[1] Blandford R D 2002 Proc. MPA/ESO/MPE/USM Joint
Astronomy Conference, Lighthouses of the Universe: The Most Luminous
Celestial Objects and Their Use for Cosmology ed Gilfanov M, Suyaev
R and Churazov E (Berlin: Springer) p 381

[2] Uzdensky D A 2005 Astrophys. J. 620 889

[3] Li L X 2002 Phys. Rev. D 65 084047

[4] Wang D X et al 2007 Mon. Not. R. Astron. Soc.
374 647

[5] Li Y et al 2007 Chin. Phys. Lett. 24 5

[6] Van Putten M H P M et al 2003 Astrophys. J.
584 967

[7] MacDonald D et al 1982 Mon. Not. R. Astron. Soc.
198 345

[8] Lynden-Bell 2003 Mon. Not. R. Astron. Soc. 341
1360

[9] Uzdensky D A et al 2007 Astrophys. J. 669 546

[10] Novikov I D and Thorne K S 1973 Black Holes ed
Dewitt C (New York: Gordon and Breach) p 345

[11] Wang D X et al 2003 Astrophys. J. 595 109

[12] Li L X 2002 Astrophys. J. 567 463

[13] Miller J M et al 2006 Nature 441 953

[14] Miller J M et al 2008 Astrophys. J. (accepted)
arXiv: 0802.2026