The isolated dark matter-poor galaxy that ran away

Abstract

Since the discovery of dark matter-deficient galaxies, numerous studies have shown that these exotic galaxies naturally occur in the Lambda CDM model due to stronger tidal interactions. They are typically satellites, with stellar masses in the $10^8-10^9\; M range, of more massive galaxies. The recent discovery of a massive galaxy lacking dark matter and also lacking a more massive neighbor is puzzling. Two possible scenarios have been suggested in the literature: either the galaxy lost its dark matter early or it had been lacking ab initio. As a proof of concept for the former assumption, we present an example from IllustrisTNG300. At present, the galaxy has a stellar mass of $M_ M with no gas, $M_ DM /M_ B 1.31$, and a stellar half-mass radius of star kpc $. It lost the majority of its dark matter early, between $z = 2.32$ and $z = 1.53$. Since then, it has continued to dwell in the cluster environment, interacting with the cluster members without merging, while accelerating on its orbit. Eventually, it left the cluster and it has spent the last $ Gyr $ in isolation, residing just outside the most massive cluster in the simulation. Thus, the galaxy represents the first example found in simulations of both an isolated dark matter-poor galaxy that lost its extended envelope early and a fairly compact stellar system that has managed to escape.

Multiple Beads on a String: Dark-matter-deficient Galaxy Formation in a Mini-Bullet Satellite–Satellite Galaxy Collision

“…The Mini-Bullet model is not the only one advanced so far to explain the DMDGs. One of the most frequently studied alternative mechanisms for the formation of these unique systems is tidal interaction that transfers dark matter to the more massive system (tidal stripping; Ogiya 2018;Jackson et al 2021;Macciò et al 2021;Ogiya et al 2022a;Moreno et al 2022;Katayama & Nagamine 2023;Mitrašinović et al 2023;Montero-Dorta et al 2024). In the case of DF2 and DF4, however, although there are measurements of their tidal distortion, the results do not require that the galaxies' dark matter was removed by tidal interaction (Keim et al 2022).…”