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We have pointed out that, when thermal relativistic electrons with an isotropic velocity distribution move through a region of dense gas or impinge upon its surface, the Cerenkov effect will produce a particular kind of atomic or ionic emission line, which we have called the “Cerenkov line-like radiation”. This prediction for the optical wavebands has been verified by laboratory experiments. In this paper, we extend this line-like radiation theory to the X-ray waveband and give the basic formulae for calculating the intensity ratio and intrinsic redshift ratio of the Cerenkov iron Kα and Kβ lines, for different ionization orders of iron. Potential application of this calculated result may be found in the study of AGNs. The recent observations of NGC3783 show that besides the iron Kα line at ∼6.4 keV, there is also a very strong iron Kβ line at ∼7.0 keV, and that the ratio of equivalent widths between the two is anomalous: EWKα/EWKβ ≈ 3.43. It is difficult to explain this by the conventional mechanism of “photoelectric absorption-fluorescence emission”. We suggest that the mechanism of Cerenkov line-like radiation can provides a way of solving this puzzle. Besides, we expect that the calculated intrinsic redshift ratio of Cerenkov iron Kα and Kβ lines could be tested in future observations. If our suggestion is further supported by observations, then our view on the physical environment around the central massive black hole of an AGN will be greatly modified: the activity becomes more energetic and violent, and the gas, much denser than previously thought. 相似文献
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T. P. Singh 《Journal of Astrophysics and Astronomy》1999,20(3-4):221-232
This article gives an elementary review of gravitational collapse and the cosmic censorship hypothesis. Known models of collapse
resulting in the formation of black holes and naked singularities are summarized. These models, when taken together, suggest
that the censorship hypothesis may not hold in classical general relativity. The nature of the quantum processes that take
place near a naked singularity, and their possible implication for observations, is briefly discussed. 相似文献
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Black hole spin in GRS 1915+105 总被引:2,自引:0,他引:2