From: Ariel Goobar (ariel@physto.se)
Date: Tue May 20 2003 - 02:53:36 PDT
-- ___________________________________________________________________ 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---------- Forwarded message ---------- Date: Tue, 20 May 2003 11:52:54 +0200 (CEST) From: Ariel Goobar <ariel@physto.se> To: Robert A. Knop Jr. <rknop@lilys.lbl.gov> Cc: scpexec@lbl.gov, hastpaper@panisse.lbl.gov Subject: Comments on draft
Hi Rob, I went through the sub3 draft and have some comments/questions which Ï list according to appearence in the text.
Sec 1.
Whis isn't the WMAP reference listed along with the other CMB ref (Jaffe et al 2001). It is quoted and referred to later on in the text.It should be in the intro as well.
Sec 2.3
This is not a critical issue. However, as I mentioned in the past, I am left uneasy after reading the discussion in page 16 on the U-B intrinsic color. It seems like an overstatement to talk about "extreme color outliers" in the very *small* statistical sample of Jha's. Whether is extreme or just a part of a continuos distribution will only show when large statistics are available.
Sec 3
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...
Sec 4.1
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.
Sec 4.3
There are a lot new things here that are not all that easy to follow. The "growth parameter f" does not strike me as the kind of thing that people are expected to know what it is. On top of that, I don't know what the Linder & Jenkins method is (nor has it been reviewed by a referee,as far as I seen) and I wouldn't put all the thrust of the analysis on that without some description. Similarly the "this distance reduced distance" ??? in Eq. 4. The reader something more here in order trust figs 11.
Sec 5.2
Type contamination. What the impact of statistics in what you call the systematic effect? You use a subsample of the data and find another best fit. How would that differ from what you would expect from any random rejection of the same number of SNe?
Sec 5.3
Malmquist bias. In teh second row of page 32 you argue there is a difference in the z-distribution of SNe between P99 and HST. However, they cover exactly the same range, thus the sentence seems a bit exagerated. Also, I feel unconfortable about the sentence below: "the bias is likely to be ~0.02" Likely because of what?
Sec 5,4
What about if you try U-B=-0.3 ? It seems like a possibility from table 6.
Bottom of page 33. The discussion leading to the quoted numbers 0.06, 1.95 and 0.09 seems unclear to me at least.
Sec 5.5
Again the issue of overcorrection...
Sec 5.6 "and less than 1% for the cases considered in P99". Percent of what? brightness or supernovae?
sec 5.8
typo: "could" missing after citing Csaki et al.
Please, do also check out previous mails I sent you with missing stuff in the acknowledgements and reference list (e.g. alphabetic order is not always followed)
Ariel
-- ___________________________________________________________________ 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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