2 research outputs found
Nuclear Interaction Gamma-Ray Lines from the Galactic Center Region
Aims. The accretion of stars onto the central supermassive black hole at the
center of the Milky Way is predicted to generate large fluxes of
subrelativistic ions in the Galactic center region. We analyze the intensity,
shape and spatial distribution of de-excitation gamma-ray lines produced by
nuclear interactions of these energetic particles with the ambient medium.
Methods. We first estimate the amount and mean kinetic energy of particles
released from the central black hole during star disruption. We then calculate
from a kinetic equation the energy and spatial distributions of these particles
in the Galactic center region. These particle distributions are then used to
derive the characteristics of the main nuclear interaction gamma-ray lines.
Results. Because the time period of star capture by the supermassive black
hole is expected to be shorter than the lifetime of the ejected fast particles
against Coulomb losses, the gamma-ray emission is predicted to be stationary.
We find that the nuclear de-excitation lines should be emitted from a region of
maximum 5 angular radius. The total gamma-ray line flux below 8 MeV is
calculated to be photons cm s. The most
promising lines for detection are those at 4.44 and 6.2 MeV, with a
predicted flux in each line of photons cm s.
Unfortunately, it is unlikely that this emission can be detected with the
INTEGRAL observatory. But the predicted line intensities appear to be within
reach of future gamma-ray space instruments. A future detection of
de-excitation gamma-ray lines from the Galactic center region would provide
unique information on the high-energy processes induced by the central
supermassive black hole and the physical conditions of the emitting region.Comment: 7 pages, 5 figures, accepted for publication in A&