ASSEMBLY OF THE OUTER GALACTIC STELLAR HALO IN THE HIERARCHICAL MODEL

Journal Article · Sun Jun 20 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/716/2/L115· OSTI ID:21451088

Murante, Giuseppe; Curir, Anna ^[1]; Poglio, Eva ^[2]; Villalobos, Alvaro ^[3]

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1. Osservatorio di Torino, Strada Osservatorio 20, I-10025, Pino Torinese (Italy)
2. Dipartimento di Fisica Generale 'Amedeo Avogadro', Universita degli Studi di Torino, Via P. Giuria 1, I-10125, Torino (Italy)
3. I.N.A.F, Osservatorio di Trieste, Via Tiepolo 11, I- 34131, Trieste (Italy)

We provide a set of numerical N-body simulations for studying the formation of the outer Milky Ways' stellar halo through accretion events. After simulating minor mergers of prograde and retrograde orbiting satellite halos 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 {approx}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 and therefore can produce the counter-rotating behavior observed in the outer Milky Way halo.

• OSTI ID: 21451088
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 716; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
GALAXIES
INCLINATION
MATTER
MILKY WAY
NONLUMINOUS MATTER
ORBITS
SATELLITES
STARS