ALMA による z = 6-9 銀河の性質と南極 THz 望遠鏡への期待
橋本拓也
筑波大学 宇宙史研究センター
テニュアトラック助教 (卓越研究員)

Outlinel Introduction- Cosmic reionization- Galaxies in the epoch of reionization (EoR)- Spectroscopyl Rest-frame FIR properties at z > 7 with ALMA
- Case study:
properties of a z = 9.1 [OIII] 88μm emitter- Statistics:
High ratios of L[OIII] 88 μm/L[CII] 158 μm
in high-z LAEs/LBGsl (Some thoughts on AAT)

Outlinel Introduction- Cosmic reionization- Galaxies in the epoch of reionization (EoR)- Spectroscopyl Rest-frame FIR properties at z > 7 with ALMA
- Case study:
properties of a z = 9.1 [OIII] 88μm emitter- Statistics:
High ratios of L[OIII] 88 μm/L[CII] 158 μm
in high-z LAEs/LBGsl Some thoughts on AAT

Cosmic Reionization
Years after the Big Bang
100 Myr
1 billion

0

first stars/galaxies

Recombination

The Big Bang

Fully ionized neutralized
1000
100Reionization

13.8 billion

Fully ionizzed

101＋z1©NAOJ

l Reionization: z ~ 20 - 6 (tuniv ~ 200 Myr - 1 Gyr)l Hydrogen ionizing photon (LyC: λ < 912 Å or E > 13.6 eV)l Key questions- What is the main driver of reionization?
- How, when and where reionization has processed ?

Cosmic Reionization
Years after the Big Bang
100 Myr1 billion

0

first stars/galaxies

Recombination

The Big Bang

Fully ionized neutralized
1000
100Reionization
101＋z

13.8 billion

Fully ionizzed
1©NAOJl Reionization: z ~ 20 - 6 (tuniv ~ 200 Myr - 1 Gyr)l Hydrogen ionizing photon (LyC: λ < 912 Å or E > 13.6 eV)l Key questions- What is the main driver of reionization? cf., blue compact galaxies! Recent consensus: abundant UV star-forming galaxies
are sufficient without demanding Pop III stars (e.g., Robertson+15)

Cosmic Reionization
Years after the Big Bang
100 Myr1 billion

0first stars/galaxies

Recombination

The Big Bang

Fully ionized neutralized
1000
100Reionization
101＋z

13.8 billion

Fully ionizzed
1©NAOJ

l Reionization: z ~ 20 - 6 (tuniv ~ 200 Myr - 1 Gyr)l Hydrogen ionizing photon (LyC: λ < 912 Å or E > 13.6 eV)l Key questions- What is the main driver of reionization?
- How, when and where reionization has processed ?
à future 21cm observations in the EoR (割愛)

Galaxies in the Epoch of Reionization
Years after the Big Bang
100 Myr
1 billion

0

first stars/galaxies

Recombination

The Big Bang

Fully ionized neutralized
1000
100Reionization
101＋z

13.8 billion

Fully ionizzed
1©NAOJ

l Galaxy candidates at z ≈ 8 - 11 owing to HST and Spitzerl Statistical properties (UV LF, SFRD)

Galaxies in the Epoch of Reionization
Years after the Big Bang
100 Myr
1 billion

0

first stars/galaxies

Recombination

The Big Bang

Fully ionized neutralized
1000
100Reionization

13.8 billion

Fully ionizzed101＋z

l Spectroscopic properties in the EoR are yet to beconstrained (redshift identification, Z, U, ne)l Galaxy formation and evolution• Ancestors of present-day galaxies• Origin of heavy elements (O, C, N etc.) and cosmic dust
• Star forming activity & ISM properties (e.g. fesc , Z, U, ne)

1
©NAOJ

Spectroscopy at z > 7l Lyα is powerful at z up to ~ 7 (e.g. VLT/MUSE: Bacon+17, Hashimoto+17b)
l but strongly attenuated by the IGM at z > 7 (e.g. Stark+10, Pentericci+12)A. K. Inoue et al. 2016, Science! Alternative emission line is essential[OIII] 88 μm[NII] 122 μm[CII] 158 μm
1216 ÅHarikane+18

観測波長 [Å] = (1+z) x 静止系波長ALMA observations at z > 7
l Far-infrared fine structure lines are useful• metallicity, U, ne (Nagao+12, Pereira-Santaella+18)
l Dust continuum
can beetsimultaneously
observed
A. K. Inoueal. 2016, Science• star-formation activity (dust production/growth/destruction)[OIII] 88 μm[NII] 122 μm[CII] 158 μm

NOEMA

Harikane+18

Observed Wavelength [Å] = (1+z) x λrest 10/51

A traditional tool at high-z: [CII] 158μm
l ~20 [CII] detections at z ~ 5 - 7 galaxies (e.g. Carniani+17, Smit+18)
Many detections in high-z QSOs

l Non-detections are reported at z > 7 (Ouchi+13, Ota+14)
ALMA [CII]HST UVz = 5.5 LBG
Capak et al. 2015 Naturez = 6.8 LBG
Smit et al. 2018 Nature11

[OIII] 88 μm in the local Universe[OIII]/[CII] luminosity ratiol ISO metal rich spirals, L[OIII] ≈ 0.5 x L[CII] (e.g. Malhotra+01, Brauher+08)
l Herschel dwarf galaxies, L[OIII] ≈ 2 x L[CII] (e.g. Madden+12, Cormier+15)
A. K.
Inoueet≈al.
Some objects
have
L[OIII]
102016,x L[CII]Science10
1Madden+12
local metal rich spirals

106

108 1010
LIR [Lsun]

1012

The first [OIII] 88 μm detection in the EoR
l LAE at zLya = 7.21 with EW0(Lyα) = 33 Å (Shibuya+12)• ALMA Band 8 follow-up observations (PI. A. K. Inoue)
A. K. Inoue et al. 2016, ScienceInoue, Tamura, Matsuo+16 Science
Contours: ALMA [OIII]
bkg: Subaru Lyα5.4σ
5.4σ

l Band 6 [CII] is undetected; L[OIII]/L[CII] > 12 (3σ: later discussion)l This pioneering work opens a new window in studies of reionization

More than N > 15 [OIII] 88 μm in the EoR
Inoue+16
LAE

Carniani+17
LAE

Laporte+17
LAE/LBG

Hashimoto+18
L AE/LBG

A. K. Inoue et al. 2016, Science

Hashimoto+19a
LAE/LBG

Tamura+19
LBG

5.4σ

also Harikane+19; Sunaga+ in prep.

Marrone+18
pair-SMG

Walter+18
Hashimoto+19b
SMG and QSO
2 QSOsOutlinel Introduction- Cosmic reionization- Galaxies in the epoch of reionization (EoR)- Spectroscopyl Rest-frame FIR properties at z > 7 with ALMA
- Case study:
properties of a z = 9.1 [OIII] 88μm emitter- Statistics:
High ratios of L[OIII] 88 μm/L[CII] 158 μm
in high-z LAEs/LBGsl Some thoughts on AAT

(1) MACS1149-JD1JD1Zheng+17• A lensed J-band dropout galaxy (Zheng+12, Nature)• Bright (H=25.7) with a magnification factor (μg) ~ 10
• One of the highest-z galaxy candidate accessible w. ALMAHST and Spitzer/IRAC images of JD1
JD1 undetected4”.6JD1 detected
W. Zheng+17

3.6 μm

4.5 μmSED of JD1• zph = 9.6 ± 0.2 (Zheng+12)• Later at zph ≈ 9.0 - 9.8(Bouwens+14, Huang+16, Kawamata+16, McLeod+16, Zheng+17)
JH140
J125

H160

Spitzer/IRAC[3.6] & [4.5]Zheng+1718

[OIII] 88μm detection at z = 9.11
• ALMA Band 7 in Cy 3 Ttot ≈ 8.7 hrs (PI: A. K. Inoue)- 白色の等高線:• We covered
the酸素zph range (9.0 – 9.8) with 4 ALMA tunings- 背景の画像：紫外光 (HST)

Hashimoto+18 NatureContours: ALMA [OIII]
Bkg: HST F160W rest-UV

FWHM = 154 ± 39 km s-1

7.4σ

7.4σ
l zOIII = 9.1096 ± 0.0006
l SED (K. Mawatari) analyses showage ≈ 300 Myr at z = 9 ! zform ≈ 15 ± 2

Dust continuum is undetected in JD1
Sν,90μm < 5.3 x (10/μg) μJy/B (3σ)

Dust continuum
@90μm

< 3σ

MBB:

