text: 260,71,1493324906443902976,60893773,James Bullock,"A quick summary of thoughts on our new FIRE et al. paper showing that dark-matter-free low-mass galaxies arise naturally and fairly frequently around massive galaxies in a cosmological-volume simulation. Paper led by @jorgito__moreno using FIREbox sim <LINK> <LINK> van Dokkum and @DanieliShany discovery of low-mass dm-poor galaxies DF2 and DF4 (red bars) v. surprising, since low-mass galaxies are usually DM-dominated. Remarkably we find several low-mass galaxies (yellow) in these sim have less DM than stars within their stellar radii. <LINK> Every one of them is a satellite of a massive (~1.e11 Mstar) host that is on an orbit that brought it within the core of the galaxy (~10 kpc from the center). Much more DM lost than stars. <LINK> Most of them have very faint tidal features <LINK> This work follows a long line of work that has shown that close encounters between low-mass galaxies and massive hosts could do this kind of thing: Haslbauer et al., Carleton et al., Sales et al., etc. Our sims do a very good job reproducing many properties of DF2 and DF4: velocity dispersion, sizes, etc. We predict that ~30% of massive hosts should have a satellite that is DM deficient. One thing that still concerns me about our work is that we find our objects are still fairly metal rich compared to DF2 and DF4. Could be scatter in Fe/H vs. Mstar -- will need to discover more DM-def. galaxies to test these things! @azifattahi @jorgito__moreno Yes, basically. Here is relevant section of table. <LINK>",https://arxiv.org/abs/2202.05836,"The standard cold dark matter plus cosmological constant model predicts that galaxies form within dark-matter haloes, and that low-mass galaxies are more dark-matter dominated than massive ones. The unexpected discovery of two low-mass galaxies lacking dark matter immediately provoked concerns about the standard cosmology and ignited explorations of alternatives, including self-interacting dark matter and modified gravity. Apprehension grew after several cosmological simulations using the conventional model failed to form adequate numerical analogues with comparable internal characteristics (stellar masses, sizes, velocity dispersions and morphologies). Here we show that the standard paradigm naturally produces galaxies lacking dark matter with internal characteristics in agreement with observations. Using a state-of-the-art cosmological simulation and a meticulous galaxy-identification technique, we find that extreme close encounters with massive neighbours can be responsible for this. We predict that approximately 30 percent of massive central galaxies (with at least 1e11 solar masses in stars) harbour at least one dark-matter-deficient satellite (with 1e8 - 1e9 solar masses in stars). This distinctive class of galaxies provides an additional layer in our understanding of the role of interactions in shaping galactic properties. Future observations surveying galaxies in the aforementioned regime will provide a crucial test of this scenario. ","Galaxies lacking dark matter produced by close encounters in a