2022年7月12日光赤天連シンポジウム

広視野近赤外線探査で解き明かす
巨大銀河の形成
但木謙一（国立天文台・アルマプロジェクト）

NASA, ESA, CSA, and STScI

emic.oup.com/mnras/article/488/3/3143/5484868 by Nation

stellar mass at fixed peak halo mass (Mpeak ) for central galaxies as a function
t confidence interval for the model posterior distribution.

巨大銀河の進化 ⇄ 初代銀河の進化
ハローの成長史と星形成銀河の割合

答えたい疑問：巨大銀河はいつ・どのように形成したのか？
解決するためのアプローチ：
劇的な進化段階にいる銀河を観測する（star-forming → quiescent）（disk → bulge）（rotation → random）

transition (empirical)
quiescent⇧star-forming

Behroozi et al. 2019現在の最遠方銀河
z=11-13, logM*=9(Jiang et al. 2021,
Harikane et al. 2022)

emic.oup.com/mnras/article/488/3/3143/5484868 by Nation

stellar mass at fixed peak halo mass (Mpeak ) for central galaxies as a function
t confidence interval for the model posterior distribution.

巨大銀河の進化 ⇄ 初代銀河の進化
ハローの成長史と星形成銀河の割合

銀河の進化

GREX-PLUSが狙う
z=4-8の銀河

transition (empirical)
quiescent⇧star-forming

現在の最遠方銀河
z=11-13, logM*=9(Jiang et al. 2021,
Harikane et al. 2022)

GREX-PLUSが狙う
z=10-15の銀河

Behroozi et al. 2019, ZINA DERETSKY/NATIONAL SCIENCE FOUNDATION/WIKIMEDIA COMMONS, Katrina Kenny & University of Adelaide

銀河の誕生

巨大銀河の進化 ⇄ 初代銀河の進化
z>15z=8-15z=5-8

Submillimeter bright galaxies
Lyman break galaxies Lyman break galaxies
Dust-obscured quasars

発見
星質量z=4-6

Quiescent galaxies

Roman

❌

✅

❌

❌

GREX-PLUS✅

✅

✅

✅

Roman

❌

❌

❌

❌

GREX-PLUS

✅

✅

✅

✅

「巨大銀河はいつ・どのように形成したのか？」

Romanではダメな理由
1. 強いダスト減光のため2 μmで検出できない
2. 銀河の星質量を知ることができない

・z>7のサブミリ波銀河を発見し、特徴付ける

・z=5-8のサブミリ波銀河の個数密度を測定する
・z=5-8のサブミリ波銀河のハロー質量を測定するRomanではできず、3-5 μmの広域探査が絶対必要

GREX-PLUSでしか見つからない2-4 μmで赤い銀河

The Astrophysical Journal, 889:137 (20pp), 2020 February 1

Mawatari et al.

The Astrophysical Journal, 889:137 (20pp), 2020 February 1
Figure 10. Same as Figure 9 but for BBG_22.

2-4 μmで赤い銀河のダスト連続光をALMAで観測すると
2μm

4μm

2μm

870μm

Balmerbreak

6.2. BBG Candidates without ALMA Detection

Figure 7. Postage-stamp images of the six BBG candidates in g, i, F814W, Y, K, [3.6], [4.5], and ALMA Band 7. The top three objects are not detected in ALMABand7, whereas the remaining three objects are detected. The panel size is always 6″×6″. The circle superposed on each panel shows the photometric aperture withdiameters of 0 6 for F814W, 2″ for ALMA Band 7, and 2× the FWHM of the PSF for the other bands.

