# Reconciling Mass Functions with the Star-Forming Main Sequence Via Mergers

## TL;DR

This paper develops an empirical galaxy evolution model combining star formation, quiescence, and mergers, resolving discrepancies in the stellar mass function evolution and proposing a testable hierarchical merging framework.

## Contribution

It introduces a novel model that separates hierarchical merging from environment-independent star formation, aligning theoretical predictions with observed galaxy mass functions.

## Key findings

- Merging and star formation together produce a consistent stellar mass function evolution.
- Hierarchical merging can be decoupled from environment-independent star formation.
- The model can be tested through galaxy correlation functions.

## Abstract

We combine star formation along the `main sequence', quiescence, and clustering and merging to produce an empirical model for the evolution of individual galaxies. Main sequence star formation alone would significantly steepen the stellar mass function towards low redshift, in sharp conflict with observation. However, a combination of star formation and merging produces a consistent result for correct choice of the merger rate function. As a result, we are motivated to propose a model in which hierarchical merging is disconnected from environmentally-independent star formation. This model can be tested via correlation functions and would produce new constraints on clustering and merging.