From: Chris Lidman (clidman@eso.org)
Date: Thu Mar 30 2006 - 11:01:52 PST
Hi Gabriele,
Thanks for the paper. I'll get back too you next week. I am currently
on Paranal at the moment
and I am flat out coordinating the work that needs to be done for the
ESO change of period that
occurs on April 1st.
Regards, Chris
On Mar 30, 2006, at 8:54 AM, Gabriele Garavini wrote:
> Hi Chris,
>
> I have been working on a new version of the evolution paper (in
> attachment).
> The main changes are related with figs 8, 9, 10.
> Briefly, there was some concern on the MgII ew values pre-max for the
> high-z, these are now solved. They were actually due to the low-z
> sample.
> It turned out that in the pre maximum bins the low-z sample is pretty
> poor. The average trend is biased toward the values of 94D that seems
> to be in some sense an outlayer.
> I've added some warnings in the text (section 3.5) about this issue
> and redone the plot 8, 9, 10 showing the 95% probability instead of
> the 68%, which seems more appropriate because of the possible error in
> the estimated central value.
>
> I would like to resubmit the paper next week if you agree. The journal
> contacted me asking what was our plan for this work.
>
>
> All the best
> Hasta la vista!
> Ciao
> Gabriele
>
>
>
> <Evolution_v3.3.pdf>
>
>
>
> On Feb 19, 2006, at 11:39 PM, Chris Lidman wrote:
>
>> Hi Gabriele,
>> Thanks for the revised version. Most of my suggestions now consist
>> of
>> minor tweaks to help improve the clarity of the paper.
>>
>> I am sure that I have missed some things, especially since I've
>> just returned from a long shift on Paranal and I am rather
>> tired. After you have read my comments, I suggest that you give the
>> paper to someone in the collaboration who can carefully read the
>> paper.
>>
>> I do not think that you should add new SNe to this paper. On this
>> point,
>> we agree. Once this paper is done, what are your plans? Are you
>> thinking
>> on working on the SNLS data set? This was the thrust of my question
>> in my earlier e-mail.
>>
>> Regards,
>>
>> Chris.
>>
>> Abstract
>> ========
>>
>> You make the following comment on the revised abstract,
>>
>> "In this way we are not mentioning at all the results of the EW for
>> the
>> low z. I know is not the main point of the paper but I wonder if it
>> wouldn't be good to put it in the abstract for making the article
>> more appealing."
>>
>> Yes, you are right. Here is another version, which could
>> probably still use some tweaking."
>>
>> "We develop a method to measure the strength of the strongest
>> absorption features in Type SNe Ia spectra and use it to make a
>> quantitative comparison between the spectra of Type Ia supernova at
>> low and high redshifts. Through the strength of these features and
>> through measurements of the Ca II H and K velocity we show that the
>> spectra of a high redshift sample, consisting of 12 SNe Ia with
>> redshifts ranging from 0.212 to 0.912, are quantitatively similar to
>> the spectra of a low redshift sample. One supernova in our
>> high redshift sample, SN 2002fd at z=0.279, is found to have spectral
>> characteristics that are associated with peculiar 91T/99aa-like
>> supernovae."
>>
>> A general comment
>> =================
>>
>> In many places of the paper you use the acronym EW. This is OK, but it
>> can lead to clumsy word constructions in some cases. I take the the
>> first line in the caption of Fig. 4 as an example. Which do you think
>> is better,
>>
>> "Measured EW values corresponding to ..."
>>
>> or
>>
>> "Equivalent width of the Fe II 4800 feature as a function of phase."
>>
>> Sometimes, it is better to spell out the acronym. This was one
>> example.
>> There are others.
>>
>> Section 1
>> =========
>>
>> 4th paragraph
>>
>> The Balland et al. paper (A&A, 445, 397) is now out. We should add
>> this article
>> to the list of references in the last sentence.
>>
>> Section 2.1
>> ===========
>>
>> 2nd paragraph
>>
>> "... over luminous object" -> "... over-luminous objects"
>>
>> Rephrase the sentence that starts with "Therefore, we consider ..." to
>>
>> "The additional scatter that would be introduced by using data with
>> lower
>> signal-to-noise ratios would obfuscate the result"
>>
>> or something similar.
>>
>> 3rd paragraph
>>
>> "... error spectrum. It was ..." -> "... error spectrum, which was
>> ..."
>>
>> 4th paragraph
>>
>> "The estimated galaxy contamination, ..." -> "The contribution of the
>> galaxy
>> light, ..."
>>
>> Figure 1 is a good start. One of the things we need to be aware of, is
>> that non-experts may think that the SNe spectra in this figure are
>> poor when the opposite is true. It is important that we do not create
>> a negative impression with this figure. Here are some suggestions to
>> make it better.
