2015/06/03-05 第2回銀河進化研究会@名古屋大学“The Mass Assembly and Color Evolution of
the Milky way-like Galaxies at z~0.5-3.0”○Takahiro Morishita1,2(The Astrophysical Journal, 805,34, 2015)

Takashi Ichikawa1, Masafumi Noguchi1, Masayuki Akiyama1, Shannon G. Patel3,
Masaru Kajisawa4,5, and Tomokazu Obata1
1 Astronomical Institute, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
2 Institute for International Advanced Research and Education, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
3 Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101, USA
4 Graduate School of Science and Engineering, Ehime University, Bunkyo-cho, Matsuyama 790-8577, Japan
5 Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577, Japan

1

Background : Where did we live?

External - Extragalactic study at z<3-4

The Astrophysical Journal, 800:39 (21pp), 2015 February 10

Red nuggets:

Clumpy galaxies:

LBGs:

The Astrophysical Journal, 731:65 (35pp), 2011 April 10

Förster Schreiber et al.

Massive (M*~1011Msun), but small

Massive (M*~1010-11Msun).

(re~1kpc). Dispersion dominated(σ~300-400km/s).

Significant star-formation activity.
No. 1, 2008
AO IMAGING OF LYMAN BREAK GAL
Rotation supported?
Star-formation activity. Disk feature?

The Astrophysical Journal, 757:81 (19pp), 2012 September 20. 1, 2008

Guo et al.

COMPACTNESS OF MASSIVE QUIESCENT GALAXIES AT z ∼ 2.3

Less massive (M*~109-10Msun), not sosmall (~2-5kpc).

Bournaud et al.

L7

Figure 8. Stacked optical spectra for our samples of “clumpy” and “stable” disks, normalized to the same continuum level in the 3800–4800 Å spectral range andto the same number of galaxies per sample, and smoothed with a Gaussian kernel of FWHM 5 Å. Wavelengths at which significant sky lines contaminate a single
spectrum, and thus potentially the stacked spectrum, are indicated: the main emission lines are left unaffected.
alaxies at different look-back times. The (Apanelshows six concentrated (n > 2.5, spheroid like)color version of this figure is available in the online journal.)

LAEs:

Figure 10. Same as Figure 9, but for the three other NIC2 targets: BX 389, BX 610, and BX 482.
ok-back time, from top-left to bottom-right: 3.9, 5.3, 7.4, 9.0, 9.7 and 10.3 Gyr back, respectively).
(A color version of this figure is available in the online journal.)
The brightness
stacked spectrathat theforHβtheemission,
normalized
units. Galaxies are shown with different surface
limitsshow
to accountcosmologicalto the same average continuum level, is marginally (≈20%)
angular size.
detailed
comparison
with the additional information from either the kinematics orstronger in clumpy galaxies than in stable disks(consistent
withis possible for BX 482 with AO-assisted
SINFONIdata.
Both the lower surface brightness
component
higher spatial resolutiondata.
z=0.681z=0.543z=0.895
z=0.649z=0.967z=0.993a somewhat highersSFR). The underlying absorption
is weak

z=0.578z=0.953

M=10.44

M=10.47

M=10.76

We performed two-dimensional Sérsic model fits on both theHα maps and the PSF-matched NIC2 images using GALFIT,
following the procedure described in Section 4.1.1. For BX 482,
we ran fits on the AO-assisted as well as the seeing-limited
erties of the clumps
identified in these two images are studied inHα data. For BX 528 and BX 389, we considered only single
sections, we use the MEx diagram and other diagnostics
to show
Paper II. The central regions of BX 482 also appear to be slightly
component fits since, at the ≈0.′′ 5 resolution of the SINFONI
that the strong [O iii] excitation by clumpy galaxies
brighter inisHa160likely-band emission than in Hα emission.
data, the merger components are unresolved in the former case,⃝⃝
C 2007 The Authors. Journal
C 2007RAS,
MNRASsimply
382,For109–120
AGNcompilation
signature, andcannotbe explained
by
a
low
gas
the other galaxies with lower resolution SINFONI data,
and the southern companion is blended with the primary galaxy
metallicity effect.
the small-scale substructure is smeared out but the overall H160
in the latter. For consistency, fits on the convolved NIC2 images
band and Hα distributions at 0.′′ 4–0.′′ 6 resolution are very similar.
were restricted to a smaller region corresponding to the deepest
For BX 389, the southern companion that is clearly separated
area with effective≈3.′′ 8 × 3.′′ 8 FOV of the SINFONI dataatz=1.085z=1.342z=1.087z=1.095
main galaxy in the original NIC2 imagez=1.220
is still apparent
3.2. MEx Diagnostic from thez=1.094
the 0.′′ 125 pixel−1 scale, and ≈2.′′ 3 × 2.′′ 3 FOV of the AO data at′′−1
at lower resolution as an extension in the outer isophotes. The
0. 05 pixel for M=10.33
BX 482. This reduced area potentially M=10.36
affects
M= 9.32
M= 9.40
M= 9.58
M=10.29well-resolved
SE and NW merger components of BX 528, andFigure 9 shows our clumpy disk and stabledisk samples
the sky background estimates, degenerate with the profile shapebridgeof [Oemissionon the MEx diagram ([O iii]/Hβ versus M∗the; J11).
Theiii] connecting them, blend together andand half-light radius. The smaller FOV as well as the broader
the these
PSF-matched
PSF both contribute to the significantly larger uncertainties for
excitation is clearly higher in clumpy disks, andmostly NIC2
lie image strikingly resembles the fairly
regular and centrally concentrated Hα line map. While in mostthethefits
performed
lower resolution maps compared toabove the empirical dividing line for AGN hostgalaxies,
defined9. Clumpy
and stable disk aresamples on
MExdiagram. on
Thethepositioncases,
the generallarge-scaleFigure
featuresof the morphologies
thosetheThemaps
at theoriginal NIC2 resolution. Table 5of thestacked inside
spectra from
8 is alsoradius
shownusing(stars).
dividinglines′′ stellarin J11.
Stablemass
disk galaxies
have andlowerbetween[O iii]excitations
andg. 2.—Relations between size and (total)stellar(left panel)
the averagedensityeffective
andstellarmass(right and Figure 11 compares
recognizableat ≈0.
5 resolution,
BX 528offers thean Figureexamplereports
thebest-fit
structuralparameters
separate the MEx-SF, MEx-AGN, and MEx-intermediate regions defined in J11.
aremostlyidentified
asnon-AGNgalaxiesontheMEx
diagram;where
thenatureofthesystemcanonlybereliablyassessedel). Large symbols with error bars are the quiescent z ∼ 2.3 galaxies. Small symbols are SDSS galaxies,
with galaxies
nottheonresults
the fromredsequence
light
Hα
with
thoseinfrom
the PSF-matched NIC2 data.
The gray-scaled
backgroundthat
colorsareindicate
theAGN
probability,
calibrated

z=1.094

ution of the, at z ∼ 1.5,
y a factor ofactor of ∼50

and the brighter substructure are comparable between the H160

cases,
slightlyhigherdisks(asconfirmed
by This similarity is reflected
7 C
O9.31
M PA R I SinOboth
N W
ITH
OT
H E RinSstable
AMP
LE
S and
band
Hα9.94emission.
in the nearly
M=
M=
9.51
M=
M=10.08
Hγ and Hδ lines). The [O ii] emission is strongera factor
1.8 multiplicity, and M20 coefficients fromequalbyvaluesof Gini,

M=10.37
5.2. Comparison of Structural Parameters

in totheexplore
stacked clumpy
spectra,while the[Oiii]hereemissiontheanalysisin Section 4.2 (see Figure 7). In the details, there
An interesting point
is how disk
the sizeevolution
found
in clumpy types is a factor 5.2 stronger in areclumpydisks,
andhoweversomenoticeable differences. In particular, a few
for the most massivewiththehigher
size evolution
obbrighter
the galaxies[O iii]/Hβcomparesemission flux
ratio
byofathefactor
3.8.peaks,
Theor clumps, visible in the NIC2 or in the Hα
image
have
no obvious counterparts in the other map. The propserved for galaxiescontinuumwith lower
masses.
comparison
can
done
shape
is quiteThis
similarin both cases.
Inbethefollowing?

M=10.38z=1.094
M=11.07

Trujillo+07,MNRAS; van Dokkum+08,ApJL; Guo+15,ApJ; Forster-Schreiber+11,ApJ; Bournaud+12,ApJ; Akiyama+08,ApJS

only a few high-mass cases lie in the MEx-intermediate or MExusing
the BPTz .∼The0.1 SDSS
galaxies. Thegalaxies
evolution of. The dotted lines indicate the expected
location of galaxies with stellar velocity dispersions of 200,
300,
and diagnostic
500 kmons!1
high-redshift
arethemuch

he Astrophysical Journal Letters, 771:L35 (7pp), 2013 July 10

van Dokkum et al.

Background : Where did we live?

