Simulation of global resistive MHD accretion flows around spinning AGNs: the impact of resistivity on the MAD state

We conduct global resistive magnetohydrodynamic (Res-MHD) simulations to study accretion flows around spinning active galactic nuclei (AGNs). For this purpose, we consider both 2D and 3D models to understand the dynamics of accretion. We perform a comparative study of these 2D and 3D models based on our Res-MHD simulations. To accurately replicate the space-time geometry of black holes, we utilize an effective Kerr potential. To explore the effects of magnetic resistivity on accretion and ejection around black holes, we vary the resistivity values as follows: \(\eta = 0.1, 0.01, 10^{-3}, 10^{-5}\), and \(\sim 0.0\) (ideal MHD). Our simulations indicate that a `magnetically arrested disk' (MAD) state is achieved in all resistive cases for both the 2D and 3D models. We observe that higher resistivity in the flow leads to significant diffusion and suppression of turbulent structures within the accretion flow. Furthermore, we find that for resistivity values below \(\eta \leq 10^{-3}\), the structure and turbulence appear qualitatively similar. Notably, we observe indications of plasmoid formation in the moderately low-resistive flow (\(\eta \leq 10^{-3}\)). We discuss the potential implications of these plasmoids in relation to radio flaring events associated with SgrA*.