Two different model-independent mapping techniques have been applied to CGRO OSSE , SMM , TGRS and balloon data and reveal a feature in the 0.511 MeV e ^ { + } -e ^ { - } annihilation radiation pattern of our galaxy centered at \ell \sim - 2 ^ { \circ } and b \sim 10 ^ { \circ } with a flux of \sim 5 \cdot 10 ^ { -4 } 0.511 MeV ph cm ^ { -2 } s ^ { -1 } .
If near the galactic center , then e ^ { + } sources are producing \sim 10 ^ { 42 } e ^ { + } s ^ { -1 } which annihilate \approx 1 - 2 kpc above the galactic plane .
A starburst episode within the inner few hundred pc of our galaxy would drive hot pair-laden gas into the halo , with the one-sidedness pointing to the site of initial pressure release at the onset of the starburst activity .
Positrons lose energy and annihilate as they are convected upward with the gas flow , and we calculate high-latitude annihilation patterns and fluxes in accord with the observations .
Changes in the ionization state when the escaping gas cools could give annihilation radiation substructure .
The fountain of hot ( \sim 10 ^ { 6 } - 10 ^ { 7 } K ) gas rising into the galactic halo would be seen through its enhanced dispersion measure , thermal emission , and recombination radiation .