Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gamma-ray bursts from internal shocks in a relativistic wind: an
  hydrodynamical study   The internal shock model for gamma-ray bursts involves shocks taking place in
a relativistic wind with a very inhomogeneous initial distribution of the
Lorentz factor. We have developed a 1D lagrangian hydrocode to follow the
evolution of such a wind and the results we have obtained are compared to those
of a simpler model presented in a recent paper (Daigne & Mochkovitch 1998)
where all pressure waves are suppressed in the wind so that shells with
different velocities only interact by direct collisions. The detailed
hydrodynamical calculation essentially confirms the conclusion of the simple
model: the main temporal and spectral properties of gamma-ray bursts can be
reproduced by internal shocks in a relativistic wind.

14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga