The origin and evolution of galaxies are closely tied to the cyclic feedback processes between stars and the interstellar medium (ISM). The aim of this thesis is to explore characteristics of the... Show moreThe origin and evolution of galaxies are closely tied to the cyclic feedback processes between stars and the interstellar medium (ISM). The aim of this thesis is to explore characteristics of the ISM, on global (galactic) scales down to sub-cloud (pc) scales. We explore new methods to investigate the ISM in external galaxies, through radio recombination line observations, and develop the tools and strategies needed to process new low-frequency observations with the Low Frequency Array. We also infer the presence of massive stars and characterize their properties and influence on the ISM. This thesis addresses the questions:- How does low-density ionized gas affect the evolution of the massive, galactic star-forming region, Cygnus X? Are the same fingerprints present in surveys of low-density ionized gas in our Galaxy?- What are the properties of star formation (star clusters) in the central starburst of the galaxy NGC 4945?- Can the ISM be explored outside of the local universe through radio recombination line observations? What are the ISM properties of a dwarf-like galaxy at z=1.1?- What techniques are best suited to detect faint radio recombination lines (at a previously unknown redshift) in extragalactic sources? Show less
Tiwari, M.; Karim, R.; Pound, M.W.; Wolfire, M.; Jacob, A.; Buchbender, C.; ... ; Tielens, A.G.G.M. 2021
The space between stars is filled with a dilute mixture of atoms, molecules, and dust grains, which we call the interstellar medium (ISM). The physics of the ISM is a crucial part in many areas of... Show moreThe space between stars is filled with a dilute mixture of atoms, molecules, and dust grains, which we call the interstellar medium (ISM). The physics of the ISM is a crucial part in many areas of astronomy, such as the formation and evolution of stars and entire galaxies. It regulates molecule- and dust grain synthesis, which together constitute the very building blocks of planetesimals required to form planetary systems and, ultimately, life itself. Recent observations have revealed that a significant fraction of the ISM is dynamic and filamentary, likely caused by radiation, winds, and supernova explosions from massive stars that constantly stir the material that resides in the ISM. However, the exact mechanisms and contributions of these interactions remain poorly understood. To advance our knowledge of the ISM of galaxies, in first principle, we need to acquire a deep understanding of the interplay between stars and their surroundings. In this thesis, I investigate the interactions between gas, dust, and stars in the ISM, by using the Orion region as a benchmark model. Show less
