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Star Formation Scaling Relations At 100pc In Star-forming Main Sequence Galaxies

Presentation #310.06 in the session “Extragalactic Interstellar Medium: PHANGS”.

Published onJun 18, 2021
Star Formation Scaling Relations At 100pc In Star-forming Main Sequence Galaxies

The formation of stars inside cold and dense molecular gas clouds is regulated by an complex interplay between small- and large-scale physics, including stellar and supernova feedback, hydrostatic pressure of the baryonic mass, and impact of non-axisymmetric structures. This regulating interplay results in scaling relations between between stellar mass, star formation, and molecular gas mass. Recent studies have demonstrated that these relations hold down to kpc and sub-kpc scales. The existence of these so-called resolved scaling relations suggests that their global counterparts are the outcome of the local mechanisms that drive star formation. However, spatial scales of ~kpc size are much larger than the typical size of individual star-forming clouds and are thus not sensitive to the non-uniformity of the spatial distribution of star formation in galactic disks, and the inherent stochasticity of the star forming process. Here, we use PHANGS survey data for 18 star-forming main sequence galaxies to probe these scaling relations at an unprecedented 100 pc, the scale of molecular clouds, to understand the mechanisms that locally regulate star formation, and how varying the spatial scale impacts our results. The scaling relations between stellar mass, molecular gas, and star formation are all recovered at 100pc, albeit with larger scatter than observed at lower resolution. The scatter of the different relations is consistent with expectations from the timescales of the star formation cycle. We also see significant variations of these relations across different environments and between galaxies. Finally, we find that the spatial distribution of the star-forming sites is a key aspect for setting the slope of these relations.

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