Tidal forces from the wake of dynamical friction: warps, lopsidedness and kinematic misalignment

TL;DR

This paper investigates how tidal forces from dynamical friction wakes in dark matter can cause observable galaxy distortions like warps and lopsidedness, providing a potential explanation for these features in isolated galaxies.

Contribution

It introduces a method to calculate tidal forces from dark matter wakes and demonstrates their role in producing galaxy warps, lopsidedness, and kinematic misalignments, linking observations to dark matter properties.

Findings

Reproduces observed galaxy warps and lopsidedness with realistic dark matter parameters.

Shows the mechanism can explain features in isolated galaxies and in loose groups.

Provides a way to constrain dark matter distribution through galaxy distortions.

Abstract

A galaxy moving through a background of dark matter particles, induces an overdensity of these particles or a wake behind it. The back reaction of this wake on the galaxy is a force field that can be decomposed into an effective deceleration (called dynamical friction) and a tidal field. In this paper we determine the tidal forces, thus generated on the galaxy, and the resulting observables, which are shown to be warps, lopsidedness and/or kinematic-photometric position angle misalignments. We estimate the magnitude of the tidal-like effects needed to reproduce the observed warp and lopsidedness on the isolated galaxy IC 2487. Within a realistic range of dark matter distribution properties the observed warped and lopsided kinematical properties of IC 2487 is possible to reproduce (the background medium of dark matter particles has a velocity dispersion of $\lesssim 80\,{\rm km\,s^{-1}}$ and the density $10^4-10^5~{\rm M_\odot\,kpc^{-3}}$, more likely at the lower end). We conclude that the proposed mechanism can generate warps, lopsidedness and misalignments observed in isolated galaxies or galaxies in loose groups. The method can be used also to constrain dark matter spatial and velocity distribution properties.