Speaker
Description
Cylindrical symmetry has multiple astrophysical applications: strings, galactic dark matter filaments, AGN / quasar jets. The general relativistic cylindrically symmetric vacuum allows for a static ground state, the Levi–Civita spacetime and multiple types of Einstein–Rosen exact waves. We analyze the static background, which allows for a strong and naked singularity as the symmetry axis and four different flat limits. Then we discuss the backreaction of cylindrical waves at second order, in the WKB approximation and under the Brill–Hartle averaging scheme, identifying the lasting effect of a passing wave on the background as an effective null dust, generating an exact radiative spacetime in the geometrical optics limit. In addition, we discuss extensions of the Einstein–Rosen waves in generalized Brans–Dicke theories, with the scalar field sourcing the waves.