Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The brightest point in accretion disk and black hole spin: implication
  to the image of black hole M87*   We propose the simple new method for extracting the value of the black hole
spin from the direct high-resolution image of black hole by using a thin
accretion disk model. In this model the observed dark region on the first image
of the supermassive black hole in the galaxy M87, obtained by the Event Horizon
Telescope, is a silhouette of the black hole event horizon. The outline of this
silhouette is the equator of the event horizon sphere. The dark silhouette of
the black hole event horizon is placed within the expected position of the
black hole shadow, which is not revealed on the first image. We calculated
numerically the relation between the observed position of the black hole
silhouette and the brightest point in the thin accretion disk, depending on the
black hole spin. From this relation we derive the spin of the supermassive
black hole M87*, $a=0.75\pm0.15$.

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The categories of this paper are: ao-sci
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The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph