From: Isobel Hook (imh@astro.ox.ac.uk)
Date: Fri Jan 09 2004 - 03:58:52 PST
Hi Gaston,
Here are my comments on the EW paper. I think it's really good work &
very well presented.
Cheers,
Isobel.
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General:
- I think it would be useful if the actual EW measurements were
tabulated. People could then look for their own trends in the data.
Also I think it would be useful to give the parameters of the
functions you fit, again so that people can easily reproduce them. I
think this paper will be widely used for comparison with new (high-z?)
datasets and I think people will use it even more if it is easy to
plot your results.
- In several cases you have found trends for 91-T like SNe to lie on a
different side of the mean curve from 1991-bg like objects. Have you
tried plotting Delta_EW (i.e. distance from the curve) against M_B?
Perhaps there would be too much scatter, but if there is a relation
then it would be very useful.
It would be good to see the data for EW(2+3) plotted as a function of
epoch as you have done for the other features.
More detailed comments:
Abstract: "... change of EW in time" - Say what time you mean,
i.e. lightcurve phase relative to maximum light
Intro: "correlate to" should be "correlate with"
"objects discovered recently present a higher degree of peculiarities"
- this makes it sound as though there is a trend of peculiarity with
discovery date, with more recent searches finding stranger objects!
That needs re-wording.
Section 2: (data description) somewhere near the start of this section
you should mention the approx redshift range of set A.
You briefly mention subtracting the host galaxy (3rd paragraph). This
needs more detail: how was the contribution estimated, what galaxy
spectrum did you subtract etc. You do give some of this info later in
the paper, so you should refer to those sections (and tables 1 and 2)
here.
When you say 1986G etc belong to the 1991bg-like subclass, what is
that classification based on, lightcurve or spectrum? this should be
stated in the text. (if these classifications are partly based on the
spectra then I would think that might bias the results a bit?).
Section 4.5 - It looks as though there may be some missing words at
the end of this section. Have you got a stray "%" which is making
Latex ignore some lines of text?
Section 4.6 - You say that fast-decliner, normal and 91T-like SNe seem
not to be distinguishable based on "S II W", but in the plot the
normals do seem to occupy a different part of the plot.
In section 5 you describe lightcurve parameters and the method for
finding delta-m15. I would put this earlier (section 2) when you
mention deltam-15 for classifying the Ias into 91T-like etc.
Table 8: when you mention t_br, remind the reader which feature that
corresponds to (MgII 4300)
Section 5.1.2. It seems to me that once you've found a function for
the relation between t_br and deltam-15, then the relation between
t_br and M_B is fixed because you know the relation between deltam-15
and M_B. So I would think you could derive the curve in the lower
panel of Fig 11 from the one in the upper panel.
I found a few more minor typos as well but I wont list those at this
stage.
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