A unified multi-wavelength model of galaxy formation

TL;DR

This paper introduces an enhanced galaxy formation model that unifies previous approaches, incorporating new physics and empirical laws, successfully explaining a wide range of observational data across multiple wavelengths and redshifts.

Contribution

The paper presents a comprehensive, unified semi-analytical galaxy formation model integrating various physical processes and empirical laws, achieving broad observational consistency within the LambdaCDM framework.

Findings

Successfully explains evolution of K-band luminosity and stellar mass functions.

Reproduces sub-mm galaxy counts and redshift distributions.

Matches diverse observational data from UV to sub-mm wavelengths.

Abstract

We present a new version of the GALFORM semi-analytical model of galaxy formation. This brings together several previous developments of GALFORM into a single unified model, including a different initial mass function (IMF) in quiescent star formation and in starbursts, feedback from active galactic nuclei supressing gas cooling in massive halos, and a new empirical star formation law in galaxy disks based on their molecular gas content. In addition, we have updated the cosmology, introduced a more accurate treatment of dynamical friction acting on satellite galaxies, and updated the stellar population model. The new model is able to simultaneously explain both the observed evolution of the K-band luminosity function and stellar mass function, and the number counts and redshift distribution of sub-mm galaxies selected at 850 mu. This was not previously achieved by a single physical model within the LambdaCDM framework, but requires having an IMF in starbursts that is somewhat top-heavy. The new model is tested against a wide variety of observational data covering wavelengths from the far-UV to sub-mm, and redshifts from z=0 to z=6, and is found to be generally successful. These observations include the optical and near-IR luminosity functions, HI mass function, fraction of early type galaxies, Tully-Fisher, metallicity-luminosity and size-luminosity relations at z=0, as well as far-IR number counts, and far-UV luminosity functions at z ~ 3-6. [abridged]