Galaxy Evolution and WFMOS

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Galaxy Evolution and WFMOS History of
Galaxies Present-day Universe SDSS WFMOS Survey
of zgt1 Universe K. Shimasaku (University of
Tokyo)
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History of GalaxiesCurrent Understanding
redshift
peak
monotonic decrease
Star Formation Rate Density Msun/yr/Mpc3
first galaxies (z30?)
galaxy morphology
galaxy clusters
reionization (z10?)
birth of Earth
now
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Age of Uniserve (x10 yr)
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z7.0
For high-z universes, our knowledge is limited to
average (and limited) properties of bright
galaxies.
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In the present-day universe, galaxy properties
depend strongly on mass and environment.
Specific SFR vs Stellar Mass for z0 Galaxies
spiral
Specific SFR /Gyr
dwarf
E, S0
Stellar Mass Msun
Brinchmann et al. 2004 (SDSS)
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Theory also predicts that galaxy evolution
depends on mass and environment.
?CDM model ?cold dark matter baryon
primordial fluctuations
primordial fluctuations

• hierarchical growth to more massive galaxies
• complex baryon processes depending on mass,
• environment, and time
• gas cooling and star formation
• feedback to gas
• SN heating ? effective in less massive
  galaxies
• AGN heating ? effective in massive
  galaxies
• environmental effect (galaxies, ICM, UV
  background)

galaxy
feedback
gas
star
cooling
environment
these processes have not been solved may be
missing some important processes
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Sloan Digital Sky Survey A definitive data set
for the present-day universe
mosaic CCD camera
multifiber spectrograph
2.5m survey telescope
- very wide field psteradian (1x108 Mpc for
zlt0.1) - rich photometry 5 bands (ugriz) - huge
number of spectra 106 galaxies, 105 QSOs
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Next Step SDSS-like Survey for zgt1 Universe
Major Science Goal Derive fundamental
properties like age, SFR, metallicity,
dust extinction, morphology, internal
structure, QSO/AGN, SMBH as functions of
redshift, environment, and galaxy mass At zgt1
spectroscopic data are much poorer than imaging
data (cf. CfA vs SDSS for z0 universe). Photomet
ric redshift cannot be a substitute for
spectroscopy. WFMOS can contribute to the above
science, if excellent imaging data pre-exist.
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What can WFMOS do?
WFMOS performance - wide FoV 1.77 deg2 -
high multiplicity 4500obj/FoV - high spec
resolution R3000-40000 - high sensitivity
around 1um For a given observing time, WFMOS
can - observe much more galaxies - observe
with much higher S/N WFMOS is thus suitable for
- statistical studies - rare objects -
clustering and environment - z6-7 surveys
(1um sensitivity) Key point how to supply
good targets to WFMOS
comoving length for 1.5deg
comoving volume for 1.77deg2
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Large-scale structure covered by WFMOS
z1 D90Mpc
z5 D200Mpc
VIRGO Consortium
We should not underestimate cosmic variance. Even
one WFMOS FoV is not wide enough.
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WFMOS Deep Sky Survey (WFDSS)
Area 40 deg2 (4E8 Mpc3/?z1) Targets
galaxies (incl. AGN) at 1ltzlt7.5 Number of
spectra 1,000,000 spectra Number of
nights 100 nights (2hr/targets) Imaging
data for target selection Hyper
Suprime-Cam Deep Surveys (1) Deep
Survey 40deg2, r27.6mag ugrizy
NB (NIR) (2) Ultra Deep Survey
3.5deg2, r28.6mag ugrizy NB
(NIR)
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Number of Targets in WFDSS
Continuum flux-limited samples (color or phot-z)
z1 106 (ilt24 M1.5) z3
3x105 (ilt25 M-20.5) z4 105 (ilt25
M-21.0) z5 104 (zlt25 M-21.4)
z6 103 (zlt25 M-21.7) Lyman alpha
emitters 104 /?z0.1 (NBlt26) 10 Coma-cluster
ancestors per ?z1 Rare objects forming
clusters (SSA22-like, z5.7 cluster-like)
forming galaxies (cooling, pop-III) etc
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Science Cases
For all redshifts spatial distribution ?
environment, dark-halo mass spectra
? SFR, age, metallicity, AGN
multiband imaging ? stellar mass, (SFR, E(B-V),
color) - mass- and environment-dependent
galaxy evolution (for chemical
evolution, see Nagao-sans talk) - cluster
formation, LSS formation - primordial
galaxies (cooling, pop-III) (- number density
of high-z galaxies) For zgt6 - galaxy
properties and reionization processes
(Ouchi-sans talk, Goto-sans talk)
redshift
SFR, Mstar, age, Z, dust, AGN
environment
dark-halo mass
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Importance of Spectroscopy
3D distribution - environment (pairs,
groups, clusters, LSS, ) - cluster and
group finding - spatial correlation
function Physical quantities - age, SFR,
metallicity, AGN, SMBH - accurate
derivation of SED, Mstar, E(B-V), Photometric
redshifts (incl. LBG-like techniques) cannot be a
substitute.
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Existing Spec Surveys are not Large and Deep
Enough
DEEP2 3.5 deg2 30,000 spectra
(0.7ltzlt1.5 1.5E7Mpc3) VVDS 2
deg2? 50,000 spectra at zgt1? zCOSMOS-deep 1
deg2 10,000 spectra (1.5ltzlt3)
Yamada Scale (T. Yamada 2008)
Survey Area Comoving Volume (Mpc3/?z1) Main Targets
1 deg2 E7 galaxy evolution
10 deg2 E8 most luminous objects, clusters, LSS
100 deg2 E9 QSOs, cosmic web
1000 deg2 E10 dark energy survey
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SKA, - FMOS, Hyper Suprime-Cam,
WFMOS, (2) ?????? ???100???????????????????
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