Universität zu Köln

Zimmermann, Birka ORCID: 0009-0005-3040-9864 (2026). Signatures of Massive Star Formation in Simulations and Synthetic Observations. PhD thesis, Universität zu Köln.

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Abstract

High-mass star formation strongly influences the evolution of galaxies through energetic feedback from ionising radiation, stellar winds, and supernovae. However, the feedback from these stars will only affect their environment on parsec scales or beyond, once they have dispersed their parental clumps. In the earliest phases, massive protostars can remain deeply embedded, delaying the expansion of large-scale HII regions. During this stage, radiative heating and radiation pressure on gas and dust may be particularly important in regulating fragmentation and accretion. In this thesis, we investigate the formation and early evolution of massive stars and their host cores up to the onset of (ultra-)compact H ii regions. We carry out radiation-(magneto)hydrodynamical simulations of the gravitational collapse of isolated, parsec-scale, turbulent cores with the FLASH code. Our models include a scheme for radiation pressure on dust and gas as well as ionising radiation, and we follow hydrogen chemistry self-consistently so that the properties of compact HII regions emerge directly from the simulations. We perform a controlled parameter study varying the initial density profile, virial parameter, and metallicity, providing a statistically meaningful sample to isolate how initial conditions shape fragmentation, accretion histories, feedback break-out, and the star formation efficiency. To connect theory to observations, we post-process the simulations with the radiative transfer code RADMC-3D to generate synthetic dust-continuum maps and ALMA-like interferometric images with CASA, which we analyse with the same methods used for observational surveys. This forward-modeling approach quantifies biases from projection, dust-temperature assumptions, and interferometric spatial filtering, and connect observable core and envelope properties to intrinsic physical quantities. By combining a physics-rich simulation suite with survey-like synthetic observations, this thesis enables a rigorous comparison between simulations and synthetic observations and provides simulation calibrated guidance for interpreting continuum-derived core masses and envelope structure in high-mass star-forming regions.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Zimmermann, Birka zimmermann@ph1.uni-koeln.de https://orcid.org/0009-0005-3040-9864 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-810541
Date:	2026
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 massive star formation; numerical simulations; synthetic observations English
Date of oral exam:	5 May 2026
Referee:	Name Academic Title Walch-Gassner, Stefanie Prof. Dr. Jacob, Arshia M. Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/81054