Circular geodesics and accretion disks in the Janis-Newman-Winicour and gamma metric spacetimes

Abstract

We study here circular timelike geodesics in the Janis-Newman-Winicour and Gamma metric spacetimes which contain a strong curvature naked singularity and reduce to the Schwarzschild metric for a specific value of one of the parameters. We show that for both the metrics the range of allowed parameters can be divided into three regimes where structure of the circular geodesics is qualitatively different. It follows that the properties of the accretion disks around such naked singularities can be significantly different from those of disks around black holes. This adds to previous studies showing that if naked singularities exist in nature, their observational signature would be significantly different from that of the black hole.

Accretion processes for general spherically symmetric compact objects

“…There are various forms of JNW metric available in the literature, however, we adopt the following form [27]:…”

Dynamics of a charged particle around a weakly magnetized naked singularity

“…While this spacetime is known under many different names, for the purposes of this paper, we shall follow references related to the context of our paper such as [20,32,33] and refer to this solution as the Janis-Newman-Winicour (JNW) spacetime. The charged generalization of this solution was obtained by Penney [34], and an exact magnetized solution was given by [35], and a further accelerating generalization was given in [36].…”

Axially Symmetric Null Dust Space-Time, Naked Singularity, and Cosmic Time Machine

“…Consequently, the study of naked singularities and space-time with such objects is of considerable current interest. In [13], the authors have enumerated three possible end states of gravitational collapse. There are a number of examples of gravitational collapse in spherically symmetric that formed naked singularities known.…”