Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetohydrodynamic Simulations of a Plunging Black Hole into a
  Molecular Cloud   Using two-dimensional magnetohydrodynamic simulations, we investigated the
gas dynamics around a black hole plunging into a molecular cloud. In these
calculations, we assumed a parallel-magnetic-field layer in the cloud. The size
of the accelerated region is far larger than the Bondi-Hoyle-Lyttleton radius,
being approximately inversely proportional to the Alfv\'en Mach number for the
plunging black hole. Our results successfully reproduce the "Y" shape in
position velocity maps of the "Bullet" in the W44 molecular cloud. The size of
the Bullet is also reproduced within an order of magnitude using a reasonable
parameter set. This consistency supports the shooting model of the Bullet,
according to which an isolated black hole plunged into a molecular cloud to
form a compact broad-velocity-width feature.

1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th