External - Extragalactic study of progenitors

igure 1. (a) Stellar mass density of the universe as a function of galaxy mass, as determined from the SDSS-GALEX z = 0.1 mass function of Moustakas et al.
013). (b) Evolution of the cumulative galaxy mass function from z = 0.1 to z = 3.5 (SDSS-GALEX and Marchesini et al. 2009). The horizontal line indicates a
onstant cumulative comoving number density of 1.1 × 10−3 Mpc−3 . (c) Mass evolution at a constant number density of 1.1 × 10−3 Mpc−3 .
A color version of this figure is available in the online journal.)

alaxies at high redshift that have the same rank order as theMilky Way does at z = 0. The implicit assumption is that rankrder is conserved through cosmic time, or that processes thatreak the rank order do not have a strong effect on the averagemeasured properties. As shown in Leja et al. (2013), the method
ecovers the true mass evolution of galaxies remarkably well in
mulations that include merging, quenching, and scatter in therowth rates of galaxies.
The present-day stellar mass of the Milky Way is approximately 5 × 1010 M⊙ (Flynn et al. 2006; McMillan 2011). Usinghe SDSS-GALEX stellar galaxy mass function of Moustakas
t al. (2013), we find that galaxies with masses > 5 × 1010 M⊙
ave a number density of 1.1 × 10−3 Mpc−3 . We then trace
he progenitors of these galaxies by identifying, at each redhift, the mass for which the cumulative number density is.1 × 10−3 Mpc−3 (see Figure 1(b)). We used the Marchesinit al. (2009) mass functions as they are complete in the relevant
mass and redshift range; we verified that the results are similar
when other mass functions are used (Ilbert et al. 2013; Muzzin
t al. 2013).
The stellar mass evolution for galaxies with the rank order

②

①

③

z~0

of the form①

log(MMW ) = 10.7 − 0.045z − 0.13z2 .

(1)

Based on the variation between mass functions of different
authors, and the results of Leja et al. (2013), we estimate thatthe uncertainty in the evolution out to z ∼ 2.5 is approximately
0.2 dex.11 More than half of the present-day mass was assembled
in the 3 Gyr period between z = 2.5 and z = 1, and as we show
later the mass growth is likely dominated by star formation at
all redshifts. The mass evolution is significantly faster than thatof more massive galaxies (van Dokkum et al. 2010; Patel et al.
2013), consistent with recent results of Muzzin et al. (2013).

②

③

z~3

3. MILKY WAY PROGENITORS FROM z = 0 TO z = 2.5
3.1. Rest-frame Images

Having determined the stellar mass evolution with redshift,
we can now select galaxies in mass bins centered on thisevolving mass and study how their properties changed. We
selected galaxies in GOODS-North and GOODS-South asvan Dokkum+10,13,ApJ; Patel+13,ApJ; Marchesini+14,ApJ; Leja+13,ApJ

Background : Where did we live?

March 20

External - Extragalactic study of progenitors
Leja, van Dokkum, & Franx

The Astrophysical Journal, 766:33 (12pp), 2013 March 20

our best theoreticalks on a broad scale,n which it is possible
galaxies. In addition,
he SAM accurately
kes the SAM usefuls of number density
to err.
er density selection
rror. In Section 3, weo et al. (2011) SAM,
n is applied to these
median stellar masse it. In Section 5, weby inferred velocity
ion 6, the suitability
niverse is discussed.
s−1 Mpc−3 through-Y SELECTION

and potential pitfalls
here. As describedat a constant numberr density of galaxies
mass evolution ofhift evolution of thensity selection thus
pendent stellar massgalaxies at a constantadvantage of being
1). Additionally, thear mass rank order oftime, then tracking
ill be effective.
igate the conditions
der holds. If stellar
tonically increasing
rank order will be②

z~0

Figure 1. Stellar mass assembly histories are shown for four representative
galaxies from the Guo et al. (2011) SAM output. Despite similar initial stellar
masses, their mass growth histories vary substantially. The primary mechanisms
for stellar mass growth (major and minor mergers, star formation) are labeled.
Furthermore, the processes interfering with number density selection—scatterin growth rate, merged galaxies, and quenching—are also labeled. In order tofor constant number density selection to produce robust results, these processes
must be either negligible or correctable.
(A color version of this figure is available in the online journal.)

①

①

②

Figure 4. Median mass growth of the true descendants (solid line) compared tothe mass growth inferred at a constant number density (dashed line) for threebins in number density. The mass evolution is reproduced correctly to within
40% (0.15 dex) over an evolution of ∼4 in mass (0.6 dex) and 11 Gyr in time.
Comparing galaxies at the same stellar mass would be off by a factor of four
(0.6 dex). Note that the mass evolution of the highest number density sample issystematically underpredicted, while the mass evolution of the two lower number
density samples are systematically overpredicted. This can be explained by thescatter in growth rates and the merging of galaxies, as described in Sections 4.1
and 4.2, respectively.
(A color version of this figure is available in the online journal.)

あとで話しましょう③③

mass growth rate, and can break rank order by either “jumping” a galaxy ahead or “leaving” a galaxy behind. An exampleof breaking rank order by scatter in growth rates is shown in
Figure 1 by the green galaxy trajectory.
Galaxy mergers will also change the cumulative number
density by decreasing the total number of galaxies above a
fixed stellar mass. This will cause a constant number density
line to underestimate the true median mass evolution. Thisz~3

van Dokkum+10,13,ApJ; Patel+13,ApJ; Marchesini+14,ApJ; Leja+13,ApJ

Figure 6. Cumulative percen
merging into a more massivea function of number density
increases with number density
galaxies more massive with w(A color version of this figureof actual growth rates f
density bin is shown in F
There is a peak at nu
This peak is populated
star formation nor signifi
period. This peak is indensity population. How
more galaxies become qdensity bin has the large
to no growth. This is lik
bins contain more massi

24

Background : Where did we live?

External - Extragalactic study of progenitors
VAN DOKKUM ET AL.
The Astrophysical Journal, 744:63 (9pp), 2012 January 1

Vol. 709

Oser et al.
Oser+12Figure 2. Projected stellar half-mass radius of the simulated galaxies at different

ure 6. Top panels: average radial surface density profiles of galaxies with a number density of 2 × 10−4 Mpc−3 as a function of redshift. The data points wereredshifts(see limits
Figure1) vs.fromthe fractionof stellar
massTheaccreted(inaremajor
mergers,
asured from the deconvolved stacked images. Error bars are 68%
confidence
derivedbootstrapping
the stacks.
same datashown
vs. radius (leftminormergers,
events),, to thestellarmassradii
formedin situ,el) and log radius (right panel). Small boxes above the panels
indicate
the pixeland
size accretionof 0.′′ 3. Thereis a clearMtrend
redshift:
at smallthe profiles
overlap,∗,accwithat large radii the profiles get progressively steeper with redshift.
Linesbest-fitting
Sersicprofiles,determinedfrom fitting
PSF-convolvedM∗,ins, inshowthethegalaxies.
The
blackborderedsymbols
indicatesystemsmodels
more to the
10implied by the best-fitting Sersic profiles. The vertical axis is ininal (not deconvolved) stacked images. Bottom panels: cumulative
mass
as a M
functionof radius, as
massivethan∗ > 6.3 × 10 M⊙ . At z ! 2 galaxies with a higher fractions of the total mass at z = 0 within a 150 kpc diameter aperture. Note that the normalization of the profiles is not a free parameter but follows from the requirementofaccretedstars
havelargersizes,
that isaccretion
systems
the total mass within this aperture is equal to Mn (z) (Equation (1)). The mass growth of galaxies of thisindicating
number density
dominatedof
by stellar
the buildupof the outerdrives the size evolution of massive galaxies.
elope, at radii !5 kpc.
color version of this figure is available in the online journal.)(A color version of this figure is available in the online journal.)

-­‐	
  	
  Massive galaxies (logMz~0~11.5)-­‐ Inside-out growth;
Bulge
rapidly,
ces in the measured effective-­‐radii
were <10% at forms
all redshifts.
This is a key result of the paper and it is quantified in the sections

e deconvolution was done with a combination of the Lucy–
below. Here it is illustrated by the red contours in Figure 5. The
11 inner (dotted) contour shows the radius at which the surface
chardson algorithm (Lucy 1974) and σ -CLEAN(M(Högbom∗ ! 10 M⊙ ), whereas for quiescent massive galaxies the74; Keel 1991), ensuring flux conservation. Lucy works wellbrightness is 5% of the peak value. This radius is very similar at
observed
fasterα <extended low surface brightness emission but does
not op-size evolution
all redshifts.isTheouter with(solid)−1.09
contour <showsthe −1.22.
radius where
Cassataetal.
(2011)
obtainvalues
from
α
=
−0.87
to α is=much
mally recover the flux in the central pixels (see, e.g., Griffiths
the surface brightness if 0.5% of the peak. This radiusal. 1994), whereas CLEAN quickly converges in−1.42
the central
largerlow redshift
highredshift.
Together,findthe twodependingonatstellar
mass. thanVan atderWel
et al. (2008)
ions but leads to strong amplification of noise in aareasof low
the shapeof thefrom
profilechanges withvalueof α ≈ contours−0.98, demonstrate
when theythat
includeresults
previous
face brightness. In practice, we applied a smoothly
varying
redshift,core ofApresent-day
massivemostlysurveysthis changes
towithα ≈the−1.20.
similar trend(α ≈galaxies−1.11)
ight function to combine the CLEAN and Lucy reconstrucin place at z = 2 but the outer parts building up gradually overfoundandfor UV-brightgalaxies (Mosleh et al. 2011).
ns, giving a weight of 1 to CLEAN in the centralispixels
time.
In
the
right
panel
of
Figure 1, we show the size evolution
weight of 1 to Lucy at radii >3 pixels. In the transition region-­‐ and then accretion on outer partz~0-­‐ Two-phase evolution.

