Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Blue Wings and Bumps via Fermi-like Acceleration of Lyman-alpha photons
  across Shocks   We explore the impact of Fermi-like acceleration of Lyman-alpha (Ly{\alpha})
photons across shock fronts on the observed Ly{\alpha} spectral line shape. We
first confirm the result of Neufeld & McKee (1988) that this mechanism gives
rise to extended blue wings which may have been observed in some radio
galaxies. Our Monte-Carlo radiative transfer calculations further show that in
a minor modification of the shell-model, in which we add an additional static
shell of hydrogen, this process can naturally explain the small blue bumps
observed in a subset of Ly{\alpha} emitting galaxies, which have been difficult
to explain with conventional shell-models. Blue bumps can be produced with an
additional column density of static hydrogen as small as $N_{HI}^{static} \ll
N_{HI}^{shell}$, and typically occur at roughly the outflow velocity of the
shell. In our model the spectra of so-called 'blue-bump objects' might reflect
an evolutionary stage in which the outflows regulating the escape of Ly{\alpha}
photons are still engulfed within a static interstellar medium.

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The categories of this paper are: stat
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The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
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The categories of this paper are: hep-lat
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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: math-ph
2
The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin