（遠⽅銀河と近傍銀河を星形成でつなぐ）
あるいは銀河・電波観測まわりの最近の研究動向
⼩⻨真也
⼯学院⼤学
コーガくん クイーンちゃん

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銀河進化研究会, Jun. 7-9 2017 @ ⼤阪⼤学

2015-2017トレンドマップ
キーワード：銀河、電波、観測

Xraycavity

Galaxychemistry

Cooling flow
Disk SF
Scaling laws

Merger induced SFinflow
Starburst

BH-host relation

Galactic Disk
Jet – companion interaction

Molecular outflow(quenching)
Galaxy2

Negative Feedback (SF quenching)• Necessary to explain “red and dead” galaxies, solve “overcooling”, etc.
• Molecular outflow observed in many galaxies• NGC1808 (Salak+16), IRAS17208, NGC1614 (Garcia-Burillo+16)• Mout ~107-8 Msun powered by starburst (+AGN)• massive molecular outflow in F11119+3257, Mout ~109 Msun (Veilleux+17)• ~10% of total molecular gas• ~100Msun/yr• Outflow via AGN or starburst only is not powerful enough (Biernacki+17)• Is quenching
really effective ?
c.f., SF can occur in outflows(Maiolino+17, Nature)

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Veilleux et al. 2017

AGN jet vs. Cooling Flow

ALMA CO(J=3-2) on Phoenix Cluster (z=0.596) BCG
Brightest X ray cluster with SFR = 500-800 Msun/yr
M(H2) = 2.1 x 1010 Msun (50% in filament)

Russell et al. 2016

In situ cold gas formation from hot gas ? Gas lifted from disk ?
Gas will eventually fall to disk --> additional fuel for AGN and disk SF

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Jet – companion interaction

JVLA 5GHz on HE0450-2958 (z=0.285) QSO-SFG pair
Evidence of Jet – companion galaxy interaction

Molnar et al. 2017

Spectral index (4-6GHz) flattenning observed in jet-SFG overlap regionàStar formation triggered by QSO Jet ?
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Merger induced SFMethanol (CH3OH) imaging of mid-stage merger VV114

Saito et al. 2017aStar formation (Paα) and methanol abundance peak at the overlap
6Gas inflow

Saito et al. 2017b, Sliwa+14, Xu+15

Merger remnant NGC1614, imaged in CO(J=1-0, 2-1, 3-2, 6-5)
“S-shaped” velocity field, indicating kpc scale non-circular motion
and consistent with dust lane in HST
Inflow rate ~ 54 Msun yr-1, SFR ~ 33 Msun yr-1, outflow rate ~ 40 Msun yr-17

Molecular tracers and physicalconditions• submm AGN/SB diagnostics
HCN/HCO+, HCN/CS (Izumi+16)
HCN enhanced in XDR, and/or
high-temperature e.g., shock (Harada+13)
CS tracing shocked regions• HCN-vib
Izumi et al. 2016
excited by 14um mid-IR, T14um > 100K
probes N(H2)>1024 cm-2 where ground state HCN, HCO+ could be self
absorbed (Aalto+15), e.g., in CONs
• Muliple-J CO (1-0 … 7-6) + non-LTE calculation (RADEX; van der Tak 2007)à density and temperature estimations8

BH – host galaxy relation• How universal is the MBH – σ relation ?
(negative feedback necessary)• BH mass determination using high resolution mmlines for galaxies with relatively relaxed cold gas

Onishi et al. 20179

Scaling laws
• Resolved main sequence• SFR vs M* at 1kpc scale for 93 localgalaxies (0.01 < z < 0.03)• Quenched galaxies breakdown in theresolved MS

Abdurro’uf et al. 2017

• logΣSFR ∝ 0.33 logΣ*• Since star formation laws (e.g., KStype) are more or less universal, thismay reflect variations in gas fraction

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Scaling laws
• Extended Schmidt-Kennicutt law• M31 at 160 pc resolution• SFR = FUV + 24um
• Gas = H2 (CO) +HI• M* = IRAC 3.6um• logΣSFR = 0.44 logΣ* + 0.43 logΣgas -10.5
Rahmani et al. 2016

• Why is there a M* dependence at this scale ?
160pc << stellar lifetime×stellar dispersion
à in situ effect from M*, not imprint of SF history

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Scaling laws
• Relation between ISM - SFR – GMC evolution• M33 and NGC300 at 100-300 pcresolution• PCA analysis using CO(1-0), CO(3-2),
dust, M*, SFR, GMC age• logΣSFR = 0.5 logΣ* + 2.1 logΣdust -6.0logΣCO32 = 0.12 logΣSFR + 0.94 logΣCO10 + 1.4
Komugi et al. 2017 tbs• Things are starting to get complicated…

12今後流⾏するとよい分野／
インプットがあると助かる分野• How to reliably measure gas mass
• Star formation condition in disks, in indiv. Clouds• How does SFR change at GMC scales with time, when
initial gas density / radiation field / metallicity change ?
• Merger simulations with user tunable parameters• <kpc scale dust observations• (sub-mm) dust distribution in galactic disks is challenging
even for ALMA. Large observing campaigns needed.

• Statistical studies in general13