Journal Article

Signatures of minor mergers in the Milky Way disc – I. The SEGUE stellar sample

Facundo A. Gómez, Ivan Minchev, Brian W. O’Shea, Young Sun Lee, Timothy C. Beers, Deokkeun An, James S. Bullock, Chris W. Purcell and Álvaro Villalobos

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 4, pages 3727-3739
Published in print July 2012 | ISSN: 0035-8711
Published online July 2012 | e-ISSN: 1365-2966 | DOI:
Signatures of minor mergers in the Milky Way disc – I. The SEGUE stellar sample

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It is now known that minor mergers are capable of creating structure in the phase-space distribution of their host galaxy’s disc. In order to search for such imprints in the Milky Way, we analyse the Sloan Extension for Galactic Understanding and Exploration (SEGUE) F/G dwarf and the Schuster et al. stellar samples. We find similar features in these two completely independent stellar samples, consistent with the predictions of a Milky Way minor-merger event. We next apply the same analyses to high-resolution, idealized N-body simulations of the interaction between the Sagittarius dwarf galaxy and the Milky Way. The energy distributions of stellar particle samples in small spatial regions in the host disc reveal strong variations of structure with position. We find good matches to the observations for models with a mass of Sagittarius’ dark matter halo progenitor ⪅1011 M. Thus, we show that this kind of analysis could be used to provide unprecedentedly tight constraints on Sagittarius’ orbital parameters, as well as place a lower limit on its mass.

Keywords: methods: analytical; methods: data analysis; methods: numerical; Galaxy: disc; Galaxy: structure; galaxies: formation; galaxies: kinematics and dynamics

Journal Article.  9846 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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