Testing black holes in non-linear electrodynamics from the observed quasi-periodic oscillations

TL;DR

This paper explores how regular black holes influenced by non-linear electrodynamics can explain high-frequency QPOs observed near black holes, providing insights into strong gravity and potential resolutions to singularities.

Contribution

It introduces a model of regular black holes with non-linear electrodynamics to explain HFQPOs and compares predictions with observations, constraining the charge parameter.

Findings

Most QPO models favor small non-linear electrodynamics charge values.

Large charge values are disfavored by observational data.

The model supports the potential of non-linear electrodynamics in black hole physics.

Abstract

Quasi-periodic oscillations (QPOs), in particular, the ones with high frequencies, often observed in the power spectrum of black holes, are useful in understanding the nature of strong gravity since they are associated with the motion of matter in the vicinity of the black hole horizon. Interestingly, these high frequency QPOs (HFQPOs) are observed in commensurable pairs, the most common ratio being 3:2. Several theoretical models are proposed in the literature which explain the HFQPOs in terms of the orbital and epicyclic frequencies of matter rotating around the central object. Since these frequencies are sensitive to the background spacetime, the observed HFQPOs can potentially extract useful information regarding the nature of the same. In this work, we investigate the role of regular black holes with a Minkowski core, which arise in gravity coupled to non-linear electrodynamics, in explaining the HFQPOs. Regular black holes are particularly interesting as they provide a possible resolution to the singularity problem in general relativity. We compare the model dependent QPO frequencies with the available observations of the quasi-periodic oscillations from black hole sources and perform a \c{hi} 2 analysis. Our study reveals that most QPO models favor small but non-trivial values of the non-linear electrodynamics charge parameter. In particular, black holes with large values of non-linear electrodynamics charge parameter are generically disfavored by present observations related to QPOs.