Probing Einstein-Maxwell-Scalar Black hole via Thin Accretion Disks and Shadows with EHT Observations of M87* and Sgr A*

We investigated the shadows and thin accretion disks of Einstein-Maxwell-Scalar (EMS) black hole. Firstly, we investigated the influence of EMS parameters on the black hole shadow using the null geodesic method and constrained these parameters based on EHT observations of M87* and Sgr A*. Furthermore, we analyzed the direct emission, lensing ring, and photon ring structures in EMS black hole. Comparing our results with the Schwarzschild and Reissner-Nordstr$\ddot{\mathrm{o}}$m (RN) black holes, we found that the Schwarzschild black hole exhibits the largest shadow radius and the highest observed intensity. Increasing the EMS model parameters leads to a reduction in intensity. Ultimately, our findings suggest that imaging black hole accretion disks does not clearly distinguish among these three types of black holes.