2021/09/03 by José A. Benavides, Laura V. Sales, Mario. G. Abadi +8 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Dark galaxy #Dark matter #Dwarf galaxy #Dwarf galaxy problem #Electrical and Electromagnetic Research #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy group #Halo #Local Group #Milky Way #astro-ph.GA
paper · pdf · doi:10.1038/s41550-021-01458-1
published as Nature Astronomy 2021 · Author's version for the main article and supplementary information (13 pages, 10 figures). Accepted for publication in Nature Astronomy
arxiv created 2021/09/03 · openalex publication_date 2021/09/06 · arxiv updated 2021/09/07 · openalex created_date 2021/09/13 · openalex updated_date 2026/08/05
Ultra-diffuse galaxies (UDGs) are the lowest-surface brightness galaxies known, with typical stellar masses of dwarf galaxies but sizes similar to larger galaxies like the Milky Way. The reason for their extended sizes is debated, with suggested internal processes like angular momentum, feedback or mergers versus external mechanisms or a combination of both. Observationally, we know that UDGs are red and quiescent in groups and clusters while their counterparts in the field are blue and star-forming. This dichotomy suggests environmental effects as main culprit. However, this scenario is challenged by recent observations of isolated quiescent UDGs in the field. Here we use ΛCDM cosmological hydrodynamical simulation to show that isolated quenched UDGs are formed as backsplash galaxies that were once satellites of another galactic, group or cluster halo but are today a few Mpc away from them. These interactions, albeit brief, remove the gas and tidally strip the outskirts of the dark matter haloes of the now quenched seemingly-isolated UDGs, which are born as star-forming field UDGs occupying dwarf-mass dark matter haloes. Quiescent UDGs may therefore be found in non-negligible numbers in filaments and voids, bearing the mark of past interactions as stripped outer haloes devoid of dark matter and gas compared to dwarfs with similar stellar content.