The Formation of Polar Disk Galaxies

TL;DR

This paper demonstrates through high-resolution simulations that polar ring galaxies form due to continuous accretion of misaligned gas, providing insight into their unique structure within hierarchical galaxy formation models.

Contribution

It reveals that polar ring galaxies are a natural outcome of angular momentum misalignment during galaxy formation in Cold Dark Matter cosmology.

Findings

Polar Ring Galaxies result from misaligned gas accretion.

Simulations reproduce observed properties of polar rings.

Angular momentum misalignment explains the formation of these galaxies.

Abstract

Polar Ring Galaxies, such as NGC4650A, are a class of galaxy which have two kinematically distinct components that are inclined by almost 90 degrees to each other. These striking galaxies challenge our understanding of how galaxies form; the origin of their distinct components has remained uncertain, and the subject of much debate. We use high-resolution cosmological simulations of galaxy formation to show that Polar Ring Galaxies are simply an extreme example of the angular moment misalignment that occurs during the hierarchical structure formation characteristic of Cold Dark Matter cosmology. In our model, Polar Ring Galaxies form through the continuous accretion of gas whose angular momentum is misaligned with the central galaxy.