No axions from the Sun
  Preliminary evidence of solar axions in XMM-Newton observations has quite
recently been claimed by Fraser et al. as an interpretation of their detection
of a seasonally-modulated excess of the X-ray background. Within such an
interpretation, these authors also estimate the axion mass to be $m_a \simeq
2.3 \cdot 10^{- 6}$ eV. Since an axion with this mass behaves as a cold dark
matter particle, according to the proposed interpretation the considered
detection directly concerns cold dark matter as well. So, the suggested
interpretation would lead to a revolutionary discovery if confirmed.
Unfortunately, we have identified three distinct problems in this
interpretation of the observed result of Fraser et al. which ultimately imply
that the detected signal - while extremely interesting in itself - cannot have
any relation with hypothetical axions produced by the Sun. Thus, a physically
consistent interpretation of the observed seasonally-modulated X-ray excess
still remains an exciting challenge.
