Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Perturbations on steady spherical accretion in Schwarzschild geometry   The stationary background flow in the spherically symmetric infall of a
compressible fluid, coupled to the space-time defined by the static
Schwarzschild metric, has been subjected to linearized perturbations. The
perturbative procedure is based on the continuity condition and it shows that
the coupling of the flow with the geometry of space-time brings about greater
stability for the flow, to the extent that the amplitude of the perturbation,
treated as a standing wave, decays in time, as opposed to the amplitude
remaining constant in the Newtonian limit. In qualitative terms this situation
simulates the effect of a dissipative mechanism in the classical Bondi
accretion flow, defined in the Newtonian construct of space and time. As a
result of this approach it becomes impossible to define an acoustic metric for
a conserved spherically symmetric flow, described within the framework of
Schwarzschild geometry. In keeping with this view, the perturbation, considered
separately as a high-frequency travelling wave, also has its amplitude reduced.

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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph