Abstract A new configuration of magnetic field (NCMF) in black hole (BH) magnetosphere is proposed by considering the effects of the screw instability. Three mechanisms of extracting energy magnetically are involved in the NCMF: (1) the Blandford—Znajek (BZ) process; (2) the magnetic coupling (MC) process; (3) a new scenario (henceforth the DL process) for extracting rotational energy from the disc, which is related to the open field lines connecting the disc with the astrophysical load. The expressions for the powers and torques of the above energy mechanisms are derived by using two kinds of the equivalent circuits. It turns out that the power and efficiency of extracting energy magnetically from the BH accretion disc are all augmented in the NCMF. It is shown that a very steep emissivity can be produced in a NCMF, which is consistent with the recent XMM-Newton observation of the nearby bright Seyfert 1 galaxy MCG-6-30-15.
Received: 21 April 2004
Revised: 31 October 2004
Accepted manuscript online:
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos 10173004, 10373006 and 10121503).
Cite this article:
Ye Yong-Chun (叶永春), Wang Ding-Xiong (汪定雄), Gong Xiao-Long (龚小龙) Magnetic extraction of energy from black hole accretion disc and its application to astrophysics 2005 Chinese Physics 14 439
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