Magnetic Flux Plays an Important Role during a Black Hole X-Ray Binary Outburst in Radiative Two-temperature General Relativistic Magnetohydrodynamic Simulations

Black hole (Bh) X-ray binaries cycle through different spectral states of accretion over the course of months to years. Although persistent changes in the Bh mass accretion rate are generally recognized as the most important component of state transitions, it is becoming increasingly evident that magnetic fields play a similarly important role. In this article, we present the first radiative two-temperature general relativistic magnetohydrodynamics simulations in which an accretion disk transitions from a quiescent state at an accretion rate of M similar to 10 - 10 M Edd to a hard-intermediate state at an accretion rate of M similar to 10 - 2 M Edd . This huge parameter space in mass accretion rate is bridged by artificially rescaling the gas density scale of the simulations. We present two jetted BH models with varying degrees of magnetic flux saturation. We demonstrate that in "standard and normal evolution" models, which are unsaturated with magnetic flux, the hot torus collapses into a thin and cold accretion disk when M greater than or similar to 5 x 10 - 3 M Edd . On the other hand, in "magnetically arrested disk" models, which are fully saturated with vertical magnetic flux, the plasma remains mostly hot with substructures that condense into cold clumps of gas when M greater than or similar to 1 x 10 - 2 M Edd . This suggests that the spectral signatures observed during state transitions are closely tied to the level of magnetic flux saturation.