Accretion flows around exotic tidal wormholes

I. Ray-tracing

¹ Astronomical Observatory of the National Academy of Sciences of Ukraine (MAO NASU), Kyiv 03143, Ukraine
² Astronomical Observatory, Taras Shevchenko National University of Kyiv, 3 Observatorna St., 04053 Kyiv, Ukraine
³ Department of Mathematics, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
e-mail: pksahoo@hyderabad.bits-pilani.ac.in

Received: 27 June 2022
Accepted: 18 July 2022

Abstract

Aims. This paper investigates the various spherically symmetric wormhole solutions in the presence of tidal forces and applies numerous methods, such as test particle orbital dynamics, ray-tracing, and microlensing.

Methods. We make theoretical predictions on the test particle orbital motion around the tidal wormholes with the use of the effective potential normalized by ℒ². In order to obtain the ray-tracing images of both geometrically thin and thick accretion disks and relativistic jets, we modified the open source GYOTO code using a python interface.

Results. We applied this technique to probe the accretion flows near Schwarzschild-like and charged Reissner-Nordström (RN) wormholes; we assumed both a charged RN wormhole and a special case with a vanishing electromagnetic charge, namely the Damour-Solodukhin (DS) wormhole. We show that the photon sphere for the Schwarzschild-like wormhole present for both thin and thick accretion disks, even for the vanishing tidal forces. Moreover, we observe that r_ph → ∞ as α → ∞, which constraints the α parameter to be sufficiently small and positive in order to respect Event Horizon Telescope observations. On the other hand, for the case of the RN wormhole, the photon sphere radius shrinks as Λ → ∞, as predicted by the effective potential. In addition to the accretion disks, we also probe the relativistic jets around the two wormhole solutions under consideration. Finally, with the help of star bulb microlensing, we approximate the radius of the wormhole shadow and find that for the Schwarzschild wormhole, R_Sh ≈ r₀ for zero tidal forces and grows linearly with α. On the contrary, the shadow radius for charged wormholes slowly decreases with the growing DS parameter, Λ.