Bird's-eye view of molecular clouds in the Milky Way

Licentiate thesis, 2021

A crucial aspect in interpreting the scaling relations relevant for star formation - the Kennicutt-Schmidt relation and the Larson relations - is how those relations depend on size-scale. This is especially so when comparing relations derived from unresolved, extragalactic data to those derived from resolved, Galactic data. We present an experiment in which the Solar neighbourhood (distance < 2 kpc) is examined from the outside, with an aim to unveil the connection between the true, "resolved" properties of star-forming regions and their beam-averaged, "unresolved" properties. To do so, we examine the density and star formation statistics in the Solar neighbourhood and determine how they appear when viewed through apertures of various sizes. We employ sub-pc resolution column density maps and star formation rates of individual molecular clouds from the literature to study the scale dependencies of molecular cloud structure from sub-pc to kpc scales. In this way, we connect the average properties of the gas in the Solar neighbourhood to the resolved properties of individual clouds. Our results will aid the interpretation of on-going and upcoming extragalactic observations, especially by shedding light on the sub-beam properties of the structures detected by them.