Dynamical horizons and black hole soft hair

In the present work, quasilocal Brown–York charges are derived that coincide in the large sphere limit with the conserved supertranslation hair and superrotation charges introduced by Hawking, Perry and Strominger in Hawking et al. (2016) and Hawking et al. (2017). Given these charges, a general scenario is outlined in which a non-rotating black hole completely evaporates after its collapse due to particle creation effects, whereby a genuine one-way traversable event horizon is never formed, but merely a two-way traversable dynamical (resp. future trapping) horizon. The formation of such a dynamical horizon has the consequence, as is demonstrated, that quasilocal energy transported by the considered charges, and thus information, can continuously escape through the black hole horizon to infinity; a mechanism which, as is argued, could possibly prevent information loss once the black hole formation and evaporation process comes to an end.