Publication date: Jul 2011
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.
Hladík, Jan; Stuchlík, Zdeněk;