RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 02 May 2024, 11:00-12:30; ZOOM or Duffield Lecture Theatre


Zipeng Hu

"Make the clouds less cloudy: modelling the ISM with simulations and synthetic observations (End of thesis talk)"

Giant molecular clouds (GMCs) are the birthplaces of stars. Multiple physics mechanisms including gravity, magnetic fields, and radiation interplay within these clouds, and set the initial conditions for star formation. However, the exact role of each mechanism is still unclear, largely due to observational biases arising from projection, chemical, and excitation effects. Simulations and simulated observations and therefore necessary for realistic interpretation of observations of the GMC formation and evolution processes. This thesis focuses on building a comprehensive picture of the structure of GMCs using this approach. The first part of the thesis provides a theoretical model that can predict the 3d density structure of GMCs that are observed only in projection, and applies it to nearby GMCs. The second part of the thesis examines measurements of magnetic field strengths, and points out that due to chemical and excitation biases the role of magnetic fields in GMC formation is less important than suggested by earlier interpretations of observations. The final part of this thesis reveals a significant discrepancy between two main star formation rate measurement methods, young stellar object counting and recombination lines, and demonstrates how this discrepancy changes with local GMC conditions.