Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational collapse of K-essence Matter in Painlev\'{e}-Gullstrand
  coordinates   We conduct numerical simulations in Painlev\'{e}-Gullstrand coordinates of a
variety of K-essence-type scalar fields under spherically symmetric
gravitational collapse. We write down generic conditions on the K-essence
lagrangian that can be used to determine whether superluminality and Cauchy
breakdown are possible. Consistent with these conditions, for specific choices
of K-essence-type fields we verify the presence of superluminality during
collapse, while for other type we do not. We also demonstrate that certain
choices of K-essence scalar fields present issues under gravitational collapse
in Painlev\'{e}-Gullstrand coordinates, such as a breakdown of the Cauchy
problem.

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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
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The categories of this paper are: eess
26
The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: math
9
The categories of this paper are: nlin
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The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat