Resolving Giant Molecular Clouds in NGC 300: A First Look with the Submillimeter Array

Abstract

We present the first high angular resolution study of giant molecular clouds (GMCs) in the nearby spiral galaxy NGC 300, based on observations from the Submillimeter Array (SMA). We target eleven 500 pc-sized regions of active star formation within the galaxy in the CO(J=2-1) line at 40 pc spatial and 1 km/s spectral resolution and identify 45 individual GMCs. We characterize the physical properties of these GMCs, and find that they are similar to GMCs in the disks of the Milky Way and other nearby spiral galaxies. For example, the GMC mass spectrum in our sample has a slope of 1.80+/-0.07. Twelve clouds are spatially resolved by our observations, of which ten have virial mass estimates that agree to within a factor of two with mass estimates derived directly from CO integrated intensity, suggesting that the majority of these GMCs are bound. The resolved clouds show consistency with Larson's fundamental relations between size, linewidth, and mass observed in the Milky Way. We find that the linewidth scales with the size as DeltaV ~ R^(0.52+/-0.20), and the median surface density in the subsample is 54 Msun/pc^(-2). We detect 13CO in four GMCs and find a mean 12CO/13CO flux ratio of 6.2. Our interferometric observations recover between 30% and 100% of the integrated intensity from the APEX single dish CO observations of Faesi et al. 2014, suggesting the presence of low-mass GMCs and/or diffuse gas below our sensitivity limit. The fraction of APEX emission recovered increases with the SMA total intensity as well as with the star formation rate.

arXiv comment16 pages, 10 figures, accepted to ApJ

References in corpus (23)

• The physical properties of star forming galaxies in the low redshift universe
• The lesser role of starbursts for star formation at z=2
• Re-examining Larson's Scaling Relationships in Galactic Molecular Clouds
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• HERACLES: The HERA CO-Line Extragalactic Survey
• The Resolved Properties of Extragalactic Giant Molecular Clouds
• Bias-free Measurement of Giant Molecular Cloud Properties
• The Equilibrium State of Molecular Regions in the Outer Galaxy
• The Second Survey of the Molecular Clouds in the Large Magellanic Cloud by NANTEN I: Catalog of Molecular Clouds
• The PdBI Arcsecond Whirlpool Survey (PAWS): Environmental Dependence of Giant Molecular Cloud Properties in M51
• The Formation and Destruction of Molecular Clouds and Galactic Star Formation
• Giant Molecular Clouds in M33 - I. BIMA All Disk Survey
• Giant Molecular Clouds in M33 -- II. High Resolution Observations
• The Mass Spectra of Giant Molecular Clouds in the Local Group
• High Resolution Molecular Gas Maps of M33
• Giant Molecular Clouds in the Local Group Galaxy M33
• Larson's third law and the universality of molecular cloud structure
• Resolved Giant Molecular Clouds in Nearby Spiral Galaxies: Insights from the CANON CO (1-0) Survey
• A supersonic turbulence origin of Larson's laws
• The Araucaria Project. An improved distance to the Sculptor spiral galaxy NGC 300 from its Cepheid variables
• Giant molecular clouds in the non-grand design spiral galaxy NGC 6946
• Molecular Cloud-scale Star Formation in NGC 300
• The Herschel Exploitation of Local Galaxy Andromeda (HELGA). VI. The distribution and properties of molecular cloud associations in M31

Cited by in corpus (14)

• Stochastic modelling of star-formation histories II: star-formation variability from molecular clouds and gas inflow
• The ALMA view of GMCs in NGC 300: Physical Properties and Scaling Relations at 10 pc Resolution
• The SEDIGISM survey: Molecular clouds in the inner Galaxy
• Star Clusters in Evolving Galaxies
• The substructure and halo population of the Double Cluster $h$ and $\chi$ Persei
• Physical properties and scaling relations of molecular clouds: the effect of stellar feedback
• WISDOM Project -- IX Giant Molecular Clouds in the Lenticular Galaxy NGC4429: Effects of Shear and Tidal Forces on Clouds
• Spatial Decorrelation of Young Stars and Dense Gas as a Probe of the Star Formation-Feedback Cycle in Galaxies
• A statistical study of giant molecular clouds traced by ${}^{13}$CO, C${}^{18}$O, CS, and CH${}_3$OH in the disk of NGC 1068 based on ALMA observations
• WISDOM Project -- XV. Giant Molecular Clouds in the Central Region of the Barred Spiral Galaxy NGC 5806
• WISDOM Project XII. Clump properties and turbulence regulated by clump-clump collisions in the dwarf galaxy NGC404
• Stellar encounters with giant molecular clouds
• MUSE crowded field 3D spectroscopy in NGC 300 III. Characterizing extremely faint HII regions and diffuse ionized gas
• Gathering dust: A galaxy-wide study of dust emission from cloud complexes in NGC 300