Fe XVII 15.014 Angstroms

Models with isotropic porosity

Note: Both MEG and HEG are being fit simultaneously

Same continuum fit as we used for the non-porous models: n=2, best-fit norm=1.71e-3.

Note that the opacity bridging law used for these isoporosity fits is Rosseland.

Fe XVII 15.014: both, isoporosity, MEG Fe XVII 15.014: both, isoporosity, HEG [14.87:15.13]
vinf=2250
β=1
powerlaw continuum, n=2; norm=1.71e-3
q=0
hinf=0.00   +/- (0.00:0.43) and for 90%
      confidence, (0.00:1.07)
taustar=1.94   +/- (1.63:2.29)
uo=0.646   +/- (0.597:0.700)
norm=5.30e-4 +/- (5.07e-4:5.49e-4)
rejection probability = 27% (C=280.82; N=308)

This best-fit model is nearly identical to the non-porous best-fit model, as a value of hinf=0.00 is preferred even when a non-zero porosity length is allowed.

Here are the 68%, 90%, and 95% joint confidence limits on hinf and taustar. The asterisk represents the best-fit model, shown as the red histograms on the above two plots.

Fe XVII 15.014: isoporous - confidence contours: hinf vs taustar MEG and HEG

And here are the joint constraints on taustar and uo:

Fe XVII 15.014: isoporous - confidence contours: taustar vs umax MEG and HEG

Here is the best-fit isoporous model with taustar=8 fixed. This represents the value implied by the literature mass-loss rate. It can be seen in the first of the two confidence limit contour plots above that this value of taustar lies outside of the 95% confidence range.

Fe XVII 15.014: both, isoporosity, taustar=8, MEG Fe XVII 15.014: both, isoporosity, taustar=8, HEG [14.87:15.13]
vinf=2250
β=1
powerlaw continuum, n=2; norm=1.71e-3
q=0
hinf=3.64   +/- (2.89:4.51) and for 90%
      confidence, (2.51:5.21)
taustar=8
uo=0.623   +/- (0.591:0.661)
norm=5.25e-4 +/- (5.07e-4:5.49e-4)
rejection probability = 50% (C=295.74; N=308)

Note that the value of the fit statistic, C=295.74, is ~15 higher than the best-fit value, which implies that the best-fit model (with taustar free) is preferred at >99.9% confidence. The porous model with high optical depth leads to a profile with a bulge on the far blue wing and also one near line center. However, this model with taustar=8 and non-zero hinf cannot be rejected outright as a bad fit. It does, however, require a terminal porosity length of at least 2.51 (even at the 90% confidence level on the taustar=8 model).

Next, we fit an anisotropic porosity model to the data.

 

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last modified: 29 April 2008