Assembly of the outer Galactic stellar halo in the hierarchical model

Abstract

We provide a set of numerical N-body simulations for studying the formation of the outer Milky Ways's stellar halo through accretion events. After simulating minor mergers of prograde and retrograde orbiting satellite halo with a Dark Matter main halo, we analyze the signal left by satellite stars in the rotation velocity distribution. The aim is to explore the orbital conditions where a retrograde signal in the outer part of the halo can be obtained, in order to give a possible explanation of the observed rotational properties of the Milky Way stellar halo. Our results show that, for satellites more massive than $\sim 1/40$ of the main halo, the dynamical friction has a fundamental role in assembling the final velocity distributions resulting from different orbits and that retrograde satellites moving on low inclination orbits deposit more stars in the outer halo regions end therefore can produce the counter-rotating behavior observed in the outer Milky Way halo.

5 pages, 3 figures, ApJL, accepted

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Cited by in corpus (8)

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• Simulating the evolution of disc galaxies in a group environment. I. The influence of the global tidal field
• Does SEGUE/SDSS indicate a dual Galactic halo?
• Icarus: a Flat and Fast Prograde Stellar Stream in the Milky Way disk
• Rotational signature of the Milky Way stellar halo
• New Signatures of the Milky Way Formation in the Local Halo and Inner Halo Streamers in the Era of Gaia
• Evidence For Multiple Accretion Events in the $Gaia$-Sausage/Enceladus Structures