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We study the optical appearance of a thin accretion disk around the strongly naked static Janis-Newman-Winicour singularity. The solution does not possess a photon sphere, which results in the formation of a complex structure of bright…

General Relativity and Quantum Cosmology · Physics 2020-12-02 Galin Gyulchev , Jutta Kunz , Petya Nedkova , Tsvetan Vetsov , Stoytcho Yazadjiev

This paper explores the unique observational signatures of accretion onto a Janis-Newman-Winicour (JNW) strongly naked singularity, particularly in the absence of a photon sphere. The surrounding spacetime of such a singularity exhibits…

General Relativity and Quantum Cosmology · Physics 2025-05-20 Zeqian Zhang

The final fate of gravitational collapse of massive stars has been a subject of interest for a long time since such a collapse may lead to black holes and naked singularities alike. Since, the formation of naked singularities is forbidden…

General Relativity and Quantum Cosmology · Physics 2020-09-16 Subhadip Sau , Indrani Banerjee , Soumitra SenGupta

The Janis-Newman-Winicour (JNW) spacetime can describe a naked singularity with a photon sphere that smoothly transforms into a Schwarzschild black hole. Our analysis reveals that photons, upon entering the photon sphere, converge to the…

General Relativity and Quantum Cosmology · Physics 2023-09-20 Deyou Chen , Yiqian Chen , Peng Wang , Tianshu Wu , Houwen Wu

In the present paper, we study the thermal properties of the geometrically thin accretion disks surrounding the null naked singularity (NNS) and the first type of Joshi-Malafarina-Narayan (JMN1) spacetimes and compare the results with the…

General Relativity and Quantum Cosmology · Physics 2022-08-31 Divya Tahelyani , Ashok B. Joshi , Dipanjan Dey , Pankaj S. Joshi

We study the linear polarization from the accretion disk around weakly and strongly naked Janis-Newman-Winicour singularities. We consider an analytical toy model of thin magnetized fluid ring orbiting in the equatorial plane and emitting…

General Relativity and Quantum Cosmology · Physics 2023-03-28 Valentin Deliyski , Galin Gyulchev , Petya Nedkova , Stoytcho Yazadjiev

We study the optical appearance of a thin accretion disk around compact objects within the Einstein-Gauss-Bonnet gravity. Considering static spherically symmetric black holes and naked singularities we search for characteristic signatures…

General Relativity and Quantum Cosmology · Physics 2021-10-27 Galin Gyulchev , Petya Nedkova , Tsvetan Vetsov , Stoytcho Yazadjiev

It is commonly thought that the final product of gravitational collapse is a black hole. Nevertheless, theoretical studies have not yet provided a final answer to the question whether black holes are the only possible outcome or whether…

General Relativity and Quantum Cosmology · Physics 2018-08-31 Honghui Liu , Menglei Zhou , Cosimo Bambi

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…

General Relativity and Quantum Cosmology · Physics 2012-06-20 Anirban N. Chowdhury , Mandar Patil , Daniele Malafarina , Pankaj S. Joshi

The Janis-Newman-Winicour (JNW) spacetime possesses a naked singularity, although it represents an exact particle-like solution to the Einstein-Klein-Gordon theory with a massless scalar field. Here, we investigate the possible formation of…

General Relativity and Quantum Cosmology · Physics 2024-08-07 Xiao Yan Chew , Il Gyeong Choi , Hyuk Jung Kim , Dong-han Yeom

Recently, it has been reported that photons can traverse naked singularities in the Janis-Newman-Winicour and Born-Infeld spacetimes when these singularities are appropriately regularized. In this paper, we investigate observational…

General Relativity and Quantum Cosmology · Physics 2023-10-11 Yiqian Chen , Peng Wang , Haitang Yang

We explore circular geodesics of neutral test particles in the gravitational field of a rotating deformed mass. The geometry around this source is described by the Quevedo-Mashhoon solution, which corresponds to a naked singularity. To this…

Motivated by the fact that the universe is dominated by dark matter and dark energy, we consider rotating black holes surrounded by perfect fluid dark matter and study the accretion process in thin disk around such black holes. Here, we are…

General Relativity and Quantum Cosmology · Physics 2023-03-09 Malihe Heydari-Fard , Sara Ghassemi Honarvar , Mohaddese Heydari-Fard

We study scalar radiation spectra from a particle in circular orbit, in the background of the Janis-Newman-Winicour (JNW) naked singularity. The differences in the nature of the spectra, from what one obtains with a Schwarzschild black…

General Relativity and Quantum Cosmology · Physics 2013-03-28 Anshuman Dey , Pratim Roy , Tapobrata Sarkar

Though the cosmic censorship conjecture states that spacetime singularities must be hidden from an asymptotic observer by an event horizon, naked singularities can form as the end product of a gravitational collapse under suitable initial…

General Relativity and Quantum Cosmology · Physics 2020-12-24 Avijit Chowdhury , Narayan Banerjee

We present the first numerical simulations of a thin accretion disk around a Reissner-Nordstr\"om (RN) naked singularity (a charged point mass). The gravity of the RN naked singularity is modeled with a pseudo-Newtonian potential that…

High Energy Astrophysical Phenomena · Physics 2025-01-07 Miljenko Čemeljić , Włodek Kluźniak , Ruchi Mishra , Maciek Wielgus

We study here images of thin accretion disks around black holes and two classes of naked singularity spacetimes and compare these scenarios. The naked singularity models which have photon spheres have single accretion disk with its inner…

General Relativity and Quantum Cosmology · Physics 2019-11-14 Rajibul Shaikh , Pankaj S. Joshi

We compare the optical appearance of a thin accretion disk in the Simpson-Visser spacetime to the Schwarzschild black hole case in this paper. We calculate and illustrate the red-shift and observed flux distributions as viewed by distant…

General Relativity and Quantum Cosmology · Physics 2022-02-01 Parth Bambhaniya , Saurabh K , Kimet Jusufi , Pankaj S. Joshi

In the present work, accretion onto a static spherically symmetric black hole in the hybrid metric-Palatini gravity is considered. The Novikov-Thorne model for a relativistic thin accretion disk is used. The energy flux, temperature…

General Relativity and Quantum Cosmology · Physics 2024-02-05 P. I. Dyadina , N. A. Avdeev

We investigate here the thermal properties of accretion disks in a spacetime for some galactic density profiles in spherical symmetry. The matter distributions have a finite outer radius with a naked central singularity. The luminosities of…

General Relativity and Quantum Cosmology · Physics 2021-01-01 Jun-Qi Guo , Pankaj S. Joshi , Ramesh Narayan , Lin Zhang
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