Bound and unbound substructures in Galaxy-scale dark matter haloes

Authors

  • Michal Maciejewski,

    Corresponding author
    1. Max-Planck-Institut für Astrophysik, Garching, Karl-Schwarzschild-Straße 1, 85741 Garching bei München, Germany
      E-mail: michalm@mpa-garching.mpg.de
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  • Mark Vogelsberger,

    1. Max-Planck-Institut für Astrophysik, Garching, Karl-Schwarzschild-Straße 1, 85741 Garching bei München, Germany
    2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
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  • Simon D. M. White,

    1. Max-Planck-Institut für Astrophysik, Garching, Karl-Schwarzschild-Straße 1, 85741 Garching bei München, Germany
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  • Volker Springel

    1. Max-Planck-Institut für Astrophysik, Garching, Karl-Schwarzschild-Straße 1, 85741 Garching bei München, Germany
    2. Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany
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E-mail: michalm@mpa-garching.mpg.de

ABSTRACT

We analyse the coarse-grained phase-space structure of the six Galaxy-scale dark matter haloes of the Aquarius Project using a state-of-the-art 6D substructure finder. Within r50, we find that about 35 per cent of the mass is in identifiable substructures, predominantly tidal streams, but including about 14 per cent in self-bound subhaloes. The slope of the differential substructure mass function is close to −2, which should be compared to ∼−1.9 for the population of self-bound subhaloes. Near r50, about 60 per cent of the mass is in substructures, with about 30 per cent in self-bound subhaloes. The inner 35 kpc of the highest resolution simulation has only 0.5 per cent of its mass in self-bound subhaloes, but 3.3 per cent in detected substructure, again primarily tidal streams. The densest tidal streams near the solar position have a 3D mass density about 1 per cent of the local mean, and populate the high-velocity tail of the velocity distribution.

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