https://doi.org/10.1140/epjst/e2008-00825-5
Dark halo or bigravity?
Dipartimento di Fisica, Universtità degli Studi dell'Aquila, 67010 Coppito (AQ), Italy and INFN, 67010 Assergi (AQ), Italy
Corresponding author: nicola.rossi@aquila.infn.it
Observations show that about the 
of the Universe is
composed by invisible (dark) matter (DM), for which many
candidates have been proposed. In particular, the anomalous
behavior of rotational curves of galaxies (i.e. the
flattening at large distance instead of the Keplerian fall)
requires that
this matter is distributed in an extended halo around the galaxy.
In order to reproduce this matter density profiles in Newtonian gravity and
in cold dark matter (CDM) paradigm (in which the
DM particles are collisionless), many ad-hoc
approximations are required.
The flattening of rotational curves can be explained by a
suitable modification of gravitational force in bigravity theories,
together with mirror matter model that predicts the existence
of a dark sector in which DM has the same physical
properties of visible matter.
As an additional result,
the Newton constant is different at distances much less and
much greater than 20 kpc.
© EDP Sciences, Springer-Verlag, 2008
