高能暂现源 · 每日文献综述

We propose a unified model for jet formation applicable to active galactic nuclei, young stellar objects, and X-ray binaries. In this model, the binding energy released from the accretion disc is primarily stored as turbulence rather than being radiated away, leading to the formation of advection-dominated accretion flows. Near the central object, a thick accretion disc with funnel-like structures develops. Within the turbulent flows, the smallest stable blobs can be accelerated beyond the escape velocity through the combination of two mechanisms ─ the Gaussian-like velocity distribution within the turbulence and a mechanism involving the combined effects of inward pressure force and angular momentum conservation. These rapidly moving blobs may exit through the funnels, collectively forming two opposing jets. This model predicts that jets originate from the innermost region of the thick disc surrounding the central object. The formation of a jet is directly related to a parameter <inline-formula><tex-math>$\eta$</tex-math></inline-formula> that describes the energy fraction stored in turbulence in units of the binding energy of the local Keplerian energy. <inline-formula><tex-math>$\eta \gt 0.5$</tex-math></inline-formula> is a minimal condition for a jet to form. This model can be extended to account for jet formation in active galactic nuclei, young stellar objects, X-ray binaries, and other analogous astronomical systems.