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渦状銀河における GMC の進化と星形成 Evolution of GMCs and star formation in spiral galaxies

渦状銀河における GMC の進化と星形成 Evolution of GMCs and star formation in spiral galaxies. NRO M33 All-Disk Survey of Giant Molecular Clouds (NRO MAGiC ) Preliminary results of ALMA cycle 0 observations of M83 CO Galactic Plane Survey by NRO 45-m telescope. Nario Kuno Nobeyama Radio Observatory.

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渦状銀河における GMC の進化と星形成 Evolution of GMCs and star formation in spiral galaxies

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  1. 渦状銀河におけるGMCの進化と星形成Evolution of GMCs and star formation in spiral galaxies NRO M33 All-Disk Survey of Giant Molecular Clouds (NRO MAGiC) Preliminary results of ALMA cycle 0 observations of M83 CO Galactic Plane Survey by NRO 45-m telescope NarioKuno Nobeyama Radio Observatory

  2. Collaborators T. Tosaki1, S.Onodera2, R. Miura3, K. Muraoka5, S. Komugi3, T. Sawada3, K. Nakanishi3, K. Kohno4, H. Kaneko6, A. Hirota7, N. Arimoto7, H. Nakanisi8, R. Kawabe3, F. Egusa9, K. Wada8 1 Joetsu University of Education 2 Meisei university 3 Chile observatory, NAOJ 4 University of Tokyo 5 Osaka Prefecture University 6Tsukuba university, 7 NAOJ 8Kagoshima University 9 ISAS

  3. Introduction • Cycle of matter in galaxies • Evolution of molecular clouds (from atomic gas to dense gas) are one of the main themes of radio astronomy

  4. Observations of GMCs in nearby galaxies • LMC: Kawamura et al. 2009, Hughes et al. 2010… • M33: Rosolowsky et al. 2007, Gratier et al. 2012… • M51: Koda et al. 2011, Egusa et al. 2011… • IC10: Leroy et al. 2006 • M31: Rosolowskyet al. 2007 Scientific objectives: • Basic properties of GMCs （mass, size, …） • Evolution of ISM ⇔ star formation process • GMC formation → dense gas → stars → destruction of GMCs GMCs in M33 and M83

  5. 1. NRO M33 All-Disk Survey of Giant Molecular Clouds (NRO MAGiC) • Moderately face-on GMCs are distributed throughout the disk and are in relation to other components (e.g. star-forming regions, arms,…) • Close to our Galaxy (D = 840 kpc) each GMC can be resolved (NRO 45m resolution： 20"~ 80 pc) • Many star-forming regions over the whole disk The best target for studying GMCs and star formation within a whole galaxy (Arimoto et al.)

  6. Data • Molecular gas : 12CO(1-0) (45m) • Warm and dense molecular gas : 12CO（3-2）（ASTE） : 13CO(1-0) (45m) • Cold dust : 1.1mm （ASTE：AzTEC） • Star-forming region : Ha（SUBARU） • Stars : B,V,R,I （SUBARU） • Atomic gas, IR … : （Archived data） Properties and evolution of GMCs

  7. High resolution & wide field mappingw/ NRO 45m/ASTE 10m + OTF • HPBW=16” @ CO(1-0) • 25 beams! + OTF • HPBW=22” @ CO(3-2) • Tsys~150K! + OTF Highly uniform quality NRO 45m Atacama Submillimeter Telescope Experiment Array receivers “25BEARS” “CATS345”

  8. 12CO(1-0) map with NRO 45m 12CO(1-0) with 45m Velocity field 1 kpc Globally galactic rotation Many GMCs are identified Tosaki et al. 2011

  9. Color : 12CO(3-2) with ASTE Grey & contour : 12CO(1-0) with NRO 45m 4.2×4.2 5×5 2.5×3 3.3×3.3 5.2×5.6 4.4×4 2.5×2.5 7.3×3.3 ΔTmb ~ 13 -20 mk Total ~ 140 arcmin2 Wide range of CO(3-2)/CO(1-0) Miura et al. 2012

  10. 1.1 mm map Komugi et al. 2011

  11. 1.1 Formation of molecular clouds 1.2 Relation between molecular gas and star formation 1.3 Evolution of Giant Molecular Clouds 1.4 Radial gradient of dust temperature

  12. 1.1 Formation of molecular clouds • Molecular gas is formed more efficiently in inner region than outer region（Tosakiet al. 2011） CO+SFR CO+HI

  13. Correlation between gas surface density and fmol fmol Σgas Two distinct sequences on the Σgas – fmol

  14. Molecular gas fraction; fmol • Function of • metallicity Z • radiation field U • gas pressure (or gas volume density n) • (Elmegreen 1993) high Z/high n⇒ efficient H2 formation high U⇒ efficient H2 destruction

  15. Sharp increase of metallicityin the central region from ~2kpc • Model calculations are consistent with the observed results quantitatively 2 kpc Vilchez et al. 1988

  16. 1.2 Relation between molecular gas and star formation • Kennicutt-Schmidt law • global correlation between surface density of gas and star formation rate • To what scale is • the Kennicutt-Schmidt law valid? M51 0.5-2kpc scale (Kennicutt et al. 2007)

  17. Breakdown of the Kennicutt-Schmidt law at high resolution (~ 80 pc) Resolution ~80pc Check by changing spatial resolution from 1kpc to 80pc • Becomes looser with higher spatial resolution ⇒The Kennicutt-Schmidt law becomes invalid in GMC scale (~80pc) Difference of evolutionary stage of GMCs ~250pc Σ(SFR)Hα,corr [Moyr-1pc-2] ~1kpc ~500pc 2σ Σ(H2)[Mo pc-2] (Onodera et al. 2010)

