Hydrostatic modeling of the integrated soft X-ray and extreme ultraviolet emission in solar active regions

Many studies of the solar corona have shown that the observed X-ray luminosity is well correlated with the total unsigned magnetic flux. In this paper we present results from the extensive numerical modeling of active regions observed with the Solar and Heliospheric Observatory (SOHO) EUV Imaging Telescope (EIT), the Yohkoh Soft X-Ray Telescope (SXT), and the SOHO Michelson Doppler Imager (MDI). We use potential field extrapolations to compute magnetic field lines and populate these field lines with solutions to the hydrostatic loop equations assuming steady, uniform heating. Our volumetric heating rates are of the form epsilon(H) similar to B-alpha/L-beta B-alpha/L-beta, where B is the magnetic field strength averaged along a field line and L is the loop length. Comparisons between the observed and simulated emission for 26 active regions suggest that coronal heating models that scale as epsilon H similar to B-alpha/L-beta, where in the closest agreement with the observed emission at high temperatures. The field-braiding reconnection model of Parker, for example, is consistent with our results. We find, however, that the integrated intensities alone are insufficient to uniquely determine the parameterization of the volumetric heating rate. Visualizations of the emission are also needed. We also find that there are significant discrepancies between our simulation results and the lower temperature emission observed in the EIT channels.