New deeper z=7 survey in SXDS Field III. Result: - Deeper Lyα LF and Constraint on XHI IV. Conclusion

  14. Lyα Luminosity FunctionAssumption (1): F(Lyα) = F(NB filter) Neutral Fractionz=7.0~49% ■△ z=5.7 ●▲ z=6.6 ◆ z=7.0 xHI=0.0 Observed DensitiesnLyα: 3.9x10-5 Mpc-3 ρLyα: 4.7x1038 erg/s/Mpc-3 xHI=0.4 xHI=0.6 Predicted Densities when xHI=0(Kobayashi et al. 2007 LAE evolution Model)nLyα: 1.1x10-4 Mpc-3 ρLyα: 9.5x1038 erg/s/Mpc-3 Attenuated Schechter LFs(Santos 2004) >6x1042 erg/s

  15. Fraction of Lyα flux in NB filter flux F(Lyα) ~ 0.7 x F(NB973) NB973 Filter Total Flux Spectrum F(Lyα) 70% F(Lyα) 30% F(UV) F(NB973)= F(Lya) + F(UV)

  16. Lyα Luminosity Function: Assumption (2): F(Lyα) = 0.7 x F(NB973) Neutral Fractionz=7.0~66% ■△ z=5.7 ●▲ z=6.6 ◆ z=7.0 xHI=0.0 Observed DensitiesnLyα: 3.9x10-5 Mpc-3 ρLyα: 4.7x1038 erg/s/Mpc-3 xHI=0.4 xHI=0.6 Predicted Densities when xHI=0(Kobayashi et al. 2007 LAE evolution Model)nLyα: 1.8x10-4 Mpc-3 ρLyα: 1.2x1039 erg/s/Mpc-3 Attenuated Schechter LFs(Santos 2004) >4.2x1042 erg/s

  17. Neutral Fraction vs Redshift Neutral Fraction XHI z=6.3, 6.7 z=7z=6.6Lyα Emitters Redshift z Fan et al.2006

  18. Outline I. Background & Motivation (1) Reionization probed by Lyα emitters at z ≿ 6 (2) Weaknesses in the previous z=7 Lyα emitter survey II. Solution: - New deeper z=7 survey in SXDS Field III. Result: - Deeper Lyα LF and Constraint on XHI IV. Conclusion

  19. Conclusion Improved statistics & depth, Observed different sky field (1) Number & Lyα luminosity densities of Lyα emitters decrease from z=5.7 and 6.6 to z=7. (2) Neutral Fraction at z=7 is XHI≿ 0.49 – 0.66. (3) Reionization seems not to be complete at z=7.

  20. We are now challenging z=7.3 Lyα Transmission, QE, flux Wavelenght (A) Final survey that can be done by Suprime-Cam + New CCDs

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