Peeling or not peeling -- is that the question ?

TL;DR

The paper revisits the structure of gravitational radiation and the asymptotic ends of spacetime, emphasizing the roles of $\mathcal{J}^{\pm}$, $i^0$, and the tension between asymptotic simplicity (peeling) and more general, possibly non-smooth ends.It surveys two complementary frameworks—Friedrich's conformal field equations and the hyperboloidal Cauchy problem—and discusses results on smooth conformal boundaries, non-linear stability of Minkowski space, and the construction of non-trivial data via Corvino gluing and related techniques.The work analyzes Friedrich's cylinder approach to space-like infinity, the emergence of logarithmic terms, and density/approximation results that connect smooth and rough asymptotics, highlighting how asymptotic structure impacts gravitational radiation.Finally, it contemplates the practical modeling of isolated systems within cosmological spacetimes, noting that end choices can generate spurious radiation and that there is no unique ‘correct’ end, thus guiding careful interpretation of observable waveforms.

Abstract

The concepts of isolated self-gravitating system, asymptotic flatness and asymptotic simplicity are reconsidered, various related results are discussed and put into perspective, basic open questions are posed.