Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ab initio simulations of accretion disks instability   We show that accretion disks, both in the subcritical and supercritical
accretion rate regime, may exhibit significant amplitude luminosity
oscillations. The luminosity time behavior has been obtained by performing a
set of time-dependent 2D SPH simulations of accretion disks with different
values of alpha and accretion rate. In this study, to avoid any influence of
the initial disk configuration, we produced the disks injecting matter from an
outer edge far from the central object. The period of oscillations is 2 - 50 s
respectively for the two cases, and the variation amplitude of the disc
luminosity is 10^38 - 10^39 erg/s. An explanation of this luminosity behavior
is proposed in terms of limit cycle instability: the disk oscillates between a
radiation pressure dominated configuration (with a high luminosity value) and a
gas pressure dominated one (with a low luminosity value). The origin of this
instability is the difference between the heat produced by viscosity and the
energy emitted as radiation from the disk surface (the well-known thermal
instability mechanism). We support this hypothesis showing that the limit cycle
behavior produces a sequence of collapsing and refilling states of the
innermost disk region.

30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