Creating a galaxy lacking dark matter in a dark matter dominated universe

TL;DR

This study demonstrates through simulations that tidal interactions in dense environments can produce galaxies with little to no dark matter, matching observed properties of certain dark matter-deficient galaxies.

Contribution

It introduces a novel simulation-based method showing how dark matter-deficient galaxies can form from typical dwarf galaxies via tidal stripping.

Findings

Dwarf galaxies can lose up to 80% of dark matter after a single pericentric passage.

Dark matter to stellar ratio can decrease from ~25 to roughly 1.

Stellar velocity dispersion and size match observed dark matter-deficient galaxies.

Abstract

We use hydrodynamical cosmological simulations to show that it is possible to create, via tidal interactions, galaxies lacking dark matter in a dark matter dominated universe. We select dwarf galaxies from the NIHAO project, obtained in the standard Cold Dark Matter model and use them as initial conditions for simulations of satellite-central interactions. After just one pericentric passage on an orbit with a strong radial component, NIHAO dwarf galaxies can lose up to 80 per~cent of their dark matter content, but, most interestingly, their central ($\approx 8$~kpc) dark matter to stellar ratio changes from a value of ${\sim}25$, as expected from numerical simulations and abundance matching techniques, to roughly unity as reported for NGC1052-DF2 and NGC1054-DF4. The stellar velocity dispersion drops from ${\sim}30$ ${\rm km\,s^{-1}}$ before infall to values as low as $6\pm 2$~ ${\rm km\,s^{-1}}$. These, and the half light radius around 3 kpc, are in good agreement with observations from van Dokkum and collaborators. Our study shows that it is possible to create a galaxy "without" dark matter starting from typical dwarf galaxies formed in a dark matter dominated universe, provided they live in a dense environment.