Figure 3. Stellar density as a function of radial distance to the galactic centerat redshift 0 (blue) and 2 (green) averaged over the most massive systems(M∗ > 2 × 1011 M⊙ at z = 0). The arrows indicate the average half-mass radii
at a given redshift. At z = 2 we find that the stellar mass profile inside the halfmass radius is still dominated by stars that have formed in situ (dotted lines).
At z = 0 the half-mass radii of our galaxies have significantly extended due toaccreted stars (dashed lines) which dominate the total density (solid lines) atlarger radii.
(A color version of this figure is available in the online journal.)

Numerous minor mergers(collapsed at early time)> Rare major merger

Black bordered symbols indicate galaxies with stellar masses
larger than 6.3 × 1010 M⊙ whose size evolution is plotted in
the right panel of Figure 1. There is a clear correlation between
the relative amount of accreted stars and in situ stars not onlyat redshift zero (Oser et al. 2010) but also at high redshifts(z ≈ 2). This indicates that stellar accretion drives the size
evolution of the systems as soon as the accreted stars startvan Dokkum+10,ApJ; Oser+10,+12,ApJ; Marchesini+14,ApJ
10

Background : Where did we live?
The Astrophysical Journal Letters, 771:L35 (7pp), 2013 July 10

van Dokkum etExternal - Extragalactic study of progenitors

van Dokkum+13?

Figure 3. Surface density profiles from z = 2.5 to z = 0, as measured from averaged, PSF-corrected rest-frame g-band images in each redshift bin. The horizontal
is linear in (a) and logarithmic in (b). The galaxy image is randomly chosen from our SDSS sample to illustrate the radial extent of the profiles. The main evolu
is in normalization, which is determined by MMW (z) (Equation (1)). The profile shapes are very similar from z ∼ 2.5 to z ∼ 1, which implies that the galaxies
building up mass at all radii. After z ∼ 1 the central regions gradually stop growing but the disk continues tobuild up.
z~0
(A color version of this figure is available in the online journal.)

-­‐	
  	
  	
  Milky way-size galaxies (logM~10.7)-­‐ Self-similar growth (z~3
to ~0.6)
rest-frame g-band images and scaled such that the total m

Inside-out (disk) growth?

It is clear from Figure 2 that present-day galaxies with themass of the Milky Way have changed over cosmic time. The
most obvious change is that galaxies became redder with time,
particularly after z ∼ 1, indicative of a decrease in the specific
SFR. The galaxies also appear brighter at lower redshift in
Figure 2, reflecting the mass evolution of Equation (1). A
striking aspect of this change in brightness, and a central resultof this Letter, is that the bulges appear to change nearly as
much as the disks, particularly at z > 1. We do not see highdensity “naked bulges” at z ∼ 2 around which disks graduallyassembled. Instead, the central densities at z ∼ 2 were much
lower than the central densities at z ∼ 0. We quantify this resultin the remainder of the Letter.

(Larson 76; Haywood+13, and more.)van Dokkum+13,ApJ; Patel+13,ApJ,
and
This
work!
3.2. Evolutionof Surface
Density
Profileswithin a diameter of 50 kpc is equal to MMW (z). Error bars w
determined from bootstrapping (see van Dokkum et al. 201
We note here that the u − g color gradients of the stacks
small (≈0.1 dex−1 ) at all redshifts, consistent with other stud(e.g., Szomoru et al. 2013).
There is strong evolution in the overall normalization of
profiles from z = 2.5 to z = 1 and less evolution thereaf
reflecting the mass evolution of Equation (1). The evolut
from z = 2.5 to z = 1 is strikingly uniform: the profiles
roughly parallel to one another in Figure 3(b), and rather thassembling only inside out the galaxies increase their mass
all radii. This is in marked contrast to more massive galaxi
which form their cores early and exclusively build up their ou
parts over this redshift range (see Figure 6 in van Dokk

Background : Where do we live?

Lookback time (Gyr)log ψ (M year –1 Mpc–3)

–0.4

0

2

4

6

8

10

12

c

–0.8
–1.2
–1.6
–2

我々の銀河は宇宙の最盛期をどのように進化してきたのだろう–2.4星質量 、星形成活動、形態、そして多様性

0

1

2

Redshift

3

4

5

6 7

8

Data reduction: Flowchart
Sample extraction based on a constantnumber density for each population(Milky Way-like and massive galaxies).

M *

1

M*,M/L,	
  UVJ,	
  SFR	  	
  for	
  each	  radial	
  pixelz

“1D conversion”
for each band.

r (pixel)





F435W
F606W
F775W
F814W
F850LP
F125W
F140W
F160W

Median stacking
for galaxies ineach z-bin andeach filter band.

Mosaic images are convolved to the FWHM of
F160W (~0.″18), and then each sample isextracted into 500×500 pixels.
(Left: Examples of convolved images, but in
200×200 pixel stamps here.)

2

Contaminants in the postage are listed andmasked (green regions in left figure) by
SExtractor, and then the local sky is subtracted.
The stamp for each filter band is converted
into one dimensional (1D) image using Eq.(6).

