NRO Legacy Project: CO Galac4c Plane Survey. Nario Kuno (NRO) et al.

Transcription

1 NRO Legacy Project: CO Galac4c Plane Survey Nario Kuno (NRO) et al.

2 Members Kagoshima univ. Handa, T., Nakanishi, H., Omodaka, T., Tanaka, A.(M2), Matsuo, T.(M2) Osaka prefecture univ. Onishi, T., (graduate student) Joetsu educa4on univ. Tosaki, T., (graduate student) Meisei univ. Onodera, S., Sofue, Y., Tsuda, Y. (M2), Ozawa, T.(M2) ISAS Tsuboi, M. NRO Kuno, N., Hirota, A.(PD) Chili observatory Higuchi, A.(PD) Mizusawa VLBI observatory Honma, M. et al. Shinnaga, H.

3 Cycle of mauer in galaxies 1.Introduc4on Evolu4on of molecular clouds (from atomic gas to dense gas) are one of the main themes of radio astronomy

4 Previous studies (from observa0ons in galac0c scale) Evolu4on of molecular gas in GMC scale Forma4on of molecular clouds Molecular gas is formed more efficiently in inner region than outer region (M33: Tosaki et al. 2011) What determine the forma4on efficiency of molecular clouds? CO+HI

5 Evolu4on of molecular clouds Varia4on of star- forming ac4vity in molecular clouds (LMC: Kawamura et al. 2009, IC342: Hirota et al. 2011, M33: Miura et al. 2012) Rela4on between proper4es of molecular clouds (evolu4onary stage, mass) and dense gas frac4on (M33: Onodera et al. 2012, in press) Evolu4on of internal structure of molecular clouds? Kawamura et al Onodera et al. 2012

6 Evolu4on of molecular clouds Varia4on of star- forming ac4vity in molecular clouds (LMC: Kawamura et al. 2009, IC342: Hirota et al. 2011, M33: Miura et al. 2012) Rela4on between proper4es of molecular clouds (evolu4onary stage, mass) and dense gas frac4on (M33: Onodera et al. 2012, in press) Evolu4on of internal structure of molecular clouds? Hirota et al. 2011

7 Probability Distribu4on Func4ons of gas density in the Milky Way AMANOGAWA- 2SB Galac4c plane survey Log- normal distribu4on => random process? (Yoda et al. 2011, submiued) Is the log- normal distribu4on kept in the scale smaller than GMCs?

8 Rela4on between star forma4on rate and surface density of molecular gas (KennicuU- Schmidt law) Break down at GMC scale (M33: Onodera et al. 2010) Why does the K- S law break down at GMC scale? Onodera et al. (2010)

9 Researchers of galaxies want to understand evolu4onary process of interstellar gas including changes of internal structures of GMCs along with their evolu4on (forma4on of dense gas) Observa4ons of internal structures of GMCs in various evolu4onary stages

10 Previous studies (from observa0ons of nearby molecular clouds) Proper4es of cores and clumps in nearby molecular clouds (< 2kpc) Core surveys Taurus molecular cloud (Onishi et al. 1996, 1998) Orion molecular cloud (Ikeda et al. 2007, 2009) Dependence of proper4es of cores on environments? Star- forming ac4vity of progenitor molecular clouds Loca4on of molecular clouds in the Galaxy Onishi et al Ikeda et al. 2007

11 Clump surveys (~ a few pc, ~10 3 Mo) Clumps associated with cluster forming regions(<2kpc)(ridge et al. 2003) Cluster forma4on by clump- clump collision(higuchi et al. 2009, 2010) Dependence of proper4es of clumps on environments? Star- forming ac4vity of progenitor molecular clouds Loca4on of molecular clouds in the Galaxy Proper4es of clumps before star forma4on? Type A Higuchi et al Type B Type C A B C

12 Researchers of star forma4on in the Galaxy want to know the rela4on between GMC proper4es/evolu4onary stage and proper4es of cores/clumps Observa4ons of more GMCs located in various places and environments in the Galaxy

13 Next step Evolu4onary process of ISM studied in GMC scale + Forma4on process of dense clumps studied in nearby GMCs Observa4ons of evolu4on of molecular clouds and PDF in clump scale is possible only in the Galaxy Large area mapping of the Galaxy to inves4gate the proper4es of molecular gas in various environments (spiral arm, bar, ac4ve/inac4ve star forming regions) Large area mapping of the Galaxy by dense gas tracer to find clumps before star forma4on => Mul4- line survey of the Galac4c plane with high angular resolu4on

14 2.Galac4c Plane Survey with the NRO 45- m telescope OTF mapping of the Galac4c plane and the outer disk in 12 CO(1-0), 13 (1-0), C 18 O(1-0) (simultaneously) Mapping area l:10 ~50 b:±1 (80 deg 2 ) Spiral arms(perseus, SagiUarius. Scutum- Centarus arms), bar sturcture, molecular gas ring l:198 ~236 b: ±1 Comparison between inner and outer regions (GemOB1, MonOB1, Maddalena cloud, CMa OB1 etc) Closer than the inner region => Noise level ~ 3 4mes higher than the inner region=> Observing 4me : ~1/9

