1. Deep Surveys for High-z Galaxies with Hyper Suprime-Cam M. Ouchi (OCIW), K. Shimasaku (U. Tokyo), H. Furusawa (NAOJ), & HSC Consortium ≲ ≳≲ ≳

2. 141h -1 Mpc Discovery of the most distant galaxy at z=7 (Iye+06) Signature of Cosmic Reionization (kashikawa+06,Shimasaku+06) Decrease of UV luminosity function (Ouchi+04,Yoshida+06,cf Iwata+03/7) First Census of Lya Blobs (Matsuda+04,Saito+06) Discovery of Large-Scale Struc.& Proto-clusters (Shimasaku+03,Ouchi+05) Detection of 1&2 halo terms (Ouchi+05, Kashikawa+06,Hamana+06) UV bright population for deep Spec. (Ando+04/06/07,Nagao+04/05) Identification of substructure around High-z clusters (Kodama+01, Nakata+05,Tanaka+06/07) Suprime-Cam Image (1 pointing: 918 arcmin 2 ) HST/ACS(1pointing) HST/ACS has (had) a superb spatial resolution +sensitivity, but the survey speed, S, for high-z galaxies is S(Suprime)  10 x S(HST)

3. HSC Surveys for High-z Galaxies Constraining reionization from large statistics (sample size and survey volume) Moreover, great statistics of z~6.6 sources (for galaxy formation cosmological implication??) ~800 comoving Mpc at z~6-7 HSC Ultra Deep Survey (UDS) HSC Deep & Wide Survey (DWS) Suprime-Cam (1 FoV) UDS: Hubble Ultra-Deep Field Science (i~28mag; for 0”.5 sources) in a 2 deg 2 and DWS: Subau/XMM Deep Field Science (i~27) in a 10-20 deg 2

4. HSC SC x30 M* HSC SC N expect （ 30hr 1 FoV) x30 y HSC: Powerful for High-z Galaxy Studies x10 Expected number of Lya emittersExpected number of dropout galaxies N expect （ 30hr 1 FoV) Our calculations show the expected numbers of high-z galaxies, N(HSC) and N(SC) are  z~3-6 : N(HSC)~ 10xN(SC) due to the large FoV  z~7 : N(HSC)~ 30xN(SC) due to the large FoV +high red-sensitivity by Hamamatsu CCDs

5. Key Sciences of HSC/UDS and DWS 1. Cosmic reionization 2. Statistics of star-forming galaxies at z=3-7.5 3. Identification of forming galaxy candidates 4. Evolution of dwarf galaxies at z=0-1.5 We do not include science with NIR images, because we have not yet selected target fields with NIR data. At this moment, we consider data with HSC and follow-up spectroscopy.

6. Evolution of neutral fraction of IGM (Fan et al. 2006) 1. Cosmic Reionization z~6: Final stage (GP test;Fan+06) z~11: WMAP3+inst. model(Page+07, Spergel+07) z~6-11: Transition of IGM status ? Cosmic reionization predicted by neumerical simulation (Iliev et al. 2006) Galaxies (blue dots) and ionized bubbles (orange)

7. Cosmic Reionization Probed with Lya Emitters (LAEs) Dijkstra et al. (2007) Lyα line profiles of galaxies at z=8 (Model prediction) Intrinsic Ly α absorbed McQuinn et al. (2007) Intrinsic LAE dist. Obsrvd LAE dist. Neutral IGM Ionized IGM 90 Mpc Neutral hydrogen of IGM is constrained by luminosity evolution and clustering properties of Lya emitters (LAEs)

8. Neutral Fraction of IGM with Luminosity Function and Correlation Function of Lya Emitters (LAEs) LF: L*(z=6.5) ~ 0.6 L*(z=5.7) -> x HI ≲ 0.45 (Kashikawa+06) CF: b~3-4 (preliminary) -> x HI ≲ 0.3 (Ouchi et al. in prep.) Weak constraints by large statistical uncertainties and field variance. With HSC, we will obtain robust measurements of LF and CF of Lya emitters complementing deep 21cm observations for HI gas with MWA, LOFAR, and SKA. ? ? ? (Large errors) LF at z=6.6 from Suprime-Cam dataCF at z=6.6 from Suprime-Cam data

9. Only a handful of z~7 dropout galaxies are identified photomerically (e.g. Bouwens & Illingworth 2006).  No UV bright z~7 galaxies with SFR no dust >20 Mo/yr whose volume density is as small as 10 -6 Mpc 3 Even in the era of JWST/ELT, such a rare population cannot be found, due to the limitation of survey area. HSC/UDS+DWS will image an area of 2- 20 deg 2 down to y~26mag (2-10 x UltraVISTA survey).  Determination of the bright-end LF  Identification of rare bright galaxies at z~7 that will be ideal targets for spectroscopy with JWST/ELTs. SFR(Mo/yr)= 30 10 1 UV Luminosity Function at z~7 2. Statistics of star-forming galaxies at z=3-7.5 UV Bright Galaxies at z~7 HST JWST/ELT HSC/UDS HSC/DWS

10. Statistics of z ≲ 6 galaxies Precision measurements of LF and CF  Constraining star-forming galaxies with numerical simulation, halo occupation distribution (HODs) and conditional luminosity func. models z=4 LBG correlation function fit by HOD model (Ouchi+06,Hamana+06) z=4 Mass-luminosity relation by conditional luminosity func. model (Cooray+06)

11. 3. Forming Galaxies (Cooling cloud/PopIII) In the first stage of galaxy formation  Primodial gas become cool and infall into the center of dark halo with cooling radiation (cooling cloud)→ spatially-extended strong Lya emission and weak HeIIλ1640.  Massive star-formation from primodial gas with flat IMF (popIII)→ strong Lya and weak HeIIλ1640 The first stage of galaxy formation is characterized by strong Lya and weak HeII  We should search for strong Lya emitters （ with a large EW), and find forming galaxies Any candidates of forming galaxies at z~3- 7.5? Theoretical models predict  A bright cooling cloud with HeIIλ1640 can be found in a volume of ~10 5 Mpc 3 at z~2-3(Yang et al. 2006).  At z=5, ~1/1000 of cosmic SFR is constibuted by popIII (Trac & Cen 2006) cooling clouds predicted by numerical simulations (Yang et al. 2006) Ly α HeII λ 1640

12. Candidates of forming galaxies?? Ouchi et al. (2007) Cannot be explained by ordinary SF (Salpeter IMF) (Matsuda et al. 2004) Lya blobs at z=3 (size~30-200 kpc) Large Lya EW objects including Lya blobs and compact Lya emitters （ e.g. Matsuda+04, Saito+06, Nilsson+06 ） We see no HeII emission line originated from cooling clouds or popIII (e.g. Dawson+04,Nagao+06,Ouchi+07, c.f. Jemenez+06) EW distribution of Lya emitters

13. Wide-field+high sensitivity are key  Small number density （ cooling cloud~10 -5 Mpc, popIII is less than that? ）  HSC data are appropriate Supply the targets to JWST and TMT for identifying HeII by spectroscopy  Distinguish with HeII from AGN using CIV1549 （ +X-ray data)  Distinguish with HeII from WR- stars using the line width (<1000km/s) Saito et al. 2006 Volume limit of SPCAM search Cooling Cloud+PopIII Search with HSC

14. 4. Evolution of dwarf galaxies at z=0-1.5 Luminosity function of z=1 galaxies in the HUDF Statistics of high-z dwarf galaxies (halo mass from clustering, stellar mass etc.) and characterize building blocks. (spectroscopic follow-up with JWST+TMT)

15. Survey Designs of HSC/UDS and DWS Key Sciences of HSC Deep Surveys 1. Cosmic reionization 2. Statistics of star-forming galaxies at z=3-7.5 3. Wide-field search for forming galaxies 4. Evolution of dwarf galaxies at z=0-1.5 (See the HSC white paper for more details) Your ideas, discussions, and participation are needed!! Summary