Shadows and precession of orbits in rotating Janis-Newman-Winicour spacetime

Abstract

In this paper, we construct the rotating Janis-Newman-Winicour (JNW) naked singularity spacetime using Newman-Janis Algorithm (NJA). We analyse NJA with and without complexification methods and find that the energy conditions do satisfied when we skip the complexification step. We study the shadows cast by rotating JNW naked singularity and compare them with the shadows cast by the Kerr black hole. We find that the shadow of the rotating naked singularity can be distinguished from the shadow of the Kerr black hole. While we analyse the precession of timelike bound orbits in rotating JNW spacetime, we find that it can have a negative (or opposite) precession, which is not present in the Kerr black hole case. These novel signatures of the shadow and orbital precession in rotating JNW naked singularity spacetime could be important in the context of the recent observation of the shadow of the M87 galactic center and the stellar dynamics of 'S-stars' around Milkyway galactic center.

Rotating black holes with an anisotropic matter field

“…Due to this property, the shape of the capturecross-section by light is transformed into an asymmetric one. An interesting astrophysical phenomenon is that the shadow of a rotating black hole has the asymmetric bright side due to this property [43,44,45,46,47,48,49,50,51,52,53,54].…”

Tidal force effects and periodic orbits in null naked singularity spacetime

“…One might come across abundant research literature concerning the aim to distinguish a naked singularity spacetime from any other spacetime which is engulfed by a null hypersurface or an event horizon. To distinguish these naked singularities, the significant work has been done in the recent literature [9][10][11][12][13][14][15][16][17], where authors investigate the shadows and orbital precession properties. Similarly, in this paper, we obtain an orbit equation of a test particle for the null-like naked singularity spacetime and we show the periastron precession of the timelike bound orbits for the same.…”

Revisiting timelike geodesics in the Fisher-Janis-Newman-Winicour-Wyman spacetime

“…For this reason, many researchers have investigated observational signatures of the F/JNWW spacetime, e.g., gravitational lensing [14], the observable images of shadows and thin accretion disks [15,16], and the behavior of circular geodesics and the properties of accretion disks [17]. In particular, recent studies have shown that a naked singularity can exhibit a negative periapsis precession [18][19][20][21][22]. The negative periapsis precession is that the periapsis precessions in the direction opposite to the direction of a particle motion.…”

“…In [19][20][21], the authors have investigated the periapsis precession of orbits with small eccentricity in the weak field approximation in the F/JNWW spacetime. Furthermore, in [22], the authors numerically calculated and showed that the periapsis precession can take a negative value in the rotating F/JNWW spacetime. In this paper, we revisit the results in [20], where the authors focus on orbits with large semi-latus and small eccentricity.…”

“…For the orbits without any assumptions, numerical calculations are often used when ones examine whether the negative periapsis precession occurs or not (for example, Refs. [22,26]). Although the numerical analysis is a powerful tool, we can more directly determine the parameter region in which the negative periapsis precession occur if we can obtain analytical solutions.…”