Properties of the accretion disc, jet and disc-wind around Kerr black hole

Abstract

Relativistic jets and disc-winds are energetic phenomena exhibited by various sources, including Active Galactic Nuclei (AGNs) and black hole X-ray binaries (BH-XRBs). Despite recent observational advances in unraveling the region close to the black hole, many aspects of jet launching and particularly the jet-disc connection in these sources are not fully understood. This study investigates the role of the aspect ratio (H/r) of the underlying accretion disc on the jet launching. In this regard, we use an axisymmetric GRMHD framework with adaptive mesh refinement and initialize our simulations with a thin accretion disc in hydro-static equilibrium. In our simulations, we observe Blandford & Znajek (BZ) jet, Blandford & Payne (BP) disc-wind and Btor dominated disc-wind. We find that the aspect ratio of the underlying accretion disc plays a crucial role in the dynamical properties of jet and disc-winds. For an accretion disc with a low aspect ratio, we observe the BZ-jet be thinner and the Btor dominated disc-wind component of the disc-wind to be broader. Further, the BP disc-wind launching radius is closer for an accretion disc with a low aspect ratio. Such a variable launching area of BP disc-wind with an aspect ratio of the underlying disc can have potential implications on understanding the origin of jet dichotomy. Additionally, from the temporal evolution of magnetic flux, we also find the discs with higher aspect ratios are more susceptible to transform into a magnetically arrested disc (MAD) and result in more intermittent wind and jet properties. © 2022, Indian Academy of Sciences.