Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic field amplification in hypermassive neutron stars via the
  magnetorotational instability   Mergers of binary neutron stars likely lead to the formation of a
hypermassive neutron star (HMNS), which is metastable and eventually collapses
to a black hole. This merger scenario is thought to explain the phenomenology
of short gamma-ray bursts (SGRBs). The very high energies observed in SGRBs
have been suggested to stem from neutrino-antineutrino annihilation and/or from
very strong magnetic fields created during or after the merger by mechanisms
like the magnetorotational instability (MRI). Here, we report on results that
show for the first time the development of the MRI in HMNSs in
three-dimensional, fully general-relativistic magnetohydrodynamic simulations.
This instability amplifies magnetic fields exponentially and could be a vital
ingredient in solving the SGRB puzzle.

25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org