From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Sat May 03 2003 - 11:34:58 PDT
Hi Ariel and Rahman,
I have a few questions related to these GL simulations. First, the values
you give below are the shifts for the SN data by themselves, right? If the
w and OM shifts are correlated, then probably the priors from CMB and
2dFGRS will limit the overall effect. Has this been included? Since the w
value we quote includes the other priors, they have to be considered
somehow in calculating a systematic uncertainty on that value of w. Since,
as Rob has noted, the GL effects might be the largest of all the
systematics, the w systematics error might be set by your treatment.
Also, given that you set Omega MACHO to 20% of OM, would the size of the
bias shrink by roughly 2/3's if you modeled an OM=0.21 universe, i.e., to
match our observations? This would reduce the bias on w to about 0.05.
Also, as you know, the w sensitivity can change a lot depending on how the
other parameters are set.
Can you explore these questions?
- Greg
On Fri, 2 May 2003, Ariel Goobar wrote:
> Hi Rob,
> I just got some results back from Rahman w.r.t GL systematcis on the fits
> of the simulated data sets:
>
> Relaxing the condition on flatness introduces
> a small bias along the major axis of the ellips
>
> bias (\Omega_M + \Omega_\Lambda ) 0.04 +- 0.19
>
> For the w-\Omega_M case (in an Omega_M=0.3 universe) , the chisquare
> minima are shifted to the average values:
>
> <w> = -0.92 +-0.1 <\Omega_M> = 0.25 +- 0.06
>
> The numbers after (+-) refer to the *standard deviation* on the
> bias.
> Rahman: please add any further information that you
> find necessary.
>
> 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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