11

Narrow-Band Imaging Narrow-Band Imaging surveys at z=7.7 with WIRCam surveys at z=7.7 with WIRCam

(CFHT) and HAWK-I (VLT)(CFHT) and HAWK-I (VLT)

J.-G. CubyJ.-G. Cuby(LAM)(LAM)

Collaborators : B. Cl Collaborators : B. Clémentément (LAM), P. Hibon (KIAS) J.Willis (Univ. (LAM), P. Hibon (KIAS) J.Willis (Univ. Victoria), C.Lidman (ESO), S.Arnouts (CFHT), JP.Kneib (LAM), Victoria), C.Lidman (ESO), S.Arnouts (CFHT), JP.Kneib (LAM),

C.Willott (CADC), ...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-ionizationRe-ionization

44

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 QSOsGunn-Peterson trough in QSOs GRBsGRBs UVLF & LyUVLF & Ly LF of Ly LF of Ly Emitters (LAEs) Emitters (LAEs) CMBCMB HI 21-cmHI 21-cm

GP trough with QSOsGP trough with QSOs

55

Only traceable until neutral Only traceable until neutral fraction (HI / H) fraction (HI / H) < 10< 10−3−3

Re-ionization with GRBsRe-ionization with GRBs

Totani et al. 2005

DLA model with z=6.295, log NHI = 21.62

From Totani

UVLF & LyUVLF & Ly LF of Ly LF of Ly Emitters (LAEs) Emitters (LAEs)

Current statusCurrent status

77

Lyα LF （ Observed ）z=5.7Phot■z=6.6Phot●z=6.6Spec▲z=7.0Spec◆

Lyα Luminosity log[L(Lyα) erg/s]

Nu

mb

er d

ensi

ty lo

g[n

(>L

) M

pc-

3 ]

Decline in n(>L) ・ galaxy evolution?・ increase in HI?・ both?

z=7LAEdetectionlimit

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. 2006In prep

Number density of LAEs unchanged over 3<z<6Fraction 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 ARAARedshift z

Reionization HistoryN

eutr

al F

ract

ion

XH

I

z=7z=6.6Lyα Emitters

Going beyond z = 7Going beyond z = 7

1313

1414

1060 nm 1190 nm

Sky Spectra in Emission and Transmission

z = 7.7 survey with WIRCAMz = 7.7 survey with WIRCAM

The DATAThe DATA

NB 1.06 NB 1.06 m, 40 hrsm, 40 hrs u*, g’, r’, i’, z’u*, g’, r’, i’, z’

CFHT-LS data (D1)CFHT-LS data (D1) J & KsJ & Ks

5 hrs WIRCAM5 hrs WIRCAM 3.6, 4.5 3.6, 4.5 mm

SWIRE (IRAC)SWIRE (IRAC)

1515

1616

Candidate selectionCandidate selectionInstrumentInstrument BandBand Int. time Int. time

(hrs)(hrs)Lim. Mag.Lim. Mag.””

MegaCamMegaCam u*u* 1010 27.427.4

MegaCamMegaCam gg’’ 11.511.5 27.827.8

MegaCamMegaCam rr’’ 2727 27.527.5

MegaCamMegaCam ii’’ 5555 27.327.3

MegaCamMegaCam zz’’ 2626 26.226.2

WIRCamWIRCam NB 1st epochNB 1st epoch 2020 24.824.8

WIRCamWIRCam NB 2nd epochNB 2nd epoch 2020 24.924.9

WIRCamWIRCam NB combinedNB combined 4040 25.225.2

WIRCamWIRCam JJ 4.54.5 24.724.7

WIRCamWIRCam KsKs 5.65.6 24.324.3

IRACIRAC 3.6 µm3.6 µm 33 22.222.2

IRACIRAC 4.5 µm4.5 µm 33 21.521.5Optical – NB > 3Optical – NB > 4 for the brightest objects

