Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Emergent gravity through non-linear perturbation   As of now, all analogue gravity models available in the literature deal with
the emergence of an acoustic geometry through linear perturbations of transonic
fluids only. It has never been investigated whether the analogue gravity
phenomena is solely a consequence of linear perturbations, or rather a generic
property of arbitrary perturbations of inhomogeneous, inviscid and irrotational
fluids. In the present work, for the first time in the literature, we
demonstrate that acoustic spacetimes may be formed through higher order
non-linear perturbations, and thus establish that analogue gravity phenomena is
rather more general than what was thought before. We consider spherically
accreting astrophysical systems as a natural classical analogue gravity model,
and develop a formalism to investigate non-linear perturbations of such
accretion flows to arbitrary order. Our iterative approach involves a coupled
set of equations for the mass accretion rate and the density of the fluid. In
particular, we demonstrate that the wave equation for the mass accretion rate
involves an acoustic metric which can be perturbatively constructed to all
orders. We numerically solve the coupled equations about the leading transonic
Bondi flow solution. This analysis uses boundary conditions set to the original
unperturbed values, with the time dependence of the mass accretion rate
perturbation taken to be exponentially damped. The perturbed solutions indicate
that second order and higher perturbations of the metric generically cause the
original acoustic horizon to oscillate and change in size. We explain this
phenomenon in detail and its implications on non-linear perturbations of
accretion flows in general.

36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci