Re: AA/2006/5400: referee report

From: Chris Lidman (clidman@eso.org)
Date: Sun Feb 04 2007 - 17:25:54 PST


Hi Gabriele,
   Congratulations on having the paper accepted.

  I can help you with the English expression; however, I have read this
paper quite
a few times, and I'm thinking that it might be better to have someone
who
is less familiar with the paper to read it, too.

Regards,

Chris.

On Feb 4, 2007, at 5:05 PM, Gabriele Garavini wrote:

>
> Dear Chris,
>
>
>
> I got the new referee report. This time the referee seems to be in
> favor of the publication of the work after some extra corrections. 
> This guy seems to have infinite time to make comments.
>
> Anyway, you know I'm out of business right now and looking for new way
> to make a liveng, so I will do my best to get this thing done asap. 
> The referee also suggests a review of the English, which I guess needs
> to be done by a native English speaker.
> I'll try to send you the new version in a week or so.
>
> All the best.
>
>      Gabriele ... the unemployed physicist.
>
>
> Begin forwarded message:
>
>> From: aanda.paris@obspm.fr
>> Date: January 23, 2007 8:51:18 PM GMT+01:00
>> To: gabri@physto.se
>> Subject: AA/2006/5400: referee report
>> Reply-To: aanda.paris@obspm.fr
>>
>> 23/01/2007
>>
>> Dr Gabriele Garavini
>>
>> gabri@physto.se
>>
>> Our Ref. : AA/2006/5400
>>
>> Dear Dr Garavini,
>>
>> Your paper "A quantitative comparison between Type Ia supernova
>> spectra
>> at low and high redshifts" was submitted to a referee who recommends
>> publication after revision (see enclosed report).
>>
>> The referee also notes that the paper would benefit from a thorough
>> read-through, and I encourage you to ask one of the many native
>> english speakers amongst your co-authors to perform this task,
>> after you will have taken the referee's suggestions into account.
>>
>> Please take the referee's comments and suggestions into account in
>> revising your work and send us the new version (two pdf files: one
>> in referee format and the other in printer 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 14473.
>>
>> In your cover letter, please indicate precisely all the changes made
>> in the revised version (pdf file: printer + referee version), and
>> mark them clearly (e.g., using boldface) in your manuscript.
>>
>> With best regards,
>>
>> Thierry Forveille
>> A&A Editor
>> ------------------
>> Referee Report
>>
>>
>> First of all, my apologies for the delay.
>>
>> The authors have made a significant effort to clarify the presentation
>> of the material in this paper, to which I am now more favourably
>> disposed. I am now in a position to recommend this paper for
>> publication after some revisions. While most revisions are minor, a
>> few are important enough for me to ask to see a revised version of the
>> document before publication. I can guarantee (unlike this time) that I
>> will reply to the authors within two weeks of receiving the revised
>> version. Since the structure of the paper will not change, I would
>> appreciate if the authors could highlight any changes (other than
>> typos etc.) in boldface to make the refereeing process easier.
>>
>> The authors have addressed all of my major concerns with this paper. I
>> comment further on some of these related issues in the General remarks
>> and Detailed comments sections below.
>>
>>
>>
>>
>> ########################
>> General remarks
>> ########################
>>
>> 1. I still think you should show the spectra of SN 1999bp in this
>> paper. You have a unique opportunity to publish these spectra in a
>> peer-reviewed paper, as opposed to a PhD thesis manuscript (in
>> which the spectra appear in different plots mixed in with other
>> supernovae).
>>
>> 2. Now that you have grouped the low- and high-z measurements
>> together, it would make sense to use the same x- and y-range for
>> these plots in Figs. 5, 6, & 8. This would make the comparison a
>> *lot* easier! Moreover, the figures would gain in clarity if you
>> added a label naming the feature analyzed in each plot.
