Phys. Rev. D. 107, L101501 (2023)
Angular Momentum and Memory Effect
Pujian Mao1,*, Jun-Bao Wu1,3, Xiaoning Wu2,4
1 Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, 135 Yaguan Road, Tianjin 300350, P. R. China
2 Institute of Mathematics, Academy of Mathematics and Systems Science and Hua Loo-Keng Key Laboratory, Chinese Academy of Sciences, 55 Zhongguancun East Road, Beijing 100190, P. R. China
3 Peng Huangwu Center for Fundamental Theory, Hefei, Anhui 230026, P. R. China
4 School of Mathematical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
* pjmao@tju.edu.cn
Abstract
It is a long-standing problem in general relativity that the notion of angular momentum of an isolated system has supertranslation ambiguity. In this paper, we argue that the ambiguity is essentially because of the gravitational wave memory. When properly subtracting the memory effect of the observer, one can introduce a supertranslation invariant definition of the angular momentum at null infinity even for dynamical process.
