Various balloon and satellite observatories have revealed what appears to be an extended source of 0.511 MeV annihilation radiation with a flux of ~10^{-3} photons cm^{-2} s^{-1} centered on the Galactic center. Positrons from radioactive products of stellar explosions can account for a significant fraction of the emission. We discuss an additional source for this emission: namely, e+e- pairs produced when X-rays generated from the ~2.6×10^6 Msolar Galactic center black hole interact with ~10 MeV temperature blackbody emission from 10^{17} g black holes within 10^{14}-10^{15} cm of the center. The number of such small-mass black holes (SMMBHs) can account for the production of the 10^{42} e+ s^{-1} that produces the observed annihilation in the inner Galaxy when transport effects are taken into account. We consider the possibility for confirming the presence of these SMMBHs in the Galactic center region with future generations of γ-ray instruments if a blackbody-like emission of ~10 MeV temperature would be detected by them. SMMBHs can be a potential candidate for the dark (invisible) matter halo.
The Observed Galactic Annihilation Line: Possible Signature of Accreting Small-Mass Black Holes in the Galactic Center
TITARCHUK, Lev;
2006
Abstract
Various balloon and satellite observatories have revealed what appears to be an extended source of 0.511 MeV annihilation radiation with a flux of ~10^{-3} photons cm^{-2} s^{-1} centered on the Galactic center. Positrons from radioactive products of stellar explosions can account for a significant fraction of the emission. We discuss an additional source for this emission: namely, e+e- pairs produced when X-rays generated from the ~2.6×10^6 Msolar Galactic center black hole interact with ~10 MeV temperature blackbody emission from 10^{17} g black holes within 10^{14}-10^{15} cm of the center. The number of such small-mass black holes (SMMBHs) can account for the production of the 10^{42} e+ s^{-1} that produces the observed annihilation in the inner Galaxy when transport effects are taken into account. We consider the possibility for confirming the presence of these SMMBHs in the Galactic center region with future generations of γ-ray instruments if a blackbody-like emission of ~10 MeV temperature would be detected by them. SMMBHs can be a potential candidate for the dark (invisible) matter halo.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.