3.30 pm, Lecture Hall 6
Soldering freedom and BMS like transformations
When two spacetimes are stitched across a null-shell placed at the horizon of a black hole, BMS-supertranslation like soldering freedom arises if one demands the induced metric on the shell should remain invariant under the translations generated by the null generators of the shell. We revisit this phenomenon on the horizon of rotating shells and obtain BMS like symmetries. We further show that superrotation like soldering symmetries in the form of conformal isometries can emerge whenever the degenerate metric of any null hypersurface admits a dependency on null (degenerate direction) coordinate.