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Small Dwarf galaxies within larger Dwarfs: Why some are luminous while most go dark


D'Onghia, E; Lake, G (2008). Small Dwarf galaxies within larger Dwarfs: Why some are luminous while most go dark. Astrophysical Journal Letters, 686(2):L61-L65.

Abstract

We consider the possibility that the Magellanic Clouds were the largest members of a group of dwarf galaxies that entered the Milky Way (MW) halo at late times. Seven of the eleven brightest satellites of the MW may have been part of this system. The proximity of some dwarfs to the plane of the orbit of the Large Magellanic Cloud (LMC) has been used to argue that they formed from tidal debris from the LMC and Small Magellanic Cloud (SMC). Instead, they may owe to the tidal breakup of the Magellanic group. This can explain the association of many of the dwarf galaxies in the Local Group with the LMC system. It provides a mechanism for lighting up dwarf galaxies and reproduces the bright end of the cumulative circular velocity distribution of the satellites in the MW without invoking a stripping scenario for the subhalos to match the satellite distribution expected according to CDM theory. Finally, our model predicts that other isolated dwarfs will be found to have companions. Evidence for this prediction is provided by nearby, recently discovered dwarf associations.

We consider the possibility that the Magellanic Clouds were the largest members of a group of dwarf galaxies that entered the Milky Way (MW) halo at late times. Seven of the eleven brightest satellites of the MW may have been part of this system. The proximity of some dwarfs to the plane of the orbit of the Large Magellanic Cloud (LMC) has been used to argue that they formed from tidal debris from the LMC and Small Magellanic Cloud (SMC). Instead, they may owe to the tidal breakup of the Magellanic group. This can explain the association of many of the dwarf galaxies in the Local Group with the LMC system. It provides a mechanism for lighting up dwarf galaxies and reproduces the bright end of the cumulative circular velocity distribution of the satellites in the MW without invoking a stripping scenario for the subhalos to match the satellite distribution expected according to CDM theory. Finally, our model predicts that other isolated dwarfs will be found to have companions. Evidence for this prediction is provided by nearby, recently discovered dwarf associations.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:October 2008
Deposited On:18 Feb 2009 16:13
Last Modified:05 Apr 2016 13:00
Publisher:Institute of Physics Publishing
ISSN:2041-8205
Funders:EU
Publisher DOI:10.1086/592995
Related URLs:http://arxiv.org/abs/0802.0001
Permanent URL: http://doi.org/10.5167/uzh-13586

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