Year: 2026
Type: article
Abstract: We consider null geodesics in the background of a spherically symmetric object in Einstein-Maxwell-dilaton (EMD) theory with coupling function f (Φ) = e^{-2λΦ} . The spherical solution is characterized by dilaton coupling λ, integrated dilaton flux D and magnetic charge P. Then, we derive geodesic equations by using the Hamilton-Jacobi approach. The radial photon orbital equation on the equatorial plane and effective potential are analyzed. The total deflection angle and trajectories of photons as a function of impact parameter b are plotted with the variation of λ, D and P. In addition, we use the Gralla-Lupsasca-Marrone (GLM) model to model intensity profiles of optically thin accretion disk around the compact object. Hence, we construct optical images of the object surrounded by three distinct emission profiles. Lastly, we investigate the radius of the innermost stable circular orbit (ISCO) for timelike geodesics.
Source: Classical and Quantum Gravity
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7117778947