47 research outputs found
A spherically symmetric and stationary universe from a weak modification of general relativity
It is shown that a weak modification of general relativity, in the linearized
approach, renders a spherically symmetric and stationary model of the universe.
This is due to the presence of a third mode of polarization in the linearized
gravity in which a "curvature" energy term is present. Such an energy can, in
principle, be identified as the Dark Energy. The model can also help to a
better understanding of the framework of the Einstein-Vlasov system.Comment: Accepted for publication by Europhysics Letter
Weak-Scale Hidden Sector and Energy Transport in Fireball Models of Gamma-Ray Bursts
The annihilation of pairs of very weakly interacting particles in the
neibourghood of gamma-ray sources is introduced here as a plausible mechanism
to overcome the baryon load problem. This way we can explain how these very
high energy gamma-ray bursts can be powered at the onset of very energetic
events like supernovae (collapsars) explosions or coalescences of binary
neutron stars. Our approach uses the weak-scale hidden sector models in which
the Higgs sector of the standard model is extended to include a gauge singlet
that only interacts with the Higgs particle. These particles would be produced
either during the implosion of the red supergiant star core or at the aftermath
of a neutron star binary merger. The whole energetics and timescales of the
relativistic blast wave, the fireball, are reproduced.Comment: 4 pp, 1 ps fig, text revised and improve