3

Stacking the geometry-corrected 1D light
profiles in each redshift bin, for each filter band.

SED foreach pixel SED fitting is conducted for each pixel in
Pixel #1
z=0.67log M*=9.2
U-V=1.52

4

5

the 1D image (“Radial SED fit”), to obtainthe stellar mass and rest-frame color.

λ Criterion: S/NF850LP>3S/NF125W>3S/NF160W>3.

λData reduction: 1.Selection of MWs and MGs
From 3D-HST catalog (Skelton+14),
Milky way progenitors (MWs):log(M*/M) = 10.66 - 0.045z - 0.13z2 (van Dokkum+13)
Massive galaxy progenitors (MGs):log(M*/M) = 11.19 - 0.068z - 0.04z2 (Patel+13)- Consistency with abundance matching.

29%- Impact of merger and quenching?

7%-> Negligible, at lower mass (Leja+13)(We’ll discuss later.)
	
 MWs

	
 MGs

Results: Stellar mass accumulation at 0.5<z<3.0

MWs

Mass growth at all radii.
“Self-similar”

MGs

Inner, and then outer.
“Inside-out”*Previous studies used light (e.g.,F160W) profiles.

Results: Color gradient and evolution
Rest-frame U-V, U-J colors
No. 2, 2009QUIESCENT GALAXIES IN A BICOLOR SEQUENCE

1887

5.3. Interpolating Rest-Frame Photometry

QuiescentStar-forming
Williams+09

At z ∼ 2.5, the U, V, and J rest-frame bands fall roughly into
the observed J, K, and IRAC 4.5 µm bands, respectively. Up tothis redshift, intrinsic U V J fluxes can thus be interpolated fromthe observed data. Filter response curves for the observed bands,
takinginto
The Astrophysical Journal, 785:18(17pp),
2014accountApril 10 atmospheric absorption and detector quanMorishita, Ichikawa
tum efficiency, were downloaded from each of the WFCAM,
Suprime-Cam, and IRAC Web sites. For rest-frame filter definitions we used the standard filter definitions without atmosphericabsorption or detector response included: the Bessell (1990) U
and V curves, and the Mauna Kea definition (Tokunaga et al.
2002) for J. Rest-frame fluxes were then interpolated following
the method of Rudnick et al. (2003).13 Uncertainties on the restframe fluxes were derived using the perturbed input catalogs
Dusty
and output redshifts from the Monte Carlo analysis describedStarin Section 5.2. Note that these color uncertainties only take into
account photometric errors (and the resulting zphot errors), andforming
do not include the uncertainties intrinsic to the templates usedfor zphot fitting.
6. EVIDENCE FOR QUIESCENT GALAXIES TO Z ∼ 2.5

Figure 8. Rest-frame color–color diagram for KAB < 22.4, zphot < 2.5 UDS
6.1. The Rest-Frame Colors of Quiescent and Star-Forming
galaxies (black points). Red points denote spectroscopically confirmed z ∼ 1
Galaxies
OPEGs from Yamada et al. (2005) with little or no detected line emission(Wλ (OII) < 5 Å). Bruzual & Charlot (2003) evolutionary tracks of passively
We use the galaxy catalog derived from the UDS/SXDS/
evolving (red line) and constantly star-forming (cyan line) stellar populations
SWIRE data, along with the photometric redshifts and interpofrom 0.1–10 Gyr are overplotted, and the arrow shows the effect of 1 mag of dust
Figureclump”
6. Top: color
selections forlated
QGsMorishita+14
and
SFGs for the same
redshiftbins in Williamsal. (2009).
Cross symbol
represents
1σ error in U − V andextinction. The extended star-forming track and the “quiescent(whichrest-frame
colorsdescribed
in ettheprevious
section,to anaredshiftbin.
Median
sSFRs
with
MADs
for QGs and SFGs are written at left top and right bottom, respectively, in each panel. Bottom: histograms of Q
overlaps with the OPEG sample) are clearly separated.

Results: Color gradient and evolution

MWs“Inside-out”

MGs“Inside-out”(Inner-outer)

Discussion✔ MGs evolve the stellar and colors in inside-out way.
❓ MWs evolve the stellar mass in self-similar way,

but the colors in inside-out way.

-­‐ What is the physical mechanism(s)?
-­‐ When did it happen?
-­‐ Where in the galaxy did it happen?

Discussion: Color gradient and evolution-­‐ Thick lines: Observed.
-­‐ Thin lines: Stellar population model,
including star formation (BC03).

The inner part of MWs suddenly
reddens at z~1.2-1.6 (T~4Gyr).

