Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropic CR diffusion and gamma-ray production close to supernova
  remnants, with an application to W28   Cosmic rays that escape their acceleration site interact with the ambient
medium and produce gamma rays as the result of inelastic proton-proton
collisions. The detection of such diffuse emission may reveal the presence of
an accelerator of cosmic rays, and also constrain the cosmic ray diffusion
coefficient in its vicinity. Preliminary results in this direction have been
obtained in the last years from studies of the gamma-ray emission from
molecular clouds located in the vicinity of supernova remnants, which are the
prime candidate for cosmic ray production. Hints have been found for a
significant suppression of the diffusion coefficient with respect to the
average one in the Galaxy. However, most of these studies rely on the
assumption of isotropic diffusion, which may not be very well justified. Here,
we extend this study to the case in which cosmic rays that escape an
accelerator diffuse preferentially along the magnetic field lines. As a first
approximation, we further assume that particles are strongly magnetized and
that their transport perpendicular to the magnetic field is mainly due to the
wandering of the field lines. The resulting spatial distribution of runaway
cosmic rays around the accelerator is, in this case, strongly anisotropic. An
application of the model to the case of the supernova remnant W28 demonstrates
how the estimates of the diffusion coefficient from gamma-ray observations
strongly depend on the assumptions made on the isotropy (or anisotropy) of
diffusion. For higher levels of anisotropy of the diffusion, larger values of
the diffusion coefficient are found to provide a good fit to data. Thus,
detailed models for the propagation of cosmic rays are needed in order to
interpret in a correct way the gamma-ray observations.

20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int