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),...

Ionized Neutral Reionized From Carilli

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

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

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

Re-ionization with GRBs Totani et al DLA model with z=6.295, log N HI = From Totani

UVLF & Ly  LF of Ly  Emitters (LAEs) Current status 7

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

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

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

… but the number density decreases beyond z=5.7 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. Data for z=6.5 : Kashikawa et al. 2006, ApJ, 648, 7 (SDF) Data for z=5.7 : Shimasaku et al. 2006, PASJ, 58, 313 (SDF) Ouchi et al. in prep (SXDF) Data for z=7.0 : Iye et al. 2006, Nature, 443, 186 (SDF) From Shimasaku

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

Going beyond z = 7 13

nm 1190 nm Sky Spectra in Emission and Transmission

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

16 Candidate selection InstrumentBand Int. time (hrs) Lim. Mag.  ”   MegaCamu* MegaCam g’g’g’g’ MegaCam r’r’r’r’ MegaCam i’i’i’i’ MegaCam z’z’z’z’ WIRCam NB 1st epoch WIRCam NB 2nd epoch WIRCam NB combined WIRCamJ WIRCamKs IRAC 3.6 µm IRAC 4.5 µm Optical – NB > 3 Optical – NB > 4 for the brightest objects Criteria: Criteria: Detection in NB1, NB2, NB1+2. Detection in NB1, NB2, NB1+2. Non-detection in optical bands (u,g, r, i, z) Non-detection in optical bands (u,g, r, i, z) u* - NB1.06 > 2.2 u* - NB1.06 > 2.2 g’ - NB1.06 > 2.6 g’ - NB1.06 > 2.6 r’ - NB1.06 > 2.3 r’ - NB1.06 > 2.3 i’ - NB1.06 > 2.1 i’ - NB1.06 > 2.1 z’ - NB1.06 > 1.0 z’ - NB1.06 > 1.0 J - NB1.06 > -0.5 J - NB1.06 > -0.5 A Posteriori Rejection of the contaminants A Posteriori Rejection of the contaminants

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

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

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

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

21 Example of electronic cross-talk on WIRCam

Possible LFs if contamination Samples of 4 objects out of 7, assuming 3 contaminants 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 More evolution in density than in luminosity for ‘Full’, ‘Bright’ and ‘Intermediate’ samples 22 Bright Intermediate Faint Iye et al., z = 6.96

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

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

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

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