15 NASA/R. Hurt

16 Observa4on plan Receiver:FOREST(T sys = O, CO) Spectrometer:SAM45(velocity resolu4on:1.3 km/s velocity width:2708 km/s) Grid spacing:15 Sensi4vity T rms (T a *)= 18 O dv = 1.3 km/s ~200 (c.f., Ikeda and Kitamura 2009, ApJ 705, L95) T rms (T a *) = 12 CO dv = 5 km/s (~ 0.2K dv = 1.3 km/s) Average density in the Milky Way- 2SB survey : 10-2 M pc - 3 Observing 4me 1 1 OTF mapping : 7.5 hr 400 hr/yr 1 deg 2 /7.5 hr 0.6 (weather factor)=32 deg 2 Total observing 4me:400 hr 3 yr (~96 deg 2 )

17 LST range

18 Previous surveys of the Galac4c plane Columbia Survey (Dame et al. 1987) 12 CO(1-0) Beam size : 9 AMANOGAWA survey (Handa et al.) 12 CO(2-1) 13 CO(2-1)

19 Galac4c Ring Survey (Jackson+ 2006) 13 CO(1-0), Beam size: 46

20 Galac4c Ring Survey Cloud/clump catalog (Rathborne+2009)» 829 clouds» 6124 clumps

21 Galac4c plane survey (Moore et al.) JCMT Legacy survey (on going) l : b : ±0.5 is planning to map the same region with our survey 12 CO(3-2), 13 CO(3-2), C 18 O(3-2) Beam size:~14

22 Advantages of NRO survey : 1 High angular resolu4on Three 4mes higher than the Galac4c Ring Survey Can resolve clumps in the main Galac4c structures (arm, bar, inner disk, outer disk)» Dependence of evolu4on of molecular gas on the loca4on in the Galaxy» Can resolve clumps in the far side of molecular gas ring (~1pc@15kpc) GRS NRO survey Nakanishi et al. 2006

23 Spitzer Bubbles Many sources smaller than 1 => candidates of distant HII regions (D>5kpc) Large area mapping with high angular resolu4on to find GMCs before massive star forma4on Churchwell et al. (2006) GLIMPSE Image

24 Advantages of NRO survey : 2 Mul4- line observa4on (simultaneously) Structure of molecular clouds : Diffuse molecular gas dense gas 12 CO:total gas 13 CO:around clumps C 18 O:dense clumps Dense clumps without star forma4on Physical proper4es of molecular gas from mul4- transi4on data (JCMT- GPS) 13 CO C 18 O NGC CO C 18 O Ridge et al AFGL490

25 Advantages of NRO survey : 3 Collabora4on with VERA Maser survey of distant clumps found by this survey => measurements of the distance with VERA Rela4on with the Galac4c structure Good targets for VERA» Maser sources before star forma4on Schematic view of Galaxy Solar neighborhood Sgr A Sun Parallax + proper motion Illustra4on courtesy: NASA/JPL- Caltech/R. Hurt (SSC/Caltech) Proper motion By 本間さん

26 3.Scien4fic purposes Transi4on from atomic gas to molecular gas Requirements for molecular clouds forma4on Comparison between the inner and outer galac4c disk How far do GMCs exist in the Galaxy? Star forma4on in low metallicity gas Radial varia4on of the I CO - N(H 2 ) conversion factor Comparison with HI Large mapping area High angular resolu4on to resolve clumpy structures of molecular gas => spa4ally high dynamic range

27 Probability Distribu4on Func4on of gas density Rela4on between PDF of gas density and the Galac4c structures Dependence on the Galactocentric distance Arm vs. interarm Bar vs. disk Effect of Angular resolu4on Can higher angular resolu4on change PDF? sample number = accuracy NRO 45- m telescope» Angular resolu4on 9min 15arcsec E.g., at 8.5kpc, 20pc 0.6pc» To get the same pixel numbers with AMANOGAWA- 2SB survey 5X5 deg 2

28 Survey of dense clumps Distribu4on of dense clumps in GMCs Where are dense clumps formed within GMCs? Where is the number density of clumps high? Interac4on of clumps? Physical proper4es of clumps mass, size, density, velocity dispersion, etc. Clump mass func4on: Universal law of mass func4on? Rela4on with IMF of stars? Difference between clumps with and without stars? (<- > IRDC Difference between clumps with and without masers

29 Varia4ons of physical proper4es of clumps located in various environments Rela4on with galac4c structures (arm, bar)? Are there the hierarchical structure (GMCs/clumps) in various environments (5 kpc ring, outer galaxy)? Rela4on with proper4es of progenitor molecular clouds Change of internal structure along with evolu4on of molecular clouds Rela4on with the mass of progenitor molecular clouds Pilot survey for Star Forma4on Legacy Project Detailed observa4ons of clumps found by this survey Important as a database of targets for ALMA observa4ons Studies of cores within clumps in the whole Galac4c disk

30 Rela4on between surface density of molecular gas and SFR KennicuU- Schmidt law Comparisons in various scales Why does the K- S law break down at GMC scale?» Varia4on of evolu4onary stage of GMC? Comparisons of K- S law with different molecular lines => understanding of K- S law Comparison with Kiso Outer Galaxy Survey (Survey of OB stars in l= ) Radial varia4on of SFR and density of molecular clouds

31 Members Kagoshima univ. Handa, T., Nakanishi, H., Omodaka, T., Tanaka, A.(M2), Matsuo, T.(M2) Osaka prefecture univ. Onishi, T., (graduate student) Joetsu educa4on univ. Tosaki, T., (graduate student) Meisei univ. Onodera, S., Sofue, Y., Tsuda, Y. (M2), Ozawa, T.(M2) ISAS Tsuboi, M. NRO Kuno, N., Hirota, A.(PD) Chili observatory Higuchi, A.(PD) Mizusawa VLBI observatory Honma, M. et al. Shinnaga, H.