all three
BBG candidates.
8 shows
the probability
SED as the “best-ﬁt” template and the one derived from each MC Figure
11. Same
as FigureFigure
9, butfor BBG_29.
distributions of the ﬁve ﬁtting parameters and the stellar mass
realization as the “MC-best” template.
of the 1000 MC-best templates. The MC-best models aremassive (M* _ 5 q 1010 Me), dust-poor (AV<0.2), metal6.2. BBG Candidates without ALMA Detectionenriched (∼Ze), and old (0.7–1 Gyr) galaxies at 5 1 z 1 8.
Here we present the SED analyses for the three BBG candidates
Their SFH is extremely bursty (τSFR=0.03 Gyr), which leads
not detected in the ALMA observations. Because the ALMA
to almost zero SFRs at the observed epoch.28 The above SED
Band7 upper limits are deeper than the Spitzer/MIPS, Herschel,properties are similar to those of local passive galaxies (e.g.,and JCMT/SCUBA-2 data, we used only the ALMA Band7 dataCox 2000; Phillipps 2005). We notethat noneageof the 1000SF
MCBBG
for the FIR range in the SED ﬁtting. The resultant number of bands
realizations result in DG/DNLE solutions, except for BBG_9.
is 15: F814W, g, r , i, z, y, Y , J , H , Ks, [3.6] , [4.5] , [5.8] , [8.0],
In BBG_9, our MC realizations result in DG solutions on rare
and ALMA Band7. In the following sections, we describe theSED ﬁtting performed separately with the three template groups28
A small SFR is also expected from the observed photometry in the FIR and(Section 6.2.1) and that performed with composite templates of theoptical bands. We estimated the SFR upper limit from the ALMA Band 7 ﬂux

quiescent galaxiesobservable only during

7.3. Cosmic Star Formation Activity at z 2 14

870μm

dust
Figure 7. Postage-stamp images of the six BBG candidates in g, i, F814W, Y, K, [3.6], [4.5], and ALMA Band 7. The top three objects are not detected in ALMA
Band7, whereas
the remaining three objects are detected. The panel size is always 6″×6″. The circle superposed on each panel shows the photometric aperture withextinction
diameters of 0 6 for F814W, 2″ for ALMA Band 7, and 2× the FWHM of the PSF for the other bands.
SED as the “best-ﬁt” template and the one derived from each MC
realization as the “MC-best” template.

do not contribute to the SMDs. Our SMD at z∼6 is broadly
consistent with the decreasing trend of passive galaxies fromz=0 to 4. The fraction contributed by the BBGs in the total
SMD including star-forming galaxies at z∼6 is only ∼1%.

4μm

all three BBG candidates. Figure 8 shows the probability
distributions of the ﬁve ﬁtting parameters and the stellar massof the 1000 MC-best templates. The MC-best models are
massive (M* _ 5 q 1010 Me), dust-poor (AV<0.2), metalenriched (∼Ze), and old (0.7–1 Gyr) galaxies at 5 1 z 1 8.
Their SFH is extremely bursty (τSFR=0.03 Gyr), which leads
to almost zero SFRs at the observed epoch.28 The above SED
properties are similar to those of local passive galaxies (e.g.,Cox 2000; Phillipps 2005). We note that none of the 1000 MC
realizations result in DG/DNLE solutions, except for BBG_9.
In BBG_9, our MC realizations result in DG solutions on rare

Here we present the SED analyses for the three BBG candidates
not detected in the ALMA observations. Because the ALMABand7 upper limits are deeper than the Spitzer/MIPS, Herschel,and JCMT/SCUBA-2 data, we used only the ALMA Band7 data
for the FIR range in the SED ﬁtting. The resultant number of bands
is 15: F814W, g, r , i, z, y, Y , J , H , Ks, [3.6] , [4.5] , [5.8] , [8.0],
ALMA Band7. In the following sections, we describe theFigure 16.andObserved
SEDs separatelyof the BBG
candidates
with
ALMA detection, where ﬁlled (open) squares correspondSED ﬁtting performed
with thethree templategroups28
A small SFR is also expected from the observed photometry in the FIR andtemplate ﬁtting.
the2σ limiting
are set as upper limits, indicated by arrows. T(Section For6.2.1)theand nondetectionthat performed withbands,
composite
templatesof the ﬂuxes
optical bands. We estimated the SFR upper limit from the ALMA Band 7 ﬂux
galaxy andAGNmodels (Section6.2.2).
K thupper limit assuming
a modiﬁed blackbody
with aobserved
dust temperatureSED,of Td=35(dotted–dashed),
and7phase(solid)
aresuperposed.
can reasonably
ﬁt thewith
their star-forming(TSF), while All three model spectra
and a conversion factor from LIR to SFR (Madau & Dickinson 2014). All three−1進化submillimeter bright galaxies

