Probing Quantum Gravity in Stellar Spacetimes: Phenomenological Insights

TL;DR

This paper investigates quantum gravitational effects on stellar spacetimes, deriving observable corrections to classical tests and analyzing scalar perturbations, highlighting potential quantum signatures in weak-field astrophysical phenomena.

Contribution

It provides a detailed phenomenological analysis of quantum gravity corrections in stellar spacetimes, including derivations of observable effects and stability analysis of scalar perturbations.

Findings

Quantum corrections modify light deflection, Shapiro delay, and redshift.

Quantum effects influence quasinormal modes and greybody factors.

Spacetime stability increases with coupling parameter, affecting emission spectra.

Abstract

We explore the weak-field phenomenology of a compact star spacetime modified by quantum gravitational corrections derived from the effective field theoretical (EFT) approach by Calmet et al. [1]. These corrections, encoded in non-local curvature-squared terms, distinguish matter-supported geometries from vacuum solutions by contributing nontrivial modifications at second order in G. Using the corrected metric, we analytically derive expressions for the deflection of light and time-like particles via the Gauss-Bonnet theorem. We further compute the perihelion advance of Mercury, Shapiro time delay, and gravitational redshift within this framework. Each classical observable acquires quantum corrections that, though exceedingly small represent potential imprints of quantum gravity. The Shapiro delay and redshift likewise exhibit finite, source-dependent deviations from their general relativistic predictions due to the modified temporal metric component. While current observational capabilities remain insufficient to detect these minute effects, the analysis demonstrates that quantum gravitational signatures are embedded even in weak-field observables. Last, we study massless scalar perturbations in static, spherically symmetric spacetimes by analyzing their quasinormal modes (QNMs) and greybody factors using the WKB method and Pade resummation. Our findings demonstrate that increasing the coupling parameter enhances spacetime stability and significantly influences emission spectra through frequency-dependent transparency. Moreover, the results underscore that quantum-corrected star metrics yield phenomenological distinctions from classical black holes, particularly near the Planck scale, where vacuum solutions lose validity.