Journal Article

On the identification of substructure in phase space using orbital frequencies

Facundo A. Gómez and Amina Helmi

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 401, issue 4, pages 2285-2298
Published in print February 2010 | ISSN: 0035-8711
Published online January 2010 | e-ISSN: 1365-2966 | DOI:
On the identification of substructure in phase space using orbital frequencies

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We study the evolution of satellite debris to establish the most suitable space to identify past merger events. We confirm that the space of orbital frequencies is very promising in this respect. In frequency space individual streams can be easily identified, and their separation provides a direct measurement of the time of accretion. We are able to show for a few idealized gravitational potentials that these features are preserved also in systems that have evolved strongly in time. Furthermore, this time evolution is imprinted in the distribution of streams in frequency space. We have also tested the power of the orbital frequencies in a fully self-consistent (live) N-body simulation of the merger between a disc galaxy and a massive satellite. Even in this case, streams can be easily identified and the time of accretion of the satellite can be accurately estimated.

Keywords: methods: analytical; methods: N-body simulations; galaxies: formation; galaxies: kinematics and dynamics

Journal Article.  9543 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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