From: Piero Rosati (prosati@eso.org)
Date: Fri Jan 26 2007 - 07:49:10 PST
Hi everyone,
fantastic proposal!
I have 2 comments, 1 correction and a question for Marc regarding Fig.
3a:
1)
Regarding the evidence of no or little dust in ellipticals, we say:
"Recent Spitzer data (Temi et al. 2005) confirms that most nearby
ellipticals have the SED’s expected for dust-free
systems."
This was also found in early-types at z~1, and I think it would be
worth mentioning it.
Rettura et al. 2006 (A&A 458, 717-726) used SED fitting with 10
bands, including the 4 IRAC bands, of 30 early-type galaxies at
0.8<z<1.2 in the field (mostly GOODS) and showed evidence of *no or
very modest dust extinction*. This is the relevant paragraph in that
paper, just to save you the time:
We have also investigated the effect of dust extinction on the best-
fit photometric-stellar masses by including a fourth free parameter,
0.0 < E( B − V ) < 0.4, following the Cardelli et al. (1989)
prescription. By performing the fit on 28 galaxies for which IRAC
photometry is available in all 4 bands, we find that in ∼40% of the
cases E( B − V ) 0 gives the best fit. In the remaining cases,
masses which are lower by 0.2 ± 0.1 dex are found, with corresponding
E( B − V ) ≤ 0.2. This test supports the validity of the dust-free
model assumption, as also widely used in the literature for early-
type galaxies.
2)
Mass-richness relation plot. It's nice, and the scatter/outliers not
surprising given the nature of any richness parameter. We don't want
to give the impression though this will be the kind of plots which
will provide the "mass calibration" of future Xray/SZ surveys. Best
mass indicators are currently physical quantities extracted from X-
ray and SZ observations: T, Mgas, Lx,Y, Yx (the so called Yx=Tx*Mgas
being the most fashionable these days). I doubt that anyone will use
n_gal in the era of precision cosmology. This is mentioned at the end
of the Cluster Science section (pag.6) but it should rather be here.
So I think we should add in this section something like:
Chandra and XMM observations of these clusters already in hand and
upcoming SZ observations will allow us to probe for the first time at
1<z<1.5 the relation between fiducial lensing masses and physical
parameters derived form X-ray and SZ measurements (Lx, Tx, Mgas, Y).
These relations provide the critical calibrations for precision
cosmology with next generation cluster surveys.
-Correction:
Pag.6: The GTO program has *four* clusters at z>1
-Question for Marc: the caption of Fig.3a (VLT based CMR) reads
"CMR in this same cluster using data from the VLT FORS and ISAAC
(transformed to the ACS i,z passbands)"
FORS has already i&z bands, how did you use ISAAC (J&K bands) to
"transform" to ACS i&z ??
Piero
On Jan 25, 2007, at 11:32 AM, Tony Spadafora wrote:
> Cluster search group,
>
> The working draft of the cycle 16 proposal on
> http://supernova.lbl.gov/HSTclusterSN/proposals/HSTc16/clusters/text/
> (HSTclusterSN/HSTclusterSN)
>
> has Wednesday's reworking of various sections. Comments are
> welcome. There are still embedded internal questions and ?'s in
> various places. Sci Just will need to be cut a little (~11 lines).
> Some of the figures need work. All of the captions and references
> will need to be checked.
>
> -Tony
>
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