| Time：1130304 (Mon.) 13:30~15:30 Speaker：Masahiro Hotta Professor, Tohoku University & LeCosPa Title：Soft Hair Symmetries at Horizons Abstract： In a Rindler-type coordinate system spanned in a region outside of a black hole horizon, we have nonvanishing classical holographic charges as soft hairs on the horizon for stationary black holes. Taking a large black hole mass limit, the spacetimes with the charges are described by asymptotic Rindler metrics. We construct a general theory of gravitational holographic charges for a (1+3)-dimensional linearized gravity field in the Minkowski background with Rindler horizons. Although matter crossing a Rindler horizon causes horizon deformation and a time-dependent coordinate shift, that is, gravitational memory, the supertranslation and superrotation charges on the horizon can be defined during and after its passage through the horizon. Asymptotic symmetries of black hole spacetimes have received much attention as a possible origin of the Bekenstein-Hawking entropy in black hole thermodynamics. In general, it takes hard efforts to find appropriate asymptotic conditions on a metric and a Lie algebra generating the transformation of symmetries with which the corresponding charges are integrable. We here propose an alternative approach to construct building blocks of asymptotic symmetries of a given spacetime metric. Our algorithmic approach may make it easier to explore asymptotic symmetries in any spacetime than in conventional approaches. As an explicit application, we analyze the asymptotic symmetries on the Rindler horizon. We find a new class of symmetries related with dilatation transformations in time and in the direction perpendicular to the horizon, which we term superdilatations. References: [1606.02443] Gravitational Memory Charges of Supertranslation and Superrotation on Rindler Horizons (arxiv.org) [2012.14050] A Lie algebra based approach to asymptotic symmetries in general relativity (arxiv.org) Place：F104, Gongguan Campus, NTNU |