>>
>> - For SNe with z > 0.4, put the label on the right. This will reduce
>> the
>> amount white space that is in the figure.
>>
>> - Make the SN labels larger
>>
>> - Remove the word epoch, put the epoch in brackets and add a note in
>> the
>> text explaining what the number in brackets means.
>>
>> - Mark the regions that are used in the EW analysis. See Balland
>> et al. for an example.
>>
>> - Try smoothing the data with a Savitsky-Golay filter. See Balland et
>> al.
>>
>>
>> Section 2.3
>> ===========
>>
>> 1st paragraph
>>
>> Maybe it is worth explaining what 91Taa means when it is first
>> used. E.g. you could say, "(We follow the convention of Li et al. when
>> describing 91T/99aa-like SNe by using 99Taa to represent this SN
>> subtype.)."
>>
>> Rephrase
>>
>> "The Ca II H&K feature ... SN 1991T like SNe."
>>
>> to read
>>
>> "The Ca II H&K feature in SN 2002fd is more prominent than the Ca II
>> H&K feature in SN 1991T, but less prominent than the Ca II
>> H&K feature in normal SNe Ia, such as SN 1994D."
>>
>> or
>>
>> "The strength of the Ca II H&K feature in SN 2002fd is between
>> that of 91Taa-like and normal SNe."
>>
>> Table 1.
>>
>> The font for footnotes "a" through "d" in the table is different to
>> the font used below the table. Same comment applies to Table 2.
>>
>> Replace
>>
>> "that could affect the cosmological measurements".
>>
>> with
>>
>> ", which might affect the derivation of cosmological parameters
>> from SNe Ia."
>>
>> Section 3
>> =========
>>
>> 1st paragraph
>>
>> "phase" -> "phase,"
>>
>> "distribution properties" -> "distributions,"
>>
>> "see for a review Filippenko (1997)" -> "see Filippenko (1997) for a
>> review"
>>
>> "case" -> "cases"
>>
>> "severe" -> "dramatic"
>>
>> "and Type Ia subtypes have been identified to account for a
>> morphological classification"
>>
>> ->
>>
>> "resulting in the definition of SNe Ia sub-types."
>>
>> "dishomogeneities" -> "dissimilarities"
>>
>> "my means" -> "by means"
>>
>> 2nd paragraph
>>
>> "compare" -> "comparing"
>>
>> "In the following section EW is defined and the properties are ...
>> discussed"
>>
>> ->
>>
>> "In the following sections, we describe how we measure the EW of the
>> broad absorption features in SN Ia spectra and we apply it to a sample
>> of nearby SNe Ia."
>>
>> I suggest that you delete the last three sentences in this paragraph,
>> unless
>> you are sure that Gaston will publish his paper.
>>
>> Section 3.1
>> ===========
>>
>> The first and second paragraph needs some rewording.
>>
>> 2nd paragraph
>>
>> "i.e." -> "because of"
>>
>> 3rd paragraph
>>
>> "As already mentioned" -> "As already mentioned,"
>>
>> In the footnote 3 on the bottom of page 6.
>>
>> "and the possible" -> "with the possible"
>>
>> In the last paragraph you can say "By definition, the rest frame EW
>> ..."
>> and you can then delete the parenthetical remark.
>>
>> Section 3.2
>> ===========
>>
>> In the spirit of the titles you have used for sections 3.1 and 3.2, I
>> would
>> suggest the abbreviated title - "Measurement technique"
>>
>> 1st paragraph
>>
>> "Measuring EW ..." -> "Measuring the EW ..."
>>
>> "since the identification of the local maxima bounding ... visually."
>>
>> ->
>>
>> "since the local maxima bounding an absorption feature can be
>> identified
>> easily."
>>
>>
>> "poor quality spectra" -> "low signal-to-noise data" I prefer this
>> because the
>> high redshift data are not poor quality data.
>>
>> "complex" -> "difficult"
>>
>> Delete the word practical
>>
>> "which minimize" -> "that minimizes"
>>
>> In the list of items on page 7.
>>
>> "on Eqn. 1" -> "in Eqn. 1"
>>
>> "To the data, ..." -> "A straight line is fitted to the data in the
>> fitting
>> regions"
>>
>> 2nd paragraph
>>
>> "Larger wavelength span would ..." -> "Larger wavelength spans would
>> ..."
>>
>> Section 3.3
>> ===========
>>
>> Last paragraph
>>
>> "presents photometric" -> "has photometric"
>>
>> "which make" -> "that make"
>>
>> Section 3.4
>> ===========
>>
>> Last paragraph
>>
>> "The decrease of EW ..." -> "The decrease in the EW ..."
>>
>> Delete "by giving the relative decrease ... types."
>>
>> You can then adjust the title of Table 6 to read
>>
>> "The fractional decrease in the EW corresponding to a 10% increase in
>> the
>> amount of contamination from the host."
