Journal Article

Applying scale-free mass estimators to the Local Group in Constrained Local Universe Simulations

Arianna Di Cintio, Alexander Knebe, Noam I. Libeskind, Yehuda Hoffman, Gustavo Yepes and Stefan Gottlöber

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 2, pages 1883-1895
Published in print June 2012 | ISSN: 0035-8711
Published online June 2012 | e-ISSN: 1365-2966 | DOI:
Applying scale-free mass estimators to the Local Group in Constrained Local Universe Simulations

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We use the recently proposed scale-free mass estimators to determine the masses of the Milky Way (MW) and Andromeda (M31) galaxy in a dark matter only Constrained Local Universe Simulation. While these mass estimators work rather well for isolated spherical host systems, we examine here their applicability to a simulated binary system with a unique satellite population similar to the observed satellites of MW and M31. We confirm that the scale-free estimators work also very well in our simulated Local Group galaxies with the right number of satellites which follow the observed radial distribution. In the isotropic case and under the assumption that the satellites are tracking the total gravitating mass, the power-law index of the radial satellite distribution N(< r) ∝r3−γ is directly related to the host’s mass profile M(< r) ∝r1−α as α=γ− 2. The use of this relation for any given γ leads to highly accurate mass estimations which is a crucial point for observer, since they do not know a priori the mass profile of the MW and M31 haloes. We discuss possible bias in the mass estimators and conclude that the scale-free mass estimators can be satisfactorily applied to the real MW and M31 system.

Keywords: methods: numerical – galaxies: evolution; galaxies: haloes; Local Group; dark matter

Journal Article.  10839 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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