Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Remarks on the black hole shadows in Kerr-de Sitter space times   This work is geared towards analysis of shadows cast by Kerr-de Sitter (KdS)
and Kerr-de Sitter Revisited (RKdS) black holes. Considering observers in the
vicinity of the static radius, we derive the impact parameters defining the
apparent positions of the shadows. Such observers are of interest to our work
because embedding diagrams have shown that de Sitter space-time is analogous to
an asymptotically flat one in the vicinity of the static radius. We also
perform a comparative analysis between our result with that in Ref.[1].
Furthermore, we numerically obtain the radii of curvature, vertical diameters
and horizontal diameters of the shadows. We find that for $\Lambda=1.11\times
10^{-52} m^{-2}$, M87* observations cannot distinguish a RKdS black hole shadow
from that of a Kerr black hole. Additionally, for the same value of $\Lambda$,
KdS and RKdS black hole shadows are identical. Previously, it has also been
shown that when $\Lambda=1.11\times 10^{-52} m^{-2}$, KdS and Kerr black hole
shadows are indistinguishable. Utilizing the 2017 EHT observations of M87* on
the allowed range of the characteristic radius of the shadow, we obtain
constraints on both black holes. When, a/M>0.812311, we observe that large
angles of inclination ($\theta>30.5107^{\circ}$) do not pass the constraints
for both KdS and RKdS black holes.

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The categories of this paper are: cond-mat
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The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: math
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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci