Astronomy Tea Talk

The Nancy Grace Roman Space Telescope will soon conduct one of the largest spectroscopic galaxy surveys ever attempted, mapping tens of millions of galaxies to study cosmic acceleration and galaxy evolution. To prepare for this, we need realistic mock datasets that capture how galaxies form and evolve, and how they will appear in spectra gathered by Roman's grism.

I will present a new framework for rapidly calibrating the Galacticus semi-analytic model of galaxy formation. Instead of fitting directly to the galaxy stellar mass function - an expensive process requiring thousands of simulated halos per likelihood evaluation - this method uses the stellar-to-halo mass relation at a small set of target halo masses, reducing each model evaluation to the simulation of only tens of galaxies. I will discuss how this speeds up model calibration, as well as its limitations, and will discuss how the approach can be extended to other properties such as galaxy sizes and supermassive black hole masses. These advances bring realistic mock Roman catalogues within reach, paving the way for robust survey design and analysis.