>>
>> 3. In many places there is a confusion between what is measured (the
>> blueshift of the absorption minimum in a given line) and its
>> interpretation-- namely the expansion velocity of the SN ejecta. In
>> particular, expressions such as "the Ca II H&K velocity" have no
>> physical meaning. Why not say what you really measure, namely
>> blueshifts of absorption minima?
>>
>> 4. Why don't you fit the same curve to all pseudo-EW data? If you
>> really like the function described by Eqn (3), why not use it to
>> fit the other pseudo-EW measurements? You could then show the
>> relation between t_br and dm15 for those other features, or at
>> least state that you found no correlation. It seems that by fitting
>> a different function to the "Mg II 4300", you are considering a
>> priori that it is special with respect to the other features you
>> analyze.
>>
>> 5. Do not extensively describe the content of Tables in the text;
>> refer the reader to the Table instead!
>>
>> 6. Notation/expression/etc.:
>>
>> - please make sure *all* instances of EW are replaced with
>> "pseudo-EW" (too many to list here).
>>
>> - sort out references in between parentheses: it should be (Smith
>> et al. 2005), not (Smith et al. (2005)).
>>
>> - please run a spell-checker on the text file to check for typos,
>> spelling mistakes, etc.
>>
>>
>>
>> ########################
>> Detailed comments
>> ########################
>>
>>
>> #
>> # Abstract
>> #
>>
>> You can say that these 12 high-z SNe Ia are from the SCP here.
>>
>> "the Ca II H&K velocity" -> blueshift of the absorption minimum in Ca
>> II H&K (yes it's longer, but physically accurate!)
>>
>>
>>
>> #
>> # 1. Introduction
>> #
>>
>> 1st para.: Maybe add Wood-Vasey et al. 2007 to the list of references
>> at the end of the first paragraph?
>>
>>
>> 2nd para.: evolution of the SNe Ia population -> remove "e" from "SN"
>>
>>
>> 4th para.:
>>
>> divesities -> diversity
>>
>> "So far, very few..." I beg to differ! And your long list of
>> references is there to prove you wrong! Maybe you can say that few
>> were compared in a *quantitative* manner.
>>
>> add a ";" after reference to Matheson et al. (2005)
>>
>> add quotes around "91T-like" here
>>
>>
>> 5th para:
>>
>> obtained the spectra -> remove "the"
>>
>> You say you analyze 14 SNe Ia, but mention 12 in your abstract.
>>
>> remove "we" from "and we perform"
>>
>> i.e. -> namely
>>
>> add hyphens: between low- and high-redshift SNe Ia.
>>
>>
>>
>> #
>> # 2. Method
>> #
>>
>> 1) 3750 -> specify units (Angstroms)
>>
>> 2) how about rephrasing this to:
>> newly-introduced pseudo-EW measurements of features associated with Ca
>> II H&K, Mg II, and Fe II [remove quotes and skip the reference
>> numbers].
>>
>>
>> # Sect. 2.1: PSEUDO-Equivalent Widths of SNe Ia
>>
>> distictive -> distinctive
>> "are very distinctive" is very vague! You mean they are different from
>> the spectra of other SN types, right?
>>
>> give a scale for the ejecta velocities (~10000 km/s)
>>
>> "There has been little work..." Careful not to offend people! How
>> about Nugent et al. 1995; Bongard et al. 2006; Branch et al. 2006;
>> Blondin et al. 2006; Haschinger et al. 2006-- would you say these
>> authors have worked "little"?!
>>
>>
>> # Sect. 2.2
>>
>> 1st para.:
>>
>> physical conditions -> physical properties
>>
>> "the continuum is hard to measure..." It is not "hard" to measure, it
>> is "impossible" to measure in SNe Ia! What you should say is that the
>> overlap of thousands of lines give rise to a "pseudo" continuum (see,
>> e.g., Pauldrach et al. 1996). This is an extremely important point to
>> clarify!
>>
>> Because of this disctinction... -> rephrase to:
>> Because of this distinction with the definition [NOTE: it is not
>> "common", it is the only one!] of EW we use the term "pseudo-EW" to
>> refer to our measurements.
>>
>>
>> 2nd para.:
>>
>> Fig.1 -> when referring to this Fig. in the text, say you are showing
>> spectra from maximum to ~1 month past maximum light.
>>
>> The caption to Fig. 1 reads better now!
>>
>> These limits are given in Table 1 -> We give ranges for these limits
>> in Table 1
>>
>>
>> 3rd para.:
>>
>> typo: pseudo-pseudo-EW (no need to overdo it!)
>>
>> "the" pseudo continuum -> a pseudo continuum
>>
>>
>> 4th para.:
>>
>> traced -> defined
>>
>> last para.:
>>
>> By definition... -> do you really need this paragraph? If you do,
>> please replace "distance" by "redshift"
>>
>>
>> # Sect. 2.3
>>
>> comma after "local SN Ia spectra"
>>
>> that minimize -> that minimizes
>>
>> I would group the last two points in your hyphenated list; remove "in
>> the fitting regions" as this is redundant
>>
>>
>>
>> #
>> # 3. Data sets
>> #
>>
>> # Sect. 3.1
>>
>> "a large number", "a wide range" -> please be more specific!
>>
>>
>> 2nd para.:
>>
>> "light curve shape biases" -> you need to be more explicit here!
>>
>> remove "SN" from "SN 1991bg-like SNe Ia"
>>
>> Although this affects... -> rephrase:
>> Although...degree, lower-luminosity SNe Ia are more commonly found in
>> bright ellipticals.
>>
>> "Moreover..." -> but don't you have the light curves for these SNe Ia?
>> Can't you check whether your S/N cuts have selected the brighter ones
>> from this sample?
>>
>> I see you still like the word "obfuscate"...
>>
>>
>> 3rd para.:
>>
>> Fig. 2 -> please trim noisy ends off spectra! (e.g. in 01ha, 01gi,
>> 01gm, 01go); I had already pointed this out in my previous report!
>>
>> 4th para.:
>>
>> Are you certain that high-z SNe Ia spectra "usually" contain
>> significant amounts of host galaxy light? For instance, what fraction
>> of all published high-z SN Ia spectra have galaxy redshifts (50%?,
>> more?).
>>
>> are usually spatially -> are often spatially
>>
>> "a template-matching technique" -> which one? Reference?
>>
>> Table 2:
>> - why do you have a hyphen in "Red-shift"?
>> - you can probably remove the "ID" column, and simply add a note to SN
>> 2000fd
>> - group footnotes b and e together
>>
>>
>> 5th para.:
>>
>> remove "-- reported in Table 2 --"
>>
>> "to account for a range of SN Ia absorption feature velocities" ->
>> actually, that is not the important point: it is the large intrinsic
>> width of SN Ia spectral features that matters here.
>>
>>
>>
>> # Sect. 3.2
>>
>> remove "low-redshift" from the first sentence; then add ", however,"
>> after "z=0.5" in the next sentence.
>>
>> Please add Matheson et al. (2005) to the list of references.
>>
>>
>> 2nd para.:
>>
>> the SN Ia type -> the SN type
>>
>> Table 3:
>> - footnote c: remove "peculiar"
>> - re-order footnotes in the table such that they appear in
>> alphabetical order
>>
>>
>> # Sect. 3.3
>>
>> Maybe remind the reader what redshift SN 2002fd is at in this first
>> sentence
>>
>>
>> 2nd para.:
>>
>> Paragraphs 2,3 & 4 can be boiled down to one!
>>
>> This percentage is higher... -> at the end of this sentence you should
>> give the percentage for 91T-like SNe Ia in high-z searches and give
>> references.
>>
>> "not exceptionally broad" -> had a dm15 consistent with "normal" SNe
>> Ia
>>
>> "broad light-curve SNe Ia" -> rephrase!
>>
>>
>> 3rd para.:
>>
>> is not inconsistent -> is consistent
>>
>> if considers -> if one considers
>>
>> remove "exact characteristics of the specific": dependent on the
>> search strategy.
>>
>> what do you mean by "and on the real properties of such objects"? This
>> is extremely vague!
>>
>>
>> # Sect. 3.4
>>
>> The spectra were put in the SN Ia restframe -> the spectra were
>> de-redshifted
>>
>> rephrase: showed some degree of contamination by galaxy light.
>>
>> for details ON
>>
>> Set B-
>> Be more concise: "Additionally, the spectra were scaled to match the
>> photometry."
>>
>> pixel-to-pixel variation
>>
>> Table 5: remove (x 10^-3) from the redshift column
>>
>>
>> 2nd para.:
>>
>> Define notation for "stretch":
>> stretch -> stretch ($s$)
>>
>>
>> 3rd para.:
>>
>> Why not show the spectra of 1999bp; it is rather painful to have to
>> look them up in the various plots of Folatelli's PhD thesis!
>>
>> fast decliner -> fast-declining
>>
>>
>>
>> #
>> # 4. Results
>> #
>>
>> (section 4.4) -> sections 4.3 & 4.4
>>
>>
>>
>> # Sect. 4.1
>>
>> The title of this section is misleading in a way; you could be more
>> specific and call it "absorption blueshifts" or (as you do earlier),
>> "absorption velocities".
>>
>> 1st para.:
>>
>> "the velocity of Ca II H&K" -> the blueshift of the Ca II H&K
>> absorption minimum. Again this is a fundamental point: from the Ca II
>> H&K absorption profile you clearly see that Ca II H&K is present
>> between ~7000 and >25000 km/s (e.g., Stehle et al. 2005), so there is
>> no such thing as "the" Ca II H&K velocity. Moreover, what you measure
>> (the velocity location of the maximum absorption in Ca II H&K) is
>> *not* the expansion velocity at a given projected radius!
>>
>> "around 22000 km/s" -> this is a blueshift, so by convention negative:
>> -22000 km/s; otherwise say "the magnitude of the blueshift..." or "the
>> magnitude of the absorption velocity..."
>>
>> slow declining -> slow-declining
>>
>> Rephrase: The shaded area represents the 1$\\sigma$ dispersion about
>> the mean for normal SNe Ia.
>>
>>
>> 2nd para.:
>>
>> "The inferred expansion velocity" -> you do not infer this from your
>> measurements! Replace this by: "The measured absorption velocity [or
>> whatever]..."
>>
>> apprximately -> approximately
>>
>> expantion -> expansion
>>
>> luminouse -> luminous (spell-checker!)
>>
>> "Ca II H& expansion velocities" -> cf. before
>>
>> comparable with that of SN 1999by -> maybe add ", a fast-declining SN
>> Ia"
>>
>>
>> 3rd para.:
>>
>> add a comma after "entire line profile"
>>
>> accurately reproduce -> accurately reproduces
>>
>> succefully -> successfully
>>
>> previous works -> previous studies
>>
>> for clarity, remove $\\sigma_z = 0.001 \\equiv$
>>
>> "by comparing their spectra" -> what do you use to do this? Add
>> references.
>>
>> The last sentence is a direct corollary from your two previous
>> sentences, and may be omitted.
>>
>> Fig.4: Can you make the font (1) larger and (2) bolder; this figure is
>> difficult to read as is.
>>
>> Table 6.:
>> - Measurements uncertainties -> Measurement uncertainties
>> - I couldn't see a reference to Table 6 in the text; please add one if
>> it isn't there
>> - "the velocities", "Ca II H&K vel" -> change these to reflect what
>> you measure
>> - if you decide to go with blueshifts, change the sign in the last
>> column
>> - UNITS! (km/s)
>>
>>
>> # Sect. 4.2
>>
>> # 4.2.1.
