Publication date: Jul 2011
Abstract:
We study gravitational redshift of photons and neutrinos radiated by the
braneworld neutron or quark stars that are considered in the framework
of the simple model of the internal spacetime with uniform distribution
of energy density, and the external spacetime described by the
Reissner-Nordström geometry characterized by the braneworld
„tidal“ charge b. For negative tidal charges, the external spacetime
is of the black-hole type, while for positive tidal charges, the
external spacetime can be of both black-hole and naked-singularity type.
We consider also extremely compact stars allowing existence of trapped
null geodesics in their interior. We assume radiation of photons from
the surface at radius R, neutrinos from the whole compact star interior,
and their motion along radial null geodesics of the spacetime. In
dependency on the compact stars parameters b and R, the photon surface
redshift is related to the range of the neutrino internal redshift and
the signatures of the tidal charge and possible existence of extremely
compact stars are discussed. When both surface (photon) and internal
(neutrino) redshift are given by observations, both compact star
parameters R and b can be determined in the framework of our simple
model.
Authors:
Hladík, Jan; Stuchlík, Zdeněk;