Deep Survey of z=7 Ly Emitters with the new red-sensitive CCDs on Subaru / Suprime-CamKazuaki 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), M. Nagashima (Nagasaki Univ.), H. Furusawa, T. Hattori (SubaruTelescope),N. Kodaka, A. Harayama (Saitama Univ.)Reionization @ Ringberg

OutlineI. Background & Motivation (1) Reionization probed by Ly emitters at z 6(2) Weaknesses in the previous z=7 Ly emitter survey

II. Solution: - New deeper z=7 survey in SXDS Field

III. Result: - Deeper Ly LF and Constraint on XHI

IV. Conclusion

OutlineI. Background & Motivation (1) Reionization probed by Ly emitters at z 6(2) Weaknesses in the previous z=7 Ly emitter survey

II. Solution: - New deeper z=7 survey in SXDS Field

III. Result: - Deeper Ly LF and Constraint on XHI

IV. Conclusion

Fan et al.2006Redshift zNeutral Fraction XHI z=7 z=6.6 Ly EmittersNeutral Fraction vs Redshift z=6.3, 6.7

Reionization Probed by Ly emitters: Ly LFNumber & Ly luminosity density decrease.

n(z=6.6)/n(z=5.7)=0.24n(z=7.0)/n(z=6.6)=0.17 to L(Lya) > 1043 erg/s

Ly LF declines.Subaru Deep Field ProjectSubaru Telescope Suprime-Cam

3 weakneses in the previous z=7 survey(1) Depth was shallow.(2) Sample is small.(3) Only one sky field was surveyed.

OutlineI. Background & Motivation (1) Reionization probed by Ly emitters at z 6(2) Weaknesses in the previous z=7 Ly emitter survey

II. Solution: - New deeper z=7 survey in SXDS Field

III. Result: - Deeper Ly LF and Constraint on XHI

IV. Conclusion

Wavelenght (A)New fully depleted CCDs on Subaru / Suprime-Cam More sensitive to 0.9 1 m lightTransmission, QE, flux>2 x more sensitive to z=7 Ly

Target Sky RegionSubaru/XMM-Newton Deep Survey FieldSXDS

z=7 LyFilter ResponseWavelength()NB973Narrowband filter to detect z=7 Ly emittersc=9755=200

New z=7 Ly emitter candidatesNo detection (< 3) NB973 25.4 (5) B V R i NB816 z NB921 NB973Equivalently, z NB973 > 1 ~

Remove spurious& transient objects using images taken in different months Color Selection Visual Inspection

10 z=7 Ly emitter candidatestentative) #Candidates 10

OutlineI. Background & Motivation (1) Reionization probed by Ly emitters at z 6(2) Weaknesses in the previous z=7 Ly emitter survey

II. Solution: - New deeper z=7 survey in SXDS Field

III. Result: - Deeper Ly LF and Constraint on XHI

IV. Conclusion

Ly Luminosity Function Assumption (1): F(Ly) = F(NB filter) xHI=0.0xHI=0.4xHI=0.6Attenuated Schechter LFs (Santos 2004)Neutral Fraction z=7.0 ~49% Observed Densities nLy: 3.9x10-5 Mpc-3 Ly: 4.7x1038 erg/s/Mpc-3 Predicted Densitieswhen xHI=0 (Kobayashi et al. 2007 LAE evolution Model) nLy: 1.1x10-4 Mpc-3 Ly: 9.5x1038 erg/s/Mpc-3 >6x1042 erg/s z=5.7 z=6.6 z=7.0

NB973 Filter Total FluxSpectrumFraction of Ly flux in NB filter fluxF(Ly) ~ 0.7 x F(NB973) F(UV)F(NB973) = F(Lya) + F(UV)70%F(Ly)30%F(Ly)

Ly Luminosity Function: Assumption (2): F(Ly) = 0.7 x F(NB973) xHI=0.0xHI=0.4xHI=0.6Attenuated Schechter LFs (Santos 2004)Neutral Fraction z=7.0 ~66% Observed Densities nLy: 3.9x10-5 Mpc-3 Ly: 4.7x1038 erg/s/Mpc-3 Predicted Densitieswhen xHI=0 (Kobayashi et al. 2007 LAE evolution Model) nLy: 1.8x10-4 Mpc-3 Ly: 1.2x1039 erg/s/Mpc-3 >4.2x1042 erg/s z=5.7 z=6.6 z=7.0

Fan et al.2006Redshift zNeutral Fraction vs RedshiftNeutral Fraction XHIz=7 z=6.6 Ly Emitters z=6.3, 6.7

OutlineI. Background & Motivation (1) Reionization probed by Ly emitters at z 6(2) Weaknesses in the previous z=7 Ly emitter survey

II. Solution: - New deeper z=7 survey in SXDS Field

III. Result: - Deeper Ly LF and Constraint on XHI

IV. Conclusion

Conclusion

(1) Number & Ly luminosity densities of Ly 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.

Improved statistics & depth, Observed different sky field

Wavelenght (A)We are now challenging z=7.3 LyTransmission, QE, fluxFinal survey that can be done by Suprime-Cam + New CCDs