Colloquium de l'IDPModified Newtonian Dynamics: What is it? Why bother? Will it go away?
Benoît Famaey. Observatoire Astronomique de l'Université de Strasbourg
Thursday 07 February 2013 14:00 - Tours - F120
A wealth of astronomical data indicate the presence of mass discrepancies in the Universe. The motions observed in a variety of classes of stellar systems exceed what can be explained by the mass visible in stars and gas. Either there is a vast amount of unseen mass in some novel form - dark matter - or the data indicate a breakdown of our understanding of dynamics on the relevant scales, or both. While many observations are in accordance with the dark matter hypothesis, there however remain some heavy clouds on our global understanding.This is illustrated by the success of the ``Modified Newtonian Dynamics'' hypothesis, which is still considered as a serious alternative to the existence of dark matter, at least in galaxies. We review the current observational successes and problems of this alternative paradigm, and briefly summarize the various theoretical attempts made to effectively embed it within a covariant theory of gravity.