To understand the formation and evolution of structure in our Universe, we need to ask how galaxies, the Universe’s building blocks, have grown and changed over time. Massive quiescent galaxies hold the answers as some of the most extreme systems in existence. The properties of these ancient cosmic fossils, which have ceased forming stars, challenge theories of cosmic structure formation, making them unique laboratories for probing the fundamental physics on which our Universe operates.
In this thesis, we scrutinise these galaxies, providing some of the most detailed constraints to date on galaxy formation out to ~10 billion years ago. Through flexible modeling of the highest quality spectroscopic data, we present novel measurements of age and chemical gradients in distant galaxies, reveal discrepancies in model predictions, and, for the first time, reliably determine the low-mass end of the stellar initial mass function in distant, massive galaxies.
Show moreTo understand the formation and evolution of structure in our Universe, we need to ask how galaxies, the Universe’s building blocks, have grown and changed over time. Massive quiescent galaxies hold the answers as some of the most extreme systems in existence. The properties of these ancient cosmic fossils, which have ceased forming stars, challenge theories of cosmic structure formation, making them unique laboratories for probing the fundamental physics on which our Universe operates.
In this thesis, we scrutinise these galaxies, providing some of the most detailed constraints to date on galaxy formation out to ~10 billion years ago. Through flexible modeling of the highest quality spectroscopic data, we present novel measurements of age and chemical gradients in distant galaxies, reveal discrepancies in model predictions, and, for the first time, reliably determine the low-mass end of the stellar initial mass function in distant, massive galaxies.
This work has revealed that the centres of galaxies may have halted their star formation first, with their outskirts being built up through mergers with small, neighbouring galaxies with lower amounts of iron. Simultaneously, we have found that current models may predict systematically biased stellar masses, with the most massive, distant galaxies being up to four times more massive than previously thought.
These findings call our current understanding of galaxy formation into question. Going forward, we must examine larger samples of galaxies with state-of-the-art telescopes, and develop sophisticated modeling methods, allowing us to paint a more complete picture of galaxy formation over cosmic time.
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