-­‐ End of the bulge/thick disk formation? (e.g., Snaith+14)-­‐ Compactness and quenching (Franx+08;Williams+10)	
  ->	
  Bulge formation and quenching (Martig+09;Genzel+14)-> Low-mass stars heat dust (Kajisawa,T.M.,+15; ポスターNo.10)

Discussion: Star formation rate (SED)
We usually assume a star formation history,
but …
Exponential: ψexp(-t/τ)Delayed: ψt*exp(-t/τ)Truncated: ψ=const. (t<τ)ψ=0 (t>τ)Stellar masses are in good agreement, but the others are not.
(See also Wuyts+11)

Discussion: Star formation main sequenceysical Journal Letters, 754:L29 (6pp), 2012 August 1

rnal Supplement Series, 214:15 (52pp), 2014 October

Whitaker et al.

Speagle et al.

ΔM(M,t) = (1-R)*SFR(M,t)*Δt
R: return fraction = 0.36

Speagle+14, ApJS

observations from the literature (see Section 5.1) plotted at several given redshifts. The
er than the likely observed scatters (∼0.3 dex) for improved clarity, and the mass bounds
mass sequence for star-forming galaxies has a nonlinear slope at 0 < z < 2.5 (dotted line is linear). The running medians and scatter are color-coded
evolutionmass
fromz = (solid
4 to lines
0 arein easily
visible.
As thefirst andhnitudea power-law
fit aboveintheSFR
massatandfixed
SFR
limitsbottom,right panel).
Whitaker+12;
seecompletenessalso
Elbaz+07,+11,
Zahid+12,
Kashino+13,
uld
beviewedaspredictionsofhigh-/low-zMSrelationsratherthansimplybest
fits ton of this figure is available in the online journal.)

Koyama+13, Whitaker+14, Steinhardt+14, Suzuki+15, and more.

ndard broadband NIR filters. The combination ofgalaxies have strong Balmer/4000 Å breaks, characterized by-band NIR images with deep optical medium andred U − V colors and bluer U − V colors relative to dusty
hotometry and Infrared Array Camera imaging overstar-forming galaxies at the same U − V color.
Whitaker et al. (2011)
demonstrated
that there is a clear
he AEGIS flexibility
and COSMOS
fields results parameterization.
orofextragalactic
our mass-dependent
Our bestMS
delineation
betweenstar-forming
andquiescentgalaxies withphotometricredshifts(∆z/(1+z)!
2%),
rest-frameer
fit isthe NMBS data set. Using the criteria U − V > 0.8 × (V − J ) +stellar population parameters. The SFRs presented
re
0.7,
U the
−Vliterature> 1.3, and−J <5.1)
1.5,plotted
5885 quiescentgalaxies
are Therconsensus”
are based MSin parton Spitzer–MIPS
at to24observationsµm
relationstaken from ourfluxes
best fitfrom(seeVSection
at several given
redshifts.
(0.84
,
t)
=
±
0.02
−
0.026
±
0.003
×
t)
log
M
log
ψ(M
ds
identified
and
they
are
excluded
from
the
bulk
of
this
analysis.
∗
∗
ved
from
the
S-COSMOS(Sanders
et
al.
2007)
and
are taken to be the “true” scatters (±0.2 dex) rather than the likely observed scatters (∼0.3 dex) for improved clarity, and the mass bounds
sampleoffixed22,816at 0visible.
<z<
is andveys.
A changing
comprehensive
overviewof the ofsurveycan evolution
fit. TheMS slopeand ∼2 orders
magnitudeinSFR
at0.03massfrom=
4 togalaxies
0 are easily
As2.5
the firstin− (6.51
±
0.24
−The
0.11
±
×
t)star-forming
, zMS
(28)
selected
independentof the SFR
indicator
stellar
Whitakeret fit,al. the(2011).
massesused
includedin thez = 0 Theand zstellar= 4 slopes
shouldbe viewed
as predictionsof high-/low-z
relations andratherthan population
simply best fits toaare derived
shifts(which would
to fit(Kriek
well byetdefault).
synthesis model parameters, enabling an unbiased measurement
usingtend
FAST
al. 2009), with
fit,
where
the
listederrorsarederivedfromof theresampling.
star formation sequence.
harlot(2003)
modelsthat
assumeaChabrier(2003)
ure is available in the online journal.)function(IMF),
solar
metallicity,
exponentially
We
The interpublication scatter around this fit is σi =ar formation histories, and dust extinction following
THE
STAR
FORMATION
SEQUENCE Our best MS
le(0.08,
0.09,
0.11)
for themedian,andmaximume intoaccount
thetrue
scatterdex,
derivedfor minimum,
flexibilityof3.ourmass-dependent
parameterization.
etal. (2000)
extinctionlaw.
rs
valuesmass
rangefitlog
M∗ = 9.7–11.1,
ons
as wellasby
thewithininterpublicationis Complementary
are determinedaddingthetheUVfittedand IRscatteremission,
to manyrespecprevious studies, Figure 1 shows the
−10
=
0.98
×
10
(L
+
3.3
L
)
(Kennicutt
1998),
om bootstrapping(via resampling),
where
2800
be
tively.IRThis
encompasses
a majoritystar
offormation
the agesequence,of the log(Muniverse⋆ )–log(SFR), in five redshift bins

Discussion: Star formation main sequence

MWs

MWs of Illustris-Solid, dashed lines: SFMS, with scatter (gray)-Points: Constant ND

MWs evolve on the main sequence.
-Difference between inner and outer parts?
-> Resolved SFRs with IFUs+AO or HST grism?
(e.g., Wuyts+13)-> Molecular gas mass map?

