Launching and quenching of black hole relativistic jets at low accretion rate

Hung Yi Pu*, Kouichi Hirotani, Hsiang Kuang Chang


研究成果: 雜誌貢獻期刊論文同行評審

6 引文 斯高帕斯(Scopus)


Relativistic jets are launched from black hole (BH) X-ray binaries and active galactic nuclei when the disk accretion rate is below a certain limit (i.e., when the ratio of the accretion rate to the Eddingtion accretion rate, ?m, is below about 0.01) but quenched when above. We propose a new paradigm to explain this observed coupling between the jet and the accretion disk by investigating the extraction of the rotational energy of a BH when it is surrounded by different types of accretion disk. At low accretion rates (e.g., when ?m ≲ 0.1), the accretion near the event horizon is quasi-spherical. The accreting plasmas fall onto the event horizon in a wide range of latitudes, breaking down the force-free approximation near the horizon. To incorporate the plasma inertia effect, we consider the magnetohydrodynamical (MHD) extraction of the rotational energy from BHs by the accreting MHD fluid, as described by the MHD Penrose process. It is found that the energy extraction operates, and hence a relativistic jet is launched, preferentially when the accretion disk consists of an outer ShakuraSunyaev disk (SSD) and an inner advection-dominated accretion flow. When the entire accretion disk type changes into an SSD, the jet is quenched because the plasmas bring more rest-mass energy than what is extracted from the hole electromagnetically to stop the extraction. Several other issues related to observed BH diskjet couplings, such as why the radio luminosity increases with increasing X-ray luminosity until the radio emission drops, are also explained.

期刊Astrophysical Journal
出版狀態已發佈 - 2012 10月 20

ASJC Scopus subject areas

  • 天文和天體物理學
  • 空間與行星科學


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