Item

Abstract

In this paper we establish a relation between the non-linearly conserved
Newman-Penrose charges and certain subleading terms in a large-$r$ expansion of
the BMS charges in an asymptotically-flat spacetime. We define the subleading
BMS charges by considering a $1/r$-expansion of the Barnich-Brandt prescription
for defining asymptotic charges in an asymptotically-flat spacetime. At the
leading order, i.e. $1/r^0$, one obtains the standard BMS charges, which would
be integrable and conserved in the absence of a flux term at null infinity,
corresponding to gravitational radiation, or Bondi news. At subleading orders,
analogous terms in general provide obstructions to the integrability of the
corresponding charges. Since the subleading terms are defined close to null
infinity, but vanish actually at infinity, the analogous obstructions are not
associated with genuine Bondi news. One may instead describe them as
corresponding to "fake news." At order $r^{-3}$, we find that a set of
integrable charges can be defined and that these are related to the ten
non-linearly conserved Newman-Penrose charges.