Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Self-gravity in thin discs and edge effects: an extension of Paczynski's
  approximation   As hydrostatic equilibrium of gaseous discs is partly governed by the gravity
field, we have estimated the component caused by a vertically homogeneous disc,
with a special attention for the outer regions where self-gravity classically
appears. The accuracy of the integral formula is better than 1%, whatever the
disc thickness, radial extension and radial density profile. At order zero, the
field is even algebraic for thin discs and writes $- 4 \pi G \Sigma(R) f_{edge}
(R)$ at disc surface, thereby correcting Paczynski's formula by a multiplying
factor $f_{edge} \gtrsim 1/2$, which depends on the relative distance to the
edges and the local disc thickness. For very centrally condensed discs however,
this local contribution can be surpassed by action of mass stored in the inner
regions, possibly resulting in $f_{edge} \gg 1$. A criterion setting the limit
between these two regimes is derived. These result are robust in the sense that
the details of vertical stratification are not critical. We briefly discuss how
hydrostatic equilibrium is impacted. In particular, the disc flaring should not
reverse in the self-gravitating region, which contradicts what is usually
obtained from Paczynski's formula. This suggests that i) these outer regions
are probably not fully shadowed by the inner ones (important when illuminated
by a central star), and ii) the flared shape of discs does not firmly prove the
absence or weakness of self-gravity.

26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph