Thin accretion disk luminosity and its image around rotating black holes in perfect fluid dark matter

TL;DR

This paper investigates how perfect fluid dark matter influences the luminosity and appearance of thin accretion disks around rotating black holes, revealing increased brightness and temperature due to dark matter effects.

Contribution

It introduces a model for accretion disks around rotating black holes in perfect fluid dark matter and compares electromagnetic spectra and images with the general relativistic case.

Findings

Dark matter reduces the innermost stable circular orbit size.

Disks in dark matter are hotter and more luminous.

Inclination angle significantly affects disk images.

Abstract

Motivated by the fact that the universe is dominated by dark matter and dark energy, we consider rotating black holes surrounded by perfect fluid dark matter and study the accretion process in thin disk around such black holes. Here, we are interested in how the presence of dark matter affects the properties of the electromagnetic radiation emitted from a thin accretion disk. For this purpose, we use the Novikov-Thorne model and obtain the electromagnetic spectrum of an accretion disk around a rotating black hole in perfect fluid dark matter and compare with the general relativistic case. The results indicate that for small values of dark matter parameter we considered here, the size of the innermost stable circular orbits would decrease and thus the electromagnetic spectrum of the accretion disk increases. Therefore, disks in the presence of perfect fluid dark matter are hotter and more luminous than in general relativity. Finally, we construct thin accretion disk images around these black holes using the numerical ray-tracing technique. We show that the inclination angle has a remarkable effect on the images, while the effect of dark matter parameter is small.