Images of shadow and thin accretion disk around Bardeen black hole surrounded by perfect fluid dark matter

TL;DR

This paper studies how perfect-fluid dark matter influences the shadow and optical appearance of Bardeen black holes, revealing observable effects on shadow size and disk brightness that could help test dark matter environments around black holes.

Contribution

It provides the first detailed analysis of the impact of perfect-fluid dark matter on black hole shadows and accretion disk images, using observational data and theoretical models.

Findings

Dark matter parameter is constrained to 10^{-1} to 10^{-2}.

Increasing dark matter enlarges the shadow and photon sphere.

Dark matter suppresses disk brightness and alters image size.

Abstract

We investigated the shadow and optical appearance of Bardeen black hole (BH) immersed in perfect-fluid dark matter (PFDM). Using the EHT data, we find that the DM parameter is restricted to a narrow allowed range, confined to values of $\mathcal{O}(10^{-1}-10^{-2})$. Additionally, we observed that increasing the DM parameter substantially enlarges the photon sphere, the critical impact parameter, and thus the shadow radius, whereas the magnetic charge $g$ produces only negligible corrections. The DM component also modifies the optical appearance of the accretion disk: higher $b$ systematically suppresses the observed radiation intensity and reduces image brightness, while changes in $g$ yield only marginal effects. Subsequently, using the Novikov-Thorne thin disk model, we analyze primary and secondary images, observed flux, and redshift patterns, showing that PFDM noticeably alters image size and brightness whereas magnetic charge has a negligible influence. No blueshifted regions appear in any configuration. These results highlight several promising observational signatures for testing DM environments and nonlinear electrodynamic effects around BHs.