7.4σ

l M* ≈ 1 x 109 x (10/μg) M¤ from SED-fitl log(Md-to-M*) < -4 to -3 (3σ) for Td = 60 - 30 K (c.f., Popping+17)
cf., log(Md-to-M*) ≈ -4 to -1 @ M* ≈ 1 x 109 M¤ at z = 0" Useful constraint for theoretical dust models (e.g., Calura+17)

[CII] 158 is undetected in MACS1149-JD1
l Deep follow-up observations for [CII] 158 μm (PI: N. Laporte)l Similar beam size as used in [OIII] 88 μm observations

green ! [OIII] 88 μm
blue ! [CII] 158 μm

Laporte incl. TH+19
l L[OIII]/L[CII] > 18.5 (3σ; the highest ratio to date: later discussion)21Outlinel Introduction- Cosmic reionization- Galaxies in the epoch of reionization (EoR)- Spectroscopyl Rest-frame FIR properties at z > 7 with ALMA
- Case study:
properties of a z = 9.1 [OIII] 88μm emitter- Statistics:
High ratios of L[OIII] 88 μm/L[CII] 158 μm
in high-z LAEs/LBGsl Some thoughts on AAT

[OIII] 88/[CII] 158 luminosity ratio@z=6-9[OIII] 35 eV[CII] 11 eVhighly-ionized ISM
has a line high ratio

Hashimoto+19a
see also TH+19bl Anti-correlation between [OIII]/[CII] and Lbol.

For LAEs/LBGs:
Td=50 K β = 1.5
is assumed

[OIII] 88/[CII] 158 luminosity ratio@z=6-9
JD1LAELBG/LAE

Y1

LBG
LAE

YD4

LBGs
[OIII] 35 eV[CII] 11 eVhighly-ionized ISM
has a line high ratio

SMGs

Bakx incl. TH+20 in prepl Anti-correlation between [OIII]/[CII] and Lbol.

For LAEs/LBGs:
Td=50 K β = 1.5
is assumed

Ubiquitously high [OIII]/[CII] ratios at z > 6
Laporte incl. TH+19

High-z galaxies◯ local galaxies● Simulations(Lagache+18, 0.1Z¤)l CMB supression on [CII]?
- TCMB > 20 K cf., [CII] Tex ≈ 92 K (dashed-line: insufficient)l High-ionization parameter in the ISM? (Inoue+16, TH+19a)- [OIII] Pion (35 eV) vs. [CII] Pion (11 eV) ! LyC escape ??
l Some clues on O/C?
(need ionization correction)

è Detailed modeling will be performed (see also Harikane+19)
è Initial results highlight the unusual ISM conditions in the EoR

25

Ongoing Works of Our Team
①Morpho-kinematic properties at z = 8 - 9
2 ALMA Cy6 projects with “A” (PIs: Hashimoto, Tamura)à A reference study for future JWST and ELTs science
Combined data have intrinsic resolution of ~ 500 x 400 pc2

Cycle 3+4+6 (θ~0”.3)
Moriwaki+18> 10σTokuoka, TH+ in prep

Ongoing Works of Our Team②[OIII] 88 μm for five z ~ 10 candidates
2 ALMA Cy7 projects with “A”-33hrs (PIs: Hashimoto, Tamura)à HST + Spitzer で得られる現在最高のサンプル
à 2 supplementary VLT observations ongoing (PI: Hashimoto)rest-frame UV lines
à If confirmed, strong(est) JWST and ELT targets③Multiple line study for “Big Three Dragons” at z = 7.15
[OIII] 52, [NII] 122, CO(7-6) & CO(6-5) & [CI](2-1)
3 ALMA Cy7 projects “B” (PIs: Matsuo, Inoue, Hashimoto)! A comprehensive understanding of ISM in the EoR
critical density; nitrogen abundance, metallicity, gas properties

Outlinel Introduction- Cosmic reionization- Galaxies in the epoch of reionization (EoR)- Spectroscopyl Rest-frame FIR properties at z > 7 with ALMA
- Case study:
properties of a z = 9.1 [OIII] 88μm emitter- Statistics:
High ratios of L[OIII] 88 μm/L[CII] 158 μm
in high-z LAEs/LBGsl Some thoughts on AAT

Dust emission in the EoR
z = 6.90 lensed SMG(s) Marrone+18 Nature
Originally discovered as a bright 2.0 and 1.4 mm sourceby the 2500 deg2 SPT survey
AATSPT~ 10 mJy!!

