The Effect of Spiral Arms on Star Formation in the Galaxy

Abstract

We have examined the ratio between the integrated luminosity of massive young stellar objects detected by the Red MSX Source (RMS) survey and the mass of molecular clouds in the Galactic Ring Survey region, as a function of Galactocentric radius. The results indicate that 60--80% of the observed increases in the star-formation rate density associated with spiral-arm features are due to source crowding within the arms. Of the remainder, most of the increase in the inner Sagittarius arm is due to an enhancement in the simple star-formation efficiency, i.e. in the number of RMS sources per unit molecular gas mass. In the inner Perseus arm, the residual increase is due to a higher than average mean source luminosity, which implies a top-heavy IMF, and this is entirely due to the presence, in the GRS region, of the W49 star-forming complex, which appears to be exceptional in its nature. The results also suggest that there is little or no increase in the star-formation efficiency on kiloparsec scales in the Scutum tangent region which includes W43. We discuss the possible role played by the spiral arms in influencing the star-formation efficiency and conclude that the most likely mechanisms are related to orbit crowding within the arms.

7 pages, 7 figures, accepted by MNRAS

References in corpus (8)

• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
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Cited by in corpus (44)

• ATLASGAL --- properties of a complete sample of Galactic clumps
• The Red MSX Source Survey: the Massive Young Stellar Population of our Galaxy
• ATLASGAL --- towards a complete sample of massive star forming clumps
• ATLASGAL --- Environments of 6.7\,GHz methanol masers
• Giant Molecular Filaments in the Milky Way
• ATLASGAL --- properties of compact HII regions and their natal clumps
• CHIMPS: the ${}^{13}$CO/C${}^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey
• The Physical Properties of Large-Scale Galactic Filaments
• The SEDIGISM survey: first data release and overview of the Galactic structure
• Star formation in Galactic spiral arms and the inter-arm regions
• The Star Formation Rate of the Milky Way as seen by Herschel
• Giant molecular filaments in the Milky Way II: The fourth Galactic quadrant
• The SEDIGISM survey: Molecular clouds in the inner Galaxy
• Star Clusters in Evolving Galaxies
• The JCMT Plane Survey: early results from the l = 30 degree field
• CHIMPS: Physical properties of molecular clumps across the inner Galaxy
• The JCMT Plane Survey: First complete data release - emission maps and compact source catalogue
• Testing the role of environmental effects on the initial mass function of low-mass stars
• Star formation scales and efficiency in Galactic spiral arms
• The Identification of a Dusty Multiarm Spiral Galaxy at $z=3.06$ with JWST and ALMA
• CHIMPS2: Survey description and ${}^{12}$CO emission in the Galactic Centre
• The prevalence of star formation as a function of Galactocentric radius
• SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution - Survey Description and Compact Source Catalogue
• The Lesser Role of Shear in Star Formation: Insight from the Galactic Ring Survey
• SEDIGISM-ATLASGAL: Dense Gas Fraction and Star Formation Efficiency Across the Galactic Disk
• Galaxy Zoo: star-formation versus spiral arm number
• The role of spiral arms in Milky Way star formation
• Feedback in W49A diagnosed with radio recombination lines and models
• Observations of the Initial Formation and Evolution of Spiral galaxies at $1<z<3$ in the CANDELS fields
• The SEDIGISM survey: The influence of spiral arms on the molecular gas distribution of the inner Milky Way
• An analysis of star formation with Herschel in the Hi-GAL Survey. II. The tips of the Galactic bar
• Young stars as tracers of a barred-spiral Milky Way
• The organization of cloud-scale gas density structure: high resolution CO vs. 3.6 $\mu$m brightness contrasts in nearby galaxies
• Continuum Observations of M51 and M83 at 1.1 mm with AzTEC
• Solenoidal turbulent modes and star formation efficiency in Galactic-plane molecular clouds
• Extreme star formation in the Milky Way: Luminosity distributions of young stellar objects in W49A and W51
• Source clustering in the Hi-GAL survey determined using a minimum spanning tree method
• Bar-spiral interaction produces radial migration and star formation bursts
• Characteristic scale of star formation. I. Clump formation efficiency on local scales
• Molecular clouds in M51 from high-resolution extinction mapping
• Autonomous Gaussian decomposition of the Galactic Ring Survey. II. The Galactic distribution of 13CO
• A 260 pc resolution ALMA map of HCN(1-0) in the galaxy NGC 4321
• Molecular cloud matching in CO and dust in M33 II. Physical properties of giant molecular clouds
• The Planck submillimeter properties of Galactic high-mass star forming regions: dust temperatures, luminosities, masses and Star Formation Efficiency