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Shadow of nulllike and timelike naked singularities without photon spheres

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arxiv 2009.07487 v2 pith:OKC3VUYZ submitted 2020-09-16 gr-qc

Dipanjan Dey , Rajibul Shaikh , Pankaj S. Joshi This is my paper · ORCID
classification gr-qc
keywords nakedshadowsingularitiesnullliketimelikeconditionsphotonblack
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In this paper, we derive general conditions for a shadow to occur, without a photon sphere in a spacetime, caused by central nulllike or timelike naked singularities. Using these conditions, we propose classes of spacetimes which have nulllike and timelike naked singularities at the center, and that fulfill these `shadow without photon sphere' conditions. Considering additional asymptotically flat conditions, we show that, for a fixed Schwarzschild mass, the timelike naked singularities can cast a shadow of a size that is equal to, greater or smaller, than the size of a black hole shadow. On the other hand, the size of shadow of a nulllike naked singularity is always less than that of a black hole. Such novel features of shadows of nulllike and timelike naked singularities in the absence of photon spheres may help us to distinguish between black holes and naked singularities observationally.

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Cited by 3 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Schwarzschild Black Holes Immersed in Born-Infeld Magnetic Fields and Their Observational Signatures

    gr-qc 2025-06 conditional novelty 6.0 of 10

    Numerically solving full Born-Infeld magnetic fields around a Schwarzschild black hole makes meridional photon orbits prolate and elongates the black hole shadow along the polar axis at high inclination.

  2. Spin precession frequencies of a test gyroscope around a naked singularity and quasi-periodic oscillations

    gr-qc 2025-05 conditional novelty 6.0 of 10

    The paper derives spin precession frequencies for a rotating naked singularity spacetime, shows they match Kerr in the weak field, and uses quasi-periodic oscillations to constrain and disfavor the model.

  3. Herrera Complexity and Shadows of Spherically Symmetric Compact Objects

    gr-qc 2025-01 conditional novelty 6.0 of 10

    The sign of the Herrera complexity factor at a light ring indicates whether that ring is a stable or unstable photon sphere, and zero-complexity compact objects cannot host external photon spheres.

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