Superradiance scattering of scalar, electromagnetic, and gravitational fields and thin accretion disk around non-commutating Kerr black hole

TL;DR

This paper investigates how non-commutative geometry affects superradiance and accretion disk properties around Kerr black holes, revealing increased amplification, temperature, and luminosity due to non-commutative effects.

Contribution

It provides the first detailed analysis of superradiance and accretion disk characteristics in non-commutative Kerr black holes, highlighting significant impacts of non-commutativity.

Findings

Amplification factor increases with black hole spin but decreases with non-commutative parameter.

Accretion disks around non-commutative Kerr black holes are hotter and more luminous.

Key properties like energy flux and efficiency are enhanced by non-commutative effects.

Abstract

We consider the non-commutative(NC) Kerr black hole where the mass of the central object is smeared over a region of linear size $\sqrt{b}$, $b$ is the strength of the NC character of spacetime. For the spacetime under consideration, we calculate the amplification factor for scalar, electromagnetic, and gravitational fields, and study various properties of a thin accretion disk. The expression for the amplification factor is obtained with the help of the asymptotic matching technique. The amplification factor is then plotted against frequency for various values of the spin $a$ and the NC parameter $b$. We find that though the amplification factor increases with $a$ but decreases with $b$, the cut-off frequency up to which we have amplification increases with $a$ and $b$. We then study the effect of the spin and the NC nature of spacetime on the energy flux, temperature distribution, emission spectrum, energy conversion efficiency, and the radius of the innermost stable circular orbit of a thin accretion disk around the black hole with the help of the steady-state Novikov-Thorne model. Our study reveals that these quantities increase with the spin and the NC parameter. We also find that the disk around the NC Kerr black is hotter and more luminous than that around the Kerr black hole and the NC Schwarzschild black hole. We can conclusively infer from our investigation that the NC nature of spacetime has a significant impact on the superradiance phenomenon as well as on various properties of thin accretion disks.