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Frias Castillo, M. (2024)

Measuring gold molecular gas across cosmic time

Doctoral Thesis
Tracing the evolution of the molecular gas content in galaxies is critical for a complete understanding of galaxy formation and evolution, as it provides the direct fuel for star formation. Studies of high-redshift (z>1) molecular gas reservoirs, most commonly traced by carbon monoxide (CO), have seen substantial growth in recent years thanks to state-of the-art sub-millimeter interferometers such as the Jansky Very Large Array or the Atacama Large Millimeter Array. However, these studies have been largely based on detections of the bright mid/high-J transitions of CO (J>=3), which have been shown to give a biased and incomplete view of the total cold molecular gas content in galaxies. This thesis presents an observational study of the cold interstellar medium of massive galaxies in the distant universe. Chapter 2 presents one of the highest—resolution studies of low-J CO in a high—redshift galaxy to-date, allowing us to map its total cold gas reservoir in unprecedented detail....Show moreTracing the evolution of the molecular gas content in galaxies is critical for a complete understanding of galaxy formation and evolution, as it provides the direct fuel for star formation. Studies of high-redshift (z>1) molecular gas reservoirs, most commonly traced by carbon monoxide (CO), have seen substantial growth in recent years thanks to state-of the-art sub-millimeter interferometers such as the Jansky Very Large Array or the Atacama Large Millimeter Array. However, these studies have been largely based on detections of the bright mid/high-J transitions of CO (J>=3), which have been shown to give a biased and incomplete view of the total cold molecular gas content in galaxies. This thesis presents an observational study of the cold interstellar medium of massive galaxies in the distant universe. Chapter 2 presents one of the highest—resolution studies of low-J CO in a high—redshift galaxy to-date, allowing us to map its total cold gas reservoir in unprecedented detail. Chapter 3 presents a survey targeting low-J CO emission in high-redshift unobscured quasar hosts, finding direct evidence for high gas fractions but very short depletion times. Chapter 4 introduces first results from the VLA Legacy Library of Molecular Gas at High Redshift project, which significantly expands the number of high-redshift galaxies with cold gas detections. Finally, Chapter 5 shows ALMA observations targeting emission from atomic carbon in a subset of the VLA targets, and demonstrates how this alternative gas tracer complements our view of cold molecular gas reservoirs at high—redshift.
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Interstellar medium
High-redshift galaxies
Molecular gas
Submillimeter astronomy
Quasars
All authors
Frias Castillo, M.
Supervisor
Werf, P. van der
Co-supervisor
Hodge, J.A.
Committee
Viti, S.; Snellen, I.A.G.; Hogerheijde, M.R.; Greve, T.R.; Marel, N. van der; Béthermin, M.
Qualification
Doctor (dr.)
Awarding Institution
Leiden Observatory, Faculty of Science, Leiden University
Date
2024-06-20
ISBN (print)
9789464735277