3 research outputs found
Solutions for f(R) gravity coupled with electromagnetic field
In the presence of external, linear / nonlinear electromagnetic fields we
integrate f(R) \sim R+2{\alpha}\surd(R+const.) gravity equations. In contrast
to their Einsteinian cousins the obtained black holes are non-asymptotically
flat with a deficit angle. In proper limits we obtain from our general solution
the global monopole solution in f(R) gravity. The scale symmetry breaking term
adopted as the nonlinear electromagnetic source adjusts the sign of the mass of
the resulting black hole to be physical.Comment: 7 pages no figure, final version for publication in European Physical
Journal
Static Spherically Symmetric Solutions in F(R) Gravity
A Lagrangian derivation of the Equation of Motion (EOM) for static
spherically symmetric metrics in F(R) modified gravity is presented. For a
large class of metrics, our approach permits to reduce the EOM to a single
equation and we show how it is possible to construct exact solutions in
-gravity. All known exact solutions are recovered. We also exibit a new
non trivial solution with non constant Ricci scalar.Comment: 8 pages, published version, some references added, a minor
modificatio
Black hole solutions in F(R) gravity with conformal anomaly
In this paper, we consider theory instead of Einstein gravity
with conformal anomaly and look for its analytical solutions. Depending on the
free parameters, one may obtain both uncharged and charged solutions for some
classes of models. Calculation of Kretschmann scalar shows that there is
a singularity located at , which the geometry of uncharged (charged)
solution is corresponding to the Schwarzschild (Reissner-Nordstr\"om)
singularity. Further, we discuss the viability of our models in details. We
show that these models can be stable depending on their parameters and in
different epoches of the universe.Comment: 12 pages, one figur