D. Cohen
DoAr 21 manuscript

f-to-i modeling figure caption
Figure file: doar21_SiXIII_ftoi.eps

Caption: Three different models of the Si XIII f/i ratio's dependence on electron density are shown: Blumenthal, Drake, & Tucker (1972) (solid curved line), a custom-computed model using the PrismSpect excitation kinematics code and the ATBASE atomic data package (MacFarlane et al. 2005) (dashed curve), and Porquet et al. (2001) (dotted curve).  The best-fit f/i ratio from our simultaneous fits of three Gaussian components and a power-law continuum component to the resonance, intercombination, and forbidden lines of the Si XIII line complex in the MEG and HEG data (shown in the bottom two panels of Fig. 14) is displayed as a thick, solid, horizontal line (at the derived value of 1.7).  As can be seen from the graph, this value implies an electron density of $n_e \approx 2.5 \times 10^{13}$ cm$^{-3}$, using the PrismSpect model.  The other two models imply slightly lower values.  The 1 sigma upper limit to the electron density (desnoted by the dash-dot line, and inferred from the lower limit to the f/i ratio) is roughly $8 \times 10^{13}$ cm$^{-3}$, with slightly lower values implied by the other two models.  The 1 -sigma upper limit to the f/i ratio implies a lower limit to the electron density, but as can be seen from the graph, the Porquet et al. (2005) model is unconstrained by the fitted upper limit of the f/i ratio, and the other two models are only marginally constrained.