Journal Article

Ultrafine dark matter structure in the solar neighbourhood

Daniele S. M. Fantin, Anne M. Green and Michael R. Merrifield

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 418, issue 4, pages 2648-2655
Published in print December 2011 | ISSN: 0035-8711
Published online December 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19656.x
Ultrafine dark matter structure in the solar neighbourhood

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Direct detection of dark matter on the Earth depends crucially on its density and its velocity distribution on a milliparsec scale. Conventional N-body simulations are unable to access this scale, making the development of other approaches necessary. In this paper, we apply the method developed by Fantin, Merrifield and Green in 2008 to a cosmologically based merger tree, transforming it into a useful instrument to reproduce and analyse the merger history of a Milky Way-like system. The aim of the model is to investigate the implications of any ultrafine structure for the current and next generation of directional dark matter detectors. We find that the velocity distribution of a Milky Way-like galaxy is almost smooth, due to the overlap of many streams of particles generated by multiple mergers. Only the merger of a 1010 M subhalo can generate significant features in the ultralocal velocity distribution, detectable at the resolution attainable by current experiments.

Keywords: methods: analytical; Galaxy: evolution; Galaxy: halo; Galaxy: kinematics and dynamics; solar neighbourhood; dark matter

Journal Article.  5337 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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