Spatial Decorrelation of Young Stars and Dense Gas as a Probe of the Star Formation–Feedback Cycle in Galaxies

Vadim Semenov

Tuesday, Dec. 6th, 15:30CET

The spatial decorrelation of dense molecular gas and young stars observed on <1 kpc scales in nearby galaxies indicates rapid dispersal of star-forming regions by stellar feedback. I will present a suite of simulations of a dwarf galaxy, where we systematically explore the sensitivity of the decorrelation to the details of star formation and feedback modeling, including a self-consistent treatment of radiative transfer and molecular chemistry. Our fiducial simulation reproduces the magnitude of decorrelation and its scale dependence measured in observations, and we show that this agreement is due to multiple aspects of feedback, including H2 dissociation, gas heating by the locally variable UV field, early mechanical feedback, and supernovae. Moreover, the decorrelation is sensitive to the modeling of the local star formation efficiency (SFE), with the observed level of decorrelation favoring the model where SFE varies with local turbulent support of star-forming gas. This provides a strong observational constraint on the SFE in the regime when the global star formation rate is independent of its value.