HerschelSPIREFoV: 8’ x 4’
θ: 18-36”

ALMACombination of AAT & SPT can find such extremely dusty galaxies in the EoR
Toward a complete picture (UV+IR) of SFRD evolution (Madau&Dickinson 2014)

Dust emission in the EoR
z = 6.90 lensed SMG(s) Marrone+18 Nature
ALMA follow-up observations targeting dust, [CII] 158, [OIII] 88l E and W component has LIR = (4.6 ± 1.2) and (33 ± 7) x 1012 L¤l E and W component has Mdust = (0.4± 0.2) and (2.5 ± 1.6) x 109 M¤
l [OIII]/[CII] luminosity ratio is ~ 2.0 and 0.5
l [OIV] 26 μm with ATT or SPICA ! AGN activity

Dust emission in the EoR

l 4 (normal) star-forming galaxies (i.e., LBGs) with dust continuum
beyond redshift z = 7 up to z = 8.3 all achieved with ALMA!
Objectredshift

λrest [μm] Sν [μJy]Ref.

A1689-zD1~ 7.590160

1670 ± 360
560 ± 100

Inoue & Hashimoto+20 subm.
Watson+15 Nature

B14-65666

7.15

90160

470 ± 128130 ± 25

Hashimoto+19a

A2744_YD4

8.3890160

99 ± 23< 11 (3σ)

Laporte+17
Laporte incl. TH+19

MACS0416-Y1

8.31

90160

137 ± 26
< 18 (3σ)

Tamura, Mawatari, TH+19
Bakx, Tamura, incl. TH+20

High Td in high-z star-forming galaxies?
Objectredshift

TdRef.

A1689-zD1~ 7.5

63 – 92 K

Watson+15
Inoue & Hashimoto+20

B14-65666

7.21

50 – 60 K

Bowler+18
Hashimoto+19aA2744_YD4

8.38

60 – 100 K Behrens+18

MACS0416-Y1

8.31> 90 K

Bakx, Tamura, incl. TH+20l A larger sample is crucial for a defitnive conclusionl High Td due to compact star-formation, strong UV radiation (e.g., Inoue&TH+20)
l Partly resolve the IRX-βUV and dust mass budget problems (Faisst+17, Behrens+18)
l High Td leads to a dust peak at higher frequency (shorter wavelength) ! strategy

2020 - 2030年代に向けて
l 多波長間の連携が極めて重要
l Subaru/HSC (< 0.6 um) + WFIRST (mid 2020: 0.6-2um)
2000平方度NASA 2020 decadal survey

l WISH (Inoue, Kodama, Iwata+) 今後提案 2-5 um
100平方度 27.5 mag (5σ) cf., JWST は視野小l AAT 200 um – 1.5mm : 広視野 (1平方度)
同程度 (> 100 平方度) の探査領域が重要 (後述)

2020 - 2030年代に向けて①例えば z = 15 の LBG (紫外選択天体) を考える
Lyman-break at (1+15) * 1216 Å ~ 20000 Å = 2 um
銀河の静止系紫外スペクトルλrest = 1216 Å

λrest = 912 Å

要は、2 um まで見えない天体(深い未検出を確定するためデータは必要... HSC + WFIRST)l WISH (2-5 um) で 静止系可視z = 15 LBGが選択可能になる2020 - 2030年代に向けて
l 例えば z = 15 の LBG (紫外選択天体) を考える
l AAT (200 um – 1.5mm) で静止系中間赤外 – 遠赤外線 (13-94 um)
z = 15 LBG のダスト連続光ピーク 付近を抑えることが可能！
重要輝線: H2 分子輝線 17/28 um; [OIV] 26 um, [OIII] 52/88 um など! 個別で未検出でも多数スタックして平均像は得られる。
② 静止系 紫外-可視で暗く 赤外で明るい dusty SB @ z > 10AAT (200 um– 1.5mm) + SPT (1.2 – 3.0mm)
同様に、静止系 紫外 – 可視 (観測波長 5 um程度まで)データは必須
多波長の2020-2030年代サーベイ予定を考慮しつつ、feasibility (感度、探査領域 etc.) が重要。
! ALMA2 を通して詳細な分光フォローアップ