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Aschwanden M.J.,Lockheed Martin | Boerner P.,Lockheed Martin | Ryan D.,Solar Terrestrial Center for Excellence | Caspi A.,Southwest Research Institute | And 2 more authors.
Astrophysical Journal | Year: 2015

We present the second part of a project on the global energetics of solar flares and coronal mass ejections that includes about 400 M- and X-class flares observed with the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) during the first 3.5 yr of its mission. In this Paper II we compute the differential emission measure (DEM) distribution functions and associated multithermal energies, using a spatially-synthesized Gaussian DEM forward-fitting method. The multithermal DEM function yields a significantly higher (by an average factor of ≈14), but more comprehensive (multi-)thermal energy than an isothermal energy estimate from the same AIA data. We find a statistical energy ratio of ≈ 2-40% between the multithermal energy Eth and the magnetically dissipated energy Ediss, which is an order of magnitude higher than the estimates of Emslie et al. 2012. For the analyzed set of M- and X-class flares we find the following physical parameter ranges: cm for the length scale of the flare areas, K for the DEM peak temperature, K for the emission measure-weighted temperature, cm-3 for the average electron density, cm-3 for the DEM peak emission measure, and erg for the multithermal energies. The deduced multithermal energies are consistent with the RTV scaling law , which predicts extremal values of erg for the largest flare and erg for the smallest coronal nanoflare. The size distributions of the spatial parameters exhibit powerlaw tails that are consistent with the predictions of the fractal-diffusive self-organized criticality model combined with the RTV scaling law. © 2015. The American Astronomical Society. All rights reserved.. Source

Aschwanden M.J.,Lockheed Martin | Boerner P.,Lockheed Martin | Caspi A.,Southwest Research Institute | McTiernan J.M.,University of California at Berkeley | And 2 more authors.
Solar Physics | Year: 2015

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 (Formula presented.), the peak emission measure (Formula presented.), the total emission measure (Formula presented.), and the multi-thermal energies (Formula presented.). We find that the AIA spatial-synthesis, the EVE+GOES, and the EVE+RHESSI method yield the most accurate results. © 2015, Springer Science+Business Media Dordrecht. Source

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