A distance of 13 Mpc resolves the claimed anomalies of the galaxy lacking dark matter

• Published in: Monthly notices of the Royal Astronomical Society Vol. 486; no. 1; pp. 1192 - 1219
• Main Authors: Trujillo, Ignacio, Beasley, Michael A, Borlaff, Alejandro, Carrasco, Eleazar R, Di Cintio, Arianna, Filho, Mercedes, Monelli, Matteo, Montes, Mireia, Román, Javier, Ruiz-Lara, Tomás, Sánchez Almeida, Jorge, Valls-Gabaud, David, Vazdekis, Alexandre
• Format: Journal Article
• Language: English
• Published: Oxford University Press 11.06.2019; Oxford University Press (OUP): Policy P - Oxford Open Option A
• Subjects: Astrophysics; Sciences of the Universe; galaxies: formation; galaxies: structure; galaxies: kinematics and dynamics; galaxies: evolution
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stz771

Abstract The claimed detection of a diffuse galaxy lacking dark matter represents a possible challenge to our understanding of the properties of these galaxies and galaxy formation in general. The galaxy, already identified in photographic plates taken in the summer of 1976 at the UK 48-in Schmidt telescope, presents normal distance-independent properties (e.g. colour, velocity dispersion of its globular clusters). However, distance-dependent quantities are at odds with those of other similar galaxies, namely the luminosity function and sizes of its globular clusters, mass-to-light ratio, and dark matter content. Here we carry out a careful analysis of all extant data and show that they consistently indicate a much shorter distance (13 Mpc) than previously indicated (20 Mpc). With this revised distance, the galaxy appears to be a rather ordinary low surface brightness galaxy (Re = 1.4 ± 0.1 kpc; M⋆ = 6.0 ± 3.6 × 107 M⊙) with plenty of room for dark matter (the fraction of dark matter inside the half-mass radius is >75 per cent and Mhalo/M⋆>20) corresponding to a minimum halo mass >109 M⊙. At 13 Mpc, the luminosity and structural properties of the globular clusters around the object are the same as those found in other galaxies.