Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Perihelion Precession and Shadows near Blackholes and Naked
  Singularities   It is now known that, apart from black holes, some naked singularities can
also cast shadows which provide their possible observable signatures. We
examine the relevant question here as to how to distinguish then these entities
from each other, in terms of further physical signatures. We point out that
black holes always admit timelike bound orbits having positive perihelion
precession. Also, while a naked singularity with a photon sphere can cast a
shadow, it could also admit positive perihelion precession for such orbits,
thereby mimicking a black hole. This indicates that compact objects with photon
spheres (shadows) always admit positive perihelion precession of timelike bound
orbits around them. On the other hand, a naked singularity without a photon
sphere could admit both positive and negative perihelion precession but need
not have a shadow. In this paper, we construct a spacetime configuration which
has a central naked singularity but no photon sphere, and it can give both
shadow and a negative perihelion precession. Our results imply that, whereas
the presence of a shadow and a positive perihelion precession implies either a
black hole or a naked singularity, the presence of a shadow and a negative
perihelion precession simultaneously would imply a naked singularity only. We
discuss our results in the context of stellar motions (motion of the `S' stars)
around the Sgr-A* galactic center.

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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: q-bio
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The categories of this paper are: physics
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th