Rohan Raha, Banibrata Mukhopadhyay, Koushik Chatterjee
ABSTRACT Using high-resolution general relativistic magnetohydrodynamic (GRMHD) simulations, we investigate accretion flows around spinning black holes and identify three distinct accretion states. Our results suggest the origin of the complex phenomenology observed across the black hole mass spectrum as the interplay between magnetic and gravitational fields. The magnetically arrested disc (MAD) state, characterized by strong magnetic fields (plasma-$\beta \ll 1$), exhibits powerful jets, highly variable accretion, and significant sub-Keplerian motion. On the other hand, weakly magnetized discs (plasma-β$\gg$1), known as the standard and normal evolution (SANE) state, show steady accretion with primarily winds. An intermediate state bridges the gap between MAD and SANE regimes, with moderate magnetic support (plasma-$\beta \sim 1$) producing mixed outflow morphologies and complex variability. This unified framework has many implications including its possible connection to extreme variability of GRS 1915+105, particularly in its hard spectral states. It also suggests the possible origin of steady jets of Cyg X-1 and the unusually high luminosities (even super-Eddington based on stellar mass black hole) of HLX-1 without requiring super-Eddington mass accretion rates. Our simulations reveal a hierarchy of time-scales that explain the rich variety of variability patterns, with magnetic processes driving transitions between states. Comparing two- with three-dimensional simulations demonstrates that while quantitative details differ, the qualitative features distinguishing different accretion states remain robust.