The Observed Galactic Annihilation Line: Possible Signature of Accreting Small-Mass Black Holes in the Galactic Center

Compton Gamma Ray Observatory, OSSE, SMM, TGRS, balloon and recent INTEGRAL data reveal a feature of the 0.511 MeV annihilation radiation of the Galactic Center with a flux of approximately 5 × 10 −4 0.511 MeV photons cm −2 s −1 . We argue that e + e − pairs can be generated when the X-ray radiation photons and ∼ 10 − 30 MeV photons interact with each other in the compact region in the proximity of the Galactic Center black hole. In fact, disks formed near black holes of 10 17 g mass should emit the ∼ 10 MeV temperature blackbody radiation. If positron (e + ) sources are producing about 10 42 e + s −1 near the Galactic Center they would annihilate on the way out and result in 0.511 MeV emission. We suggest that the annihilation radiation can be an observational consequence of the interaction of the accretion disk radiation of the SMall Mass Black Holes (SMMBHs) with X-ray radiation in the Galactic Center. This is probably the only way to identify and observe these SMMBHs.