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The orientation and kinematics of inner tidal tails around dwarf galaxies orbiting the Milky Way

Klimentowski, Jarosław ; Łokas, Ewa L. ; Kazantzidis, Stelios ; Mayer, Lucio ; Mamon, Gary A. ; Prada, Francisco

In: Monthly Notices of the Royal Astronomical Society, 2009, vol. 400, no. 4, p. 2162-2168

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    Titre
    • The orientation and kinematics of inner tidal tails around dwarf galaxies orbiting the Milky Way
    Auteur
    • Klimentowski, Jarosław. Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland
    • Łokas, Ewa L.. Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland
    • Kazantzidis, Stelios. Center for Cosmology and Astro-Particle Physics; and Department of Physics; and Department of Astronomy, The Ohio State University, Physics Research Building, 191 West Woodruff Avenue, Columbus, OH 43210, USA
    • Mayer, Lucio. Institute for Theoretical Physics, University of Zürich, CH-8057 Zürich, Switzerland
    • Mamon, Gary A.. Institut d'Astrophysique de Paris (UMR 7095: CNRS and Université Pierre & Marie Curie), 98 bis Bd Arago, F-75014 Paris, France
    • Prada, Francisco. Instituto de Astrofísica de Andalucia (CSIC), Apartado Correos 3005, E-18080 Granada, Spain
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Monthly Notices of the Royal Astronomical Society, 2009, vol. 400, no. 4, p. 2162-2168. Blackwell Publishing Ltd
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:291559
    Summary
    Using high-resolution collisionless N-body simulations, we study the properties of tidal tails formed in the immediate vicinity of a two-component dwarf galaxy evolving in a static potential of the Milky Way (MW). The stellar component of the dwarf is initially in the form of a disc and the galaxy is placed on an eccentric orbit motivated by cold dark matter based cosmological simulations. We measure the orientation, density and velocity distribution of the stars in the tails. Due to the geometry of the orbit, in the vicinity of the dwarf, where the tails are densest and therefore most likely to be detectable, they are typically oriented towards the MW and not along the orbit. We report on an interesting phenomenon of ‘tidal tail flipping': on the way from the pericentre to the apocentre, the old tails following the orbit are dissolved and new ones pointing towards the MW are formed over a short time-scale. We also find a tight linear relation between the velocity of stars in the tidal tails and their distance from the dwarf. Using mock data sets, we demonstrate that if dwarf spheroidal (dSph) galaxies in the vicinity of the MW are tidally affected their kinematic samples are very likely contaminated by tidally stripped stars which tend to artificially inflate the measured velocity dispersion. The effect is stronger for dwarfs on their way from the pericentre to the apocentre due to the formation of new tidal tails after pericentre. Realistic mass estimates of dSph galaxies thus require removal of these stars from kinematic samples