Galaxy Formation Spanning Cosmic History

TL;DR

This paper introduces an improved semi-analytic galaxy formation model that incorporates updated physics and extensive parameter tuning, enabling more accurate predictions across cosmic history and unprobed regimes.

Contribution

It presents a new implementation of the Galform model with enhanced physics and thorough parameter optimization, surpassing previous models in realism and predictive power.

Findings

Model matches a wide range of observational data

Improved physics allows reliable high-redshift predictions

Extensive parameter search ensures good data agreement

Abstract

Over the past several decades, galaxy formation theory has met with significant successes. In order to test current theories thoroughly we require predictions for as yet unprobed regimes. To this end, we describe a new implementation of the Galform semi-analytic model of galaxy formation. Our motivation is the success of the model described by Bower et al. in explaining many aspects of galaxy formation. Despite this success, the Bower et al. model fails to match some observational constraints and certain aspects of its physical implementation are not as realistic as we would like. The model described in this work includes substantially updated physics, taking into account developments in our understanding over the past decade, and removes certain limiting assumptions made by this (and most other) semi-analytic models. This allows it to be exploited reliably in high-redshift and low mass regimes. Furthermore, we have performed an exhaustive search of model parameter space to find a particular set of model parameters which produce results in good agreement with a wide range of observational data (luminosity functions, galaxy sizes and dynamics, clustering, colours, metal content) over a wide range of redshifts. This model represents a solid basis on which to perform calculations of galaxy formation in as yet unprobed regimes.