Expanded haloes, abundance matching and too-big-to-fail in the local group
Entity
UAM. Departamento de Física TeóricaPublisher
Oxford University Press on behalf of the Royal Astronomical SocietyDate
2015-05-19Citation
10.1093/mnras/stv864
Monthly Notices of Royal Astronomical Society 450.4 (2015): 3920-3934
ISSN
0035-8711 (print); 1365-2966 (online)DOI
10.1093/mnras/stv864Funded by
The authors thank the MICINN (Spain) for the financial support through the MINECO grant AYA2012-31101Project
Gobierno de España. AYA2012-31101Editor's Version
http://dx.doi.org/10.1093/mnras/stv864Subjects
Galaxies: dwarf; Galaxies: formation; Galaxies: haloes; Local group; FísicaNote
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reservedRights
© 2015 The Authors: Published by Oxford University Press on behalf of the Royal Astronomical SocietyAbstract
Observed kinematical data of 40 Local Group (LG) members are used to derive the dark matter halo mass of such galaxies. Haloes are selected from the theoretically expected LG mass function and two different density profiles are assumed, a standard universal cuspy model and a mass-dependent profile which accounts for the effects of baryons in modifying the dark matter distribution within galaxies. The resulting relations between stellar and halo mass are compared with expectations from abundance matching. Using a universal cuspy profile, the ensemble of LG galaxies is fit in relatively low-mass haloes, leaving 'dark' many massive haloes of Mhalo ≳ 1010 M⊙: this reflects the 'too-big-to-fail' problem and results in a Mstar- Mhalo relation that differs from abundance matching predictions. Moreover, the star formation efficiency of isolated LG galaxies increases with decreasing halo mass when adopting a cuspy model. By contrast, using the mass-dependent density profile, dwarf galaxies with Mstar ≳ 106 M⊙ are assigned to more massive haloes, which have a central cored distribution of dark matter: the 'too-big-to-fail' problem is alleviated, the resultant Mstar-Mhalo relation follows abundance matching predictions down to the completeness limit of current surveys, and the star formation efficiency of isolated members decreases with decreasing halo mass, in agreement with theoretical expectations. Finally, the cusp/core space of LG galaxies is presented, providing a framework to understand the non-universality of their density profiles
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Google Scholar:Brook, Chris B.
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Di Cintio, Arianna
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