Null and Timelike Geodesics near the Throats of Phantom Scalar Field Wormholes

Abstract

We study geodesic motion near the throats of asymptotically flat, static, spherically symmetric traversable wormholes supported by a self-gravitating minimally coupled phantom scalar field with an arbitrary self-interaction potential. We assume that any such wormhole possesses the reflection symmetry with respect to the throat, and consider only its observable “right half”. It turns out that the main features of bound orbits and photon trajectories close to the throats of such wormholes are very different from those near the horizons of black holes. We distinguish between wormholes of two types, the first and second ones, depending on whether the redshift metric function has a minimum or maximum at the throat. First, it turns out that orbits located near the centre of a wormhole of any type exhibit retrograde precession, that is, the angle of pericentre precession is negative. Second, in the case of high accretion activity, wormholes of the first type have the innermost stable circular orbit at the throat while those of the second type have the resting-state stable circular orbit in which test particles are at rest at all times. In our study, we have in mind the possibility that the strongly gravitating objects in the centres of galaxies are wormholes, which can be regarded as an alternative to black holes, and the scalar field can be regarded as a realistic model of dark matter surrounding galactic centres. In this connection, we discuss qualitatively some observational aspects of results obtained in this article.

Ultracompact stars with polynomial complexity by gravitational decoupling

“…All of these solutions are known as BH mimickers and correspond to objects that, given their high compactness, the motion of test particles around them seems indistinguishable when compared with the physics around a BH (see [6], for a recent review). Some examples of BH mimickers found in literature encompasses regular BH [7][8][9], a e-mail: econtreras@usfq.edu.ec (corresponding author) traversable wormholes [10][11][12][13] and ultracompact stars [14], among others, and in this work we shall focus our attention in the latter.…”

On null geodesics and shadow of hairy black holes in Einstein-Maxwell-dilaton gravity

“…The study of geodesic structure around hairy black holes has been carried out in [55]- [56]. For the analysis of time-like and null-like geodesics in the background of wormhole geometries, see [57]- [59].…”

Editorial to the Special Issue “Selected Papers from the 17th Russian Gravitational Conference—International Conference on Gravitation, Cosmology and Astrophysics (RUSGRAV-17)”

“…In articles [10,11] the collapsing wormholes sustained by dustlike matter and a discrete version of the Schwarzschild solution are considered, respectively. Null and timelike geodesics near the throats of phantom scalar field wormholes are investigated in [12]. Some other problems in the physics of black holes, such as matter accretion versus semiclassical bounce in the Schwarzschild interior [13], a description of black holes in terms of the axiomatic set theory [14], and an analysis of black hole formation in (2 + 1)-dimensional spacetime with the negative cosmological constant due to the collapse of a dust shell [15] are also discussed.…”