Aaron C. Vincent, Pierrick Martin, James M. Cline
We compare the full-sky morphology of the 511 keV gamma ray excess measured
by the INTEGRAL/SPI experiment to predictions of models based on dark matter
(DM) scatterings that produce low-energy positrons: either MeV-scale DM that
annihilates directly into e+e- pairs, or heavy DM that inelastically scatters
into an excited state (XDM) followed by decay into e+e- and the ground state.
By direct comparison to the data, we find that such explanations are consistent
with dark matter halo profiles predicted by numerical many-body simulations for
a Milky Way-like galaxy. Our results favor an Einasto profile over the cuspier
NFW distribution and exclude decaying dark matter scenarios whose predicted
spatial distribution is too broad. Our analysis is independent of the details
of the DM model, and we obtain a good fit to the shape of the signal using six
fewer degrees of freedom than previous empirical fits to the 511 keV data. We
find that the ratio of flux at Earth from the galactic bulge to that of the
disk is between 1.9 and 2.4, taking into account that 73% of the disk
contribution may be attributed to the beta decay of radioactive 26Al.
View original:
http://arxiv.org/abs/1201.0997
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