The Interplay of Star Formation and Radiation Feedback in the Interstellar Medium

Star formation in galaxies are governed by the complex interplay of several nonlinear physical mechanisms operating in the interstellar medium (ISM). However, in spite of this underlying complexity, there is overwhelming evidence for fundamental scaling relations and trends governing the conversion of gas to stars that imply a self-regulating physical mechanisms at play. In this talk, I will introduce the idea that radiation feedback from massive stars is a vital ingredient in this self-regulating picture of star formation and touch upon evidence garnered in this direction over the last decade. I will present quantitative insights we obtain from novel radiation-hydrodynamic numerical simulations on feedback-regulated star formation in GMCs spanning conditions resembling weakly star-forming galaxies in the local Universe to massive, compact GMCs, typical of high-pressure environments at higher redshifts. In addition, I will discuss how radiation feedback sculpts the turbulent ISM locally in HII regions, modifies the dynamical properties of gas and magnetic fields in them, and contemplate what this might imply for the possibility that additional star formation may be triggered locally by feedback.