From: Ariel Goobar (ariel@physto.se)
Date: Tue May 20 2003 - 05:18:15 PDT
So, then you probably can tell me what the significance of
E(B_V)>0.1 is in terms of intrinsic spread. I, at least, have not seen
any evidence that this would correspond to more than 2 sigma. Furthermore
it all boils down to your template, which, I think disagrees with
Serena's by a non-negligible amount in this context. Have you checked
how the K-corrections change for the two choices of template?
On Tue, 20 May 2003, Robert A. Knop Jr. wrote:
> On Tue, May 20, 2003 at 11:52:54AM +0200, Ariel Goobar wrote:
> > Here is where my largest worries are and I would appriciate your
> > comments on the following. You have neglected the possibility
> > of intrinsic color dispersion in Fig 4. Thus, you argue that there are
> > 4 SNe which are "clearly" reddened. I would think that at least one of them
> > (z=0.64) is likely to be red rather than reddened. In addition you
> > have ommited the K-correction error, also critical for the interpretation
> > on reddening. This will become an issue in section 4.1 onwards...
>
> Intrinsic is included. The cut includes not only E(B-V)>2sigma, but
> also E(B-V)>0.1. That latter takes into account any intrinsic
> dispersion.
>
> I don't believe K-correction errors to be significant compared to
> statistical uncertainties esp. on E(B-V).
>
> > Now you are worrying about overcorrection for reddening. Well, overcorrection
> > is exactly what may happen if you mix up red and reddened SNe. I think that
> > *at least* as plausible as trying to fiddle around with other R_B.
>
Let's stick to the z=0.64 case. What is your bottom line there? How
firm is your statement "clearly reddened"?
> I disagree. The most reddened supernoave are around 0.45 or
> thereabouts, which is both where the K-corrections are best determined,
> and where we're comparing to a B-V color which is well known. I don't
> think an intrinsic dispersion in color can explain how red the three
> reddened low-redshift supernovae are.
>
> > What about if you try U-B=-0.3 ? It seems like a possibility from table 6.
>
> It goes the other way, not quite as far as it goes when I use U-B=-0.5.
> I haven't done this in a long time, but that's what I saw way back when
> when I did do it.
>
> I don't really consider either U-B=-0.3 or U-B=-0.5 plausible, as noted
> in the text. The former gives a "too blue" supernova problem, the
> latter gives too red supernovae.
>
> -Rob
>
>
-- ___________________________________________________________________ Ariel Goobar (www.physto.se/~ariel) Department of Physics, Stockholm University AlbaNova University Center, SE-106 91 Stockholm, SWEDEN tel: +46 8 55378659 fax: +46 8 55378601
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