Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational waves from the Papaloizou-Pringle instability in black
  hole-torus systems   Black hole (BH)--torus systems are promising candidates for the central
engine of gamma-ray bursts (GRBs), and also possible outcomes of the collapse
of supermassive stars to supermassive black holes (SMBHs). By three-dimensional
general relativistic numerical simulations, we show that an $m=1$
nonaxisymmetric instability grows for a wide range of self-gravitating tori
orbiting BHs. The resulting nonaxisymmetric structure persists for a timescale
much longer than the dynamical one, becoming a strong emitter of large
amplitude, quasiperiodic gravitational waves. Our results indicate that both,
the central engine of GRBs and newly formed SMBHs, can be strong gravitational
wave sources observable by forthcoming ground-based and spacecraft detectors.

33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th