Observations

Numerous models have been proposed to explain the unexpected wealth of galaxies at Cosmic Dawn revealed by JWST. These models are all tuned to reproduce the abundance of galaxies, requiring new measurements to figure out which ones are actually right. An obvious candidate for these constraints come from clustering, but to do so with JWST requires innovating methodology. Here I show how clustering can be measured from pure-parallel JWST surveys, and how it gives us a unique handle on why galaxies seem to not be going through a wild and bursty teenage phase.

The existence of ultramassive quiescent galaxies, which have already completed their life cycle at a mere 7% of the age of the Universe, is among the most puzzling of recent discoveries. We provide a statistical argument for interpreting these observations in the context of their environments, which explains their accelerated formation.

Galaxies are often modelled as disjoint composites of distinct spectral components, implying that different wavelength ranges are only weakly correlated. They are not. We construct a data-driven model to predict infrared emission from optical spectra, achieving almost lossless predictions. Traditional fitting methods are incapable of making predictions, being biased by model misspecifications.

Solving the issue of spatially varying PSFs for the COSMOS survey