Benchmark Test of Differential Emission Measure Codes and Multi-thermal Energies in Solar Active Regions

Abstract

We compare the ability of 11 differential emission measure (DEM) forward-fitting and inversion methods to constrain the properties of active regions and solar flares by simulating synthetic data using the instrumental response functions of the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) and EUV Variability Experiment (SDO/EVE), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and the Geostationary Operational Environmental Satellite/X-ray Sensor (GOES/XRS). The codes include the single-Gaussian DEM, a bi-Gaussian DEM, a fixed-Gaussian DEM, a linear spline DEM, the spatial-synthesis DEM, the Monte-Carlo Markov Chain DEM, the regularized DEM inversion, the Hinode/X-Ray Telescope (XRT) method, a polynomial spline DEM, an EVE+GOES, and an EVE+RHESSI method. Averaging the results from all 11 DEM methods, we find the following accuracies in the inversion of physical parameters: the EM-weighted temperature $T_{\mathrm{w}}^{\mathrm{fit}}/T_{\mathrm{w}}^{\mathrm{sim}}=0.9\pm0.1$ , the peak emission measure $\mathit{EM}_{\mathrm{p}}^{\mathrm{fit}}/\mathit{EM}_{\mathrm{p}}^{\mathrm{sim}}=0.6\pm0.2$ , the total emission measure $\mathit{EM}_{\mathrm{t}}^{\mathrm{fit}}/\mathit{EM}_{\mathrm{t}}^{\mathrm{sim}}=0.8\pm0.3$ , and the multi-thermal energies $E_{\mathrm{th}}^{\mathrm{fit}}/\mathit{EM}_{\mathrm{th}}^{\mathrm {approx}}=1.2\pm0.4$ . We find that the AIA spatial-synthesis, the EVE+GOES, and the EVE+RHESSI method yield the most accurate results.