Astrochemical Investigations of Complex Organics in Cold Molecular Cloud Cores

Licentiate thesis, 2024

Astrochemistry is the study of the formation and evolution of molecules in the interstellar medium (ISM) of the Milky Way and other galaxies. Molecules start to accumulate in the coldest and densest regions of the ISM, namely molecular clouds, and as of this date, 307 interstellar molecules are identified. The major focus of this thesis is on a particular group of interstellar molecules, so-called complex organic molecules (COMs), i.e., carbon-bearing molecules composed of at least six atoms. Interstellar COMs and other molecules are studied by a combination of observations, experiments, and models, with the focus of this thesis being on observations. Another focus will be on observations of COMs in very cold (< 10 K) and dense (> 10e5 cm−3) molecular cloud regions.

This thesis is separated into two parts: part I is giving an overview about various important concepts and methods related to the detection, identification, and analysis of interstellar molecules (chapters 1 – 4), and part II is presenting the published paper this thesis is based on. Chapter 1 provides some
background to my motivation to obtain a degree in astrochemistry, and to some basic concepts related to the formation of interstellar molecules. Some fundamental physical concepts widely used throughout this work will be introduced in that chapter as well. Chapter 2 introduces some important concepts and methods related to the derivation of molecular abundances from radio astronomical observations. Chapter 3 then gives a brief summary of the published paper this thesis is based on. Lastly, chapter 4 introduces some currently running and future projects (which I am part of) with the goal to add to the overall understanding of COM formation in the cold ISM.