Remarks on infinite towers of gravitational memories

TL;DR

This paper presents an alternative approach to understanding infinite towers of gravitational memories using Newman-Penrose formalism, showing they relate to a single supertranslation rather than multiple symmetries.

Contribution

It offers a new realization of gravitational memory towers and links them to a single supertranslation, simplifying previous complex symmetry structures.

Findings

Memories at each order are associated with the same supertranslation.

Provides an alternative formalism for gravitational memory analysis.

Shows that infinite towers can be understood through a unified supertranslation.

Abstract

An infinite tower of gravitational memories was proposed in \cite{Compere:2019odm} by considering the matter-induced vacuum transition in the impulsive limit. We give an alternative realization of the infinite towers of gravitational memories in Newman-Penrose formalism. We also demonstrate that the memories at each order can be associated to the same supertranslation instead of infinite towers of supertranslations or superrotations.