Universität zu Köln

Haid, Sebastian ORCID: 0000-0001-7541-4935 (2018). The Impact of Stellar Feedback from Massive Stars in the Interstellar Medium. PhD thesis, Universität zu Köln.

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Abstract

The impact of stellar feedback from massive stars is important for the evolution of the interstellar medium and the structures within. Stellar winds, ionizing radiation, and supernovae are considered as the most important processes in shaping molecular clouds, influence rate of star formation, drive turbulences, and even expel gas out of the Galactic disc. Despite understanding the energy contribution from massive stars, the impact of stellar feedback, i.e. the resulting momentum, is still debated and the relative importance of the processes remains unclear. This thesis contains three scientific papers that investigate feedback processes in detail. Three-dimensional, radiation-hydrodynamic simulations are performed to study the relative impact of stellar winds and ionizing radiation from massive stars in homogeneous media. The cold and dense environment is dominated by the radiative feedback. Over the lifetime of the massive star, imparted momentum becomes equally or more important than the impact from a supernova explosion. Stellar wind is the dominant process in warm and rarefied environments. The idea is expanded to a molecular cloud environment that self-consistently evolves from a SN-driven, multiphase interstellar medium in the galactic disc. The first three Myr in the cloud evolution are investigated under the influence of ionizing radiation. Due to the prevailing dense structures, stellar winds can be neglected. The radiative impact is determined by dense, well-shielded structures, which are able to enclose massive stars and their surrounding ionized bubbles. Mutual interactions of feedback and well-shielded regions determine the morphological evolution of molecular clouds. The final type-II supernova impact is investigated by a novel, one-dimensional description including the adiabatic and radiative phases of the evolution. The momentum input form a supernova shock increases with lower densities. Additionally, supersonic turbulence boosts the impact. These three studies indicate that the importance of the individual feedback processes depends on the environmental properties.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Haid, Sebastian haid@ph1.uni-koeln.de orcid.org/0000-0001-7541-4935 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-91104
Date:	December 2018
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics I
Subjects:	Physics
Uncontrolled Keywords:	Keywords Language Astrophysik UNSPECIFIED Theoretische Physik UNSPECIFIED
Date of oral exam:	9 April 2018
Referee:	Name Academic Title Walch-Gassner, Stefanie Prof. Dr. Porciani, Cristiano Prof. Dr. Saur, Joachim Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/9110