The metallicity distribution of the halo and the satellites of the Milky Way in the hierarchical merging paradigm
Abstract
Aims: To account for the observed differential metallicity distribution (DMD) of the Milky Way halo, a semi-analytical model is presented in the framework of the hierarchical merging paradigm for structure formation.
Methods: It is assumed that the Milky Way halo is composed of a number of sub-haloes with properties either as observed in the dwarf satellite galaxies of the Local group (shape of metallicity distribution, effective yield) or derived from calculations of structure formation (sub-halo distribution function).
Results: With reasonable assumptions for the parameters involved, we find that the overall shape and effective yield of the Galactic halo DMD can be reproduced in the framework of such a simple model. The low metallicity tail of the DMD presents a deficiency of stars with respect to the simple model predictions (akin to the G-dwarf problem in the solar neighborhood); it is suggested that an early infall phase can account for that problem, as well as for the observed DMDs of dwarf satellite galaxies.
Conclusions: Accretion of galaxies similar (but not identical) to the progenitors of present day dwarf satellites of the Milky Way may well have formed the Galactic halo.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2008
- DOI:
- 10.1051/0004-6361:20079330
- arXiv:
- arXiv:0807.1502
- Bibcode:
- 2008A&A...489..525P
- Keywords:
-
- Galaxy: abundances;
- Galaxy: formation;
- Galaxy: halo;
- Astrophysics
- E-Print:
- 10 pages, 6 fig. to appear in Astronomy and Astrophysics