The Structure, Chemistry, and Evolution of Atomic and Molecular Gas in the Diffuse Interstellar Medium

Download or read book The Structure, Chemistry, and Evolution of Atomic and Molecular Gas in the Diffuse Interstellar Medium written by Daniel R. Rybarczyk and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interstellar medium (ISM) is organized in different phases with distinctive temperatures, densities, and ionization. The complex interplay between the different phases of the ISM governs the physical and chemical evolution of galaxies. In this thesis, I focus on characterizing the neutral phases of the ISM, particularly the atomic hydrogen (HI) and diffuse molecular gas, using observations at radio wavelengths. To interpret and contextualize our observations, I also compare observational results to chemical models and multiphase ISM simulations. I present the largest sample of sensitive HI absorption ever constructed using data compiled from seven previous surveys. With this sample, I investigate correlations between the properties of the multi-phase HI and other key tracers of the interstellar environment. I provide constraints for the environments in which cold HI (the cold neutral medium, "CNM") and molecular gas are likely to form in the diffuse ISM. I also discuss observations of cold HI structures at physical scales