Probing a polymerized black hole with the frequency shifts of photons

TL;DR

This paper investigates quantum effects on photon frequency shifts around a polymerized black hole, deriving observable relations and analyzing the influence of plasma, with findings indicating quantum effects are negligible in frequency shifts.

Contribution

It provides new formulas linking black hole parameters to observables and explores plasma effects on photon frequency shifts in a quantum gravity context.

Findings

Frequency shifts decrease with the quantum parameter.

Quantum effects are negligible in total frequency shifts.

Plasma reduces the redshift and blueshift of photons.

Abstract

As is well-known, black hole plays an important role in probing the quantum effects of gravity in the strong-field regime. In this paper, we focus on a polymerized black hole and investigate the quantum effects on the redshift, blueshift and gravitational redshift of photons emitted by massive particles revolving around this black hole. With a general relativistic formalism, we obtain two elegant and concise expressions for the mass of the black hole and the quantum parameter in terms of few direct observables, and find that all the frequency shifts of photons decrease with the quantum parameter. By expanding the total frequency shift for large orbit of the emitter, low peculiar redshift, and small azimuthal angle, we find that the leading contributions to the frequency shift are originated from the kinematic shift and peculiar shift, and the quantum effects make a negligible contribution. In addition, we study the effects of the plasma on the redshift/blueshift for the first time, and conclude that the presence of plasma results in the decrease of the redshift/blueshift.