Light deflection in Weyl gravity: critical distances for photon paths

TL;DR

This paper investigates light deflection in Weyl gravity, analyzing weak and strong field regimes, and identifies unique features and critical distances for photon paths due to the theory's peculiar properties.

Contribution

It provides a detailed analysis of photon trajectories in Weyl gravity, highlighting the role of conformal invariance and distinguishing between weak and strong field effects.

Findings

Photon geodesics are independent of the conformal factor.

Weyl gravity's effects on light deflection are significant in strong fields.

Critical distances for photon paths are identified in Weyl gravity.

Abstract

The Weyl gravity appears to be a very peculiar theory. The contribution of the Weyl linear parameter to the effective geodesic potential is opposite for massive and nonmassive geodesics. However, photon geodesics do not depend on the unknown conformal factor, unlike massive geodesics. Hence light deflection offers an interesting test of the Weyl theory. In order to investigate light deflection in the setting of Weyl gravity, we first distinguish between a weak field and a strong field approximation. Indeed, the Weyl gravity does not turn off asymptotically and becomes even stronger at larger distances. We then take full advantage of the conformal invariance of the photon effective potential to provide the key radial distances in Weyl gravity. According to those, we analyze the weak and strong field regime for light deflection. We further show some amazing features of the Weyl theory in the strong regime.