Supernova Feedback Keeps Galaxies Simple

TL;DR

This paper demonstrates that supernova feedback and self-regulated star formation can explain the observed uniformity in neutral hydrogen surface density across diverse galaxies, revealing a fundamental simplicity in galaxy properties.

Contribution

It introduces a model where supernova feedback maintains a constant neutral hydrogen surface density, explaining the observed galaxy scaling relations within hierarchical formation.

Findings

Neutral hydrogen surface density is nearly constant across galaxies.

Supernova feedback regulates star formation and galaxy properties.

The model reproduces the observed linear relation between hydrogen mass and surface area.

Abstract

Galaxies evolve continuously under the influence of self-gravity, rotation, accretion, mergers and feedback. The currently favored cold dark matter cosmological framework, suggests a hierarchical process of galaxy formation, wherein the present properties of galaxies are decided by their individual histories of being assembled from smaller pieces. However, recent studies have uncovered surprising correlations among the properties of galaxies, to the extent of forming a one-parameter set lying on a single fundamental line. It has been argued in the literature that such simplicity is hard to explain within the paradigm of hierarchical galaxy mergers. One of the puzzling results, is the simple linear correlation between the neutral hydrogen mass and the surface area, implying that widely different galaxies share very similar neutral hydrogen surface densities. In this work we show that self-regulated star formation, driven by the competition between gravitational instabilities and mechanical feedback from supernovae, can explain the nearly constant neutral hydrogen surface density across galaxies. We therefore recover the simple scaling relation observed between the neutral hydrogen mass and surface area. This result furthers our understanding of the surprising simplicity in the observed properties of diverse galaxies.