by david.paneque » Tue Feb 09, 2016 1:01 am
Posted on behalf of Adiv Gonzalez
Hi all
The referee has sent his reply. He basically insist that we should change "measurement" to "constraint" or "upper limit" in the title and the text. Please see his reply in the following lines
Referee Report
I feel rather strongly that the results of this manuscript should not
be described as a "measurement" or "detection" of the EBL, as I
discussed in my previous report. If the authors insist on
characterizing their results this way, I think at this point it will
save everybody time if they ask the scientific editor to overrule my
objection, or ask for another referee. Otherwise, I think we will
just go around in circles. Rather than the standard format of quoting
the authors followed by my response, I give a summary of both the
authors' position and my position. I hope the authors will think the
summary is fair to them. I think this summary will be more useful to
the editor and/or future referee.
I would like to say once again that, aside from this disagreement, the
authors present an interesting, well-written paper that should be
published in A&A.
The authors' position:
1) The authors put an upper limit on the EBL based on MAGIC
observations of the source 1ES 1011+496 and the primarily assumption
that its gamma-ray spectrum is concave. This upper limit is reliable
and robust.
2) Their lower limit on the EBL depends strongly on the assumed form
for the intrinsic gamma-ray spectrum of 1ES 1011+496, and so the
lower-limit is not particularly robust. It their response to my first
report, the authors modified the manuscript in several places to say
this.
3) Despite the fact that it is not robust, the authors think the lower
limit is still meaningful. This is because the intrinsic spectrum is
"describable by one of the simple concave function" they use (listed
in Table 1 of the manuscript, and described in a previous paper by the
HESS Collaboration).
4) The authors put the word "detection" in quotation marks in several
places as an indication that it is "not a formal detection". In at
least one instance they replaced the word "detection" with
"constraint" in response to my last report.
5) Previous papers have used similar techniques and referred to the
result as a "detection". It is not completely clear which papers the
authors are referring to in their last response, but I assume they
mean the paper by the HESS Collaboration (2013, A&A, 550, A4).
Keeping the phrase "measurement" in the title and other places will
allow readers to compare this result with the previous results by the
HESS Collaboration.
6) All of the assumptions are clearly spelled out in the manuscript.
The readers can read the details of the technique for themselves and
determine for themselves whether or not the phrases "measurement of
the EBL" or "detection of the EBL" are justified.
7) The lower limit on the EBL is not particularly interesting. The
authors' exact words: "the goal is not to detect the EBL, since there
is no doubt that some level of EBL must exist at least from the
resolved galaxies. In this sense the lower constraint is of no big
interest as long as it does not go significantly above the lower
limits from galaxy counts (and it doesn't)."
The referee's position/response:
1) The authors put an upper limit on the EBL based on MAGIC
observations of the source 1ES 1011+496 and the primarily assumption
that its gamma-ray spectrum is concave. This upper limit is reliable
and robust. I completely agree with the authors about the upper
limit.
2) The lower limit on the EBL depends strongly on the assumed form for
the intrinsic gamma-ray spectrum of 1ES 1011+496, and so the
lower-limit is not particularly robust. The authors and I seem to be
in agreement about this also, at least to a certain extent.
3) I do not think the lower limit is meaningful because of this lack
of robustness. Unlike the upper limit, the lower limit does not
depend only on the assumption that the intrinsic spectrum is concave,
but depends on the particular choice of function to model the
intrinsic spectrum. I think there are many possibilities for the
intrinsic spectrum that are not adequately described by one of their
simple functions. The intrinsic spectrum could have peculiarities due
to the (poorly understood) particle acceleration process, or cutoffs
from internal absorption, or cutoffs in the electron distribution, or
turnover in the Klein-Nishina cross-section at high energies (the
latter two assume the gamma-rays are produced by Compton scattering).
If the gamma-rays are produced by a hadronic process, the shape of the
gamma-ray spectrum is even less well-understood.
4) Because the lower limit is not meaningful, I do not think the
result should be characterized as a "detection of the EBL" or a
"measurement of the EBL". Instead phrases like "constraint" or "upper
limit" should be used. I do not think putting "detection" in
quotation marks is an adequate substitute for using the phrase
"constraint". Also I note their are many instances of the phrase
"measurement of the EBL" without quotation marks. This includes in
the title of the paper, the abstract, the last paragraph of Section 1,
the title of Section 4, etc. I disagree with all of these uses.
5) I also disagree with the HESS Collaboration's characterization of
their result as a "measurement". I stated this in my first report.
6) Let's face it, most readers are not going to dig into the details
of this paper. If they read the title of the paper, where a
"measurement" is claimed, they are going to think there is a robust,
meaningful, upper AND lower limit on the EBL. Words matter, and I
think the title of the manuscript gives a misleading impression.
7) In none of my reports have I given an opinion on how interesting
the lower limit is relative to the upper limit.
Final thoughts from the referee: The fact that the authors "partially
agree" with me about the lower limit, and that they do not think the
lower limit is particularly interesting, indicates that this is mostly
a semantics argument. But, I do feel that the semantics are important
in this case. Consider if MAGIC put only an upper limit on the
gamma-ray flux from a particular source. This would not be
characterized as a "detection" or "measurement". If an upper limit on
gamma-ray flux was described as a measurement in the title and
abstract of a paper, a referee would certainly object.
