SEDIGISM-ATLASGAL: Dense Gas Fraction and Star Formation Efficiency Across the Galactic Disk

Abstract

By combining two surveys covering a large fraction of the molecular material in the Galactic disk we investigate the role the spiral arms play in the star formation process. We have matched clumps identified by ATLASGAL with their parental GMCs as identified by SEDIGISM, and use these giant molecular cloud (GMC) masses, the bolometric luminosities, and integrated clump masses obtained in a concurrent paper to estimate the dense gas fractions (DGF${}_{\mathrm{gmc}}=\sum M_{\mathrm{clump}}/M_{\mathrm{gmc}}$) and the instantaneous star forming efficiencies (i.e., SFE${}_{\mathrm{gmc}}=\sum L_{\mathrm{clump}}/M_{\mathrm{gmc}}$). We find that the molecular material associated with ATLASGAL clumps is concentrated in the spiral arms ($\sim$60% found within $\pm$10 km s${}^{-1}$ of an arm). We have searched for variations in the values of these physical parameters with respect to their proximity to the spiral arms, but find no evidence for any enhancement that might be attributable to the spiral arms. The combined results from a number of similar studies based on different surveys indicate that, while spiral-arm location plays a role in cloud formation and HI to H${}_2$ conversion, the subsequent star formation processes appear to depend more on local environment effects. This leads us to conclude that the enhanced star formation activity seen towards the spiral arms is the result of source crowding rather than the consequence of a any physical process.

15 pages, 12 figures. Full list of affiliations can be found at the end of the paper

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Cited by in corpus (24)

• ATLASGAL -- Evolutionary trends in high-mass star formation
• The EDGE-CALIFA survey: The role of spiral arms and bars in driving central molecular gas concentrations
• CHIMPS2: Survey description and ${}^{12}$CO emission in the Galactic Centre
• The SEDIGISM survey: a search for molecular outflows
• The formation and early evolution of embedded star clusters in spiral galaxies
• The SEDIGISM survey: The influence of spiral arms on the molecular gas distribution of the inner Milky Way
• The organization of cloud-scale gas density structure: high resolution CO vs. 3.6 $\mu$m brightness contrasts in nearby galaxies
• OGHReS: Large-scale filaments in the outer Galaxy
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• Large-scale Velocity-coherent Filaments in the SEDIGISM Survey: Association with Spiral Arms and Fraction of Dense Gas
• A Kpc Scale Molecular Wave in the Inner Galaxy: Feather of the Milky Way?
• Star cluster formation and feedback in different environments of a Milky Way-like galaxy
• OGHReS: Star formation in the Outer Galaxy ($\ell =250^{\circ }$-$280^{\circ }$)
• RJ-plots: An improved method to classify structures objectively
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- IV. Radio Recombination Lines and evolution of star formation efficiencies
• The SEDIGISM survey: Molecular cloud morphology. II. Integrated source properties
• Characteristic scale of star formation. I. Clump formation efficiency on local scales
• ATLASGAL-selected massive clumps in the inner Galaxy. X. Observations of atomic carbon at 492 GHz
• Molecular clouds in M51 from high-resolution extinction mapping
• A 260 pc resolution ALMA map of HCN(1-0) in the galaxy NGC 4321
• What drives the wheels of evolution in NGC 1512? A UVIT study
• OGHReS: Star formation in the Outer Galaxy II ($\ell =180^{\circ }$-$280^{\circ }$)
• The Planck submillimeter properties of Galactic high-mass star forming regions: dust temperatures, luminosities, masses and Star Formation Efficiency
• Molecular cloud matching in CO and dust in M33 II. Physical properties of giant molecular clouds