An Unbiased CO Survey Toward the Northern Region of the Small Magellanic Cloud with the Atacama Compact Array. II. CO Cloud Catalog

Abstract

The nature of molecular clouds and their statistical behavior in subsolar metallicity environments are not fully explored yet. We analyzed data from an unbiased CO($J$ = 2-1) survey at the spatial resolution of ~2 pc in the northern region of the Small Magellanic Cloud with the Atacama Compact Array to characterize the CO cloud properties. A cloud-decomposition analysis identified 426 spatially/velocity-independent CO clouds and their substructures. Based on the cross-matching with known infrared catalogs by Spitzer and Herschel, more than 90% CO clouds show spatial correlations with point sources. We investigated the basic properties of the CO clouds and found that the radius--velocity linewidth ($R$-${\sigma }_v$) relation follows the Milky Way-like power-low exponent, but the intercept is ~1.5 times lower than that in the Milky Way. The mass functions ($dN/dM$) of the CO luminosity and virial mass are characterized by an exponent of ~1.7, which is consistent with previously reported values in the Large Magellanic Cloud and in the Milky Way.

18 pages, 9 figures. Accepted for publication in The Astrophysical Journal

References in corpus (24)

• CASA, the Common Astronomy Software Applications for Radio Astronomy
• Structural Analysis of Molecular Clouds: Dendrograms
• The Resolved Properties of Extragalactic Giant Molecular Clouds
• Bias-free Measurement of Giant Molecular Cloud Properties
• A distance determination to the Small Magellanic Cloud with an accuracy of better than 2 percent based on late-type eclipsing binary stars
• The Perils of Clumpfind: The Mass Spectrum of Sub-structures in Molecular Clouds
• The Spitzer Survey of the Small Magellanic Cloud: Discovery of Embedded Protostars in the HII Region NGC 346
• Star cluster formation and cloud dispersal by radiative feedback: dependence on metallicity and compactness
• Chemical distribution of HII regions towards the Galactic anticentre
• Photodissociation Region Diagnostics Across Galactic Environments
• Evolutionary Description of Giant Molecular Cloud Mass Functions on Galactic Disks
• FRagmentation and Evolution of dense cores Judged by ALMA (FREJA). I (Overview). Inner $\sim$1000 au structures of prestellar/protostellar cores in Taurus
• ALMA Observations of a Quiescent Molecular Cloud in the Large Magellanic Cloud
• Discovery of Star Formation in the Extreme Outer Galaxy Possibly Induced by a High-velocity Cloud Impact
• ALMA observations of N83C in the early stage of star formation in the Small Magellanic Cloud
• An Unbiased CO Survey Toward the Northern Region of the Small Magellanic Cloud with the Atacama Compact Array. I. Overview: CO Cloud Distributions
• An ALMA study of the massive molecular clump N159W-North in the Large Magellanic Cloud: A possible gas flow penetrating one of the most massive protocluster systems in the Local Group
• CO(2-1) Survey at 9 parsec resolution in the SMC
• ALMA reveals a cloud-cloud collision that triggers star formation in N66N of the Small Magellanic Cloud
• The 1.1 mm Continuum Survey of the Small Magellanic Cloud: Physical Properties and Evolution of the Dust-selected Clouds
• Formation of High-Mass stars in an isolated environment in the Large Magellanic Cloud
• Resolved star formation in the metal poor star-forming region Magellanic Bridge C
• Sequential Star Formation in the Young SMC Region NGC 602: Insights from ALMA
• ALMA resolves molecular clouds in the metal poor Magellanic Bridge A

Cited by in corpus (7)

• ACA CO($J=2-1$) Mapping of the Nearest Spiral Galaxy M33. I. Initial Results and Identification of Molecular Clouds
• Metallicity Dependence of Molecular Cloud Hierarchical Structure at Early Evolutionary Stages
• Inadequate turbulent support in low-metallicity molecular clouds
• SuperCAM CO(3-2) APEX survey at 6 pc resolution in the Small Magellanic Clouds
• ALMA 0.1 pc View of Molecular Clouds Associated with High-Mass Protostellar Systems in the Small Magellanic Cloud: Are Low-Metallicity Clouds Filamentary or Not?
• CO Observations of the SMC-N66 Hii Region with ALMA: Properties of Clumps along Filamentary Molecular Clouds and Possible Expansion Motion
• Compact and High Excitation Molecular Clumps in the Extended Ultraviolet Disk of M83