The Fundamental Plane of Early-Type Galaxies as a Confounding Correlation

TL;DR

This paper proposes that the fundamental plane of early-type galaxies is a confounding correlation caused by an underlying parameter related to galaxy diversification, challenging the traditional physical interpretation.

Contribution

It introduces the idea that the fundamental plane is an artifact of a confounding parameter, offering a new perspective on galaxy scaling relations.

Findings

The fundamental plane may be a confounding correlation rather than a direct physical relation.

Galaxy evolution and diversification influence multiple scaling relations.

Many galaxy scaling relations could be evolutionary correlations rather than fundamental laws.

Abstract

Early-type galaxies are characterized by many scaling relations. One of them, the so-called fundamental plane is a relatively tight correlation between three variables, and has resisted a clear physical understanding despite many years of intensive research. Here, we show that the correlation between the three variables of the fundamental plane can be the artifact of the effect of another parameter influencing all, so that the fundamental plane may be understood as a confounding correlation. Indeed, the complexity of the physics of galaxies and of their evolution suggests that the main confounding parameter must be related to the level of diversification reached by the galaxies. Consequently, many scaling relations for galaxies are probably evolutionary correlations.