Alexander Tielens
Astronomy Department University of Maryland, College Park
Feedback by massive stars and the ecology of galaxies
The interaction of massive stars with their environments regulates the evolution of galaxies through a process called feedback. Mechanical input by massive stars stirs up the interstellar medium, greatly influencing the star formation efficiency of molecular clouds as, on the one hand, this disperses star forming molecular cloud cores and, on the other hand, it creates dense shells of swept up gas that are prone to gravitational collapse. In addition, the radiative energy input by massive stars creates ionized gas regions surrounded by dense photo-dissociation regions, and the spectral characteristics of these regions dominate the emission of galaxies. This gas heating also controls the cloud and intercloud phases of the interstellar medium and thereby the overall structure of the interstellar medium. I will review the status of the field, focusing on the key questions. Specifically, I will cover the potential of [CII] 1.9 THz fine-structure line observations to address the radiative and mechanical feedback by massive stars. This transition is the dominant cooling line of neutral atomic gas that is swept up in dense shells and hence directly probes the radiative feedback, while the sub-km/s spectral resolution provided by heterodyne techniques provides a window on the mechanical feedback by massive stars on their direct environment. In this review, I will highlight results obtained by upGREAT/SOFIA programs and the first results of the Galactic/Extragalactic ULDB Spectroscopic Terahertz Observatory, GUSTO, mission.
