标题： 剪切黑洞吸积日冕中相对论喷流的形成 显示英文标题

标题： Formation of Relativistic Outflows in Shearing Black Hole Accretion Coronae

摘要： 我们考察了在许多活动星系核中观测到的相对论喷流可能由紧邻双温度吸积盘上方稀薄日冕中的质子费米加速提供能量的可能性。在这种图景中，加速是由于日冕中磁场所产生的剪切运动，这些磁场锚定在下面的开普勒盘上。日冕中的质子具有幂律分布，因为那里的密度太低，无法通过质子-质子碰撞使通过费米加速提供的能量热化。然而，同样的剪切加速机制也在盘本身中起作用，不过在那儿密度足够高以发生热化，因此盘中的质子具有麦克斯韦分布。日冕中的粒子加速导致发展出一种压力驱动的风，该风经过临界点后，在远离黑洞的地方转变为相对论喷流。我们将风的临界条件与盘和日冕的结构方程相结合，得到一个耦合的盘/日冕/风模型。利用耦合模型，我们计算了喷流的渐近洛伦兹因子$\Gamma_\infty$作为流出物在日冕中起始圆柱半径的函数。我们的结果表明$\Gamma_\infty \lapprox 10$，这与类星体中超光速运动的观测结果一致。我们展示了喷流与宽线发射云之间的碰撞可以产生足够亮度的高能辐射，以驱动从类星体观测到的$\gamma$射线。主题词：辐射机制：非热，吸积，吸积盘，粒子加速，伽马射线：理论 显示英文摘要

摘要： We examine the possibility that the relativistic jets observed in many active galactic nuclei may be powered by the Fermi acceleration of protons in a tenuous corona above a two-temperature accretion disk. In this picture the acceleration arises as a consequence of the shearing motion of the magnetic field in the corona, which is anchored in the underlying Keplerian disk. The protons in the corona have a power-law distribution because the density there is too low for proton-proton collisions to thermalize the energy supplied via Fermi acceleration. The same shear acceleration mechanism also operates in the disk itself, however, there the density is high enough for thermalization to occur and consequently the disk protons have a Maxwellian distribution. Particle acceleration in the corona leads to the development of a pressure-driven wind that passes through a critical point and subsequently transforms into a relativistic jet at large distances from the black hole. We combine the critical conditions for the wind with the structure equations for the disk and the corona to obtain a coupled disk/corona/wind model. Using the coupled model we compute the asymptotic Lorentz factor $\Gamma_\infty$ of the jet as a function of the cylindrical starting radius at the base of the outflow, in the corona. Our results suggest that $\Gamma_\infty \lapprox 10$, which is consistent with observations of superluminal motion in blazars. We show that collisions between the jet and broad-line emission clouds can produce high-energy radiation with a luminosity sufficient to power the $\gamma$-rays observed from blazars. Subject headings: radiation mechanisms: non-thermal, accretion, accretion disks, acceleration of particles, gamma rays: theory