Volume 640, August 2020
|Number of page(s)||10|
|Published online||21 August 2020|
Spectroscopic study of MATLAS-2019 with MUSE: An ultra-diffuse galaxy with an excess of old globular clusters⋆,⋆⋆
Observatoire Astronomique de Strasbourg (ObAS), Universite de Strasbourg – CNRS, UMR 7550, Strasbourg, France
2 Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstraße 25/8, Innsbruck 6020, Austria
3 Univ. Lyon, ENS de Lyon, Univ. Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon, UMR5574, 69007 Lyon, France
4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
5 University of Tampa, 401 West Kennedy Boulevard, Tampa, FL 33606, USA
6 DARK, Niels-Bohr Institute, Lyngbyvej 2, Copenhagen, Denmark
7 Department of Physics & Astronomy, Youngstown State University, Youngstown, OH 44555, USA
8 Department of Astronomy, Yonsei University, Seoul 03722, Republic of Korea
9 UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
Accepted: 8 June 2020
The MATLAS deep imaging survey has uncovered a plethora of dwarf galaxies in the low density environment it has mapped. A fraction of them are unusually extended and have low surface brightness. Among these so-called ultra-diffuse galaxies, a few seem to host an excess of globular clusters (GCs). With the integral field unit spectrograph MUSE we have observed one of these galaxies – MATLAS J15052031+0148447 (MATLAS-2019) – located toward the nearby group NGC 5846 and measured its systemic velocity, age, and metallicity, and that of its GC candidates. For the stellar body of MATLAS-2019 we derive a metallicity of −1.33−0.01+0.19 dex and an age of 11.2−0.8+1.8 Gyr. For some of the individual GCs and the stacked GC population, we derive consistent ages and metallicities. From the 11 confirmed GCs and using a Markov Chain Monte Carlo approach we derived a dynamical mass-to-light ratio of 4.2−3.4+8.6 M⊙/L⊙. This is at the lower end of the luminosity-mass scaling relation defined by the Local Group dwarf galaxies. Furthermore, we could not confirm or reject the possibility of a rotational component in the GC system. If present, this would further modify the inferred mass. Follow-up observations of the GC population and of the stellar body of the galaxy are needed to assess whether this galaxy lacks dark matter, as was suggested for the pair of dwarf galaxies in the field of NGC 1052, or if this is a misinterpretation arising from systematic uncertainties of the method commonly used for these systems and the large uncertainties of the individual GC velocities.
Key words: galaxies: kinematics and dynamics / galaxies: stellar content / galaxies: dwarf
The reduced datacube is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A106
© O. Müller et al. 2020
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.