{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/the-muse-faint-survey-ii-the-dark-matter","title":"The MUSE-Faint survey. II. The dark matter-density profile of the ultra-faint dwarf galaxy Eridanus 2","arxiv_id":"2101.00253","date":"2021-01-01","proceeding":null,"authors":["Sebastiaan L. Zoutendijk","Jarle Brinchmann","Nicolas F. Bouché","Mark den Brok","Davor Krajnović","Konrad Kuijken","Michael V. Maseda","Joop Schaye"],"abstract":"Aims. We use stellar line-of-sight velocities to constrain the dark matter-density profile of Eridanus 2, an ultra-faint dwarf galaxy ($M_\\mathrm{V} = -7.1$, $M_* \\approx 9 \\times 10^4\\,M_\\odot$). We furthermore derive constraints on fundamental properties of self-interacting and fuzzy dark matter scenarios. Methods. We present new observations of Eridanus 2 from MUSE-Faint, a survey of ultra-faint dwarf galaxies with MUSE on the Very Large Telescope, and determine line-of-sight velocities for stars inside the half-light radius. Combined with literature data, we have 92 stellar tracers out to twice the half-light radius. We constrain models of cold dark matter, self-interacting dark matter, and fuzzy dark matter with these tracers, using CJAM and pyGravSphere for the dynamical analysis. Results. We find substantial evidence for cold dark matter over self-interacting dark matter and weak evidence for fuzzy dark matter over cold dark matter. We find a virial mass $M_{200} \\sim 10^8\\,M_\\odot$ and astrophysical factors $J(\\alpha_\\mathrm{c}^J) \\sim 10^{11}\\,M_\\odot^2\\,\\mathrm{kpc}^{-5}$ and $D(\\alpha_\\mathrm{c}^D) \\sim 10^2$-$10^{2.5}\\,M_\\odot\\,\\mathrm{kpc}^{-2}$. We do not resolve a core ($r_\\mathrm{c} < 47\\,\\mathrm{pc}$, 68-% level) or soliton ($r_\\mathrm{sol} < 7.2\\,\\mathrm{pc}$, 68-% level). These limits are equivalent to an effective self-interaction coefficient $f\\Gamma < 2.2 \\times 10^{-29}\\,\\mathrm{cm}^3\\,\\mathrm{s}^{-1}\\,\\mathrm{eV}^{-1}\\,c^2$ and a fuzzy-dark-matter particle mass $m_\\mathrm{a} > 4.0 \\times 10^{-20}\\,\\mathrm{eV}\\,c^{-2}$. The constraint on self-interaction is complementary to those from gamma-ray searches. The constraint on fuzzy-dark-matter particle mass is inconsistent with those obtained for larger dwarf galaxies, suggesting that the flattened density profiles of those galaxies are not caused by fuzzy dark matter. (Abridged)","url_abs":"https://arxiv.org/abs/2101.00253v3","url_pdf":"https://arxiv.org/pdf/2101.00253v3.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"the-muse-faint-survey-ii-the-dark-matter","repo_url":"https://github.com/AnnaGenina/pyGravSphere","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}