Semi-Analytic Galaxy Evolution (SAGE): Model Calibration and Basic Results

TL;DR

The paper introduces SAGE, a flexible semi-analytic galaxy formation model, detailing its calibration on multiple simulations and presenting new physics modules for galaxy evolution processes.

Contribution

It provides a modular, customizable codebase for galaxy formation modeling, with updated physics and calibration across three major N-body simulations.

Findings

Successful calibration on Millennium, Bolshoi, and GiggleZ simulations.

Enhanced physics modules for gas accretion, feedback, and galaxy mergers.

Consistent reproduction of local galaxy population properties.

Abstract

This paper describes a new publicly available codebase for modelling galaxy formation in a cosmological context, the "Semi-Analytic Galaxy Evolution" model, or SAGE for short. SAGE is a significant update to that used in Croton et al. (2006) and has been rebuilt to be modular and customisable. The model will run on any N-body simulation whose trees are organised in a supported format and contain a minimum set of basic halo properties. In this work we present the baryonic prescriptions implemented in SAGE to describe the formation and evolution of galaxies, and their calibration for three N-body simulations: Millennium, Bolshoi, and GiggleZ. Updated physics include: gas accretion, ejection due to feedback, and reincorporation via the galactic fountain; a new gas cooling--radio mode active galactic nucleus (AGN) heating cycle; AGN feedback in the quasar mode; a new treatment of gas in satellite galaxies; and galaxy mergers, disruption, and the build-up of intra-cluster stars. Throughout, we show the results of a common default parameterization on each simulation, with a focus on the local galaxy population.