Angular Momentum across the Hubble sequence from the CALIFA survey

TL;DR

This study examines how stellar angular momentum varies across different galaxy types in the Hubble sequence, revealing peculiar properties of spiral galaxies and implications for galaxy evolution and dark matter influence.

Contribution

It provides new insights into the angular momentum distribution of spiral galaxies and challenges fading as the sole mechanism for galaxy transformation.

Findings

Spiral galaxies have diverse angular momentum properties.

Low-mass spirals are dark matter dominated, explaining low angular momentum.

Fading alone cannot account for spiral to lenticular transformation.

Abstract

We investigate the stellar angular momentum of galaxies across the Hubble sequence from the CALIFA survey. The distribution of CALIFA elliptical and lenticular galaxies in the $\lambda_{\rm Re}-\epsilon_{\rm e}$ diagram is consistent with that shown by the Atlas$^\mathrm{3D}$ survey. Our data, however, show that the location of spiral galaxies in this diagram is significantly different. We have found two families of spiral galaxies with particularly peculiar properties: (a) spiral galaxies with much higher $\lambda_{\rm Re}$ values than any elliptical and lenticular galaxy; (b) low-mass spiral galaxies with observed $\lambda_{\rm Re}$ values much lower than expected for their apparent flattening. We use these two families of objects to argue that (1) fading alone cannot explain the transformation of spiral to lenticular galaxies, and (2) that those low-mass spiral galaxies are in fact dark matter dominated, which explains the unusually low angular momentum.