Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three-dimensional simulations of non-stationary accretion by remnant
  black holes of compact object mergers   (abridged) Three-dimensional hydrodynamic simulations with an Eulerian PPM
code are presented for the time-dependent evolution of accretion tori around
nonrotating and rotating stellar-mass black holes (BHs), using a
pseudo-Newtonian gravitational potential to approximate the effects of general
relativity. The initial configurations are assumed to be remnants of binary
neutron star (NS) or NS+BH mergers and consist of a 4 solar mass BH with varied
spin, girded by a torus with a mass between 0.01 and 0.2 solar masses. The
evolution of tori without and with physical shear viscosity is simulated, using
a realistic equation of state and following the energy loss and lepton number
change due to neutrino emission by a neutrino-trapping scheme. The
time-dependent efficiency of converting rest-mass energy to neutrinos is found
to reach 10 percent, the efficiency of converting neutrino energy into a
pair-photon fireball by neutrino annihilation can reach several percent. The
rate of the latter process declines with time much less steeply than the total
neutrino luminosity, because the ongoing protonization of the torus ensures a
rather stable product of neutrino and antineutrino luminosities. The neutrino
emission increases steeply with higher viscosity, larger torus mass, and larger
BH spin in corotation with the torus. For rotation rates as expected for
post-merger BHs (a > 0.5) and reasonable values of the alpha viscosity (alpha ~
0.1), the considered tori release sufficient energy in neutrinos to account for
the energetics of the well-localized short gamma-ray bursts recently detected
by Hete and Swift, if collimation is invoked as predicted by hydrodynamic jet
simulations.

3
The categories of this paper are: physics
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph