From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Thu May 22 2003 - 10:21:21 PDT
Hi Rob,
Ok, this is perfect. Can you find a suitable place in the text to
say that we have also performed the analysis without correcting for
stretch and find the same best-fit cosmological parameters, albeit
a worse value of $\chi^2$.
On Thu, 22 May 2003, Robert A. Knop Jr. wrote:
> On Thu, May 22, 2003 at 08:27:55AM -0700, Greg Aldering wrote:
> > One thing that would make this issue more robust is if we had done a
> > fit with alpha=0 and could say the cosmology wasn't much affected.
>
> OK, I just did that. (Once I managed to get my fits running on PDSF,
> it's possible to do some of them quickly if the jobs don't get backed
> up. It still takes a while to redo everything, more from the
> administration of keeping track of it all, although the CPU time gets
> non-negligible.)
>
> The OM_flat is basically identical; the contours *do* slide along their
> major axis up and to the right, though. (See attached postscript.)
> Script-M is slightly different (goes from -3.48+-.05 to -3.45+-0.05),
> which is probably just due to the mean stretch of the low-z sample not
> being 1.0. The chisquare gets quite a bit worse, which is unsurprising
> given that the best-fit value of alpha was several sigma away from 0.
>
> This is enough for us to say honestly that the cosmology is not affected
> my if you do a fit without alpha. (The shift along the major axis is
> smaller than the "fit method" systematic we're already using.) Where
> should that sentence go into the paper? It probably depends on whether
> or not we leave in the stretch/luminosity figure.
>
> -Rob
>
> --
> --Prof. Robert Knop
> Department of Physics & Astronomy, Vanderbilt University
> robert.a.knop@vanderbilt.edu
>
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