Shadow of a Noncommutative Thin-Shell Gravastar

Abstract

One of the main challenges in astronomy is the direct observation of black holes. However, distinguishing black holes from ultra-compact horizonless objects through photon observations can be difficult, since the latter may also possess unstable circular photon orbits. An example of an Ultra-Compact Object is a Gravastar (gravitational vacuum star), initially proposed by Mazur and Mottola. For definition purposes, we construct a spherically symmetric thin-shell gravastar model within a noncommutative model, in which these effects are integrated by a Lorentzian distribution of the energy density with a minimum width $\sqrtθ$. The model is constructed using the cut-and-paste technique to connect a nonsingular de Sitter interior to a noncommutative Schwarzschild exterior, satisfying the Israel junction conditions on the interface hypersurface $Σ$. We examine the stability of the model through its energy conditions, highlighting the influence of the noncommutative parameter on its behavior. {Model stability was also investigated using the parameter $η$, derived from the linearized stability analysis.} We also show that, owing to noncommutativity, the photon trajectories and deflection angles change as the noncommutative parameter increases. Our proposed gravastar model, with noncommutative geometry on its exterior, can be considered a stable and viable alternative to the charged black hole in the context of this type of gravity.