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The baryons in the Milky Way satellites

Parry, O.H.; Eke, V.R.; Frenk, C.S.; Okamoto, T.

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O.H. Parry

T. Okamoto


We investigate the formation and evolution of satellite galaxies using smoothed particle hydrodynamics (SPH) simulations of a Milky Way (MW) like system, focusing on the best resolved examples, analogous to the classical MW satellites. Comparing with a pure dark matter simulation, we find that the condensation of baryons has had a relatively minor effect on the structure of the satellites’ dark matter haloes. The stellar mass that forms in each satellite agrees relatively well over three levels of resolution (a factor of ∼64 in particle mass) and scales with (sub)halo mass in a similar way in an independent semi-analytical model. Our model provides a relatively good match to the average luminosity function of the MW and M31. To establish whether the potential wells of our satellites are realistic, we measure their masses within observationally determined half-light radii, finding that they have somewhat higher mass-to-light ratios than those derived for the MW dSphs from stellar kinematic data; the most massive examples are most discrepant. A statistical test yields an ∼6 per cent probability that the simulated and observationally derived distributions of masses are consistent. If the satellite population of the MW is typical, our results could imply that feedback processes not properly captured by our simulations have reduced the central densities of subhaloes, or that they initially formed with lower concentrations, as would be the case, for example, if the dark matter were made of warm, rather than cold particles.


Parry, O., Eke, V., Frenk, C., & Okamoto, T. (2012). The baryons in the Milky Way satellites. Monthly Notices of the Royal Astronomical Society, 419(4), 3304-3318.

Journal Article Type Article
Acceptance Date Oct 9, 2011
Online Publication Date Feb 21, 2012
Publication Date Feb 21, 2012
Deposit Date Jan 27, 2012
Publicly Available Date Apr 22, 2016
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 419
Issue 4
Pages 3304-3318
Related Public URLs


Published Journal Article (1.3 Mb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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