Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The radial gradient of cosmic ray intensity in the Galaxy   The dependence of the cosmic ray intensity on Galactocentric distance is
known to be much less rapid than that to be thought-to-be sources: supernova
remnants. This is an old problem ('the radial gradient problem') which has led
to a number of possible 'scenarios'. Here, we use recent data on the
supernova's radial distribution and correlate it with the measured HII electron
temperature ({\em T}). We examined two models of cosmic ray injection and
acceleration and in both of them the injection efficiency increases with
increasing ambient temperature {\em T}. The increase is expected to vary as a
high power of {\em T} in view of the strong temperature dependence of the tail
of the Maxwell-Boltzmann distribution of particle energies. Writing the
efficiency as proportional to $T^n$ we find $n\approx 8.4$. There is thus, yet
another possible explanation of the radial gradient problem.

11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci