From: Andy Howell (howell@astro.utoronto.ca)
Date: Fri Jul 09 2004 - 14:18:07 PDT
Gerson,
Do the SNe with known redshifts have known types? I remember that not all
could be spectroscopically confirmed as SNe Ia. This would explain why
SNe are too faint, too low stretch, etc.
-Andy
On Fri, 9 Jul 2004, Gerson Goldhaber wrote:
> Dear Mamoru, Naoki and Chris,
> In preparation for our collaboration meeting I am looking at the
> Subaru data in greater detail. Let me first state that these SNe are an
> excellent sample which should give us important cosmological information.
> There are 13 SNe with unknown redshift.
> From the lightcurve fits, and particularly the maximum magnitudes, I
> got a very rough estimate of the expected redshifts.
>
> z > 1.3 SuF02-076, -086
> z > 1 SuF02-J01, -051, -057, -014, -004, -J02
> z 0.9 to 1 SuF02-058, -056
> z < 0.8 SuF02-034, SXDS_2-9, SXDS_2-4
>
> Is there any information from photo-z, or could we get host galaxy spectra?
> Together with the measured redshifts, there is thus a potentially very
> substantial set of SNe with z > 1, namely 16.
> Other comments.
> 1. I have plotted the SNe with known redshift on a Hubble plot,for our
> favorit cosmology and find that the SNe magnitudes are dimmer than
> expected by about 0.7 mag. ie. they follow the hubble curve with larger
> magnitudes by about this offset. Calibration?
> 2. As I mentioned before, I question the calibration on Julian day
> 52616. Data taken on this day is high in normalized flux, with respect
> to all other dates. This was noticeable in SNe : SuF02-000, -004, -012,
> -019, -057, -081. The correction factor needed to bring these point in
> agreement with the other data points is about 0.7 in flux.
> 3. Other SNe with some apparently inconsistent points are: SuF02-007,
> -017, -034, -065, -071, -082
> 4.Two SNe SuF02-019 and -082 appear too dim by about 1.5 magnitudes.
> Could they be at a higher redshift??
> 5.Two of the SNe SuF2-014 and -081 have exceptionally small stretch,
> about 0.45. In our earlier study we had one such SN,
> sn9571 at z=0.866, which Greg had studied. These 3 form a rather unique
> set which needs to be explained. The one other SN I know of in the
> Hamuy et al SN sn1992br with stretch measured between 0.53 to 0.63
> (depending on the details of the fit). Alex Conley has several with
> stretch arround somewhat over 0.6.
> Hopefully we will be able to resolve some of these matters at our
> collaboration meeting.
> cheers Gerson
>
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