Any complete standardized SNIa data out there?

[[Mod. note -- Long lines wrapped and excessively-quoted text trimmed;
posters, please do this yourself. -- jt]]

(Steve Willner) wrote in message
...
(sean) wrote in message
...
The method I used was to take individual
SN lightcurves from Knops paper pages 11-12( R.A. Knop
arXiv:astro-ph/0309368 vl 12 Seop 2003) and compare them with ones
supplied in Adam G. Reiss` paper pages 23-25 (arXiv:astro-ph/9810291
vl 19 Oct 1998).

[[ ... trimmed by moderator ... ]]

As you can see the Knop mags are in a different `mag` format from
Reiss`.

Yes, as noted above, Knop et al. use linear flux density. One
magnitude is close to a factor of 2.5, as you no doubt know.



No I didnt but, thanks for that information. I assume then that a
decay in linear from 1 to 0.4 is equivelent to a decay in log of 1 mag
as you suggest.

[[Mod. note -- Magnitudes are defined so that a difference of 5 magnitudes
is a factor of 100 in (linear) flux density. Thus a difference of 1
magnitude is a factor of 100**0.2 = 2.512, and more generally a factor
of X is a magnitude difference of 2.5*log10(X).
-- jt]]

I`m not sure what you mean "by consistent with 1" ? Is that when you
compare the ratio between the days it takes a low redshift SN to
decay by one mag as compared to how many days a high redshift SN
decays the same mag? So if its `1` then thats a 1/1 ratio ie they both
decay at the same rate ? .


I checked 1995E (Reiss pg 23 of his paper..... arXiv:astro-ph/9810291
vl 19 Oct 1998).. and I seem to get completely different results from
reading the data that you have.
I agree with you that it takes only about 17 days to decay by one
mag in the B band lightcurve of 1995E.
However with the I band in 1997ek (Knop) I found that the 0.4 reading
is clearly stated in the tables as being 22 days and not 29 days, as
you claim, after the highest (peak luminosity ) reading for SN1997ek .
This is the HST reading of 1.54 on julien day 50846 which on the graph
is represented in linear as 0.4 mag. (It is clearly the brightest mag
reading in I band for that SN despite being placed at about 8 days
past peak on the graph.I assume thats for convenience to fit a
theoretical template. Nonetheless it is the brightest mag for I band
and thus for me the decay is 22 days from 1 to 0.4 )

So the ratio I get is 22 days for high redshift as compared to 17 days
for low redshift which is much closer to 1 than you have calculated.



And to explain this small difference without invoking any time
dilation at all , I do the following calculation..The high redshift I
band (Knop ) which you calculate as being an emission wavelength of
438nm is compared to the Reiss B band , but , remembering that Reiss B
band is still a 0.1 redshift, this means that the low redshift 1995E
B band actually was an emission wavelength of 390nm. Thats a 50nm
difference between the two that are being compared incorrectly as like
for like. And if one then notes that the time it takes a low redshift
530nm V band from Reiss 30 days to decay by one mag on average from
his survey as compared to the 17 days for the average B band to
decay 1 mag then it becomes obvious that the shorter the wavelength
the shorter the time it takes to decay one mag for the same SN. In
other words extrapolating a 12 day difference in decay rates for a low
redshift 530nm band to 430nm band one could say that it would
probably be even six day less for a 390nm when compared to a 438nm
lightcurve for both to decay by one mag . That means a 390nm
emission wavelength of a SNtype 1a actually should decay about 6 days
faster over 1 mag then a 438 nm emission wavelength. . And thats what
we see as the 438nm lightcurve (originally I band observed at
redshift0.85) decays 1 mag in 22 days whereas the 390nm lightcurve
(originally a B band observed at 0.1 redshift) decays at 17 days .
Thats a 5 day difference which is close to the 6 day I calculated
above meaning no time dilation is observed. So to me the apparent time
dilation is only an artifact of incorrectly comparing different
emission wavelength lightcurves together as like for like.


Hopefully this also answers Craigs concerns except maybe his
following question about filter bandwidths ..."How do you address the
fact that the filter bandpasses of the optical instruments involved
are broad, not narrow, and therefore are not necessarily compatible
with associating them with a single wavelength?"....
I cant answer that except maybe to ask him the same question regarding
the pro time dilation arguments use of the same data I use.
thanks
Sean