AC1 - Spectral and Temporal properties of Black Holes and neutron stars and the theoretical models |
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Speaker |
Laurent, Philippe |
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Coauthors |
Titarchuk, Lev; Seifina, E.; Chardonnet, P. |
| Talk Title |
Electron-Positron Pairs Creation Close to a Black Hole Horizon. Red-shifted Annihilation Line in the Emergent X-ray Spectra |
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Abstract |
We consider a Compton cloud (CC) surrounding a black hole (BH) in an accreting black hole system, where electrons propagate with thermal and bulk velocities. In that cloud, soft (disk) photons may be up-scattered out of these energetic electrons and attain several MeV energies. They could then create pairs due to photon-photon interactions. In this paper, we study the formation of the 511 keV annihilation line due to these interactions, which result in the creation of electron-positron pairs, followed by the annihilation of the created positrons with the CC electrons. The appropriate conditions of annihilation line generation take place very close to a BH horizon, within a few hundred meters from it. As a result, the created annihilation line should be seen by the Earth observer as a blackbody bump at energies around 20 keV. This transient feature should occur in any accreting black hole systems, galactic or extragalactic. Observational evidences for this feature in several galactic black hole systems will be also detailed. |
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Talk view |
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