Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Flares as fingerprints of inner solar darkness   X-ray flares and other solar brightenings have been discarded as potential
axion signatures. An axion X-ray signal must appear exclusively near the disk
centre, and its spectrum must peak at ~4.2keV, contrary to observation. We
argue here that due to Compton scattering off the (plasma) electrons the
outward propagation of X-rays from axions converted near the Sun's surface can
explain energy distribution and non direcivity. Simulation points at the
photosphere as the birth place of the presumed axion conversion, implying an
axion rest mass of ~0.01eV. At present, even optimistic parameter values can
not reproduce the measured intensities. The simulated photon spectrum peaks at
low energies. Quiet Sun hard X-rays are in favour of massive and/or light axion
involvement.

3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an