46 research outputs found
Boson stars in the centre of galaxies?
We investigate the possible gravitational redshift values for boson stars
with a self-interaction, studying a wide range of possible masses. We find a
limiting value of z_lim \simeq 0.687 for stable boson star configurations. We
can exclude the direct observation of boson stars. X-ray spectroscopy is
perhaps the most interesting possibility
Inflation, bifurcations of nonlinear curvature Lagrangians and dark energy
A possible equivalence of scalar dark matter, the inflaton, and modified
gravity is analyzed. After a conformal mapping, the dependence of the effective
Lagrangian on the curvature is not only singular but also bifurcates into
several almost Einsteinian spaces, distinguished only by a different effective
gravitational strength and cosmological constant. A swallow tail catastrophe in
the bifurcation set indicates the possibility for the coexistence of different
Einsteinian domains in our Universe. This `triple unification' may shed new
light on the nature and large scale distribution not only of dark matter but
also on `dark energy', regarded as an effective cosmological constant, and
inflation.Comment: 20 pages, 8 figures, Proceedings of the 11th Marcel Grossmann Meeting
(MG11) in Berlin, Germany, July 23-29, 200