Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Hawking Energy on the Past Lightcone in Cosmology   This work studies the Hawking energy in a cosmological context. The past
lightcone of a point in spacetime is the natural geometric structure closely
linked to cosmological observations. By slicing the past lightcone into a
1-parameter family of spacelike 2-surfaces, the evolution of the Hawking energy
down the lightcone is studied. Strong gravitational fields may generate
lightcone self-intersections and wave front singularities. We show that in the
presence of swallow-tail type singularities, the Hawking energy and its
variation along the null generators of the lightcone remains well-defined and
subsequently discuss its positivity and monotonicity.

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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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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: nlin