≲≳WFMOSによる銀河進化研究（ショートコメント）

大内 正己(Carnegie Institution of Washington)

Synergy with HyperSuprime-Cam (HSC)~1.5 degFoV of HSC (+WFMOS)

Subaru/HyperSuprime-Cam

FoV of Suprime
FoV of FOCASFoV of HSC (+CCDs conf.)Subaru/HyperSuprime-Cam: (FoV~1.5deg diam: x10
Suprime-Cam) is being developed. Planned FL in 2011.
 Powerful for various studies from cosmology, galaxy formation,

Galactic astronomy.

The size of HSC FoV just fits to that of WFMOS (~1.5degdiam) sharing the Subaru top-end hub+PFU.
→Great synergy between HSC and WFMOS!!
1) Determination of Luminosity Function at z<7.5
Critical for cosmic reionization and galaxy formation
Lya LF of Lya emitters at z=6.6

UV LF of dropout galaxies at z=5

No evolution?
?
Decrease

Lya LF at z~7 :Evolved? → signature of reionization (Kashikawa+06)
 No evolution? → no signature of reioinzation (Malhotra+04) Field variance? ( Hu+06)


UV LF at z=5-7 at the bright end
Evolution → signature of hierarchical structure formation(e.g. Ouchi+04, Bouwens+07)
 No evolution → UV-bright galaxies following down-sizing (Iwata+03,07, Giavalisco+05)
Large systematic uncertainties of HSC photometric samples in estimation ofcontamination rates and completeness. (e.g. z~3 LBG LF claim by spec. redshift
survey of VVDS by Le Fevre+05, Paltani+06).

2) Constraining Neutral Fraction with Lya Profiles
Lyα line profiles of galaxies atz=8 (Model prediction)
IntrinsicLyα

z=6.6Composite ofKeck/DEIMOS Spectra

absorbed

Dijkstra et al. (2007)
Kashikawa et al. (2006)

Lya profiles give constraints on neural fraction of IGM in the epoch of reionization.
Suprime-Cam+DEIMOS studies: Based on a composite of ~10 spectra of Lya emitters at z=6.5
Lyα profile is well explained by a galactic wind model. No significant feature of neutral IGM isfound in a Lyα emission line... → No constraints on reionization (Kashikawa +06).

Higher S/N spectra (i.e. more objects for stacking analysis) with mediumhigh spectral resolution (R~3000-4000) are needed.

3) Mapping out high-z
Universe for tracing
large-scale structuresand proto-clusters
N=401

Ouchi et al.
2005
WFMOS FoV

concentration B

z=5.7±0.05

5σ-level excess

concentration A

white circles=No spec-z

Suprime-Cam has revealed the filamentary LSSs at z~6. Proto-cluster
candidates are identified with FOCAS (+DEIMOS; Ouchi et al. 2005).
A number of photometically selected Lya emitters have no spec-z.
The 3-dimensional view of the high-z Universe has not obtained yet!!

4) Statistics of faint emission/absorption lines
in high-z galaxies
Composite spectrum of LBGs
Composite spectra of LAEs

Ouchi et al. (2008)

Ando et al. (2007)HeII emission line for identifying primeval galaxies (coldaccretion and popIII)

 No HeII lines from premeval population are detected in spec.(+compositespec.; e.g. Dawson+07,Ouchi+08; c.f. Jimenez & Haiman 2006)

UV absorption lines to constrain metallicity. Composite spectraof 8 LBGs at z~5 (Ando+07, see+Shapley+03).→ More spectra
to give strong constraints on the history of metal enrichment.

5) Identifying a rare population (a) :Extended Lyα sources at z<7.5Ouchi et al. ApJ submitted17kpc!!

Large area WFMOS spectroscopy will allow us not only to carry out statisticalstudies, but also to identify rare interesting objects at high-z.
HSC+WFMOS surveys will provide a number of extended Lya sources (Lyablobs).
Up to z~7. An example of z=6.595. ~3” (=17kpc) spatial extension in a narrowband with very bright Lya emission (L[Lya]=4x1043 erg/s) + Spitzer detection.
→ massive galaxy formation with outflow? Key for understanding early galaxy
formation, metal enrichment, reionization.

5) Identifying a rare population (b) :Gravitationally lensed high-z galaxies

The brightest (i=19.0) lensed galaxy
found in the SDSS field (z=2.7)
Allam et al. (2007)

Expected number of strongly lensedgalaxies by HSC surveys(Oguri et al.) Strongly lensed objects in HSC fields (c.f. galaxy-cluster) We expect ~400 lensed galaxy candidates from HSC

surveys.WFMOS identification by spending sparefibers.→ studying halo profiles+ giving lensed high-z
galaxies for studies with TMT-AO (+JWST,SPICA).

SummaryHyper Suprime-Cam (HSC) Surveys
WFMOS spectroscopy is quite suitable for objects found by HSC surveys

Science drivers of WFMOS spectroscopy in the HSC fields
1. Determination of UV+Lyaluminosity functions at z<7.5
2. Lya profile for consraining cosmic reionization
3. Mapping the high-z Universe for understanding strucure formation
4. Statistics of high-z UV spectra for primeval gal. and dynamics/metal abundance
5. Spc. Identification of rare extended LAEs and gravitationally-lensed obj.

(質疑応答 — Q:質問, A:回答, C:コメント — 氏名無しは発表者の発言, 敬称略)(Q) スリット分光に比べて、ファイバー分光は効率が悪くなると思うがどうか？ (長尾)(A) ファイバー径を絞って、S/N が上がるように工夫する必要がある。また、ファイバーによるスループットロス
は FMOS の例をみても 50 ％までは行かないと思うので、WFMOS の高い multiplicity で十分ロスを補えるだろう。
(A) ファイバーによるスループッットロスは短波長側ほど大きくなるので、FMOS と単純に比較してはならないだろう。589nm だと数％のロスになる。 (高見)(C) 夜光の差し引きが一番大変。径を小さくすると夜光が入り難くなるので、多少はましになるだろう。 (大藪)(C) R=3000 以上など、波長分解能が高くなれば、夜光の間を見ることができるので、引きやすくなるだろう。