We present results of simulations of the spectrum of the accretion flow on to the supermassive black hole in our Galactic Centre, Sagittarius A*, generated with a coupling of Monte Carlo (MC) radiation and general relativistic magnetohydrodynamic codes. In our modelling, we use the two‐dimensional harm grmhd code to first model the physical parameters of the disc, then feed its results into our two‐dimensional MC photon transport code. We will discuss results obtained which fit radio, infrared and Chandra‐obtained flaring or quiescent X‐ray data points, as well as the validity of the amount of scaling of input parameters (density, temperature and magnetic field) required to fit these points. harm output will be used to suggest whether the scaling is within reasonable limits.

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 twodimensional 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 3 × 10 7 cm −3 , equivalent to horizon accretion rates betweenṁ =Ṁ/Ṁ Edd ≈ 2 × 10 −6 and 1 × 10 −5 (withṀ 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.

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