Publication date: Jan 2019
Abstract:
The aim of the present research is the analysis of the photon motion in
the regular spacetimes arising as solutions of the Einstein gravity
coupled with a non-linear electrodynamics (NED). The photons no longer
follow the null geodesic of the background spacetime, but the null
geodesics of an effective geometry where the electromagnetic non-
linearity is directly reflected in addition to the spacetime geometry.
Motion of photons is compared to the motion of neutrinos that are not
directly affected by the non-linearities of a non-Maxwellian
electromagnetic field, and follow null geodesics of the background
spacetime. We determine shadows of the regular Bardeen black holes,
representing a special solution of the general relativity coupled with
NED related to a magnetic charge, both for photons and neutrinos, and
compare them to the shadow of the related Reissner-Nordstrom black
holes. We demonstrate that the direct NED effects give clear signature
of the presence of the regular black holes, on the level going up to 20%
that is detectable by recent observational techniques. We also
demonstrate strong influence of the NED effects on deflection angle of
photons moving in the Bardeen spacetimes, and on the time delay of the
motion of photons and neutrinos in vicinity of the black hole horizon.
Authors:
Stuchlík, Zdenek; Schee, Jan;