Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instabilities in neutron-star postmerger remnants   Using nonlinear, fully relativistic, simulations we investigate the dynamics
and gravitational-wave signature associated with instabilities in neutron star
postmerger remnants. For simplified models of the remnant we establish the
presence of an instability in stars with moderate $T/|W|$, the ratio between
the kinetic and the gravitational potential energies. Detailed analysis of the
density oscillation pattern reveals a \emph{local} instability in the inner
region of the more realistic differential rotation profile. We apply Rayleigh's
inflection theorem and Fj{\o}rtoft's theorem to analyze the stability criteria
concluding that this \emph{inner local} instability originates from a shear
instability close to the peak of the angular velocity profile, and that it
later evolves into a fast-rotating m=2 oscillation pattern. We discuss the
importance of the presence of a corotation point in the fluid, its connection
with the shear instability, and comparisons to the Rossby wave and Papaloizou
Pringle instabilities considered in the wider literature.

1
The categories of this paper are: cs
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th