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We discuss the effects of a comptonizing corona on the appearance of the reflection components, and in particular of the reflection hump, in the X-rays spectra of accreting black holes. Indeed, in the framework of a thermal corona model, we expect that part (or even all, depending on the coronal covering factor) of the reflection features should cross the hot plasma, and thus suffer Compton scattering, before being observed. We have studied in detail the dependence of these effects on the physical (i.e. temperature and optical depth) and geometrical (i.e. inclination angle) parameters of the corona, concentrating on the slab geometry . Due to the smoothing and shifting towards high energies of the comptonized reflection hump, the main effects on the emerging spectra appear above 100 keV. We have also investigated the importance of such effects on the interpretation of the results obtained with the standard fitting procedures. We found that fitting Comptonization models, taking into account comptonized reflection, by the usual cut-off power law + uncomptonized reflection model, may lead to an underestimation of the reflection normalization and an overestimation of the high energy cut-off. We discuss and illustrate the importance of these effects by analysing recent observational results as those of the galaxy NGC 4258. We also find that the comptonizing corona can produce and/or emphasize correlations between the reflection features characteristics (like the iron line equivalent width or the covering fraction) and the X-ray spectral index similar to those recently reported in the literature. We also underline the importance of these effects when dealing with accurate spectral fitting of the X-ray background.
Narrow absorption lines seen in the 2-10 keV spectra of active galaxies and Galactic black holes are normally attributed to iron in high velocity outflows or inflows. We consider the possibility that such features could arise naturally in the accreti
The geometry of the accretion flow around stellar-mass black holes can change on timescales of days to months. When a black hole emerges from quiescence (that is, it turns on after accreting material from its companion) it has a very hard (high-energ
It has been suggested that adiabatic energy losses are not effective in stationary jets, where the jet expansion is not associated with net work. Here, we study jet solutions without them, assuming that adiabatic losses are balanced by electron reacc
We attempt to explain the observed radio and gamma-ray emission produced in the surrounds of black holes by employing a magnetically-dominated accretion flow (MDAF) model and fast magnetic reconnection triggered by turbulence. In earlier work, standa