Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Change of a Weibel-type to an Alfv\'enic shock in pair plasma by
  upstream waves   We examine with particle-in-cell (PIC) simulations how a parallel shock in
pair plasma reacts to upstream waves, which are driven by escaping downstream
particles. Initially, the shock is sustained in the two-dimensional simulation
by a magnetic filamentation (beam-Weibel) instability. Escaping particles drive
an electrostatic beam instability upstream. Modifications of the upstream
plasma by these waves hardly affect the shock. In time, a decreasing density
and increasing temperature of the escaping particles quench the beam
instability. A larger thermal energy along than perpendicular to the magnetic
field destabilizes the pair-Alfv\'en mode. In the rest frame of the upstream
plasma, the group velocity of the growing pair-Alfv\'en waves is below that of
the shock and the latter catches up with the waves. Accumulating pair-Alfv\'en
waves gradually change the shock in the two-dimensional simulation from a
Weibel-type shock into an Alfv\'enic shock with a Mach number that is about 6
for our initial conditions.

34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg