Dynamics and Radiative Signatures of Accretion Flows onto a Kerr-like Wormhole

TL;DR

This study uses GRMHD and GRRT simulations to explore accretion flows onto a Kerr-like wormhole, revealing distinctive observational signatures that could distinguish wormholes from black holes.

Contribution

First detailed GRMHD and GRRT simulations of accretion onto a Kerr-like wormhole, highlighting unique observational features of such exotic objects.

Findings

Emissions near the wormhole throat can dominate the observed signal.

Spin influences the dynamics through frame-dragging effects.

Light curves show a clear quasi-periodic modulation.

Abstract

Wormholes are a hypothetical object that connects disparate points in spacetime. It is a theoretically well-motivated black hole alternative and offers a potential observationally testable arena for probing strong-field gravity with horizon-scale images. We perform general relativistic magnetohydrodynamic (GRMHD) simulations and general relativistic radiative transfer (GRRT) calculations of accretion flows onto a Kerr-like wormhole. Adopting a Kerr black-bounce metric with a fixed throat parameter $\ell = 2.5\,\rm M$, we explore the effects of spin using both two- and three-dimensional simulations. The accretion flow is initialized as a magnetized geometrically thick torus near one mouth of the wormhole, while the opposite mouth is initially gas-free. We find that the spin parameter influences the dynamical properties on both sides of the wormhole through the frame-dragging effects. Based on the GRMHD results, we compute ray-traced images at $230\,\mathrm{GHz}$ using \texttt{RAPTOR}, and analyze the horizon-scale image structure through higher-order photon trajectories. Our GRRT calculations show that emissions originating from the immediate vicinity of the throat can dominate, in contrast to the case of a Kerr black hole. It provides the variable component of the signal and imprints a clear quasi-periodic modulation in the light curves. These properties would be useful to either confirm or rule out such exotic compact objects through horizon-scale observations.