# Threshold Drop in Accretion Density if Dark Energy is Accreting onto a Supermassive Black Hole

## TL;DR

This paper investigates how dark energy, modeled as viscous modified Chaplygin gas, affects accretion density profiles around supermassive black holes, revealing a threshold drop in accretion when viscosity and dark energy effects are considered.

## Contribution

It introduces a novel analysis of viscous dark energy's impact on accretion densities near black holes using an alpha-disc model and compares results with observational data.

## Key findings

- Wind strength increases with dark energy as accreting agent.
- Accretion density exhibits a threshold drop with specific viscosity and dark energy effects.
- Results align with existing observational data.

## Abstract

Galactic structures are supposed to be formed out of dark matter clustering. Some examples of supermassive black holes in the central regions of high redshift galaxies say that the concerned supermassive black holes have completed their constructions in a time less than it generally should be. To justify such discrepancies, we are forced to model about existences of black hole mimickers and exotic phenomena acting near the supermassive black holes. Motivated by these we study the natures of exotic matters, especially dark energy near the black holes. We choose modified Chaplygin gas as dark energy candidate. Again, the descriptions of gravitational waves or the attenuations of them when they are tunnelling through cosmological distances help us to measure the shear viscosity of the medium through which the waves have been travelled. Delayed decaying models of dark matters also suggest that dark energy and viscosity may come up as a byproduct of such decays or interactions. We consider the viscous nature of the medium, i.e., the dark energy. To do so, we choose an alpha-disc model as proposed by Shakura and Sunyaev. We study the variations of densities through accretion and wind branches for a different amount of viscosity regulated by the Shakura-Sunyaev's alpha parameter, spin parameter and different properties of accreting fluids, viz, the properties of adiabatic fluid and modified Chaplygin gas. We compare these results with each other and some existing density profiles drawn from observational data-based simulations. We follow that our result supports the data observed till date. Specifically, we see the wind to get stronger for dark energy as accreting agent. Besides, we see the accretion to have a threshold drop if the viscosity is chosen along with the repulsive effects of dark energy.