Fakultät für Physik und Astronomie
STEPHEN PHILLIPS hostreviews.co.uk / UNSPLASH

How galactic dynamics and stellar feedback shape the giant molecular cloud population in galaxies

Sarah Jefferson , ARI

Giant molecular clouds (GMCs) form the communication channel between the galactic environment and the sub-cloud physics of star formation and stellar feedback. Recent observations reveal galaxy-scale trends in GMC properties (e.g. surface densities, velocity dispersions, and turbulent pressures), demanding a systematic and predictive theory of the GMC lifecycle across the parameter space of observable star-forming environments. In this contribution, I will combine a simple analytic theory for the influence of galactic dynamics on GMC lifetimes/evolution with a statistical sample of ~60,000 numerically-simulated GMCs across three isolated disc galaxies in the moving-mesh code Arepo. The analytic predictions depend on just three sets of galactic-scale observables: the rotation curve, surface densities and velocity dispersions of the host galaxy. The numerical simulations incorporate the features required to accurately model the influence of stellar feedback on the ISM, including stochastic star formation, mechanical supernova feedback, pre-supernova feedback from HII regions, and ISM chemistry. Using this combined analytic/numerical framework, I will show (1) that stellar feedback truncates the GMC lifetime across a wide range of galactic environments, and (2) that the lifetimes and properties of GMCs are predicted to follow clear galactic-dynamical trends driven by gravitational instability, galactic shearing, radial orbital perturbations, and cloud-cloud collisions. These results reveal that the complex interplay between galactic dynamics and stellar feedback plays a crucial role in setting the course of GMC evolution, and therefore in determining the star formation rates of the galaxies they live in.

ARI Institute Colloquium
9 Jul 2020, 11:15
Astronomisches Rechen-Institut, Mönchhofstraße 12-14, Via Zoom. Please contact the organizers (Eva Grebel or Joachim Wambsganß) if you need the Zoom link.

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