Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Retrolensing by two photon spheres of a black-bounce spacetime   We investigate retrolensing by two photon spheres in a novel black-bounce
spacetime suggested by Lobo et al. which can correspond to a Schwarzschild
black hole, a regular black hole, and a traversable wormhole including an
Ellis-Bronnikov wormhole. In a case, the wormhole has a throat which acts as a
photon sphere and it has another photon sphere outside of the throat. With the
sun as a light source, an observer, and the wormhole are lined up in this
order, sunlight reflected slightly outside of the throat and barely outside and
inside of the outer photon sphere can reach the observer. We show that the
light rays reflected by the outer photon sphere are dominant in retrolensing
light curves in the case.

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The categories of this paper are: hep-th
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The categories of this paper are: q-bio
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The categories of this paper are: math
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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: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