On the connection between shape and stellar population in early-type galaxies

TL;DR

This paper uncovers a fundamental relation linking the shape, stellar mass, and mass-to-light ratio of early-type galaxies, revealing their interconnected physical properties and providing new constraints for galaxy formation theories.

Contribution

It identifies a three-dimensional plane relation among shape, stellar mass, and mass-to-light ratio in early-type galaxies, highlighting their interdependence.

Findings

ETGs occupy a plane in the 3D space of shape, mass, and M*/L

Galaxy shape and stellar population are physically connected

The relation constrains galaxy formation and evolution models

Abstract

We report on the discovery of a relation between the stellar mass $M^*$ of early-type galaxies (hereafter ETGs), their shape, as parametrized by the Sersic index $n$, and their stellar mass-to-light ratio $M^*/L$. In a 3D log space defined by these variables the ETGs populate a plane surface with small scatter. This relation tells us that galaxy shape and stellar population are not independent physical variables, a result that must be accounted for by theories of galaxy formation and evolution.