129 research outputs found
Self-gravitating stringlike configurations from nonlinear electodynamics
We consider static, cylindrically symmetric configurations in general
relativity coupled to nonlinear electrodynamics (NED) with an arbitrary
gauge-invariant Lagrangian of the form , . We
study electric and magnetic fields with three possible orientations: radial
(R), longitudinal (L) and azimuthal (A), and try to find solitonic stringlike
solutions, having a regular axis and a flat metric at large , with a
possible angular defect. Assuming the function to be regular at small
, it is shown that a regular axis is impossible in R-fields if there is a
nonzero effective electric charge and in A-fields if there is a nonzero
effective electric current along the axis. Solitonic solutions are only
possible for purely magnetic R-fields and purely electric A-fields, in cases
when tends to a finite limit at large . For both R- and A-fields,
the desired large asymptotic is only possible with a non- Maxwell behaviour
of at small . For L-fields, solutions with a regular axis are
easily obtained (and can be found by quadratures) whereas a desired large
asymptotic is only possible in an exceptional solution; the latter gives rise
to solitonic configurations in case \Phi(F) = \const \cdot \sqrt{F}. We give
an explicit example of such a solution.Comment: 7 pages, Latex-2e,gc.sty, to appear in Grav. & Cosmo
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