From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Wed Mar 19 2003 - 22:19:31 PST
I reexamined the trends of E(B-V) with redshift for the old P99
fits and Rob's new fits. I confirm my assertion of Tuesday that:
a) P99 had no "too blue" problem --- E(B-V) has no trend with
redshift in the P99 dataset
b) There is a systematic trend such that Rob's E(B-V)'s become
systematically more negative (bluer) than the P99 E(B-V) as the
redshift increases. The trend is close to linear, and roughly
E(B-V) ~ 0 around z = 0.4 and reaching E(B-V) ~ -0.2 by z = 0.8.
What is this based on? I used the table of P99 and Rob E(B-V)'s
assembled by Gerson. I checked with latest_sne.dat and Rob's paper to
ensure that I am plotting the correct columns, and that the values in
Gerson's table match for a random selection of half a dozen SNe.
Interestingly, the E(B-V)'s for 9784 are quite consistent between the
two treatments.
(Also, just for completeness, 976 is very blue in P99, but it has
large error bars and apparently Rob did not try to obtain a color. Thus
this "too blue" SN is not in Rob's sample.)
Comments?
Greg
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