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M33 高密度分子ガス観測にむけて Dense Cloud Formation & Global Star Formation in M33

M33 高密度分子ガス観測にむけて Dense Cloud Formation & Global Star Formation in M33. 田村陽一 ( 東大・天文 M1 , ALMA-J/NAOJ) 第 4 回 銀河ショップ @ 北海道大学 October 18-19, 2004. M33. 01 h 34 m +30 o 40' SA(s)cd 0.85Mpc 56 o 71'x42'. R.A. Decl. Type Distance Inclination Diameter Weak bulge No SMBH?

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M33 高密度分子ガス観測にむけて Dense Cloud Formation & Global Star Formation in M33

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  1. M33高密度分子ガス観測にむけて Dense Cloud Formation & Global Star Formation in M33 田村陽一(東大・天文M1, ALMA-J/NAOJ) 第4回 銀河ショップ @ 北海道大学 October 18-19, 2004

  2. M33 01h 34m +30o 40' SA(s)cd 0.85Mpc 56o 71'x42' • R.A. • Decl. • Type • Distance • Inclination • Diameter • Weak bulge • No SMBH? (Merritt et al. 2001) • Huge star forming region in outer disk • NGC 604, NGC595..

  3. M33 • Spitzer/IRAC (3.6, 4.5, 8 um) • Hα Polomski et al. 2004 Cheng et al. 1996

  4. M33 • NGC604 HST/STScI

  5. Why M33? • なにより近い． • GMCの空間分布が直接わかる． • Inclinationが小さい． • Disk/armの存在 • すばる望遠鏡で個々の星が分解されている． • High-mass star? / low-mass star? • Color → Type → Age of GMCs • 比較的低赤緯 → ALMAへ • NMA/すばるによる高分解能観測によって，現時点で最も詳細に星形成の大局的な描像を知りうる唯一の銀河.

  6. GMCs in M33 • C. Wilson et al. w/ OVRO array • 系外銀河GMCの先駆的研究　 • The BIMA All-Disk Survey (Engargiola et al. 2003) • 12CO(1-0) • 148 GMCs detected • Heyer et al. w/ FCRAO 14m (2004) • Diffuseな成分も検出 • M(H2) = 2.6x108 Mo • MWに類似した性質 • Size, Mass,…

  7. NGC505 NGC604 Wilson & Scoville GMCs in M33 BIMA on FCRAO14m (Engargiola et al. 2003, Heyer et al. 2004)

  8. The BIMA All-Disk Survey • (Engargiola et al. 2003) • 148GMCs detected • Mmolecule =4.5x107Mo • 2.5x104Mo - 8x105Mo • Lifetime = 10-20 Myr Engargiola et al. 2003, Deul & der Hulst 1987

  9. GMC Mass Spectrum of M33 • dN/dM=K(M/Mo)-α • α=2.6 for M33 • 3x104-8x106 Mo • ~2000 GMCs • Index α • 1.5-1.8 for MW (e.g. Solomon et al. 1987) • 1.5(1.9)±0.5 for LMC (Mizuno et al. 2001) Engargiola et al. 2003

  10. GMC Formation in M33 • The BIMA Survey II (Rosolowsky et al. 2004) • BIMA C array (4" resolution ⇔ 20pc) • 20 GMCs resolved • Size, Line width → Virial mass • Angular momentum • HI gasの凝集 • 理論より角運動量が小さい． • GMC形成理論に対する大きな制限 • 磁場によるブレーキ?

  11. Star Formation in M33 • Schmidt Law • ΣSFR ∝ (Σmolecule)n • n=0.9±0.1 (Engargiola et al. 2003) • n=1.36±0.08 (Heyer et al. 2004) • SFR = 0.24 Mo yr-1 • 分子ガス消費時間 = 1.9x108 yr • 比較的短い． • Mass spectrumと関連?

  12. Star Formation in M33 • GMC ⇔ HII region offset Δr • 典型的には~150pc HII region GMC Δr Engargiola et al. 2003

  13. Phase Transitions of Gases and Star Formation in Arms HI 175 pc GMC Dense gas / Core Star formation Wilson & Scoville 1991

  14. Dense Molecular Gas Observation with Nobeyama Millimeter Array

  15. Phase Transitions of Gases and Star Formation in Arms • HI filaments • GMCs • Dense Molecular Clouds • 13CO, HCN, HCO+ • …and Star formation • Hα / free-free emission • Main sequence stars • Subaru/Suprime-Cam HI GMC Dense gas / Core Star formation

  16. Phase Transitions of Gases and Star Formation in Arms • Clock • (OB) Stars • すばる/Suprime-Cam • Arm - HII region offset • 江草ほか • なんてん ~ GMC phases • Yamaguchi et al. 2001 HI GMC Dense gas / Core Star formation

  17. Dense Gas Observation with NMA • Armにそって • GMCを複数個 • 似たmass/sizeのものを選択 • Gasの流れを追う • ガスの時間変化/進化/相転移 • 大規模星形成領域 • Pre- Star Formation • Ongoing Star Formation • Post- Star Formation NMA FoV@110GHz

  18. Dense Gas Observation with NMA GMC Young Stars Dense Molecular Gas Spiral Arm HII Region

  19. How are GMCs in Extra-Galaxies seen with ALMA?

  20. The Local Group Galaxies • ~0.1" Resolution ⇔ 0.4 pc ~ 1x105 AU @ M33 (0.85Mpc) • MCの内部構造(clump, filament,..)まで見える． • 系内GMC研究への歩み寄り(相補的) • [CI] line • GMC forming stage, Photo-Dissociation Region

  21. Nearby Galaxies with D<20Mpc • ~0.1" Resolution ⇔ 10 pc @ Virgo (20Mpc) • FoV of ALMA = 40" ⇔ 4kpc • 前述のNMAやBIMAのM33の観測をVirgo clusterで． • 数~10視野程度でdisk全体をカバーできる． • 1視野あたり~102 GMCs! • 銀河ごとのGMCの性質を統計的に議論することが可能． • Flocculent ⇔ Grand-design ? • GMC mass spectrum • Schmidt law

  22. Summary • Armにおけるガス進化・大局的な星形成をこれから見たい． • Dense gas observation w/ NMA • M33/disk galaxyにおける銀河規模のGMCの諸性質が見えてきた． • The BIMA All-Disk Survey • C. Wilson et al. w/ OVRO • The Local Group Galaxies • MWと相補的 • Nearby galaxies • 様々な銀河で103-104 GMCを統計的に扱うことが可能に． より小さいスケールへ より多くのサンプルを

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