X-ray annual modulation observed by XMM-Newton and Axion Quark Nugget Dark Matter. (arXiv:2004.00632v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ge_S/0/1/0/all/0/1">Shuailiang Ge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rachmat_H/0/1/0/all/0/1">Hikari Rachmat</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Siddiqui_M/0/1/0/all/0/1">Md Shahriar Rahim Siddiqui</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Waerbeke_L/0/1/0/all/0/1">Ludovic Van Waerbeke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhitnitsky_A/0/1/0/all/0/1">Ariel Zhitnitsky</a>
The XMM-Newton observatory shows evidence with an $11 sigma$ confidence
level for seasonal variation of the X-ray background in the near-Earth
environment in the 2-6 keV energy range (Fraser et al. 2014). The
interpretation of the seasonal variation given in Fraser et al. 2014 was based
on the assumption that solar axions convert to X-rays in the Earth’s magnetic
field. There are many problems with this interpretation, since the axion-photon
conversion must preserve the directionality of the incoming solar axion. At the
same time, this direction is avoided by the observations because the
XMM-Newton’s operations exclude pointing at the Sun and at the Earth. The
observed seasonal variation suggests that the signal could have a dark matter
origin, since it is very difficult to explain with conventional astrophysical
sources. We propose an alternative explanation which involves the so-called
Axion Quark Nugget (AQN) dark matter model. In our proposal, dark matter is
made of AQNs, which can cross the Earth and emit high energy photons at their
exit. We show that the emitted intensity and spectrum is consistent with Fraser
et al. 2014, and that our calculation is not sensitive to the specific details
of the model. We also find that our proposal predicts a large seasonal
variation, on the level of 20-25%, much larger than conventional dark matter
models (1-10%). Since the AQN emission spectrum extends up to $sim$100 keV,
well beyond the keV sensitivity of XMM-Newton, we predict the AQN contribution
to the hard X-ray and $gamma$-ray backgrounds in the Earth’s environment. The
Gamma-Ray Burst Monitor instrument (GBM), aboard the Fermi telescope, is
sensitive to the 8 keV-40 MeV energy band. We suggest that the multi-year
archival data from the GBM could be used to search for a seasonal variation in
the near-Earth environment up to 100 keV as a future test of the AQN framework.
The XMM-Newton observatory shows evidence with an $11 sigma$ confidence
level for seasonal variation of the X-ray background in the near-Earth
environment in the 2-6 keV energy range (Fraser et al. 2014). The
interpretation of the seasonal variation given in Fraser et al. 2014 was based
on the assumption that solar axions convert to X-rays in the Earth’s magnetic
field. There are many problems with this interpretation, since the axion-photon
conversion must preserve the directionality of the incoming solar axion. At the
same time, this direction is avoided by the observations because the
XMM-Newton’s operations exclude pointing at the Sun and at the Earth. The
observed seasonal variation suggests that the signal could have a dark matter
origin, since it is very difficult to explain with conventional astrophysical
sources. We propose an alternative explanation which involves the so-called
Axion Quark Nugget (AQN) dark matter model. In our proposal, dark matter is
made of AQNs, which can cross the Earth and emit high energy photons at their
exit. We show that the emitted intensity and spectrum is consistent with Fraser
et al. 2014, and that our calculation is not sensitive to the specific details
of the model. We also find that our proposal predicts a large seasonal
variation, on the level of 20-25%, much larger than conventional dark matter
models (1-10%). Since the AQN emission spectrum extends up to $sim$100 keV,
well beyond the keV sensitivity of XMM-Newton, we predict the AQN contribution
to the hard X-ray and $gamma$-ray backgrounds in the Earth’s environment. The
Gamma-Ray Burst Monitor instrument (GBM), aboard the Fermi telescope, is
sensitive to the 8 keV-40 MeV energy band. We suggest that the multi-year
archival data from the GBM could be used to search for a seasonal variation in
the near-Earth environment up to 100 keV as a future test of the AQN framework.
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