Dark-sector modifications to Kerr and Reissner-Nordstrom black hole evaporation

TL;DR

The paper analyzes how Schwarzschild, Kerr, and Reissner-Nordström black holes evaporate when additional dark-sector particle species are present, focusing on the coupled evolution of mass, charge, and angular momentum via Page factors. By defining $f(M,x^*)$, $g(M,a^*)$, and $h(M,Q^*)$ and computing emission spectra with greybody factors (including an optical-limit approximation) in a semi-classical background, the authors quantify how beyond-Standard Model degrees of freedom alter the evaporation hierarchy. A key finding is that with sufficiently many dark-sector degrees of freedom (roughly a few hundred), the conventional sequence—charge first, then spin, then mass—can be inverted, allowing effective charge growth and near-extremal configurations; Schwinger pair production and superradiance reintroduce charge neutralization and rapid spin-down under certain conditions. The work shows that greybody factors and quantum processes qualitatively modify BH evolution, highlighting the need for multivariate models including dark sectors to predict realistic evaporation histories and potential observational signatures.

Abstract

We present a comprehensive comparative analysis of the evaporation dynamics of Schwarzschild, Kerr, and Reissner- Nordstrom black holes, focusing on the evolution of their mass, charge, and angular momentum, using detailed calculations of the corresponding Page factors. We investigate the evolution of black holes during the evaporation process, emphasizing how these quantities evolve relative to one another. Our study incorporates the effects of greybody factors, near-extremal conditions, and the introduction of additional particle species beyond the Standard Model. We demonstrate that the addition of particle degrees of freedom may significantly alter the evaporation hierarchy, potentially leading to scenarios in which the effective black hole charge increases during evaporation. Additionally, we examine the impact of Schwinger pair production and of super-radiance on charged, spinning black hole evaporation. These findings offer new insights into the complex interplay between different black hole parameters during evaporation and highlight the importance of considering additional particle species in the process.

Figures (14)

• Figure 1: Lognormalized mass loss rates as a function of lifetime for different effective charge. Increasing effective charge lowers the overall temperature of the BH, slowing particle emission. The initial BH mass is set at $10^{17}$ g as larger masses will not significantly change the initial mass loss rate.
• Figure 2: Charge loss rate due to Hawking radiation for various spins normalized by the initial effective charge $Q^*$ of a BH.
• Figure 3: Lines of $\frac{\frac{1}{M} dM/dt}{\frac{1}{Q^*} dQ^*/dt}$ lognormalized for a RN BH for various effective charge values. Initial conditions are for a $M = 10^{17} g$ BH and no included DM.
• Figure 4: Approximate black hole mass threshold for massive particles to significantly contribute to the normalized mass loss rate. All massive particles have a nonzero emission rate at all times, but are exponentially supressed by their respective greybody factor. Significant emission occurs when $T_{BH} \approx m_{p}$. Influence of a light, neutral dark sector on the normalized mass loss rate is included to illustrate its effect.
• Figure 5: Illustration of the effects of adding spin 0, chargeless DM to the BH evaporation spectrum while varying the number of degrees of freedom. Initial conditions are for a BH with mass $1^{17} g$, effective charge $Q^* = 0.9$ and introduced dark matter with $m_{DM} = 0$ GeV. Adding larger degrees of freedom will result in a transition from a regime where $\frac{1}{Q}\frac{dQ}{dt}$ is dominant to a regime where$\frac{1}{M}\frac{dM}{dt}$ begins to dominate. Such a transition is illustrated for the same initial parameters in Fig. \ref{['fig:crossover']}, and occurs when the lines reach a maximum of 1. Illustration only shows rates when the BH is considered charged, afterwards the BH is considered static.