>>
>> 1st para.:
>>
>> encountered pseudo-EWs -> measured pseudo-EWs
>>
>> The sigmas of these simulations -> the widths (or standard deviations)
>> of these distributions
>>
>>
>> 2nd para.:
>>
>> What do you mean by the "nature" of the broad SN Ia features? Do you
>> mean to say: "Due to the large intrinsic width of SN Ia features"?
>>
>> (10 A/pixel) -> this is looks like an instrumental resolution rather
>> than a width of a SN Ia feature!
>>
>>
>> 4th para.:
>>
>> Say where 0.32 mag come from? Why not test this up to 1 mag of
>> reddening?
>>
>> "The nature of these quantities..." -> rephrase to: "This is expected
>> since the pseudo-EWs are defined over a limited wavelength range"
>>
>>
>> 5th para.:
>>
>> from 0 to 50% -> up to 50%
>>
>> relative decrease in the pseudo-EW per each 10%... -> is the relative
>> decrease linear with galaxy contamination fraction?
>>
>> Table 7:
>> - rename the "Host type" column to reflect what you measure, namely
>> the "fractional decrease in pseudo-EW" [you can add a note to the
>> table or refer to the text for more details]
>>
>>
>> # 4.2.2.
>>
>> mean curve -> mean trend
>>
>> only for normal supernovae -> for normal SNe Ia only
>>
>> The curve was built...-> please rephrase this sentence to be more
>> clear and succinct
>>
>>
>> 2nd para.:
>>
>> This due -> This is due
>>
>> Rephrase the above sentence: "This is due to the increasing optical
>> depth of Fe II lines from around maximum light onward..."
>>
>>
>> 3rd para.:
>>
>> Rephrase 1st sentence: "The evolution of pseudo-EWs is similar for all
>> Ia subtypes, but offset..."
>>
>> You can remove the rest of the paragraph starting with "Column 1..."
>>
>>
>> 5th para.:
>>
>> You can safely remove the first three sentences. Then start the 4th
>> sentence with "1991T-like SNe Ia show systematically..."
>>
>> Do you need this paragraph? You are repeating what you just say in the
>> the 3rd para.!
>>
>>
>> 6th para.;
>>
>> sample is shown -> sample are shown
>>
>>
>> # 4.2.3.
>>
>> First sentence: "Various ions correspond to feature #3."
>>
>> Fig. 6: Last sentence of caption -> say these are nearby supernovae.
>>
>> 2nd para.:
>>
>> Here's a good place to introduce the t_br notation:
>> "The phase at which this increase takes place, t_br, ..."
>>
>> the SNe Ia subtype -> the SN Ia subtype
>>
>>
>> 3rd para.:
>>
>> Again, what are (A,B,tau,t)? (you already define t_br); say that A & B
>> are simple constants, t is the SN phase, and tau is some e-folding
>> time scale.
>>
>> I still do not understand the motivation for this complex functional
>> form. If its sole purpose is to determine t_br, can't you do that by
>> spline fitting? If not, why don't you use the *same* functional form
>> to fit the other pseudo-EW measurements? Please make the motivation
>> clear!
>>
>> In any case, you should state the values of (A,B,t_br,tau) in Fig. 6
>>
>> Table 9: three SNe Ia subtypes -> three SN Ia subtypes
>>
>> quanify -> quantify
>>
>> to classify supernovae -> to classify type-Ia supernovae
>>
>> the pseudo-EW tend -> the pseudo-EW measurements tend [or "the
>> pseudo-EWs tend..."]
>>
>> add a comma after "light)"
>>
>> with SN 1992A measuring -> with SN 1992A pseudo-EWs having
>> intermediate...
