Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutralino Annihilations and the Gas Temperature in the Dark Ages   Assuming the dark matter is made entirely from neutralinos, we re-visit the
role of their annihilation on the temperature of diffuse gas in the high
redshift universe. We consider neutralinos of particle mass 36 GeV and 100 GeV,
respectively. The former is able to produce ~7 electron/positron particles per
annihilation through the fremionic channel, and the latter ~53 particles
assuming a purely bosonic channel. High energy electron/positron particles
up-scatter the Cosmic Microwave Background (CMB) photons into higher energies
via the inverse-Compton scattering. The process produces a power-law
electron/positron energy spectrum of index -1 in the energy range of interest,
independent of the initial energy distribution. The corresponding energy
spectrum of the up-scattered photons is a power-law of index -1/2, if
absorption by the gas is not included. The scattered photons photo-heat the gas
by releasing electrons which deposit a fraction (14%)of their energy as heat
into the ambient medium. For uniformly distributed neutralinos the heating is
insignificant. The effect is greatly enhanced by the clumping of neutralinos
into dense haloes. We use a time-dependent clumping model which takes into
account the damping of density fluctuations on mass scales smaller than
~10^{-6}M_sol. With this clumping model, the heating mechanism boosts the gas
temperature above that of the CMB after a redshift of z 30. By z\approx 10 the
gas temperature is nearly 100 times its temperature when no heating is invoked.
Similar increase is obtained for the two neutralino masses considered.

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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
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The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
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The categories of this paper are: supr-con
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
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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: solv-int
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The categories of this paper are: math-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: q-alg