Strong Gravitational Lensing by Sgr A* and M87* Black Holes embedded in Dark Matter Halo exhibiting string cloud and quintessential field

TL;DR

This paper explores how dark matter halos around black holes like Sgr A* and M87* affect strong gravitational lensing, revealing enhanced deflection angles and potential observational signatures that distinguish these black holes from standard Schwarzschild black holes.

Contribution

It introduces a detailed analysis of gravitational lensing by black holes embedded in dark matter halos with string cloud and quintessential fields, highlighting the impact of dark matter parameters on lensing effects.

Findings

Deflection angles increase with dark matter parameters.

Dark matter halos significantly enhance gravitational bending.

Observational tests can distinguish black holes with dark matter halos.

Abstract

We investigate the strong gravitational lensing phenomena caused by a black hole with a dark matter halo. In this study, we examine strong gravitational lensing with two significant dark matter models: the universal rotation curve model and the cold dark matter model. To do this, we first numerically estimate the strong lensing coefficients and strong deflection angles for both the universal rotation curve and cold dark matter models. It is observed that the deflection angle, denoted as $\alpha_D$, increases with the parameter $\alpha$ while holding the value of $\gamma \cdot 2M$ constant. Additionally, it increases with the parameter $\gamma \cdot 2M$ while keeping the value of $\alpha$ constant. The strong deflection angle, $\alpha_D$, for the black hole with a dark matter halo, with parameters $\alpha=0$ and $\gamma \cdot 2M$, greatly enhances the gravitational bending effect and surpasses the corresponding case of the standard Schwarzschild black hole ($A=0, B=0, \alpha=0, \gamma \cdot 2M=0$). Furthermore, we investigate the astrophysical consequences through strong gravitational lensing observations, using examples of various supermassive black holes such as $M87^{*}$ and $SgrA^{*}$ located at the centers of several galaxies. It is observed that black holes with dark matter halos can be quantitatively distinguished and characterized from the standard Schwarzschild black hole ($A=0, B=0, \alpha=0, \gamma \cdot 2M=0$). The findings in our analysis suggest that observational tests for black holes influenced by dark matter halos are indeed feasible and viable.