Si XIV 6.182 Angstroms

Models with isotropic porosity

Note: Both MEG and HEG are fit simultaneously. There are 109 MEG counts and 49 HEG counts in the spectral region we fit (and plot below). See the fitting log.

Same continuum fit as we used for the non-porous models: n=2, best-fit norm=7.62e-4. View the spectral region near the line: MEG or HEG.

Si XIV 6.182: isporous MEG
Si XIV 6.182: isporous HEG 		[6.13:6.24]
vinf=2250
β=1
powerlaw continuum, n=2; norm=7.62e-4
q=0
hinf=12.2   +/- (unconstrained)
taustar=99.9   +/- (0.14:unconstrained)
uo=0.742   +/- (0.660:0.829)
norm=7.80e-6 +/- (6.67e-6:9.02e-6)
rejection probability = 41% (C=129.38; N=128)

Note that very high values of optical depth and porosity length are mildly preferred. But the unrealistic global best-fit shown here shows only a 1.2 improvement in ΔC over the non-porous best-fit model.

Here are the 68%, 90%, and 95% joint confidence limits on taustar and uo based on fitting the MEG and HEG data together. The asterisk indicating the best-fit model is at a high optical depth, but even higher values (off the grid) provide slightly better fits.

Si XIV 6.182: joint uo taustar constraints using MEG+HEG data, allowing for isoporosity

Compare these confidence regions to the ones we derived for the non-porous models. These are much less constraining, because larger values of taustar are possible when porosity is included. The more relevant confidence limits for these porous models, though, are the ones projected into taustar - h space:

Si XIV 6.182: joint h taustar constraints using MEG+HEG data, allowing for isoporosity

Here too, of course, the model fitting rules out very little of parameter space: just the high optical depth, no porosity portion and also regions with very small optical depths.

Next, we fit anisotropic porosity models to the data.

 

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last modified: 2 June 2008