Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropic Gravitational Collapse and Cosmic Jets   Consider a dynamic general relativistic spacetime in which the proper
infinitesimal interval along one spatial coordinate direction decreases
monotonically with time, while the corresponding intervals increase along other
spatial directions. In a system undergoing such complete anisotropic
collapse/expansion, we look for the formation of a cosmic double-jet
configuration: free test particles in the ambient medium, relative to the
collapsing system, gain energy from the gravitational field and asymptotically
line up parallel and antiparallel to the direction of collapse such that their
Lorentz factors approach infinity. A strong burst of electromagnetic radiation
is expected to accompany this event if some of the free test particles carry
electric charge. Previous work in this direction involved mainly Ricci-flat
spacetimes; hence, we concentrate here on inhomogeneous perfect fluid
spacetimes. We briefly explore the possible connection between these
theoretical cosmic jets and astrophysical jets. We also discuss other general
relativistic scenarios for the formation of cosmic jets.

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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
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The categories of this paper are: physics
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: acc-phys