Shadows of naked singularity in Brans-Dicke gravity

Abstract

We investigate the observational features of exact vacuum solutions in Brans-Dicke (BD) gravity, focusing on their implications for black hole shadow imaging. Motivated by the Event Horizon Telescope (EHT) observations, we revisit a class of BD solutions that exhibit a naked singularity. These solutions, despite lacking a conventional event horizon, exhibit photon spheres and produce shadow-like features. We analyze null geodesics and perform ray-tracing simulations under a simplified, optically thin accretion disk model to generate synthetic images. Our results show that BD naked singularities can cast shadows smaller than those of Schwarzschild black holes of equivalent mass. We identify the parameter space $-3/2<\omega <0$ as physically viable, ensuring attractive gravity and the absence of ghost fields. These findings suggest that BD naked singularities are possible candidates for compact astrophysical objects.

Accepted for publication in EPJC. 7 pages, 3 figures. It contains some additional comments and references

References in corpus (20)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• The Confrontation between General Relativity and Experiment
• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A${}^{\ast }$
• Black Hole Shadows, Photon Rings, and Lensing Rings
• Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
• An Update on Monitoring Stellar Orbits in the Galactic Center
• Brans-Dicke wormholes in the Jordan and Einstein frames
• Key Science Goals for the Next-Generation Event Horizon Telescope
• Brans wormholes
• Shadows and photon rings of regular black holes and geonic horizonless compact objects
• Images and photon ring signatures of thick disks around black holes
• Shadow of a Naked Singularity without Photon Sphere
• The Vainshtein Mechanism in the Cosmic Web
• The Parametrized Post-Newtonian-Vainshteinian Formalism
• Revisiting the Brans solutions of scalar-tensor gravity
• The GRAVITY+ Project: Towards All-sky, Faint-Science, High-Contrast Near-Infrared Interferometry at the VLTI
• The jet and resolved features of the central supermassive black hole of M 87 observed with EHT
• An independent hybrid imaging of Sgr A* from the data in EHT 2017 observations
• A detailed first-order post-Newtonian analysis of massive Brans-Dicke theories: numerical constraints and the $\beta$ parameter meaning

Cited by in corpus (3)

• Energy conditions in static, spherically symmetric spacetimes and effective geometries
• Optical appearance of regularized compact objects without an exterior photon sphere
• Images and photon regions of continuous photon sphere spacetime