>>
>> outlayer -> outlier
>>
>> has to be considered -> is
>>
>> type Ia SNe Ia -> type Ia SN
>>
>> asses -> assess
>>
>> remove "supernova" from "interesting supernova physics"
>>
>>
>> 4th para.:
>>
>> indent this paragraph
>>
>> correlated to -> correlated with
>>
>> Be careful when you make the claim that the Mg II pseudo-EW is
>> correlated with photometric properties. What you really show is that
>> it is correlated with spectroscopic peculiarities, and therefore
>> (maybe) with M_B...
>>
>> remove "with weights on both axes"
>>
>> you can remove the dot product in Eqn. 4
>>
>> footnote 7: evolutionary curve -> trend
>>
>> Table 10: the caption makes no sense. What is a "lightcurve spectral"
>> parameter?
>> - footnote b: realted -> related
>>
>>
>> 5th para.:
>>
>> optical detectors -> optical spectrographs
>>
>> Since several -> However, since several
>>
>>
>> # 4.2.4.
>>
>> lines from heavy elements -> lines from iron-peak elements
>>
>> remove hyphen in front of "-objects"
>>
>> This is possibly due -> This is due...
>> Rephrase this confused sentence: "This is primarily due to the
>> strength of the Ca II H&K line when compared with Mg II and Fe II".
>>
>> absoprtion -> absorption
>>
>> interval span -> interval spanned
>>
>>
>> 2nd para.:
>>
>> The large pseudo-EW measurements for Ca II H&K in SN 1999bm could
>> simply be due to Si II 3858! The Ca II H&K line is so strong that,
>> even when you detect high-velocity components in the Ca II IR triplet,
>> these are not necessarily resolved in the H&K absorption.
>>
>>
>> 3rd para.:
>>
>> The *pseudo*-EW
>>
>> as function -> as a function
>>
>> What do you use to define an "outlier" here? Do you determine this by
>> eye, or a sigma-clipping algorithm etc.
>>
>>
>>
>> # Sect. 4.3 PSEUDO-EW...
>>
>> remove "peculiar" from "peculiar 91T-like SNe Ia"
>>
>> put "see Fig. 8" in between parentheses
>>
>> Fig. 8: Slow-decliner -> Slow-declining
>>
>> with the normal -> with normal
>>
>>
>> 2nd para.:
>>
>> Please rephrase this first sentence!
>>
>> host galaxy contamination uncertainties -> systematic uncertainties
>> related to the level of host galaxy contamination
>>
>> Table 11:
>> - day -> epoch
>> - "Note" appears twice
>> - EW -> pseudo-EW
>> - UNITS! (Angstroms)
>>
>>
>> # Sect. 4.4
>>
>> Rephrase the 2nd sentence: "We can look for systematic differences
>> between the low- and high-redshift SNe Ia by comparing the mean
>> trends..."
>>
>>
>> 3rd para.:
>>
>> You can remove the text up until "...is also included." Add some of
>> this text as notes to Table 12. Start this paragraph with "The
>> hypothesis that..."
>>
>> behavior -> evolution
>>
>> accepted -> confirmed
>>
>>
>>
>> #
>> # 5. Summary and Conclusions
>> #
>>
>>
>> 2nd para.:
>>
>> the velocities of the ejecta -> cf. previous notes...
>>
>>
>> 3rd para.:
>>
>> hyphen in "low-redshift sample"
>>
>> parallel to each other -> rephrase! "The pseudo-EW measurements follow
>> similar trends, but offset..."
>>
>> occures -> occurs (three places)
>>
>>
>> 5th para.:
>>
>> remove "and pointing out that" and start the next sentence with "This
>> feature can be used..."
>>
>>
>> 6th para.:
>>
>> small when compared to the number of SNe Ia -> you mean high-z SNe Ia?
>>
>> End with a good punch line, e.g.: "The case study presented here
>> offers a simple method to analyze the spectra observed in these
>> surveys and look for systematic differences between SNe Ia at
>> different redshift."
>>
>>
>>
European Southern Observatory
Alonso de Cordova 3107, Vitacura
Casilla 19001, Santiago 19
CHILE

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