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Ionized

Narrow-Band Imaging surveys at z=7.7 with WIRCam (CFHT) and HAWK-I (VLT) J.-G. Cuby (LAM) Collaborators : B. Cl ément (LAM), P. Hibon (KIAS) J.Willis (Univ. Victoria), C.Lidman (ESO), S.Arnouts (CFHT), JP.Kneib (LAM), C.Willott (CADC),. Ionized. Neutral. Reionized.

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Ionized

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  1. Narrow-Band Imaging surveys at z=7.7 with WIRCam (CFHT) and HAWK-I (VLT)J.-G. Cuby(LAM) Collaborators : B. Clément (LAM), P. Hibon (KIAS) J.Willis (Univ. Victoria), C.Lidman (ESO), S.Arnouts (CFHT), JP.Kneib (LAM), C.Willott (CADC), ...

  2. Ionized Neutral Reionized From Carilli

  3. Dark Ages Epoch of Reionization Age of Enlightenment • last phase of cosmic evolution to be tested • bench-mark in cosmic • structure formation • indicating the first • luminous structures From Carilli

  4. Re-ionization • When did it start ? • When did it end ? • What sources caused it, … • Gunn-Peterson trough in QSOs • GRBs • UVLF & Lya LF of Lya Emitters (LAEs) • CMB • HI 21-cm

  5. GP trough with QSOs • Only traceable until neutral fraction (HI / H) < 10−3

  6. Re-ionization with GRBs Totani et al. 2005 DLA model with z=6.295, log NHI = 21.62 From Totani

  7. UVLF & Lya LF of Lya Emitters (LAEs)Current status

  8. 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] From Ota

  9. luminosity functions Far-UV Luminosity function of LBGs Data from SDF Yoshida et al. 2006, ApJ, in press (z=4, 5) Shimasaku et al. 2005, PASJ, 57, 447 (z=6) Bright LBGs decrease in number with redshift (see however Iwata et al. 2003, PASJ, 55, 415) From Shimasaku

  10. luminosity functions Lyman α luminosity function of LAEs Data from SXDF Ouchi, Murozono et al. 2006 In prep Data from SDF Shimasaku et al. 2006, PASJ, 58, 313 (z=5.7) Number density of LAEs unchanged over 3<z<6 Fraction of ‘young’ galaxies increases with redshift? From Shimasaku

  11. … but the number density decreases beyond z=5.7 Data for z=5.7 : Shimasaku et al. 2006, PASJ, 58, 313 (SDF) Ouchi et al. in prep (SXDF) Data for z=6.5 : Kashikawa et al. 2006, ApJ, 648, 7 (SDF) Data for z=7.0 : Iye et al. 2006, Nature, 443, 186 (SDF) Ouchi et al. 2006, in press intrinsic evolution of LAEs? Increase in the neutral fraction of the IGM is more likely, as the change in the far-UV LF is much milder. From Shimasaku

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

  13. Going beyond z = 7

  14. 1060 nm 1190 nm Sky Spectra in Emission and Transmission

  15. z = 7.7 survey with WIRCAM The DATA • NB 1.06 mm, 40 hrs • u*, g’, r’, i’, z’ • CFHT-LS data (D1) • J & Ks • 5 hrs WIRCAM • 3.6, 4.5 mm • SWIRE (IRAC)

  16. Candidate selection • Criteria: • Detection in NB1, NB2, NB1+2. • Non-detection in optical bands (u,g, r, i, z) • u* - NB1.06 > 2.2 • g’ - NB1.06 > 2.6 • r’ - NB1.06 > 2.3 • i’ - NB1.06 > 2.1 • z’ - NB1.06 > 1.0 • J - NB1.06 > -0.5 • A Posteriori Rejection of the contaminants Optical – NB > 4 for the brightest objects Optical – NB > 3

  17. u Chi2 z NB1+2 J Ks A WIRCam candidate

  18. 7 LAE at z = 7.7 candidates • 1 LBG at z > 7 candidate

  19. LF of z = 7.7 Lya LAE • Assumes that the 7 candidates are real • Most serious candidates build up the bright end of the z=7.7 LF -> bright end robust Hibon et al. submitted

  20. Possible sources of contamination • EROs • K band rejection • Low z interlopers • Ha at z = 0.61 • [OIII] at z = 1.1 • [OII] at z = 1.8 • High z (> 7) LBGs • Electronic crosstalk • Guide windows • Persistence • Noise • Transients • 2 epoch data • T-dwarfs

  21. Example of electronic cross-talk on WIRCam

  22. Possible LFs if contamination • Samples of 4 objects out of 7, assuming 3 contaminants • 20 ‘Bright’ samples w two brightest objects • 10 ‘Intermediate’ samples w/o brightest but w second brightest • 5 ‘Faint’ samples w/o the two brightest objects • More evolution in density than in luminosity for ‘Full’, ‘Bright’ and ‘Intermediate’ samples Bright Faint Intermediate Iye et al., z = 6.96

  23. LyαLF（Model vs.Observation） Implications LAE evolution model(Kobayashi et al.2007) • Using model from Kobayashi, we derive a neutral hydrogen fraction: • xHI = 0.4 for the ‘Full’ sample • xHI = 0.6 for the ‘Faint’ sample Number densitylog[n(>L) Mpc-3] Increase in HI Lyα Luminosity log[L(Lyα) erg/s]

  24. On going program with HAWK-I (I) • z = 7.7 • 100 hrs LP • 2008-2009 • 4 fields • 2 empty fields • 2 clusters

  25. On going program with HAWK-I (II) Field: Cluster : 4 pointings more efficient in number of targets than a single pointing for texp ~ 100 hrs. A few 10s of LAEs expected

  26. Conclusions • Spectroscopic follow-up (badly needed...) • MOIRCS, x-shooter • If bright objects are confirmed, more evolution in density than in luminosity (within the Schechter formalism) • Future work: • 2008 : HAWK-I • 2009 : VISTA • One NB1190 program in UltraVista (5-yr LP) • 2013 : JWST • 2018 : ELT (EAGLE)

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