Studying ISM and star formation in M33 with ALMA Sachiko Onodera & NRO MAGiC Team: (M33 All-disk Survey of Giant Molecular Clouds) N. Kuno 1, T. Tosaki 2, S.Onodera 1, R. Miura 3, K. Muraoka 4, S. Komugi 5, T. Sawada 6, K. Nakanishi 6, K. Kohno 3, H. Kaneko 7, A. Hirota 1, R. Kawabe 1 1 NRO, NAOJ, 2 Joetsu Univ. of Education, 3 Univ. of Tokyo 4 Osaka Prefecture Univ., 5 ISAS/JAXA, 6 ALMA Project Office, NAOJ 7 Graduate Univ. for Advanced Studies M33-chan by T.Sawada

Evolution of ISM/star formation What controls each process? metallicity radiation field pressure Compression by arm/bar Gravitational instability Cloud-cloud collision Diffuse ISM (atomic gas) Dense ISM (molecular gas) Dense core Star formation Dissipation of ISM

M33:the Best Field for GMC Study Close to our Galaxy (D = 840 kpc) each GMCs can be resolved (1"~ 4 pc) Observable with ALMA (Decl.= 30°) Moderately face-on Distribution of GMCs in the whole disk, in relation to other components (e.g. star-forming regions) Star-forming regions over the whole disk NGC604 NGC595 IC133 SUBARU Suprime-cam (BVHα)

Advantages to Milky Way – Without blending in line-of-sight – Much larger sample number In equal distance In various evolutional stages The best target for studying GMCs and star formation in a whole galaxy M33:the Best Field for GMC Study

NRO MAGiC & our previous M33 works Integrated intensity map Velocity field 12CO(1-0) with 45m Onodera+ (2010) Tosaki+ (submitted) 13CO(1-0) with 45m Miura+ (in prep.) Muraoka+ (in prep.) 12CO(3-2) with ASTE Tosaki+ (2007) Miura+ (in prep.) Onodera+ (in prep.) 1.1mm dust continuum with ASTE/AzTEC Komugi+ (submitted) HCN & continuum with NMA Miura+ (in prep.) CO (1-0) map (Tosaki+ submitted)

Color : 12 CO(3-2) with ASTE Grey & contour : 12 CO(1-0) with NRO 45m ΔT mb ~ mk 5×5 7.3× × × ×3 3.3× ×4 2.5×2.5 Total ~ 140 arcmin 2 Wide range of CO(3-2)/CO(1-0) Miura et al. 2010, in prep. (Miura+ in prep.)

M33 AzTEC / ASTE ・ D= 0.84 Mpc, opt. size = 70’ x 40’ ・ obsered , 30 hours on source  avg. τ 220GHz = 0.06 ・ 30’ x 30’ x 2 field, 28” = 120pc res.  most of SF disk ・ 1σ = 4-5 mJy/b = ~ 600 M o dust ・ 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) 1kpc Komugi et al submitted to ApJ Cold dust temperature map Smooth gradient from G.C> to outer R

Difference of evolutionary stages among GMCs ～ 6′ 1.4kpc (Onodera, PhD thesis 2009)

To what scale is the Kennicutt- Schmidt law valid? the surface density of molecular gas mass vs SFR in the highest resolution (~80pc) to date Correlation evident in 1kpc, 500pc Becomes looser with higher resolution, and finally breaks down ⇒ GMC scale (~80pc) is where the K-S law becomes invalid Σ(SFR) Hα,corr [M o yr -1 pc -2 ] (Onodera+ 2010) Σ(H2)[M o pc -2 ] Resolution ~80pc ~250pc ~500pc ~1kpc 2σ2σ

Low SF activity ⇒ fraction of dense gas Higher mass GMCs have higher fraction of dense gas? (Onodera+, in prep.) GMC evolution? Red Σ(SFR)> 1x10 -8 Mopc -2 Blue Σ(SFR) < 1x10 -8 Mopc -2 Muraoka+ 2007

Difference of evolutionary stages among GMCs LVG calculation using I(12CO1-0)/I(13CO1-0) & I(12CO3-2)/I(12CO1-0) Definition: Tk>30K WARM n(H2) > 2000 cm -3 DENSE SFR > 10 8 Mo yr -1 pc -2 ACTIVE SF (Miura+ in prep.)

