Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear Evolution of the Radiation-Driven Magneto-Acoustic Instability
  (RMI)   We examine the nonlinear development of unstable magnetosonic waves driven by
a background radiative flux -- the Radiation-Driven Magneto-Acoustic
Instability (RMI, a.k.a. the "photon bubble" instability). The RMI may serve as
a persistent source of density, radiative flux, and magnetic field fluctuations
in stably-stratified, optically-thick media. The conditions for instability are
present in a variety of astrophysical environments, and do not require the
radiation pressure to dominate or the magnetic field to be strong. Here we
numerically study the saturation properties of the RMI, covering three orders
of magnitude in the relative strength of radiation, magnetic field, and gas
energies. Two-dimensional, time-dependent radiation-MHD simulations of local,
stably-stratified domains are conducted with Zeus-MP in the optically-thick,
highly-conducting limit. Our results confirm the theoretical expectations of
Blaes and Socrates (2003) in that the RMI operates even in gas
pressure-dominated environments that are weakly magnetized. The saturation
amplitude is a monotonically increasing function of the ratio of radiation to
gas pressure. Keeping this ratio constant, we find that the saturation
amplitude peaks when the magnetic pressure is comparable to the radiation
pressure. We discuss the implications of our results for the dynamics of
magnetized stellar envelopes, where the RMI should act as a source of
sub-photospheric perturbations.

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The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
3
The categories of this paper are: physics
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph
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The categories of this paper are: stat