arXiv subjects

Kauntey Acharya

Publications and source records attributed to Kauntey Acharya.

4 recordsLinked to original sources

arXiv2025

High Energy Particle Collisions in the vicinity of Naked Singularity

In this paper, we investigate particle acceleration and high-energy collisions in the Joshi-Malafarina-Narayan (JMN-1) naked singularity, which, in the absence of an event horizon, allows infalling particles to turn back under specific angular momentum conditions. These outgoing particles can then collide with infalling ones, enabling the JMN-1 singularity to act as a natural high-energy particle accelerator. We derive the necessary expressions to compute the center-of-mass energy of two colliding particles and find that this energy can reach extremely high values, potentially even approaching Planck energy scales. We also explore the implications of these results, including the possible formation of microscopic black holes that could decay via Hawking radiation, releasing energy on the order of $10^{26} eV$ due to the extreme gravitational fields near the naked singularity. This scenario offers significant advantages. If horizonless compact objects exist in nature, these high-energy collisions could substantially influence the surrounding physical processes and might give rise to distinct observational signatures.

gr-qc↗

arXiv2024

Joshi--Malafarina--Narayan singularity in weak magnetic field

The importance and significance of magnetic fields in the astrophysical scenario is well known. Many domains of astrophysical black hole physics such as polarized shadow image, high energy emitting processes and jet formation are dependent on the behavior of the magnetic fields in the vicinity of the compact objects. In light of this, we determine the master equation and master differential equation that determine the spatial behavior of the magnetic field inside a matter distribution or vacuum region, of general spherically symmetric metric, which is immersed in a test magnetic field. We also investigate here the case of JMN-1 singularity immersed in a uniform weak magnetic field and determine the behavior of magnetic fields by defining electromagnetic four potential vector. We find that the tangential component of the magnetic field is discontinuous at the matching surface of the JMN-1 singularity with the external Schwarzschild metric, resulting in surface currents. We define the covariant expression of surface current density in this scenario. We also analyze the behavior of center-of-mass energy of two oppositely charged particles in the geometry of the magnetized JMN-1 singularity. We briefly discuss the possible scenarios which would possess a discontinuous magnetic field and implications of the same and future possibilities in the realm of astrophysics are indicated.

gr-qc↗

arXiv2023

Energy extraction from Janis-Newman-Winicour naked singularity

In general, energy extraction methods such as the Penrose process and the magnetic Penrose process are thought to be reliant on the existence of an ergoregion. Inside an ergoregion, there are negative energy states that allow a particle to extract energy and escape to an observer at infinity. In this paper, we considered the electromagnetic field in the rotating Janis-Newman-Winicour (JNW) spacetime. This concept is feasible because an accretion disc forms an electromagnetic field around compact objects. After that, we briefly examine negative energy orbits and their significance in energy extraction. The ergoregion is absent in a rotating JNW geometry, but we show that the effective ergoregion is there. The change in a negative energy orbit concerning the magnetic field (B), spin parameter (a), and electric charge (Q) is analyzed. We find that the total energy extraction efficiency within this process can be around $60\%$ for the rotating JNW naked singularity.

gr-qc↗

arXiv2022

Rotational energy extraction from the Kerr black hole's mimickers

In this paper, the Penrose process is being used to extract rotational energy from regular black holes. Initially, we consider the rotating Simpson-Visser regular spacetime which describes the class of geometries of the Kerr black hole's mimickers. The Penrose process is then studied through conformally transformed rotating singular and regular black hole solutions. These both Simpson-Visser and conformally transformed geometries depend on mass, spin, and an additional regularisation parameter $l$. In both cases, we investigate how the spin and regularisation parameter $l$ affects the configuration of an ergoregion and event horizons. Surprisingly, we find that the energy extraction efficiency from the event horizon surface is not dependent on the regularisation parameter $l$ in the Simpson-Visser regular spacetimes and hence it does not vary from the Kerr black hole case. While, in the conformally transformed singular and regular black holes, we obtain the efficiency rate of extracted energies are extremely high compared to the Kerr black hole scenario. This distinct signature of the conformally transformed singular and regular black holes would be useful to distinguish them from the Kerr black hole in observation.

gr-qc↗