Observation with ALMA: inside GMCs

Massive star formation Massive stars are formed in GMC （ M>10 5 Mo ） Most stars （ 70‐90% ） in GMCs are formed in clusters Lada et al., 1991, ApJ 371, 171 Carpenter, 2000, AJ 120, 3139 Lada & Lada, 2003, ARAA 41, 57 (cluster mass Mo) Clusters are formed in dense gas clumps size:~1pc, Mo, density ： cm -3 (Higuchi et al. 2009, ApJ 705, 468; Lada & Lada 2003) e.g., volume filling factor 8% (Rosette Molecular Cloud) (Williams et al. 1995, ApJ 451, 252)

Clumps related with massive star formation M > 100 Mo, size ~ 1 pc – Fraction of total mass/volume of GMCs? – Distribution? – Maximum mass? Evolution of GMCs/star formation? Environment/galactic structure ? Properties of GMCs Massive star formation

Revealing clump formation within GMCs Internal structure along with GMC evolution Fraction of denser gas and diffuser gas Their distribution ↓ Formation mechanisms of dense clump Relation to properties of their natal GMCs ↓ Cluster, massive star formation

Rosette Molecular Cloud 13CO(1-0) Bell Lab. 7m Beam Size ～ 0.7pc Williams et al ApJ 451, 252 GMC Observation inside MW

Williams et al. 1995, ApJ 451, 252 Stars are formed in Massive clumps (>a few 100Mo) With IRAS source

Dense clumps associated with embedded clusters Higuchi et al. 2009, ApJ 705, 468

Strategy 1: Cold dust continuum

Cold dust continuum from dense clumps The Lagoon Nebula Dense clump cm -3 Gray scale : 850um (SCUBA) Contour : CO(2-1), CO(3-2) (Tothill et al. 2002, ApJ 580, 285)

1.1mm continuum – Comparison with ASTE1.1mm map ↓ Fraction of clump mass to total mass Komugi et al submitted to ApJ

Targets: GMC complexes in much different stages of evolution Contour : CO(1-0) Gray scale : Ha Without star formation M~10 6 Mo NGC 604 With active star formation M~10 6 Mo 5.5′

Required integration time Total flux of Massive clump （ ~1pc, ~400Mo ） (Tothill et al eq.1:T d =27K, β=1.7, gas/dust=100) S(1.1mm) ~ 0.3mJy Estimation by ALMA sensitivity calculator – 270GH ｚ (1.1mm ） – T sys ～ 160K – FOV ： ~30″ （ ~10 pc ） – Beam size: 0.3″ （ ~1 pc ） – dF=8GHz – S rms = 0.1mJy 25min/FoV

15 fields for each ->13hrs/FoV -> total ～ 17hrs

In full operation clump survey for ALL GMCs – 12m×64 だと 1 視野あたり 3 分 より詳しく密度構造を知るために、多輝 線観測（高密度ガスのトレーサーを含む ） 例えば、 CO(3-2) の場合 – ビームサイズ： 0.3″ – 速度分解能： 0.5km/s – T rms = １ K – 積分時間＝ 2.8 時間 (12m×16)

Strategy 2: Dense gas tracers

HCN detection in NGC604 SF is not active CO(3-2)/CO(1-0) ～ 0.5 In earlier stage of SF (Miura+ 2010) (Tosaki+ 2007)

Target: (1) NGC604-2& NGC604-4 (2) EPRB1 & EPRB2 Object: Stars earlier than O5 type Size, distribution of clumps Lines: CO(3-2),HCO+(4-3) CN(4-3), CS(2-1) In ES (B=250m) In full operation 0.16” 23hr/FoV With ALMA

Strategy 3: 90GHz continuum

90GHz continuum in NGC604 Well correlated with 24um 24um is a good tracer of SFR （ e.g. Calzetti+07) Dust-embedded young stars Comparison to 24um

Similarities between two SFEs similar even if we suppose all 89GHz emission is from free-free (Miura+ 2010)

With ALMA Target candidates –24um+Ha catalogue for each HII region (Verley+09) –3.6cm, 20cm radio continumm (Tabatabaei+07) 11 objects –MidInfrared (Hippelen+) In ES –FoV~60 ” ( ～ 250pc) –low resolution ~3 ” – –rms~0.1mJy –band width 8GHz –int.time 3 min /FoV !

Strategy 4: 12CO(1-0) line

12CO(1-0) survey in smaller scales Internal structure of GMCs – Velocity information Evolutionary stages – virialized or not? Filament and/or larger scale clumps? MC survey with a wide mass range （ M > a few 1000 Mo, R > 5pc ） – Intermediate-mass star formation – GMC formation – aggregation of smaller MCs or mere single large cloud?

With ALMA Intermediate mass MC （ ~5pc, δv~2km/s, M~5000Mo ） →Tmb=1.5K velocity resolution=0.635km/s) In ES – 115GHz CO(1-0) – T sys ~141K – FOV ： ~70″(~280 pc) – Beam size: 1″(~4pc) – dF = kHz (0.635km/s) – S rms = 0.5K – 3.75 hrs/FOV GMC1 (the most massive GMC) 2 fields

Summary GMC evolution & star formation – Massive star formation – Internal structure – Especially massive clumps in ALMA ES Strategies for ALMA – Cold dust continuum: massive clumps – Dense gas tracer lines: dense clumps – 90GHz continuum: embedded SF – CO(1-0) line: internal structure