Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-04-11
Astrophys.J.592:1089-1099,2003
Astronomy and Astrophysics
Astrophysics
27 pages, 6 figures, ApJ accepted
Scientific paper
10.1086/375798
The iron K line is perhaps the most important spectral diagnostic available in the study of accreting black holes. The line is thought to result from the reprocessing of external X-rays by the surface of the accretion disk. However, as is observed in the solar corona, illumination by energetic particles may also produce line emission. In principle, such a process may be uncorrelated with the observed X-rays and could explain some of the unexpected variability behavior of the Fe line. This paper compares predictions of iron K flux generated by impacting electrons and protons to that from photoionization. Non-thermal power-laws of electrons are considered as well as thermal distributions of electrons and virialized protons. The electrons are thought to originate in a magnetically dominated accretion disk corona, while the protons are considered in the context of a two phase (hot/cold) accretion scenario. In each case, the Fe K flux from particle impact is found to be < 1% of that produced by photoionization by a hard X-ray power-law (normalized to the same energy flux as the particles). Thus, the electrons or protons must strike the disk with 100--10,000 times more energy flux than radiation for particle impact to be a significant producer of Fe K flux. This situation is difficult to reconcile with the observations of hard X-ray spectra, or the proposed particle acceleration mechanisms in the accretion disk corona. Truncated accretion flows must be externally illuminated by hard X-rays in order to produce the Fe line, as proton impact is very inefficient in generating line emission. In contrast to the Sun, our conclusion is that, with the possible exception for localized regions around magnetic footpoints, particle impact will not be an important contributor to the X-ray emission in accreting black holes.
Ballantyne David R.
Fabian Andrea C.
No associations
LandOfFree
The Contribution of Particle Impact to the Production of Fe K Emission from Accreting Black Holes 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 The Contribution of Particle Impact to the Production of Fe K Emission from Accreting Black Holes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Contribution of Particle Impact to the Production of Fe K Emission from Accreting Black Holes will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-410884