Observational Signatures of Janis-Newman-Winicour Strongly Naked Singularity

Abstract: This paper explores the unique observational signatures of accretion onto a Janis-Newman-Winicour (JNW) strongly naked singularity, particularly in the absence of a photon sphere. The surrounding spacetime of such a singularity exhibits pronounced reflective properties, causing light rays traveling in its vicinity to undergo reflection and produce paired imaging trajectories in both accretion disk and hot spot models. Our simulations reveal that this reflection effect generates additional images in the gravitational lensing patterns and significantly alters the temporal brightness profiles of the lensed images. These reflection-induced paired images, together with their inclination-dependent behavior, offer distinct observational signatures that could potentially distinguish a JNW strongly naked singularity from a black hole based on future high-resolution observations.