Weekly seminars

# Monte-Carlo simulations of X-ray radiation transfer close to a black hole

## par Philippe Laurent (CEA Saclay, APC Paris)

Europe/Paris
Petit Amphi (Annecy-le-Vieux)

### Petit Amphi

#### Annecy-le-Vieux

9 chemin de Bellevue 74940 ANNECY LE VIEUX
Description
In this seminar, I will present the results we obtained from radiation transfer simulations, in particular Comptonisation, close to a black hole horizon. These results was obtained with a general relativistic code, which also implements Compton, pair and photoelectric effects. We have applied it to galactic black hole binaries, and demonstrated, with L. Titarchuk, that the power law spectral component observed from such binaries in their high/soft state should be due to the Comptonisation of photons on free-falling electrons. We have also shown that the observed iron lines may be red-skewed due to Comptonisation in an outflow surrounding the black hole. In the past year, we have computed that pair creation could also occur very close to the horizon, and, due to the gravitational redshift, the resulting 511 keV gamma-ray lines may appear to an external observer as a thermal-like'' continuum.
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