Galaxies and Cladistics

TL;DR

This paper introduces astrocladistics, a novel phylogenetic approach adapted from biological systematics, to classify and understand galaxy evolution using multiwavelength data and evolutionary concepts.

Contribution

It pioneers the application of phylogenetic systematics to galaxies, proposing astrocladistics as a new method for galaxy classification and evolutionary analysis.

Findings

Successfully applied to several galaxy samples

Demonstrated potential for improved galaxy classification

Highlighted challenges specific to galaxy data

Abstract

The Hubble tuning fork diagram, based on morphology and established in the 1930s, has always been the preferred scheme for classification of galaxies. However, the current large amount of multiwavelength data, most often spectra, for objects up to very high distances, asks for more sophisticated statistical approaches. Interpreting formation and evolution of galaxies as a ?transmission with modification' process, we have shown that the concepts and tools of phylogenetic systematics can be heuristically transposed to the case of galaxies. This approach, which we call ?astrocladistics', has successfully been applied on several samples. Many difficulties still remain, some of them being specific to the nature of both galaxies and their diversification processes, some others being classical in cladistics, like the pertinence of the descriptors in conveying any useful evolutionary information.