Discussion: Star formation main sequence

MWs-Solid, dashed lines: SFMS, with scatter (gray)-Points: Constant ND-Dotted: Abundance matching (Behroozi+13), with scatter (green)

Discussion: Variety in the radial profile-­‐ Variety of light profile = “Morphological variety”-­‐ Scatter around the median.

Discussion: Variety in the radial profile -MWs
z~0.7

z~2.8

Discussion: Variety in the radial profile -MGs
z~0.7

z~2.8

GALAXEV, to see when each region becomes “unusually” red or quenchedat each redshift, where we define (U V ) ⌘ (U V )obs (U V )model .
We see the excess of (U V )obs in the inner regions (r < 2.5 kpc) at z ⇠are seen in the outer regions for either sample.

Discussion: Variety in the radial profile -MGs

We define the variety of the galaxy profile by evaluating
the distribution of residuals as,x

1 X fi,median fi,obs=||,
norm,xSx ifi,median(8)

where we set x < 2.5 kpc and 2.5 < x < 10 kpc in theTheparts of ofMWsshow Sxfollowing to -­‐see
the outerradial dependence
the variety.
is the total pixel within the range of x. In Fig. 12 wevariety at z>1.0, and decrease
show the distribution of norm,x for each redshift bin.
Then we evaluate
the dispersion, , around the mean ofat z<1.0.
the distribution, which is given in each panel. Since the-­‐ Star formation
scatter of backgroundnoise for eachlight profile
could
activityin thea↵ect the quantity, we calculate the error for by as-outer part and quenching?

-­‐ Both parts of MGs rapidly
decrease the variety.
-­‐ We scarcely see the variety at
z~0.5.

su
Th
th

in
ha
er
sc
pe
th
la
M
ou
re

Summary:
MWs
Mass growth 7% of MW(z~0) at

MGs“Self-similar”

29% of MW(z~0) at “Inside-out”
z~3
Rapid bulge
formation, and thenminor merger.

z~3

Mechanism

Normal starformation?

Need accurate
SFR maps.

UVJ Color

Inner-to-outer.

Central part
Inner-to-outer.
quenched at z~1.2.

Central part at z>2.4.
(Whole at z~2.0.)

Variety

Outer parts stillshow various
profiles.

Star formation in
the outer part?

Now show“Homogeneity.”

Rapidly decreasesince z~2.0.

In the era of TMT, we need resolved study;- Very accurate study of normal galaxies at z~1, when
the bulge and thick/thin disk formed (=quenched).
- Star formation (including dust attenuation),stellar kinematics/metallicity.
24Summary:
MWs
Mass growth 7% of MW(z~0) at

MGs“Self-similar”

z~3

29% of MW(z~0) at “Inside-out”
z~3

Mechanism

Normal starformation?

Need accurate
SFR maps.

UVJ Color

Inner-to-outer.

Central part
Inner-to-outer.
quenched at z~1.6.
宇宙初期銀河分析装置

Rapid bulge
PI M.Akiyama
formation, and thenminor merger.
TMT-AGE project : TMT Analyzer for Galaxies
in the Early universe
Central part at z>2.4.
(Whole at z~2.0.)

VarietyThirtyMeter Telescope(TMT) 30m望遠鏡での多天体補償光学系と多天体分光器
show various
the outer part?
since z~2.0.
“Homogeneity.”
Outer parts still

Star formation in

Rapidly decrease

Now show

profiles.

最近の観測ではすばる望遠鏡をもってしても分光観測によって正体を明らかにすることのできない宇宙初期の銀河が多数見つかっています。30m望遠鏡はこのような銀河の「正体」を明らかにすることを一つの目的としすばる望遠鏡の次の世代の望遠鏡として検討が進められています。我々のグループではこの30m望遠鏡に、国立天文In the era of TMT, we need resolved study;
台の補償光学系チームや京都大学の面分光チームと協力して赤外線、多天体面分光、多天体補償光学、観測装置- を実現しようと基礎実験をしています。鍵となるのは広い視野の中の多数の天体に対して同時に補償光学を効かVery accurate study of normal galaxies at z~1, when
せる多天体補償光学系です。その概念図です。
the bulge and thick/thin disk formed (=quenched).
- Star formation (including dust attenuation),stellar kinematics/metallicity.
25