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In this paper we propose a new mechanism, Penrose pair production in massive, canonical (with a/M = 0.998) Kerr black holes, as a power source in quasars, Seyfert galaxies, radio galaxies, and BL Lac objects (i.e., what one usually refers to as active nuclei). As a working hypothesis, we postulate that massive (10^8 M0 or around this value) Kerr black holes reside in the centers of these objects. We also postulate that an accretion disk is formed. In a variety of models, hot, inner disks are expected. If the temperature is sufficiently high-as, for example, in the two-temperature model-then MeV photons enter the ergosphere. The blueshift may boost up the energy of the infalling photons to near Ge V values. When this happens, photons can scatter off the tangentially moving protons and produce e +, e- pairs. The protons that cross the event horizon give their energy to the ejected pairs (of the order of GeV). This is a Penrose process. Conditions are derived for this mechanism to be important, and it is found that a selfconsistent requirement is that these very hot inner disks are also spatially thick. The process can work only if the rmb torms target region gets filled up with plasma. This cannot happen in steadystate disks; therefore, Penrose pair production can occur only during periods of instabilities. This may help to explain the variability of the extragalactic compact objects. Moreover, this mechanism may be of profound astrophysical importance in helping to explain the vast energies, synchrotron emission-and variability-of the variable, compact extragalactic sources. Time-dependent calculations of hot, thick disks are needed, but the present work illustrates that such calculations cannot ignore Penrose processes like the one we suggest.


This article was originally published in Astrophysical Journal, volume 229, in 1979. DOI: 10.1086/156928

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IOP Publishing



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