7 research outputs found
Signatures of Topological Defects
We argue that due to various restrictions cosmic strings and monopole-string
networks are not likely to produce the observed flux of ultra-high energy
cosmic rays (UHECR). Among the topological defects studied so far, the most
promising UHECR sources are necklaces and monopolonia. Other viable sources
which are similar to topological defects are relic superheavy particles. All
these sources have an excess of pions (and thus photons) over nucleons at
production. We demonstrate that in the case of necklaces the diffuse proton
flux can be larger than photon flux, due to absorption of the latter on
radiobackground, while monopolonia and relic particles are concentrated in the
Galactic halo, and the photon flux dominates. Another signature of the latter
sources is anisotropy imposed by asymmetric position of the sun in the Galactic
halo. In all cases considered so far, including necklaces, photons must be
present in ultra-high energy radiation observed from topological defects, and
experimental discrimination between photon-induced and proton-induced extensive
air showers can give a clue to the origin of ultra-high energy cosmic rays.Comment: version accepted for publication in Phys. Rev. D. No changes in the
conclusions and in figure
Scalar-field Pressure in Induced Gravity with Higgs Potential and Dark Matter
A model of induced gravity with a Higgs potential is investigated in detail
in view of the pressure components related to the scalar-field excitations. The
physical consequences emerging as an artifact due to the presence of these
pressure terms are analysed in terms of the constraints parting from energy
density, solar-relativistic effects and galactic dynamics along with the dark
matter halos.Comment: 26 pages, 3 figures, Minor revision, Published in JHE
Rapidly rotating pulsar radiation in vacuum nonlinear electrodynamics
In this paper we investigate vacuum nonlinear electrodynamics corrections on
rapidly rotating pulsar radiation and spin-down in the perturbative QED
approach (post-Maxwellian approximation). An analytical expression for the
pulsar's radiation intensity has been obtained and analyzed