  18. Correlation between CO(3-2) and SFR => CO(3-2) traces denser and warmer gas SFR vs. CO(1-0) intensity SFR vs. CO(3-2) intensity (Onodera et al. 2012 PASJ in press)

  19. 1.3 Evolution of Giant Molecular Clouds • Variation of star-forming activity in molecular clouds （Miura et al. 2012） CO(1-0) + young stars CO(3-2) + young stars • 71 GMCs • Ha, 24um => HII regions • Stellar groups • Optical data => age of stars Ha + young stars CO(3-2)/CO(1-0) Type C: With HII regions With young stellar groups (< 10 Myr)

  20. Type A: No HII regions No young stellar groups 1 % Type B: With HII regions No young stellar groups 20 % Classification of GMCs: 4 types of GMCs Type C: With HII regions With young stellar groups (< 10 Myr) 45 % Type D: With HII regions With old stellar groups (10-30 Myr) 34 % • Life time of a GMC with a mass > 105 M => 20-40 Myr

  21. 1.3 Evolution of Giant Molecular Clouds • Relation between properties of molecular clouds (evolutionary stage, mass) and dense gas fraction （Onodera et al. 2012） • CO(3-2)/CO(1-0) => • fraction of warm and dense gas • GMCs with high SFR have higher CO(3-2)/CO(1-0) ratio • => higher dense and warm gas fraction • (Consistent with the correltion between CO(3-2) and SFR) • Higher mass GMCs have higher CO(3-2)/CO(1-0) ratio (for GMCs with low SFR) • => higher dense gas fraction Red > 5x10-9Mo yr-1 pc-2 Blue < 5x10-9Mo yr-1 pc-2 Muraoka+ 2007

  22. 1.4 Radial gradient of dust temperature M33 AzTEC / ASTE Komugi et al. 2011 ・D= 0.84 Mpc, opt. size = 70’ x 40’ ・obsered 2007-08, 30 hours on source  avg. τ220GHz = 0.06 ・30’ x 30’ x 2 field, 28” = 120pc res.  most of SF disk ・1σ = 4-5 mJy/b = ~ 600 Modust ・1100 um concentrated along spiral arms, SF regions. Good spatial correlation w/ HI overdensity regions ・can be used for : Dust physics (w/ AKARI, Spitzer, Herschel) GMC evolution, SF studies (w/ CO, HI) star cluster / galaxy evolution (w/ Subaru) Cold dust temperature map from 1.1mm and Spitzer data 1kpc Smooth gradient from G.C> to outer R

  23. 2. Preliminary results of ALMA cycle 0 observations of M83 (PI: A. Hirota) • Mapping of M83 in 12CO(1-0) • HPBW=2.3”~50pc • GMCcan be resolved • Best target for the comparison of GMC properties in spiral arms, bar, and central region • => Influence on the GMC properties and their star forming activity Hubble 45m+NMA 200pcX100pc

  24. ALMA Cycle 1 observations (PI: A. Hirota)

  25. 3．CO Galactic Plane Survey with the NRO 45-m telescope FOREST 2X2 beam X 2 Pols X 2SB • OTF mapping of the Galactic plane and the outer disk in 12CO(1-0), 13(1-0), C18O(1-0)(simultaneously) with FOREST • Mapping area • l：10°～50°b：±1°　（80 deg2) • Spiral arms（Perseus, Sagittarius. Scutum-Centarus arms）, bar sturcture, molecular gas ring • l：198°～236°b：±1° • Comparison between inner and outer regions(GemOB1, MonOB1, Maddalena cloud, CMaOB1 etc) • Closer than the inner region => Noise level ~ 3 times higher than the inner region=> Observing time : ~1/9

  26. NASA/R. Hurt

  27. Advantages of NRO survey • High angular resolution • Can resolve clumps in the main Galactic structures (arm, bar, inner disk, outer disk) • Multi-line observation(simultaneously) • Structure of molecular clouds : Diffuse molecular gas – dense gas • Collaboration with VERA • measurements of the distance with VERA GRS NROsurvey Nakanishi et al. 2006

  28. Members • ISAS Tsuboi, M. • NRO Kuno, N., Umemoto, T., Hirota, A.（PD）, Matsui K. (PD) • Chili observatory Higuchi, A.（PD） • Mizusawa VLBIobservatory Honma, M. et al. • JCMT: CO(3-2) • Mini-TAO: Paα • Kagoshima univ. Handa, T., Nakanishi, H., Omodaka, T.,Tanaka, A.（M2）, Matsuo, T.（M2）, Kamezaki(D1), Yoshida(M1), • Osaka prefecture univ. Onishi, T., Nishimura (D2), Tokuda (M2) • Joetsu education univ. Tosaki, T., Odaka(M1) • Meiseiuniv. Onodera, S., Sofue, Y., Tsuda, Y.（M2）, Ozawa, T.（M2）

  29. Summary • M33 • Molecular gas is formed more efficiently in the inner region than outer region • The Kennicutt-Schmidt law becomes invalid in GMC scale (~80pc) for CO(1-0), but it is still valid for CO(3-2) • Life time of GMCs is estimated to be 20-40 Myr • Correlations between • star forming activity and CO(3-2)/CO(1-0) ratio of GMCs • GMC mass and CO(3-2)/CO(1-0) ratio • The cold dust temperature gradually decreases with radius • M83 • Excellent data of the ALMA cycle 0 • Larger area will be mapped by ALMA cycle 1 observations • CO Galactic Plane Survey with the NRO 45-m • GMC evolution and dense clump formation

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