Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Energy Cascade from Warm Dark Matter Decays   We use a set of Monte Carlo simulations to follow the cascade produced by a
primary electron of energy E_in in the intergalactic medium. We choose
E_in=3-10 keV as expected from the decay of one of the most popular Warm Dark
Matter (WDM) candidates, sterile neutrinos. Our simulation takes into account
processes previously neglected such as free-free interactions with ions and
recombinations and uses the best available cross sections for collisional
ionizations and excitations with H and He and for electron-electron collisions.
We precisely derive the fraction of the primary electron energy that heats the
gas, ionizes atoms and produces line and continuum photons as a function of the
ionization fraction. Handy fitting formulae for all the above energy
depositions are provided. By keeping track of the individual photons we can
distinguish between photons in the Ly-alpha resonance and those with energy E <
10.2 eV that do not interact further with gas. This separation is important
because a Ly-alpha background can heat or cool the gas depending on the nature
of the photons, and can have effects on the 21 cm radiation emitted by neutral
H, which will probably become detectable at z > 6 in the near future by the
next generation radio interferometers.

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The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
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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: stat
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The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex