BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Juan Valiente Kroon (Queen Mary University of London) DTSTART:20240606T133000Z DTEND:20240606T143000Z DTSTAMP:20260423T023020Z UID:jomarec/35 DESCRIPTION:Title: BMS-supertranslation charges at the critical sets of null infinity\nb y Juan Valiente Kroon (Queen Mary University of London) as part of JoMaReC - Joint Online Mathematical Relativity Colloquium\n\n\nAbstract\nFor asym ptotically flat spacetimes\, a conjecture by Strominger states that asympt otic BMS-supertranslations and their associated charges at past null infin ity can be related to those at future null infinity via an antipodal map a t spatial infinity. We analyse the validity of this conjecture using Fried rich's formulation of spatial infinity\, which gives rise to a regular ini tial value problem for the conformal field equations at spatial infinity. We show that for a generic class of asymptotically Euclidean and regular initial data\, BMS-supertranslation charges are not well-defined at the cr itical sets where null infinity meets spatial infinity unless the initial data satisfies an extra regularity condition. We also show that given init ial data that satisfy the regularity condition\, BMS-supertranslation char ges at the critical sets are fully determined by the initial data and that the relation between the charges at past null infinity and those at futur e null infinity directly follows from our regularity condition. This is jo int work with Mariem Magdy Ali Mohamed and Kartik Prabhu.\n LOCATION:https://researchseminars.org/talk/jomarec/35/ END:VEVENT END:VCALENDAR