accretion discs in binary systems of stellar-mass black holes as the static radius exceeds in many orders dimension of the binary systems. But it can be relevant for accretion discs in galaxies with large active nuclei as the static radius puts limit on the extension of the discs well inside the galaxies. Moreover, the agreement (up to one order) of the dimension of the static radius related to the mass parameter of central black holes at nuclei of large galaxies with extension of such galaxies suggests that the RRCC could play an important role in formation and evolution of such galaxies. Of course, the first step in confirming such a suggestion is modelling of the influence of the RRCC on self-gravitating accretion discs.

Acknowledgments {#acknowledgments .unnumbered}
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The present work was supported by the Czech grant MSM 4781305903 and by the Committee for Collaboration of Czech Republic with CERN. The author would like to acknowledge Drs Stanislav Hledík and Petr Slaný for collaboration and the excellent working conditions at the CERN’s Theory Division and SISSA’s Astrophysics Sector, respectively, where part of the work was realized.

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N. Bahcall, J. P. Ostriker, S. Perlmutter and P. J. Steinhardt, , 1481 (1999).

