Lopsided Galaxies in a cosmological context: a new galaxy-halo connection by Silvio Varela-Lavin et al. on Wednesday 30 November

Disc galaxies commonly show asymmetric features in their morphology, such as

warps and lopsidedness. These features can provide key information regarding

the recent evolution of a given disc galaxy. In the nearby Universe, up to ~30

percent of late-type galaxies display a global non-axisymmetric lopsided mass

distribution, but little attention has been paid to the origin of this

perturbation. In this work, we study the origin of lopsided perturbations in

simulated disc galaxies extracted from the TNG50 simulation of the IllustrisTNG

project. We statistically explore different excitation mechanisms for this

perturbation, such as direct satellite tidal interactions and distortions of

the underlying dark matter distributions. We also characterize the main

physical conditions that lead to lopsided perturbations. 50 percent of our

sample galaxy have lopsided modes $m=1$ greater than ~0.12. We find a strong

correlation between internal galaxy properties, such as central stellar surface

density and disc radial extension with the strength of lopsided modes. The

majority of lopsided galaxies have lower central surface densities and more

extended discs than symmetric galaxies. As a result, such lopsided galaxies are

less self-gravitationally cohesive, and their outer disc region is more

susceptible to different types of external perturbations. However, we do not

find strong evidence that tidal interactions with satellite galaxies are the

main driving agent of lopsided modes. Lopsided galaxies tend to live in

asymmetric dark matter halos with high spin, indicating strong galaxy-halo

connections in late-type lopsided galaxies.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16577v1