panels are the same as the left ones but in the NIR wavelength
BBGrange.
candidates have SFR 1 10 M: yr(3σ). Almost the same constraint is

Fitting with Either Galaxy or AGN or XzLBG Template Groupobtained from the observed ﬂux upper limit in the Y band that roughly
the descendant BBGs are always 6.2.1.
observableonce the Balmer
corresponds to the rest-frame UV wavelength at the best-ﬁt redshifts. The SFRs ofFirst, we perform the SED ﬁtting with the Galaxy group
the BBG candidates are an order smaller than those of the z∼6 star-forming
break matures. Assuming the BBGtemplates
observable
timeduration
as(Table 3). As a result of 1000 MC runs, we foundgalaxies on the main sequence (Speagle et al. 2014) with similar stellar masses
thattheBBGmodels
at
5z

8are
signiﬁcantly
favoredfor(∼5×10 M ).
T
 T  T  0.2ofGyrwith,
whereT
2qU
SF of 12 1
SFHlog (LIR L :) 1 12.6 because
IR luminosityof theYuichi Harikane ht
0.2 Gyr is required to develop
the Balmer
break,we obtained (e.g., Blain10 et al. 2002).
so-called“negativeK correction”
Yuma Sugahara htt
the number density ofFigure
the 16star-forming
progenitors
as DNLE model spectra atshows
someDG
andSeijiFujimoto
https
Mawatari
etal.
2020
−38
nnqT Tx 5.6 q 10 (T 60 Myr) Mpc
10e

ALMA2: 観測周波数帯域が２倍以上に向上[CII] Redshift
1.0

121080.86754

現状のALMAの帯域
7.5 GHz0.60.4~170 GHz

0.20.0150200250
iobs [GHz]300350

現状：周波数設定を変えて何回も観測しなければならない
広帯域化の恩恵：
1. 連続光感度の向上 → quiescent galaxiesの確認
2. 一度にカバーできる赤方偏移範囲が拡大 → submillimeter bright galaxiesの分光確認

Required observations and expected results
Predicted number densities

Popping et al.

2 mJy

S850 μm>2 mJy sources
redshiftN [deg-2]

N [200 deg-2]

4<z<5~40~8000

5<z<6~10~2000

6<z<7~2~400

目標・z>7のサブミリ波銀河を発見し、特徴付ける・z=5-8のサブミリ波銀河の個数密度を測定する
・z=5-8のサブミリ波銀河のハロー質量を測定する
100平方度クラスの広域探査が必要

solid lines mark our predictions for the number counts when accounting for all thePopping et al. 2020

Submillimeter bright galaxies at z>64Zavalaetal.
CO(2 ! 1) detection in a z = 6 galaxy星質量 vs 星形成率

3JVLAによるCO(2-1)

