arXiv subjects

Marco Refuto

Publications and source records attributed to Marco Refuto.

4 recordsLinked to original sources

arXiv2026

Poincar\'e asymptotic expansion in black hole theory

In studying the dynamics of fields in black hole theory, the method of separation of variables makes it possible to isolate the radial part of the full solution in many important physical cases. This occurs by virtue of the existence of the principal tensor in Petrov-D metrics. We first review this mathematical result in order to introduce several cases where it is possible to study the radial solution via the Poincar\'e asymptotic series expansion, a tool exploited in recent work by the authors in order to investigate the behaviour of the field at spacelike infinity, a point in the neighbourhood of which only approximate solutions are computable by virtue of its irregular nature. We obtain a series which can be computed to any degree of accuracy, allowing for a deeper analysis of this challenging spacetime region. An application to quasinormal modes is eventually provided.

gr-qc↗

arXiv2026

Superdilations at Schwarzschild null infinity

Relying on the definition of asymptotic conformal Killing horizons, the generators of asymptotic conformal symmetries at future null infinity in Schwarzschild space-time are considered. The algebra they close is an extended version of the BMS one due to the emergence of superdilations. Several features are then studied, such as the related non-trivial charge, ruling out the hypothesis that superdilations are pure gauge transformations. Their effect on a pair of celestial observers can be understood as an angle-dependent redshift, connected to the local non-vanishing flux of the charge.

gr-qc↗

arXiv2025

DSR-relativistic spacetime picture and the phenomenology of Planck-scale-modified time dilation

The most active area of research in quantum-gravity phenomenology investigates the possibility of Planck-scale-modified dispersion relations, focusing mainly on two alternative scenarios: the "LIV" scenario, characterized by a specific mechanism of breakdown of relativistic symmetries, and the "DSR" scenario, which preserves overall relativistic invariance but with deformed laws of relativistic transformation. Two recent studies of modified dispersion relations, one relying on Finsler geometry and one based on heuristic reasoning, raised the possibility of potentially observable effects for time dilation and argued that this might apply also to the LIV and DSR scenarios. We observe that the description of Lorentz transformations in the LIV scenario is such that time dilation cannot be modified. The DSR scenario allows for modifications of time dilation, and establishing their magnitude required us to obtain novel results on the effects of finite DSR boosts in the spacetime sector, with results showing in particular that the modification of time dilation is too small for experimental testing.

gr-qc↗

arXiv2025

New perspectives on the irregular singular point of the wave equation for a massive scalar field in Schwarzschild spacetime

For a massive scalar field in a fixed Schwarzschild background, the radial wave equation obeyed by Fourier modes is first studied. After reducing such a radial wave equation to its normal form, we first study approximate solutions in the neighborhood of the origin, horizon and point at infinity, and then we relate the radial with the Heun equation, obtaining local solutions at the regular singular points. Moreover, we obtain the full asymptotic expansion of the local solution in the neighborhood of the irregular singular point at infinity. We also obtain and study the associated integral representation of the massive scalar field. Eventually, the technique developed for the irregular singular point is applied to the homogeneous equation associated with the inhomogeneous Zerilli equation for gravitational perturbations in a Schwarzschild background.

gr-qc↗