From: clidman (clidman@eso.org)
Date: Mon Nov 03 2003 - 20:25:30 PST
Hi Gaston,
I think that the paper is improving with each iteration. However, I do
not think it is ready to go to the entire collaboration just yet. I
hope that we can finish this stage of the internal review process in
one or two iterations.
Most of my comments concern the wording that you have chosen in
several places. However, I do have a couple of important points that
I will address first. I will send you the less important comments in
a day or two.
Distance indicators.
====================
Page 9.
Patat et al. I think that this reference is outdated. Please check the
more recent work of Freedman et al. You will find that SBF and Cephied
distances are in much better agreement.
Averaging the distance estimates of Saha et al. and Freedman et al for
1981B, 1989B and 1990N is bad. You should use one or the other, and I
would suggest that you use just the Freedman et al. estimates for
these 3 SNe. For 91T, you have no choice, you have to use Saha et
al. It is important to stress, as you do in the text, that the Saha et
al. derive larger distances and hence infer SNe Ia to be brighter than
Freedman et al. This is very interesting, because 91T sticks above
the best fits in figures 11 and 12.
Primary versus Secondary Calibrators
====================================
The argument that alpha(2+3) can be use as a second parameter is not
convincing. If you remove 91T, whose absolute luminosity may have been
over-estimated, then a straight line fit is probably equally
plausible. Even with 91T, the error on the slope in equation 7 is
0.03. The slope is a 2 sigma result. However, I think that you should
still show this plot, but I do not think that the result is
significant enough to stake a claim.
The probability argument in the sentence that follows equation 7
should be removed. I do not think that you understand the errors
(mostly from the distance) to make this sort of comparison.
The correlation between alpha(2+3) and absolute magnitude is better
than the correlation between Delta_m15 and absolute magnitude. Hence
we should be arguing that alpha(2+3) is a better primary calibrator.
Why is the scatter in Delta_m15 and absolute magnitude (0.33
magnitudes) so much worse that what has been derived before. This
needs to be understood.
Cheers, Chris.
-- Chris Lidman European Southern Observatory Alonso de Cordova 3107 Casilla 19001 Santiago 19, CHILE Tel. 56 2 463 3106 FAX 56 2 463 3001
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