From: Serena Nobili (serena@lpnhep.in2p3.fr)
Date: Mon Jan 24 2005 - 09:40:04 PST
Hi Chris (and SCPexec)
thanks for your comments. I am now working at excluding 1999Q from all the
text and plots. I should be ready shortly with the new version.
I think it would be profitable to have a discussion tomorrow night at the
executive meeting. Would that be possible for you?
Cheers
Serena
On Sun, 23 Jan 2005, Chris Lidman wrote:
> Hi Serena,
> I've gone through the replies to the referees report and I provide
> comments in the attached file. I've also reprocessed the SOFI data with
> different software and I get the same result. The details are in the
> attachment.
>
> Cheers, Chris.
>
> On Mon, 2005-01-10 at 12:30, Serena Nobili wrote:
> > Dear all,
> >
> > here is the referee's report on the Iband paper. It sounds quite tough at
> > the beginning, but it is not that terrible after all. One major point is
> > on 1999Q. He seems to want us to state clearly how much is our magnitude
> > of the SOFI point. I certainly need a quick feedback on this comment, while
> > I work on the rest.
> > Thank you in advance for you help.
> > Cheers,
> >
> > Serena
> >
> > ---------- Forwarded message ----------
> > Date: Fri, 07 Jan 2005 19:57:34 +0100
> > From: aanda.paris@obspm.fr
> > To: serena@lpnhep.in2p3.fr
> > Subject: AA/2004/2463
> >
> > 07/01/2005
> >
> > Dr Serena Nobili
> >
> > serena@lpnhep.in2p3.fr
> >
> > Our Ref. : AA/2004/2463
> >
> > Dear Dr Nobili,
> >
> > Your paper "Restframe I-band Hubble diagram for type Ia supernovae up to z sim~0.5" was submitted to a competent referee who recommended publication after substantial revision (see enclosed report).
> >
> > Please take all of the referee's comments and suggestions into account in revising your work and send us the new version (in referee format) at your earliest convenience. Instructions for resubmission can be found at address https://mms-aanda.obspm.fr/is/aa. Your author ID number is 13552.
> >
> > In your cover letter, please indicate precisely all the changes made in the revised version, and mark them clearly (e.g., using boldface) in your manuscript.
> >
> > With best regards,
> >
> > Francoise Combes
> > A&A Editor
> >
> > -----------------------------
> > Referee Report
> >
> > The use of Type Ia Supernovae for cosmology has produced remarkable
> > results. The checking of these results is of utmost importance and the
> > paper 'Restframe I-band Hubble diagram for type Ia supernovae up to z
> > sim~0.5' by Nobili et al. is trying to present such a check.
> >
> > The paper has two main topics: The necessary establishment of the
> > I-band light curves of Type Ia Supernovae and the construction of an
> > I-band Hubble diagram. The former is a precondition for the latter. The
> > paper has to remain exploratory, since there are not enough data to
> > populate the Hubble diagram at redshifts z>0.3 where the cosmological
> > effects start to become significant.
> >
> > There are several shortcomings with this paper and it should be modified
> > considerably before it can be recommended for publication. However,
> > the paper can be brought to a stage where it can be published with some
> > effort.
> >
> > The light curve fitting is rather ad hoc. The motivation to use B-band
> > light curves to construct a surrogate I-band light curve is not
> > explained anywhere. The authors should give a reason, why they chose
> > this route and not another. There are obvious shortcomings from this
> > approach that are not described in the paper. E.g. the late decline of
> > the I band, which is typically faster than in B can not be described
> > with this method at all. This means that after about 40 days past
> > maximum, the I light curves can not be fit any longer. The paper does
> > not use these late-phase data, but it should be made clear that the
> > proposed model can only fit the maximum phase. By the way, the approach
> > by Contardo et al. allowed them to fit the light curves, within the
> > stated limitations, over a much longer time than what is proposed here.
> > Another issue are the rise times. The paper states that it is 'assumed
> > that the rising part of the light curve in I-band is the same as in
> > B-band' to then on the next page say 'the trend in the residuals' in the
> > fit to SN 1994D 'shows the limitations of the model.' An inspection of
> > Figure 1 shows that this is evident in all cases where data in the rise
> > is available. In all cases the fit has strong systematic deviations,
> > when the peak is defined through pre- and post-maximum data. SN 1994D is
> > just the case in point. It seems important to make the paper consistent
> > in this respect.
> > The above draws the result of Figure 2 into question. This figure is
> > remarkably different from what was found in Contardo et al. (their
> > Figure 4). This discrepancy should be discussed in the paper.
> > Another example is the exclusion of two (SNe 1997br and
> > 1998ab; both 'spectroscopically peculiar') supernovae due to the Monte
> > Carlo fits. They happen to be the two with the smallest ratios between
> > peak and dip in the light curves. The fact that the Monte Carlo fits
> > fail to reproduce these light curves consistently is probably an
> > indication that the model fails here as well.
> >
> > Table 2 should list the number of data points used in the fit. This
> > would help the reader to assess the goodness of the fit as well.
> > Especially, since these light curves are then later used to fit the
> > distant supernovae, it would be good to restrict the construction of
> > light curve 'templates' to only objects that have an over-constrained
> > fit, i.e. more than let's say 10 phases spread over at least over the
> > two peaks. Establishing a template with 6 data points appears unreliable
> > given the model.
> >
> > Light curves are stretched according to values derived from the B light
> > curves. What would be the rationale to apply the same stretch in I as
> > well?
> >
> > The fits are done in flux units. Does that mean the magnitudes are
> > converted into flux, fit and then converted back into magnitudes? Why is
> > this done like this? How are the errors treated? This is an important
> > detail that needs to be explained.
> >
> > The authors should decide what they want to do with SN 1999Q. As it is
> > right now, they introduce the data for this supernova to quickly reject
> > them as non-consistent. That would be OK, if they then would refrain
> > from presenting all the analyses as with the other two objects. I
> > suggest to either accept the published (Riess et al.) data as they are
> > or, if the data can not be used, reject them and leave it at that. It
> > does not make sense to fit a light curve, calculate a brightness and put
> > the point into the Hubble diagram, if the data can not be trusted. The
> > authors should indicate, why the data can not be trusted. Just saying 'a
> > re-analysis of the publicly available SofI data suggest that the
> > published J-band magnitude may be too faint' is not good enough. The
> > public data contain all the information necessary to derive a reliable
> > value. If it differs from the published result the difference should be
> > stated explicitly.
> >
> > In several places the paper is confusing in the way it presents the
> > samples. The abstract quotes 26 local supernovae, but the reader is
> > confronted with different numbers (42, 28) in the text. It might be useful
> > to state the sample selection (redshift range and exclusion of
> > spectroscopically peculiar supernovae) in the abstract so that this is
> > clear from the beginning. Maybe the selection criteria could be
> > summarised again at the beginning of section 3.
> >
> > The use of references is sometimes unclear and appears also occasionally
> > arbitrary. It would be good to carefully go through the paper again and
> > sort these out. Suggestions are made below as well.
> >
> > Specific comments:
> >
> > 1. 'spectroscopic peculiar' should be changed to 'spectroscopically
> > peculiar' throughout the text.
> >
> > 2. add Schmidt et al. (1998) to the reference list to the first sentence
> > in the introduction.
> >
> > 3. add '(similar to Riess et al. 2000)' as a reference to the first
> > sentence of the last paragraph of section 1.
> >
> > 4. The references for SN 1991T (section 2.2) are rather strange. It
> > appears as if there is a mix-up with the following sentence. The
> > references for SN 1991T should be Filippenko et al. 1991, Ruiz-Lapuente
> > et al. 1991 and Phillips et al. 1992. The references for Li et al. 2001,
> > Howell 2001 and Garavini et al. 2004 presumably refer to SNe 1995bd,
> > 1997br, etc.
> >
> > The sentence starting with 'However, not all of these show ...' is
> > unclear. Which supernovae are meant with 'these'? SN 1986G, SN 1993H or
> > others?
> >
> > 5. In one paragraph Type Ia Supernovae are called 'standard candles' and
> > the next (only two lines down) they are described to show 'a variety of
> > properties.' It is passages like these that confuse the reader.
> >
> > 6. What does 'somewhat deviant' mean (caption of figure 6)? This
> > statement should be quantified.
> >
> > 7. There is a change from observed redshift to a redshift corrected to
> > the CMB frame between Tables 2 and 3. This should be explicitly stated
> > either in the text or the captions to Table 3.
> >
> > 8. Table 4 and its discussion in the text are meaningless. Since the
> > fits in the Hubble diagram is done with all data sets the smallest
> > sample one will have the least weight and hence largest uncertainty.
> > With the larger uncertainty the 'offset' automatically can be larger.
> > Not surprisingly, all samples are consistent with each other within the
> > errors. This table and the corresponding section should be dropped.
> >
> > 9. The first sentence of the third paragraph in section 5 should start
> > with 'The low statistics of the high redshifts sample is insufficient
> > ...' No statement can be made whether the concordance model is favoured
> > or not from the presented data.
> >
> > 10. In the same paragraph there is a garbled sentence, the meaning of
> > which did not become clear. However, as suggested above the discussion
> > of SN 1999Q should be dropped here anyway.
> >
> > 11. It appears from the fits that a dust model with R_V=9.5 is the most
> > favoured case, given the data. For the Monte Carlo simulation to check
> > for the sample size to reject a dust hypothesis the number of individual
> > data points per individual supernova must be important as well. This
> > should be described.
> >
> > 12. The fourth paragraph of section 8 should start: 'J-band measurements
> > of one high-redshift supernova plus published data of one more were used
> > to extend ...'
> > Also, instead of saying 'seemingly inconsistent information' on SN 1999Q
> > the authors should be more explicit. It is alright to say that the authors do
> > not trust the data and hence discarded this object.
> >
> > 13. There is an interesting mismatch in the interpretation between
> > concordance model and the analysis of potential dust in the conclusions.
> > The 'concordance model ... is found in better agreement with the data
> > than other models' but the dust analysis yielded 'no firm limits on the
> > presence of grey dust.'
> >
> >
> >
>
------------------------------------------------------------------------ http://supernovae.in2p3.fr/~serena/ Tel +33 1 44277329
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