Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray Line Emission from Supernova Ejecta Fragments   We show that fast moving isolated fragments of a supernova ejecta composed of
heavy elements should be sources of K_alpha X-ray line emission of the SN
nuclear-processed products. Supersonic motion of the knots in the intercloud
medium will result in a bow-shock/knot-shock structure creation. Fast
nonthermal particles accelerated by Fermi mechanism in the MHD collisionless
shocks diffuse through a cold metallic knot, producing the X-ray emission. We
modeled the X-ray emission from a fast moving knot of a mass M ~ 10^{-3} \Msun,
containing about 10^{-4} \Msun of any metal impurities like Si, S, Ar, Ca, Fe.
The fast electron distribution was simulated using the kinetic description. We
accounted for nonlinear effects of shock modification by the nonthermal
particles pressure. The K_alpha line emission is most prominent for the knots
propagating through dense molecular clouds. The bow shock should be a radiative
wave with a prominent infrared and optical emission. In that case the X-ray
line spectrum of an ejecta fragment is dominated by the low ionization states
of the ions with the metal line luminosities reaching L_x \gsim 10^{31} erg/s.
High resolution XMM and Chandra observations are able to detect the line
emission from the knots at distances up to a few kpcs. The knots propagating
through tenuous interstellar matter are of much fainter surface brightness but
long-lived. The line spectra with higher ionization states of the ions are
expected in that case. Compact dense knots could be opaque for some X-ray lines
and that is important for their abundances interpretation. The ensemble of
unresolved knots of galactic supernovae can contribute substantially to the
iron line emission observed from the Galactic Center region and the Galactic
ridge.

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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys