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Title: How far do Galactic positrons travel before annihilating?
Plain: If positrons made in the disk can drift into the bulge before annihilating, ordinary disk sources could explain the bulge glow.
Precise: Determine the distribution of propagation distances of positrons born at energies below a few MeV in the warm, hot and neutral phases of the interstellar medium, with slowing-down times of $\sim 1e5\text{ to }1e7\,\mathrm{yr}$ and realistic magnetic turbulence. Answer: the fraction of disk-born positrons that annihilate in the bulge, compared with the observed bulge-to-disk ratio and line width.
Settled by: Transport calculations with measured interstellar turbulence spectra, validated against the line width and positronium fraction.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: contested
Status note: (empty)
Posed since: (empty)