Speaker
Description
In this work, we investigate the global structure of shock-induced general relativistic magneto-hydrodynamic (GRMHD) accretion flows around a Kerr black hole, where the disk is threaded by the radial ($b^r$) and the toroidal ($b^\phi$) magnetic fields. In doing so, we consider an advective, axisymmetric, and optically thin accretion flow that is confined in the disk mid-plane. In addition, we adopt the relativistic equation of state and obtain the trans-magnetosonic accretion solutions in the ideal MHD limit. In a magnetized flow, the inflowing matter experiences centrifugal repulsion and an additional barrier due to the magnetic pressure that eventually causes a discontinuous shock transition of the flow variables following the necessary shock conditions. With this, we examine the shock dynamics with the variation of radial magnetic flux ($\Phi$) and the iso-rotation parameter ($F$) rather than the local magnetic fields ($b^r,b^\phi$). However, the shock properties and dynamics of the post-shock corona (PSC) are largely driven by the radial magnetic flux ($\Phi$), whereas the effect of $F$ is less significant. It is worth mentioning that the toroidal magnetic field jumps significantly across the shock front, resulting in a highly magnetized PSC. We further identify the effective region of the parameter space for standing fast-MHD shocks and observe that shock forms for a wide range of flow parameters, namely energy ($E$), angular momentum ($L$), and radial magnetic flux ($\Phi$), respectively. Meanwhile, we observe that the shocked GRMHD flow fails to achieve the Magnetically Arrested Disk (MAD) state in the mid-plane, yet it sustains a `SANE' (Standard And Normal Evolution) flux. Finally, we discuss the astrophysical importance of low-angular momentum accretion flows in the realm of GRMHD.
