Paper: astro-ph/0507280
Date: Tue, 12 Jul 2005 11:11:17 GMT (45kb)

Title: The Galaxy in the cosmological context

Authors: F. Combes (Observatoire de Paris, LERMA)
Comments: 4 pages, 2 figures, Introduction to the Galaxy workshop, SF2A-2005,
to be published by EdP-Sciences, F. Casoli, T. Contini, J-M. Hameury & L.
Pagani (eds)
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A new view on our Galaxy has recently emerged, with large consequences on its
formation scenarios. Not only new dwarf satellites have been detected, still
orbiting and tidally disrupting, but also a multitude of stellar streams or
tidal debris have been observed suggesting the formation of the halo through
successive accretions. The large scatter in the age-metallicity relation in the
solar neighborhood points towards several accretion episodes, while the
chemical evolution of the disk requires a more or less continuous gas infall.
The global kinematics and morphology refined by large surveys such as 2MASS
suggest the existence of two embedded bars, as is frequently observed in
external galaxies. The mass of the central black hole has been refined through
stellar proper motions, and is compatible with the M$_{bh}$-$\sigma$ relation
valid for all bulges. The baryonic dark matter is no longer thought to lie in
compact objects, and on the contrary, more dark cold gas is revealed by
gamma-ray observations. The star forming history can be built, and confronted
to numerical models of galaxy evolution both through hierarchical and secular
scenarios. Our Galaxy plays thus the role of a prototype to probe galaxy
formation theories, and in particular thin and thick disk formation.

\\ ( http://arXiv.org/abs/astro-ph/0507280 , 45kb)