>>
>> Replace
>>
>> "Since the SNe ... on that end"
>>
>> with
>>
>> "Since SNe Ia near maximum light are generally bluer than their hosts,
>> errors in estimating the amount of host galaxy contamination
>> leads the larger EW errors for features at redder wavelengths."
>>
>>
>> Section 3.5
>> ===========
>>
>> 1st paragraph
>>
>> The first sentence is not necessary. The second is sufficient.
>>
>> Section 3.5.1
>> =============
>>
>> 1st paragraph
>>
>> "The values of the EW increase constantly ..." -> "The EW increases
>> ..."
>>
>> 3rd paragraph.
>>
>> The paragraphs starts with "This", which might confuse the
>> reader. Perhaps, the new paragraph should start with the 2nd last
>> sentence of the 2nd paragraph, i.e. the one that starts with "The
>> different sub-types ..."
>>
>> \delta is used in the text, \Sigma in the table. Actually, in this
>> case
>> \delta is more appropriate for columns 6 and 8. I'm sorry if I have
>> changed my mind on this point.
>>
>> \delta is in the footnote. The footnote appears on the page before
>> the table.
>>
>> Section 3.5.2
>> =============
>>
>> 3rd paragraph.
>>
>> "Other SN subtype ..." -> "Other SN subtypes ..."
>>
>> Section 4
>> =========
>>
>> in point 2
>>
>> "equivalent width measurements" -> "the equivalent widths"
>>
>> Section 4.1.1
>> =============
>>
>> 1st paragraph
>>
>> "would tend to" -> "might"
>>
>> 3rd paragraph
>>
>> "data quality range found in our data set" -> "signal-to-noise ratios
>> in the
>> data,"
>>
>> "estime" -> "estimate"
>>
>> The biggest weakness of the technique we use to estimate the amount of
>> host galaxy subtraction is that we use a fixed number of galaxy
>> templates.
>> In real data, host galaxy SEDs will be more varied, so the estimate in
>> how accurate we can remove the flux of the host galaxy is probably
>> an underestimate.
>>
>> Section 4.1.2
>> =============
>>
>> 1st paragraph.
>>
>> "Figs. 9 and 8" -> "Figs. 8 and 9"
>>
>> EW's indicates possession, which is not the case here. Use EWS.
>> Personally,
>> I find the acronym EWS rather ugly. It might look nicer if you spell
>> out the acronym. Also "measured EW values" is better written
>> "equivalent
>> widths".
>>
>> The semi-colon after "parenthesis" should be a full stop.
>>
>> "possible fitting regions uncertainties" -> "possible fitting region
>> uncertainties"
>>
>> 5th paragraph
>>
>> "Fig. 10 show" -> "Fig. 10 shows" and a full stop at the end of the
>> sentence.
>>
>> "low-redshift normal and under-luminous" -> normal and under-luminous
>> low-reshift"
>>
>> Last paragraph.
>>
>> "lower metallicity progenitor" -> "lower metallicity progenitors"
>>
>> The other possibility, of course, is that the Lentz models are wrong.
>>
>> Table 10.
>>
>> The first sentence is messy. Try
>>
>> A statistical comparison of the equivalent widths of high-redshift SNe
>> with the equivalent widths of normal and under-luminous low-redshift
>> SNe.
>>
>> If it is possible, replace the word "faint" with the word
>> "under-luminous",
>> so that it is clear that the faint and under-luminous SNe are the
>> same.
>>
>> Section 5
>> =========
>>
>> 1st paragraph
>>
>> "We also find based on spectral properties alone that, .." -> "We also
>> find, based on spectral properties alone, that ..."
>>
>> 3rd paragraph
>>
>> "EWof" -> "EW of" (occurs twice)
>>
>> Last paragraph.
>>
>>
>> "difference in" -> "differences between"
>> "has" -> "has been" in the last sentence
>>
>> I feel that something is lacking in this paragraph.
>>
>> European Southern Observatory
>> Alonso de Cordova 3107, Vitacura
>> Casilla 19001, Santiago 19
>> CHILE
>>
>> Ph. 56 2 463 3106
>> FAX 56 2 463 3001
>>
>>
> ========================================================
> Department of Physics, Stockholm University
> AlbaNova University Center, SE-106 91 Stockholm, SWEDEN
> Fax: +46 8 55378601 Phone: +46 8 55378769 ,
> e-mail: gabri@physto.se
> ICQ: 148161845, AIM: gabrigaravini, msn: garavini@in2p3.fr
> skype: gabrielegaravini
>
>
>
European Southern Observatory
Alonso de Cordova 3107, Vitacura
Casilla 19001, Santiago 19
CHILE
Ph. 56 2 463 3106
FAX 56 2 463 3001
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