Dark matter distribution and its impact on the evolution of galaxy disks

TL;DR

This paper reviews how dark matter halos influence galaxy disk evolution, affecting bar formation, stability, and galaxy morphology through gravitational interactions and angular momentum exchange.

Contribution

It provides a comprehensive review of the effects of dark matter halo shapes and dynamics on galaxy disk evolution, highlighting new insights into bar development and galaxy morphology.

Findings

Dark halos weaken bars in galaxies.

Misaligned infall can produce polar ring galaxies.

Dark matter influences galaxy lopsidedness.

Abstract

The role of dark matter halos in galaxy disk evolution is reviewed, in particular the stabilisation of disks through self-gravity reduction, or the bar development through angular momentum exchange. Triaxial dark halos tend to weaken bars. When the dark mass inside the bar region is negligible, the bar develops through angular momentum exchange between inner and outer disk, and between stars and gas. Self-regulating cycles on the bar strength may develop in the presence of external gas accretion. Dynamical friction on dark halos slows down bars, which puts constraints on the dark matter amount inside the inner disk. During galaxy formation, baryons can lose most of their angular momentum if the infall is misaligned with the dark matter axes. Stable disks can form aligned with the minor axis of the dark halo. A sudden change in the infall direction, otherwise steady, can produce the peculiar polar ring galaxies. The dark matter halo can then be aligned along the polar disk. Misaligned infall can also maintain lopsidedness, which is only rarely due to galaxy interactions and mergers.