Investigating the formation and evolution of the most massive galaxies in the Universe

Mitra, Dipanjan 2025. Investigating the formation and evolution of the most massive galaxies in the Universe. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The discovery of dusty star-forming galaxies (DSFGs) nearly three decades ago has profoundly transformed our understanding of galaxy evolution. Recognized as the progenitors of present-day elliptical and spheroidal galaxies, DSFGs, often referred to as proto-spheroidal galaxies, exhibit extreme star formation rates of about 100 to 1000 solar masses per year. They dominate the star-forming galaxy population at redshifts greater than about 1.5, making a substantial contribution during the epoch of cosmic noon, around redshift 2. DSFGs have been extensively studied through a range of ground- and space-based facilities, including SCUBA-2, Herschel, and ALMA. This thesis aims to advance our understanding of DSFG evolution by combining observational data with theoretical modelling and simulations. I adopt a physical model for the high-redshift progenitors of spheroidal galaxies, believed to constitute the bulk of DSFGs at redshift greater than about 1.5, and enhance it by integrating its dynamical outputs with a formalism for spectral energy distribution (SED) modelling. This framework is used to interpret existing observations and to make predictions for ongoing and upcoming missions such as JWST, Euclid, and LSST. Using this improved model, I evaluate the constraints that Euclid will place on DSFGs at redshift greater than about 1.5 identified in wide-area surveys such as Herschel-ATLAS. The results indicate that Euclid will provide robust stellar mass estimates for most bright DSFGs at these redshifts. I further investigate the potential improvements that LSST photometry could offer when combined with Euclid data. Additionally, I assess the ability of JWST’s JADES survey to constrain the physical properties of DSFGs in the GOODS-South field, finding that JWST will enable reliable stellar mass estimates for the majority of these sources. Finally, I extend the application of the modified model to dusty quasars, believed to represent a transitional phase between starburst and unobscured quasar stages, and predict their number densities across large survey areas. The thesis concludes by discussing the broader implications of these findings and outlining promising directions for future research on dusty, high-redshift galaxy populations.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	Dusty star-forming galaxies, Galaxy evolution, High-redshift galaxies, Spectral energy distribution, Euclid, JWST, LSST, Herschel-ATLAS, Dusty quasars, Stellar mass estimation
Funders:	STFC
Date of First Compliant Deposit:	13 October 2025
Last Modified:	13 Oct 2025 15:21
URI:	https://orca.cardiff.ac.uk/id/eprint/181606

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