Physical Models of Galaxy Formation in a Cosmological Framework

TL;DR

This review discusses current galaxy formation models within a cosmological framework, highlighting their convergence, core physical processes, and the need for more physically grounded simulations and observational constraints.

Contribution

It provides a comprehensive overview of semi-analytic and hydrodynamic models, emphasizing their agreement, core processes, and the challenges in understanding complex interactions.

Findings

Models show remarkable convergence in predicting galaxy properties.

Core processes include accretion, stellar winds, black hole feedback, and mergers.

Emerging simulations and upcoming observations will refine understanding.

Abstract

Modeling galaxy formation in a cosmological context presents one of the greatest challenges in astrophysics today, due to the vast range of scales and numerous physical processes involved. Here we review the current status of models that employ two leading techniques to simulate the physics of galaxy formation: semi-analytic models and numerical hydrodynamic simulations. We focus on a set of observational targets that describe the evolution of the global and structural properties of galaxies from roughly Cosmic High Noon ($z\sim 2-3$) to the present. Although minor discrepancies remain, overall, models show remarkable convergence between different methods and make predictions that are in qualitative agreement with observations. Modelers seem to have converged on a core set of physical processes that are critical for shaping galaxy properties. This core set includes cosmological accretion, strong stellar-driven winds that are more efficient at low masses, black hole feedback that preferentially suppresses star formation at high masses, and structural and morphological evolution through merging and environmental processes. However, all cosmological models currently adopt phenomenological implementations of many of these core processes, which must be tuned to observations. Many details of how these diverse processes interact within a hierarchical structure formation setting remain poorly understood. Emerging multi-scale simulations are helping to bridge the gap between stellar and cosmological scales, placing models on a firmer, more physically grounded footing. Concurrently, upcoming telescope facilities will provide new challenges and constraints for models, particularly by directly constraining inflows and outflows through observations of gas in and around galaxies.