13,781 research outputs found
Modified gravity revealed along geodesic tracks
The study of the dynamics of a two-body system in modified gravity
constitutes a more complex problem than in Newtonian gravity. Numerical methods
are typically needed to solve the equations of geodesics. Despite the
complexity of the problem, the study of a two-body system in gravity
leads to a new exciting perspective hinting the right strategy to adopt in
order to probe modified gravity. Our results point out some differences between
the {\em semiclassical} (Newtonian) approach, and the {\em relativistic}
(geodesic) one thus suggesting that the latter represents the best strategy for
future tests of modified theories of gravity. { Finally, we have also
highlighted the capability of forthcoming observations to serve as smoking gun
of modified gravity revealing a departure from GR or further reducing the
parameter space of gravity}. \keywords{ gravity \and binary system
\and geodesics \and precessionComment: 7 Pages, 2 figures. Accepted for publication on The European Physics
Journal
Analysis of the Yukawa gravitational potential in gravity I: semiclassical periastron advance
The {\it concordance} cosmological model has been successfully tested
throughout the last decades. Despite its successes, the fundamental nature of
dark matter and dark energy is still unknown. Modifications of the
gravitational action have been proposed as an alternative to these dark
components. The straightforward modification of gravity is to generalize the
action to a function, , of the scalar curvature. Thus one is able to
describe the emergence and the evolution of the Large Scale Structure without
any additional (unknown) dark component. In the weak field limit of the
-gravity, a modified Newtonian gravitational potential arises. This
gravitational potential accounts for an extra force, generally called fifth
force, that produces a precession of the orbital motion even in the classic
mechanical approach. We have shown that the orbits in the modified potential
can be written as Keplerian orbits under some conditions on the strength and
scale length of this extra force. Nevertheless, we have also shown that this
extra term gives rise to the precession of the orbit. Thus, comparing our
prediction with the measurements of the precession of some planetary motions,
we have found that the strength of the fifth force must be in the range
whit the characteristic scale length to fixed to the
fiducial values of AU.Comment: 9 pages, 5 figures, accepted for publication in Phys. Rev.
Women and Reparations
Reparations for victims of gross human rights violations are becoming an increasingly
acknowledged feature in post-authoritarian and post-conflict societies coping with the
legacy of a violent past. Despite some recent progress much more work needs to be done
for massive reparations programs to respond better to the needs of women. This article,
resting as it does on a comprehensive conception of reparations, outlines both the procedural
and substantive components of reparations programs necessary for the programs to
fulfill the goal of providing (partial) justice to women
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