Two different model-independent mapping techniques have been applied t
o Compton Gamma Ray Observatory OSSE, SMM, TGRS, and balloon data and
reveal a feature in the 0.511 MeV e(+)-e(-) annihilation radiation pat
tern of our Galaxy centered at I similar to -2 degrees and b similar t
o 10 degrees with a flux of approximately 5 x 10(-4) 0.511 MeV photons
cm(-2) s(-1) If near the Galactic center, then positron (e(+)) source
s are producing about 10(42) e(+) s(-1), which annihilate approximate
to 1-2 kpc above the Galactic plane. A starburst episode within the in
ner few hundred parsecs of our Galaxy would drive hot pair-laden gas i
nto the halo, with the one-sidedness pointing to the site of initial p
ressure 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 ac
cord with the observations. Changes in the ionization state when the e
scaping gas cools could give annihilation radiation substructure. The
fountain of hot (similar to 10(6)-10(7) K) gas rising into the Galacti
c halo would be seen through its enhanced dispersion measure, thermal
emission, and recombination radiation.