Analytical solutions for timelike orbits around Damour-Solodukhin wormholes

TL;DR

This paper derives exact analytical solutions for timelike particle orbits around Damour-Solodukhin wormholes, revealing distinctive features of their geodesic structure compared to black holes.

Contribution

It provides closed-form solutions for particle trajectories in Damour-Solodukhin wormhole spacetimes, including special cases with degenerate roots and throat traversals.

Findings

Innermost stable circular orbit (ISCO) linked to triple-root configurations.

Logarithmic and power-law divergences near the throat for certain trajectories.

Regular trajectories when the throat is a simple root, allowing smooth passage.

Abstract

We investigate timelike geodesics around Damour-Solodukhin wormholes, which are Schwarzschild-like geometries characterized by a deformation parameter $\lambda$ that determines the radius of the throat, $r_{\rm th}$. The radial potential admits four roots, including the throat radius itself, allowing the throat to merge with other roots and form double, triple, and quartic degeneracies. In particular, triple-root configurations associated with the throat determine the innermost stable circular orbit (ISCO), providing a potential observational distinction from Schwarzschild black holes. Using the Mino-time parametrization, we derive particle trajectories with closed-form analytical solutions in terms of incomplete elliptic integrals for both bound and unbound motion. In particular, we focus on double or triple roots are located at the throat, the azimuthal angle and coordinate time exhibit logarithmic or power-law divergences as the particle approaches the throat. By contrast, trajectories remain regular when the throat corresponds to a simple root, allowing particles to traverse smoothly between the two asymptotically flat regions. We also derive exact homoclinic solutions associated with the throat and compute the corresponding Lyapunov exponent. In addition, inspiral and plunge trajectories through the throat are analyzed. These results provide analytic insights into particle dynamics and possible observational signatures of the wormholes.