Regular Black Holes from Proper-Time flow in Quantum Gravity and their Quasinormal modes, Shadow and Hawking radiation

TL;DR

The paper presents a class of regular black holes derived from proper-time renormalization group flows in asymptotically safe gravity, achieving singularity resolution while preserving exterior Schwarzschild behavior. It conducts a thorough phenomenological analysis of axial gravitational perturbations, computing quasinormal modes with WKB, Leaver, and time-domain methods, and demonstrates significant q-dependent deviations from Schwarzschild. The study also examines grey-body factors and Hawking radiation, showing suppressed emission and cooler Hawking temperatures, with implications for primordial black hole dark matter. Additionally, it analyzes shadows and ISCOs, finding compatibility with observations, and confirms the eikonal regime null geodesic correspondence, supporting the physical robustness of the model across regularization schemes.

Abstract

We derive a class of regular black holes from the proper-time renormalization group approach to asymptotically safe gravity. A central challenge is the robustness of physical predictions to the regularization scheme. We address this by computing key observables for our quantum-corrected black holes, which are non-singular and asymptotically Schwarzschild. We calculate the quasinormal mode spectrum, finding significant deviations from the classical case. The Hawking radiation spectrum is strongly suppressed, implying a slower evaporation rate and relaxed constraints on primordial black holes as dark matter. Shadows and ISCO radii remain consistent with observations. Our results demonstrate that the singularity resolution and its primary observational implications are robust physical outcomes.

Figures (12)

• Figure 1: The thick blue line shows the scale factor of the new regular collapse mode with $q=1.40$, while the dashed orange line is the classical OSD collapse model.
• Figure 2: The behavior of the metric function $f(R)$ for different values of the parameter $q$ for $M_0=1$. There are an inner and an outer horizon for $q>1.37$, one horizon for the critical value $q=1.37$ and no horizon for minor values of this.
• Figure 3: Effective potential as a function of the tortoise coordinate of the $l=2$ axial gravitational perturbations for different valus of $q$ and Schwarzschild.
• Figure 4: Real part of frequencies for $l=2,3$ for various values of the parameter with Leaver method. Schwarzschild values are also present for comparison
• Figure 5: Imaginary part of frequencies for $l=2,3$ for various values of the parameter with Leaver method. Schwarzschild values are also present for comparison