Effect of dark matter on the shadow of a distorted and deformed compact object

This work investigates observational properties, namely the shadow and photon ring structure, of emission profiles originated near compact objects. In particular, we consider a distorted and deformed compact object characterized by quadrupoles and surrounded by an optically thin and geometrically thin accretion disk with different emission profiles modeled by the Johnson's Standard-Unbound (SU) distribution in the reference frame of the emitter. Under these assumptions, we produce the observed intensity profiles and shadow images for a face-on observer. Our results indicate that, due to the fact that modifications of the quadrupole parameters affect the radius of the innermost stable circular orbit (ISCO) and the photon sphere (PS), the observed shadow images and their properties are significantly influenced by the quadrupole parameters and emission profiles. Furthermore, we analyze the impact of the presence of a dark matter halo in the observational imprints considered and verify that both the increase in the matter contained in the halo or decrease in the length-scale of the halo lead to an increase in the size of the observed shadow. Our results indicate potential degeneracies between the observational features of distorded and deformed compact objects with those of spherically symmetric blackholes, which could be assessed by a comparison with the current and future generation of optical experiments in gravitational physics.