Ultra diffuse galaxies in the MATLAS low-to-moderate density fields

Astronomy and Astrophysics, vol. 654, pp. A105

Abstract

Recent advances in deep dedicated imaging surveys over the past decade have uncovered a surprisingly large number of extremely faint low surface brightness galaxies with large physical sizes called ultra diffuse galaxies (UDGs) in clusters and, more recently, in lower density environments. As part of the Mass Assembly of early-Type GaLAxies with their fine Structures (MATLAS) survey, a deep imaging large program at the Canada-France-Hawaii Telescope (CFHT), our team has identified 2210 dwarf galaxies, 59 (∼3%) of which qualify as UDGs. Averaging over the survey area, we find ∼0.4 UDG per square degree. They are found in a range of low to moderate density environments, although 61% of the sample fall within the virial radii of groups. Based on a detailed analysis of their photometric and structural properties, we find that the MATLAS UDGs do not show significant differences from the traditional dwarfs, except from the predefined size and surface brightness cut. Their median color is as red as the one measured in galaxy clusters, albeit with a narrower color range. The majority of the UDGs are visually classified as dwarf ellipticals with log stellar masses of ∼6.5 − 8.7. The fraction of nucleated UDGs (∼34%) is roughly the same as the nucleated fraction of the traditional dwarfs. Only five (∼8%) UDGs show signs of tidal disruption and only two are tidal dwarf galaxy candidates. A study of globular cluster (GC) candidates selected in the CFHT images finds no evidence of a higher GC specific frequency S N for UDGs than for classical dwarfs, contrary to what is found in most clusters. The UDG halo-to-stellar mass ratio distribution, as estimated from the GC counts, peaks at roughly the same value as for the traditional dwarfs, but spans the smaller range of ∼10 − 2000. We interpret these results to mean that the large majority of the field-to-group UDGs do not have a different formation scenario than traditional dwarfs.

Authors 13

1. Francine R. Marleau

   Universität Innsbruck

   Affiliation as printed

   Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstraße 25/8, Innsbruck 6020, Austria

2. Rebecca A. Habas

   Centre National de la Recherche Scientifique · Observatoire astronomique de Strasbourg · Université de Strasbourg

   Affiliation as printed

   Observatoire Astronomique de Strasbourg (ObAS), Universite de Strasbourg – CNRS, UMR 7550, Strasbourg, France

3. Mélina Poulain

   Universität Innsbruck

   Affiliation as printed

   Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstraße 25/8, Innsbruck 6020, Austria

4. Pierre–Alain Duc

   Centre National de la Recherche Scientifique · Observatoire astronomique de Strasbourg · Université de Strasbourg

   Affiliation as printed

   Observatoire Astronomique de Strasbourg (ObAS), Universite de Strasbourg – CNRS, UMR 7550, Strasbourg, France

5. Oliver Müller

   Centre National de la Recherche Scientifique · Observatoire astronomique de Strasbourg · Université de Strasbourg

   Affiliation as printed

   Observatoire Astronomique de Strasbourg (ObAS), Universite de Strasbourg – CNRS, UMR 7550, Strasbourg, France

6. Sungsoon Lim

   Yonsei University

   Affiliation as printed

   Department of Astronomy, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 03722, Republic of Korea

7. Patrick R. Durrell

   Youngstown State University

   Affiliation as printed

   Youngstown State University, One University Plaza, Youngstown, OH 44555, USA

8. Rubén Sánchez-Janssen

   Royal Observatory · UK Astronomy Technology Centre

   Affiliation as printed

   UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

9. Sanjaya Paudel

   Yonsei University

   Affiliation as printed

   Department of Astronomy, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 03722, Republic of Korea

10. Syeda Lammim Ahad Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands

11. Abhishek Chougule

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

    Affiliation as printed

    Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal

    Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

12. Michal Bílek

    Nicolaus Copernicus Astronomical Center · Polish Academy of Sciences

    Affiliation as printed

    Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland

13. Jérémy Fensch

    École Normale Supérieure de Lyon · Centre National de la Recherche Scientifique · Centre de Recherche Astrophysique de Lyon

    Affiliation as printed

    Univ. Lyon, ENS de Lyon, Univ. Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon, UMR5574, 69007 Lyon, France