arXiv subjects

Baijun Zeng

Publications and source records attributed to Baijun Zeng.

4 recordsLinked to original sources

arXiv2026

Perturbations of a Schwarzschild black hole and Newman-Unti gauge

In this paper, we derive the complete transformations of a generic first order perturbative metric in Schwarzschild spacetime to the Newman-Unti (NU) gauge in series expansion near null infinity. This allows us to determine the asymptotic shear, the mass aspect and the angular momentum aspect of the perturbative fields. As a direct application, we derive the corresponding asymptotic NU data for quasinormal modes (QNMs) of a Schwarzschild black hole. The total energy and angular momentum of QNMs obtained from the asymptotic NU data vanish but classical supertranslation charges are non-trivial, which can be applied to fix the BMS frame at first perturbative order.

gr-qc↗

arXiv2026

From harmonic to Newman-Unti coordinates at the second post-Minkowskian order

In this paper, we present the complete transformations of a generic metric from (generalized) harmonic to Newman-Unti coordinates up to the second post-Minkowskian order $(G^2)$. This allows us to determine the asymptotic shear, the Bondi mass aspect, and the angular-momentum aspect at both orders.

gr-qc↗

arXiv2025

Note on post-Minkowskian expansion and Bondi coordinates

In this note, we transform the linear order (at order $G$) metric from a system of pointlike bodies source in the post-Minkowskian expansion to the Bondi coordinates. We show that the Bondi 4-momentum and angular momentum coincide with the relativistic definitions of 4-momentum and angular momentum for the system of pointlike bodies. The angular momentum computed at the null infinity is free of supertranslation ambiguity.

gr-qc↗

arXiv2025

Supertranslation ambiguity in post-Minkowskian expansion

The supertranslation ambiguity of angular momentum is a long-standing problem in general relativity, which arises the puzzle of the angular momentum loss in the post-Minkowskian (PM) expansion. The angular momentum loss in gravitational scattering is of order $G^2$ in the linear response theory but of order $G^3$ in the amplitudes-based methods. In this paper, we propose a generic prescription to fix the supertranslation ambiguity in the PM expansion which will uniquely determine the angular momentum loss. The proposal is self-contained and involves only the null infinity data.

gr-qc↗