From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Fri Jan 26 2007 - 14:34:23 PST
Hi Dan,
Yes, thanks, I saw that paragraph in the paper.
However, 60% of early-types having some dust doesn't really
strengthen our case for why all our cluster elliptical SNe
will be dust-free, and E(B-V) ~ 0.2 is a lot of dust from a
cosmology perspective. So I wanted to see the actual
distribution of E(B-V) from the fits to determine whether a
stronger statement can be made.
Cheers,
Greg
On Fri, 26 Jan 2007, Daniel Stern wrote:
>
> i just searched for the word "dust" in alessandro's paper and found the
> following relevant paragraph:
>
> "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 $ {\sim } $$ 40\%$ of the cases E(B-V)=0
> gives the best fit. In the remaining cases, masses which are lower by $0.2
> \pm 0.1$ dex are found, with corresponding $E(B-V) \le 0.2$. This test
> supports the validity of the dust-free model assumption, as also widely
> used in the literature for early-type galaxies."
>
> --> so half the time he gets no dust and the other half of the time he
> gets E(B-V)<0.2.
>
> On Fri, 26 Jan 2007, Greg Aldering wrote:
>
> >
> > Hi Piero,
> >
> >
> > I took a look at thne Rettura et al paper hoping to find
> > the fitted E(B-V) values for each galaxy, but apparently
> > they are not published. Would you, Peter, Dan or Adam happen
> > to have them?
> >
> > Thanks,
> >
> > Greg
> >
> >
> > On Fri, 26 Jan 2007, Piero Rosati wrote:
> >
> > > 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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