Publikace ÚTF

The Gauss{Bonnet gravity is a special case of so-called Quadratic
Gravity, which is an extension of Einstein's theory with additional terms in action
that are quadratic combinations of the Riemann tensor and its contractions. These
corrections are needed, for example, in perturbative quantum gravity. We consider
the family of Kundt spacetimes, which is dened in a purely geometrical way
by admitting a shear-free, twist-free and expansion-free null geodesic congruence.
In particular, we focus on the Kundt solutions without gyratonic terms, and we
investigate the constraints imposed by the Einstein{Gauss{Bonnet eld equations.
The conditions for the metrics to be of various algebraic types are also studied.