The NANTEN CO survey and SKA Kengo Tachihara (Nagoya University) - - PowerPoint PPT Presentation

The NANTEN CO survey and SKA

Kengo Tachihara (Nagoya University) and the NANTEN team

The NANTEN2 project

• 4m radio telescope at the Atacama desert in Chile
• Large-scale survey of ISM in the milky way and

nearby galaxies

• Observe in mm and submm wavelengths
• Conducted under international collaboration
• Nagoya U., Osaka Prefecture U.
• Universität zu Köln, Universität Bonn
• University of New South Wales, Sydney, Macquarie and so on
• Universidad de Chile Seoul National U. ETH Zurich

Instruments

• Low frequency receiver (by Nagoya Univ.)
• 100GHz : CO (J=1-0) and its isotopes
• 200GHz : CO (J=2-1)
• to be upgraded to the 4-beam 2-band receiver
• High frequency (2-band) receiver (by U. Köln)
• 500GHz : CO (J=4-3), CI (3P1-3P0)
• 800GHz : 12CO (J=7-6), 13CO (J=8-7), CI (3P2-3P1)

Instruments

• Low frequency receiver (by Nagoya Univ.)
• 100GHz : CO (J=1-0) and its isotopes
• 200GHz : CO (J=2-1)
• to be upgraded to the 4-beam 2-band receiver
• High frequency (2-band) receiver (by U. Köln)
• 500GHz : CO (J=4-3), CI (3P1-3P0)
• 800GHz : 12CO (J=7-6), 13CO (J=8-7), CI (3P2-3P1)

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The NANTEN Galactic Plane Survey (NGPS)

• 1st generation NANTEN CO survey
• Covering 6350 deg2
• Revealed many molecular clouds/cores
• 8´ grid spacing with 2.6´ beam

The NANTEN2 Super CO Survey (NASCO)

Image: Planck 1 year result , Black shade: MCs by NGPS

Cover 70% of the whole sky with the multi- beam receiver and the On-The-Fly mapping

NASCO survey initial result

Cluster-forming cloud

• Westerlund 2 cloud
• 5000 Mo at 5 kpc
• Clusters of ~300

young stars

• 2 molecular clouds

with different V

• Formation model by

Cloud-cloud collision

Galactic longitude Galactic latitude

(Ohama et al. 2010)

TeV !-ray from SNR

RX J1713.7!3946

(Fukui et al. 2012)

Color: Np(H2+HI) Contours: TeV !-ray Azimuthal intensity distribution proton origin scenario of high energy !-ray

High latitude clouds

—sites where molecular clouds form—

LAB all-sky HI 21 cm survey

High latitude clouds

—sites where molecular clouds form—

LAB all-sky HI 21 cm survey

MBM 53, 54, 55 complex

MBM53 MBM54 MBM55

12CO(J=1-0)

Magnani et al. 1985

Yamamoto et al. 2003

Complex cloud morphology

Planck’s Dust clouds

The Planck all-sky CO map

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Two phase gas model

• ISM consist of warm (~ 104 K)

and cold (< 100 K) neutral medium (WNM and CNM)

• shock compression of diffuse

WNM => small-scale CNM formed by thermal instability

• Turbulent molecular cloud

formation

• Turbulence is sustained long

due to subsonic random motion wrt. the warm gas

Thermal instability of shocked layer (Koyama & Inutsuka 2000, 2002)

SHOCK!

Numerical simulations

x y z

log n [cm-3] 100 10-1 10-2 10-3 10-4 1.0 10 100 nember density : n [ cm-3 ] probability density

• 3D MHD simulation of

colliding flow

• Chemical reaction
• Radiative heating & cooling,
• Thermal conduction, etc...

Thermal instability

Larson’s law

Inoue & Inutsuka 2012

Small scale structures of the cloud surface

Peak Ta

Channel map NRO 45m telescope

(Tachihara et al. 2012)

Complex velocity field

• 1

1 2 3 4 5 6 1 2 3 4 5 6 7

average V = 1.48 km/s A V = 0.57 km/s B V = 0.63, 0.59 km/s C V = 0.51 km/s

Ta (K) VLSR (km/s)

clump R = 6300 AU, M = 0.03 Mo

pillar arc

Channel map

12CO spectra "Vsmall ~ 0.6 km/s, "Vave ~ 1.5 km/s

Super-sonic turbulence is by ensemble of small-scale structures

Conclusion

• NANTEN2 is surveying our Galaxy in CO
• Many interesting astronomical objects
• Collaborating with Planck satellite
• Interest in molecular formation from HI
• SKA will be a nice complementary partner
• f NANTEN2!