Volume 542, June 2012
|Number of page(s)||7|
|Section||Galactic structure, stellar clusters and populations|
|Published online||07 June 2012|
Leo IV and V – A possible dwarf galaxy pair?
Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile
Received: 11 November 2011
Accepted: 30 March 2012
The last few years have seen the discovery of many faint and ultra-faint dwarf spheroidal galaxies around the Milky Way. Among these is a pair of satellites called Leo IV and Leo V. This pair is found at large distances from the Milky Way (154 and 175 kpc, respectively). The fairly small difference in radial distance, and the fact that they also show a close projected distance on the sky, has led to the idea that we might be seeing a new pair of bound galaxies – like the Magellanic Clouds. In this paper we investigate this speculation by means of a simple integration code (confirming the results with full N-body simulations). Because the luminous mass of the two faint dwarfs is far too low to allow them to be bound, we simulate the pair assuming extended dark matter haloes. Our results show that the minimum dark matter mass required for the pair to be bound is quite high – ranging from 1.6 × 1010 M⊙ to 5.4 × 1010 M⊙ (within the virial radii). Computing the mass of dark matter within a commonly adopted radius of 300 pc shows that our models are well within the predicted range of dark matter content for satellites so faint. We therefore conclude that it could be possible that the two galaxies constitute a bound pair.
Key words: galaxies: dwarf / galaxies: individual: Leo IV / galaxies: halos / methods: numerical / galaxies: individual: Leo V
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.