Electron‐Positron Annihilation Radiation from Sagittarius A East at the Galactic Center

Maps of the Galactic electron-positron annihilation radiation show evidencefor three distinct and significant features: (1) a central bulge source, (2)emission in the Galactic plane, and (3) an enhancement of emission at positivelatitudes above the Galactic Center. In this paper, we explore the possibilitythat Sgr A East, a very prominent radio structure surrounding the Galacticnucleus, may be a significant contributer to the central bulge feature. Themotivation for doing so stems from a recently proposed link between this radioobject and the EGRET gamma-ray source 2EG J1746-2852. If this association iscorrect, then Sgr A East is also expected to be a source of copious positronproduction. The results presented here show that indeed Sgr A East must haveproduced a numerically significant population of positrons, but also that mostof them have not yet had sufficient time to thermalize and annihilate. As such,Sgr A East by itself does not appear to be the dominant current source ofannihilation radiation, but it will be when the positrons have cooledsufficiently and they have become thermalized. This raises the interestingpossibility that the bulge component may be due to the relics of earlierexplosive events like the one that produced Sgr A East.Comment: This manuscript was prepared with the AAS Latex macros v4.0 It is 37 pages long and has 16 figure