2012ApJ...746...87H

Spectral fits to M87 core data from radio to hard X-ray are generated via a specially selected software suite, comprised of the High-Accuracy Relativistic Magnetohydrodynamics GRMHD accretion disk model and a two-dimensional Monte Carlo radiation transport code. By determining appropriate parameter changes necessary to fit X-ray-quiescent and flaring behavior of M87's core, we assess the reasonableness of various flaring mechanisms. This shows that an accretion disk model of M87's core out to 28 GM/c ² can describe the inner emissions. High spin rates show GRMHD-driven polar outflow generation, without citing an external jet model. Our results favor accretion rate changes as the dominant mechanism of X-ray flux and index changes, with variations in density of approximately 20% necessary to scale between the average X-ray spectrum and flaring or quiescent spectra. The best-fit parameters are black hole spin a/M > 0.8 and maximum accretion flow density n ≤ 3x10⁷/cm3, equivalent to horizon accretion rates between {dot}m = {dot}M/{dot}M_Edd ≈ 2x 10^–6 and 1x10^–5 (with {dot}M_Edd defined assuming a radiative efficiency η = 0.1). These results demonstrate that the immediate surroundings of M87's core are appropriate to explain observed X-ray variability.