Criteria:Criteria: DDetection inetection in NB1, NB2, NB1, NB2,

NB1+2.NB1+2. Non-detection in optical Non-detection in optical

bands (u,g, r, i, z)bands (u,g, r, i, z) u* - NB1.06 > 2.2u* - NB1.06 > 2.2 g’ - NB1.06 > 2.6g’ - NB1.06 > 2.6 r’ - NB1.06 > 2.3r’ - NB1.06 > 2.3 i’ - NB1.06 > 2.1i’ - NB1.06 > 2.1 z’ - NB1.06 > 1.0z’ - NB1.06 > 1.0

J - NB1.06 > -0.5J - NB1.06 > -0.5 A Posteriori Rejection of A Posteriori Rejection of

the contaminantsthe contaminants

1717

A WIRCam candidateA WIRCam candidate

u Chi2 z

NB1+2 J Ks

7 LAE at 7 LAE at z = 7.7 z = 7.7 candidatescandidates

1 LBG at 1 LBG at z > 7 z > 7 candidatecandidate

1818

1919

LF of z = 7.7 LyLF of z = 7.7 Ly LAE LAE

Assumes that the 7 Assumes that the 7 candidates are realcandidates are real

Most serious Most serious candidates build up the candidates build up the bright end of the z=7.7 bright end of the z=7.7 LFLF

-> bright end robust-> bright end robust

Hibon et al. submittedHibon et al. submitted

Possible sources of contaminationPossible sources of contamination

Electronic crosstalkElectronic crosstalk Guide windowsGuide windows

PersistencePersistence NoiseNoise

TransientsTransients 2 epoch data2 epoch data

T-dwarfsT-dwarfs

2020

EROsEROs K band rejectionK band rejection

Low z interlopersLow z interlopers Ha at z = 0.61Ha 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) LBGsHigh z (> 7) LBGs

2121

Example of electronic cross-talk Example of electronic cross-talk on WIRCamon WIRCam

Possible LFs if contaminationPossible LFs if contamination

Samples of 4 objects out of Samples of 4 objects out of 7, assuming 3 contaminants7, assuming 3 contaminants 20 ‘Bright’ samples w two 20 ‘Bright’ samples w two

brightest objectsbrightest objects 10 ‘Intermediate’ samples w/o 10 ‘Intermediate’ samples w/o

brightest but w second brightest but w second brightestbrightest

5 ‘Faint’ samples w/o the two 5 ‘Faint’ samples w/o the two brightest objectsbrightest objects

More evolution in density More evolution in density than in luminosity for ‘Full’, than in luminosity for ‘Full’, ‘Bright’ and ‘Intermediate’ ‘Bright’ and ‘Intermediate’ samplessamples

2222

Bright

IntermediateFaint

Iye et al., z = 6.96

ImplicationsImplications

Using model from Using model from Kobayashi, we Kobayashi, we derive a neutral derive a neutral hydrogen fraction:hydrogen fraction: xxHIHI = 0.4 for the = 0.4 for the

‘Full’ sample‘Full’ sample xxHIHI = 0.6 for the = 0.6 for the

‘Faint’ sample‘Faint’ sample

2323

Lyα Luminosity log[L(Lyα) erg/s]

LAE evolution model　　 (Kobayashi et al.2007)

Num

ber

dens

ity

log[

n(>

L) M

pc-3]

Increase in HI

Lyα LF （ Model vs. Observation ）

On going program with HAWK-I (I) On going program with HAWK-I (I) z = 7.7z = 7.7 100 hrs LP100 hrs LP

2008-20092008-2009

4 fields4 fields 2 empty fields2 empty fields 2 clusters2 clusters

2424

2525

On going program with HAWK-I (II)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

2626

ConclusionsConclusions

Spectroscopic follow-up (badly needed...)Spectroscopic follow-up (badly needed...) MOIRCS, x-shooterMOIRCS, x-shooter

If bright objects are confirmed, more evolution in density If bright objects are confirmed, more evolution in density than in luminosity (within the Schechter formalism)than in luminosity (within the Schechter formalism)

Future work:Future work: 2008 : HAWK-I2008 : HAWK-I 2009 : VISTA2009 : VISTA

One NB1190 program in UltraVista (5-yr LP)One NB1190 program in UltraVista (5-yr LP)

2013 : JWST2013 : JWST 2018 : ELT (EAGLE)2018 : ELT (EAGLE)