Flux density [mJy]28
2400:41:20

16Declination

SFR [M O• /yr]32

The 3.6 and 4.5 µm Spitzer/IRAC observations wereVelocity [km/s]
also used along with theFIR photometry
to constrain
1000
500
0-500-1000
1000
the stellar mass of the galaxy through a spectral energy distribution (SED)
fittingtechnique using the enCO(2-1)
atz=6.03
2ergy balance code magphys (da Cunha et al. 2008).
First, since the emission of G09-83808 is blended with
1
that from the foregroundz = 0.776 lensing galaxy in100
the IRAC bands (see Zavala et al. 2018), the light distributionoftheforegroundgalaxy
wasmodeledusing
G09-83808
0galfit (Peng et al. 2002) and a Sérsic profile (Sérsic
IllustrisTNG-300
Pearson et al. 20181963). Then, the emission from the foreground galaxy
Schreiber et al. 2015
was subtracted-1
from each image, and the photometry of
101011the background32.67
source was measured
the galfit 32.88
32.74 from 32.81
32.95
101046.4 46.2 9:00:46 45.8 45.645.4generated residual images using SExtractor (BertinFrequency [GHz]
Stellar Mass [M O• ]Right ascension& Arnouts 1996). Finally, combining the deblended
Spitzerphotometry,whichprobes the rest-frame
optiFigure
2.
TheCO(2!
1)
transition
fromG09-83808.
Left:
Velocity-integrated
intensity(moment-zero)map of the CO(2 !
Figure 1. G09-83808 in the context of the main-sequence1
日本のファシリティを活かした観測戦略
Romanではダメな理由
calstellar
emission,with theFIR data,
the best-fit1)
lineover⇡800kmscenteredat
32.81
GHz.
Adouble-arc
structure
is visible
due toSED
the gravitational lensing. Theof star-forming galaxies. The best-fit SFR and stellar mass
forG09-83808
wasderived,
from
which
astellarmassofapertureused
toextract
the1D
spectrum
isindicatedwiththedashedblackline,
while
the
beam-sizeof the observations isof
G09-83808,
andtheirassociateduncertainties,
arerep1.
GREX-PLUSで赤い銀河を選択
1. 銀河の星質量を知ることができない+8.4Right: 10
shown
ellipse in the Mbottom
left.
Extracted
around correcting
the expected frequency of the line at=7.8
was spectrum
inferred (after
resented by the red solid circle.
Thewithgraytheandyellow
gold regions?
4.2 ⇥ 10 M
2. represents
強いダスト減光のため22. magnification).
ALMA+ngVLA(2035~)でフォローアップ
z = 6.029μmで検出できない(graydashed line).
line represents
the best-fit Gaussian function (with ⌫obs = 32.810 ± 0.002 GHz andthe main-sequence relationshipsof Schreiber
et al.The dotted
for redgravitational
FWHM= 0.040 ±extrapolated
0.005 GHz). The solid line represents the best-fit with two Gaussian components adopted to better describe(2015) and Pearson et al. (2018),
respectively,
With these measurements in hand, we can place ourthe double-peakis also noticeable in other transitions (see Appendix A).
to z = 6. For the sake of comparison
we also profile
includeofz the⇡ 6line, whichtarget in the context of the main-sequence of star formstar-forming galaxies from the IllustrisTNG-300 simulation
the expense of angular resolution (producing a synthe(12 + log(O/H) ⇡ 8.34 8.54) via
the detection ofing galaxies.
Zavala et al. 2022

Dust-obscured quasars
2-4 μmで赤い銀河quiescentgalaxies

dusty star-forming
galaxies

宇宙論的シミュレーションによる
z=7 クエーサーの個数密度予測

obscured+unobscured

dust-obscured
quasars

10倍以上
unobscured

dust-obscured quasars unobscured quasars
Davies et al. 2019

Ni et al. 2020

まとめ

ハローの成長史と星形成銀河の割合

emic.oup.com/mnras/article/488/3/3143/5484868 by Nation

stellar mass at fixed peak halo mass (Mpeak ) for central galaxies as a function
t confidence interval for the model posterior distribution.

銀河の進化

GREX-PLUSが狙う
z=4-8の銀河

現在の最遠方銀河
z=11-13, logM*=9(Jiang et al. 2021,
Harikane et al. 2022)

GREX-PLUSが狙う
z=10-15の銀河

Behroozi et al. 2019, ZINA DERETSKY/NATIONAL SCIENCE FOUNDATION/WIKIMEDIA COMMONS, Katrina Kenny & University of Adelaide

銀河の誕生