From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Wed Apr 30 2003 - 22:04:48 PDT
I have been playing with the residuals of the HST-eleven from the
extinction-corrected OM,OL fit. I decided to see whether we can
constrain R_B using those SNe. I backed-out the 4.3*(E(B-V)) and put in
a different R_B. I also backed-out the 4.3*sigma(E(B-V)) uncertainty
and put in the new error. For z > 0.7, I also backed-out the intrinsic
U-B error and then put it back in using the new R_B. (I realize this
doesn't capture the changes due to the affect of color on
K-corrections, but this probably isn't the main effect.)
What I find is that with SN1998aw included, the best fit is
R_B = 2.2 (+0.7,-0.6) with Chi^2/DOF ~ 1. If I exclude SN1998aw,
the best fit is R_B = 4.0 (+2.5,-1.7) with Chi^2/DOF ~ 3/4. The
errant behavior of SN1998aw is consistent with Rob's finding that
it is a 2.6-sigma outlier to the extinction-correction OM,OL fit
(it is over-corrected for extinction). Note that the mean shifts
as well when R_B is changed, but the best R_B is similiar with or
without correcting for the shift in the mean. I should note that I
find a 0.09 mag shift in the mean towards fainter magnitudes when
SN1998aw is not included among the 11. (The shift would be much
smaller when the P99 SNe are added, but I didn't calculate this.)
Note that the 1-sigma lower bound on R_B is in the range 1.6-2.3;
maybe this bound can be related to Alex and Ramon's simulations.
Cheers,
Greg
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