New analytical model of rotating black hole with dark matter halo: constraints from EHT observations and accretion disk

In this paper, we begin with a static black hole (BH) embedded in a Dehnen-type dark matter (DM) halo and apply the Newman–Janis algorithm (NJA) to construct a rotating black hole solution surrounded by a dark matter halo. We then examine the validity of the resulting spacetime geometry. Furthermore, we investigate the optical properties of a newly obtained rotating BH in the DM halo, including the geometrical structure of the black hole shadow, the light deflection angle using the Ono–Ishihara–Asada (OID) method, the photon sphere, and the dependence of the shadow radius on the DM halo parameters. Additionally, assuming that the spacetime of a supermassive black hole (SMBH) is described by the newly obtained rotating solution, we constrain the model parameters using shadow size measurements from the Event Horizon Telescope (EHT) and Gravity collaboration observations of M87∗ and Sgr A∗. We further perform a Markov Chain Monte Carlo (MCMC) analysis to constrain the DM halo parameters ρs and rs, as well as the BH mass M and the spin parameter a. Our results show that the best-fit values of ρs and rs are consistent with previous results, supporting the physical reasonability of the proposed model considered here. Finally, we analyze the electromagnetic radiation flux from the rotating BH in the DM halo using a ray-tracing approach.