[b][color=#FF0000]Posted on behalf of Adiv Gonzalez[/color][/b]
Hi all
The referee has sent his reply. He basically insist that we should change "measurement" to "constraint" or "upper limit" in the title and the text. Please see his reply in the following lines
Referee Report
I feel rather strongly that the results of this manuscript should not
be described as a "measurement" or "detection" of the EBL, as I
discussed in my previous report. If the authors insist on
characterizing their results this way, I think at this point it will
save everybody time if they ask the scientific editor to overrule my
objection, or ask for another referee. Otherwise, I think we will
just go around in circles. Rather than the standard format of quoting
the authors followed by my response, I give a summary of both the
authors' position and my position. I hope the authors will think the
summary is fair to them. I think this summary will be more useful to
the editor and/or future referee.
I would like to say once again that, aside from this disagreement, the
authors present an interesting, well-written paper that should be
published in A&A.
The authors' position:
1) The authors put an upper limit on the EBL based on MAGIC
observations of the source 1ES 1011+496 and the primarily assumption
that its gamma-ray spectrum is concave. This upper limit is reliable
and robust.
2) Their lower limit on the EBL depends strongly on the assumed form
for the intrinsic gamma-ray spectrum of 1ES 1011+496, and so the
lower-limit is not particularly robust. It their response to my first
report, the authors modified the manuscript in several places to say
this.
3) Despite the fact that it is not robust, the authors think the lower
limit is still meaningful. This is because the intrinsic spectrum is
"describable by one of the simple concave function" they use (listed
in Table 1 of the manuscript, and described in a previous paper by the
HESS Collaboration).
4) The authors put the word "detection" in quotation marks in several
places as an indication that it is "not a formal detection". In at
least one instance they replaced the word "detection" with
"constraint" in response to my last report.
5) Previous papers have used similar techniques and referred to the
result as a "detection". It is not completely clear which papers the
authors are referring to in their last response, but I assume they
mean the paper by the HESS Collaboration (2013, A&A, 550, A4).
Keeping the phrase "measurement" in the title and other places will
allow readers to compare this result with the previous results by the
HESS Collaboration.
6) All of the assumptions are clearly spelled out in the manuscript.
The readers can read the details of the technique for themselves and
determine for themselves whether or not the phrases "measurement of
the EBL" or "detection of the EBL" are justified.
7) The lower limit on the EBL is not particularly interesting. The
authors' exact words: "the goal is not to detect the EBL, since there
is no doubt that some level of EBL must exist at least from the
resolved galaxies. In this sense the lower constraint is of no big
interest as long as it does not go significantly above the lower
limits from galaxy counts (and it doesn't)."
The referee's position/response:
1) The authors put an upper limit on the EBL based on MAGIC
observations of the source 1ES 1011+496 and the primarily assumption
that its gamma-ray spectrum is concave. This upper limit is reliable
and robust. I completely agree with the authors about the upper
limit.
2) The lower limit on the EBL depends strongly on the assumed form for
the intrinsic gamma-ray spectrum of 1ES 1011+496, and so the
lower-limit is not particularly robust. The authors and I seem to be
in agreement about this also, at least to a certain extent.
3) I do not think the lower limit is meaningful because of this lack
of robustness. Unlike the upper limit, the lower limit does not
depend only on the assumption that the intrinsic spectrum is concave,
but depends on the particular choice of function to model the
intrinsic spectrum. I think there are many possibilities for the
intrinsic spectrum that are not adequately described by one of their
simple functions. The intrinsic spectrum could have peculiarities due
to the (poorly understood) particle acceleration process, or cutoffs
from internal absorption, or cutoffs in the electron distribution, or
turnover in the Klein-Nishina cross-section at high energies (the
latter two assume the gamma-rays are produced by Compton scattering).
If the gamma-rays are produced by a hadronic process, the shape of the
gamma-ray spectrum is even less well-understood.
4) Because the lower limit is not meaningful, I do not think the
result should be characterized as a "detection of the EBL" or a
"measurement of the EBL". Instead phrases like "constraint" or "upper
limit" should be used. I do not think putting "detection" in
quotation marks is an adequate substitute for using the phrase
"constraint". Also I note their are many instances of the phrase
"measurement of the EBL" without quotation marks. This includes in
the title of the paper, the abstract, the last paragraph of Section 1,
the title of Section 4, etc. I disagree with all of these uses.
5) I also disagree with the HESS Collaboration's characterization of
their result as a "measurement". I stated this in my first report.
6) Let's face it, most readers are not going to dig into the details
of this paper. If they read the title of the paper, where a
"measurement" is claimed, they are going to think there is a robust,
meaningful, upper AND lower limit on the EBL. Words matter, and I
think the title of the manuscript gives a misleading impression.
7) In none of my reports have I given an opinion on how interesting
the lower limit is relative to the upper limit.
Final thoughts from the referee: The fact that the authors "partially
agree" with me about the lower limit, and that they do not think the
lower limit is particularly interesting, indicates that this is mostly
a semantics argument. But, I do feel that the semantics are important
in this case. Consider if MAGIC put only an upper limit on the
gamma-ray flux from a particular source. This would not be
characterized as a "detection" or "measurement". If an upper limit on
gamma-ray flux was described as a measurement in the title and
abstract of a paper, a referee would certainly object.
