Paper: astro-ph/0601478
Date: Fri, 20 Jan 2006 16:06:54 GMT (798kb)

Title: Modified Newtonian Dynamics, an Introductory Review

Authors: Riccardo Scarpa

Comments: To Appear in the proceeding of the "First crisis in cosmology"
conference, published in the American Institute of Physiscs' proceedings
series, Vol. 822. (includes 13 pages and 12 figures)
\\
By the time, in 1937, the Swiss astronomer Zwicky measured the velocity
dispersion of the Coma cluster of galaxies, astronomers somehow got acquainted
with the idea that the universe is filled by some kind of dark matter. After
almost a century of investigations, we have learned two things about dark
matter, (i) it has to be non-baryonic -- that is, made of something new that
interact with normal matter only by gravitation-- and, (ii) that its effects
are observed in stellar systems when and only when their internal acceleration
of gravity falls below a fix value a0=1.2x10-8 cm s-2. This systematic, more
than anything else, tells us we might be facing a failure of the law of gravity
in the weak field limit rather then the effects of dark matter. Thus, in an
attempt to avoid the need for dark matter, the Modified Newtonian Dynamics.
MOND posits a breakdown of Newton's law of gravity (or inertia) below a0, after
which the dependence with distance became linear. Despite many attempts, MOND
resisted stubbornly to be falsified as an alternative to dark matter and
succeeds in explaining the properties of an impressively large number of
objects without invoking the presence of non-baryonic dark matter. In this
paper, I will review the basics of MOND and its ability to explain observations
without the need of dark matter.

\\ ( http://arXiv.org/abs/astro-ph/0601478 , 798kb)