Astronomy and Astrophysics – Astrophysics
Scientific paper
1997-09-29
Astronomy and Astrophysics
Astrophysics
The paper has been expanded (by about 10%) to provide a more detailed discussion of the physics described. None of the results
Scientific paper
Some recent work has shown that the spectrum of Seyfert 1 Galaxies is very similar to that of several Galactic Black Hole Candidates (GBHCs) in their hard state. However, the smallness of the observed reflection component in Cygnus X-1, in addition to other constraints, seem to rule out the two-phase model (otherwise successful in the case of Seyfert Galaxies) for GBHCs. Here, we show that the latter conclusion is based on a number of key assumptions that probably are not valid when the overlying corona is patchy, e.g., when it is comprised of localized magnetic flares above the disk. We show that in GBHCs the energy deposited by the X-rays cannot be re-radiated fast enough to maintain equilibrium, unless the X-ray skin heats up to the Compton temperature, at which point the gas is mostly ionized. This leads to a substantially reduced cooling rate for the active regions due to the correspondingly smaller number of re-injected low-energy photons. We model this effect by introducing a transition layer situated between the corona and the cold disk, and find that the resulting spectrum is harder than that obtained with the standard (and unrealistic) two-phase model. We apply this model to Cygnus X-1 and show that it can account for its observed spectrum. This analysis therefore seems to provide a consistentpicture for both Seyfert Galaxies and GBHCs within the same framework, with differences arising due to the changing physical conditionsin the two categories of sources, rather than due to an ad hoc variation of the model parameters.
Melia Fulvio
Nayakshin Sergei
No associations
LandOfFree
X-rays From Magnetic Flares In Cygnus X-1: A Unified Model With Seyfert Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with X-rays From Magnetic Flares In Cygnus X-1: A Unified Model With Seyfert Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-rays From Magnetic Flares In Cygnus X-1: A Unified Model With Seyfert Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-486608