Simulation of the Isotropic Ultra-High Energy Photon Flux in the Solar Magnetic Field

Round 1

Reviewer 1 Report

I find interesting the research performed (in general) by the CREDO collaboration regarding the indirect detection (or not) of UHE photons. 

However, In this paper it is very hard to find new results important enough to be considered for publication as a new article. In my opinion, the most relevant work was already published in the reference [11] from the present manuscript.

I kindly ask the author to emphasize what is the novelty of this manuscript  compared to the previously published paper in [11].

I also noticed some minor language inconsistencies: 

- page 6, line 164: "The influence of simulation input parameters on the distribution has been the subject of the previous study [11]" -> which distribution ? Did you mean the spatial distribution of the secondary photons at the atmosphere ?

- page 8, the paragraph bellow Eq. 10 : "Due to the fact that ( ˜θ, ϕ˜) are defined in the local coordinate system related to the position on the start sphere. Generated angles are firstly transformed to local Cartesian system" - I guess it should be reformulated as one sentence;

- page 9, line 210: "the particles’ propagation" - please reformulate;

- caption of Fig 4: "the exemplary simulation 3" -> maybe "the exemplary simulation from Figure 3";

- Is missing the point at the end of the caption of Fig 5;

- page 12: "photons’ impact parameters" -> photon’s impact parameters;

- page 12: "They justified the consideration of the cumulative distribution of secondary photons." -> incomplete sentence or misplaced ? 

- page 12: "And for the heliocentric latitude..." -> never start a sentence with "and";

- the reference 19 "Albert, A.; et al. for the Auger Collab." belongs to the HAWC Collaboration, NOT to the Pierre auger Collaboration. Please check all the references;

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The idea is quite interesting, especially in relation to the possibility of detecting simultaneous showers arising from secondary particles of a photon primary that interacted with the Solar magnetic field.

I only have some conceptual comments about the article and some suggestions for clarifications that are necessary for the text for a good understanding of the work.

The abstract is not very clear in relation to the work proposals and possible results.
A good part of the work focuses on modifying the simulation code and adjusting the parameters necessary to optimize it, which in itself is a substantial merit to the work, however, this should be more clear in the summary. The first impression that the summary gives is that the proposed final observables (energy spectrum of the photons (primary/secondary?), the density as a function of this energy range and the geographic orientation of the particles at the top of the atmosphere) will be part of the final results, as it is already possible to use it by simulators of extensive atmospheric showers (CAE) from the distribution of secondary multiples of photons at the top of the atmosphere. However, what is found throughout the text is a work, quite interesting in relation to updating the PRESHOWER code, but at the same time it does not make clear the specificity of these observables as input parameters in CAE simulators.
It is clear that these specifics are the result of a progression of the work, and do not need to be contained in this article. I just emphasize that the summary needs to be clear that the work is very focused on updating and optimizing the code and the final results corroborate the success of your update.

The last part of the abstract, "The novel advantage of such non-observation results ... " does not take into account the fact that non-observation may also be related to the extreme technical difficulty of the measurement, since measuring extensive showers produced by multiple primaries at the top of the atmosphere is a proposal with serious technological limitations; mainly with regard to trigger time and the numerous fluctuations related to detector length, or multiple detectors.

What would a reader expect to find in this article given the title and abstract? I leave the following questions as examples:

1) despite the mention of the "energy spectrum", only events with 100EeV were simulated. There is also no mention in the article about the energy spectrum of secondary photons, which would be a very expected result. I understand that this should be a future work, so it would be important to make it clearer throughout the text; and if possible already in the summary.

2) the density of secondary photons at the top of the atmosphere depends on the energy of the primary. This is also not clear in the text.

3) In my view, a possible detection of these multiple primaries is feasible when the detector is "pointed" towards the Sun. This cuts the duty cycle in half. Considering the sphericity of the earth maybe to 60% or 70%. Therefore, of the 324 successes (in one year), we would have between 162 and 227 detectable events. It's a considerable reduction. It is important to mention this in the text.

4) the results of the work focus on the spatial distribution of secondary photons at the top of the atmosphere. This is a very relevant result that should be mentioned in the abstract.

5) The number of simulated events is unclear. Would it be the 100,000 on line 195? However in figure 5 10^10 simulations are mentioned for each limit. It would be very useful to create a specific subsection for the al input parameters of the code.

6) I understand that the solar magnetic field is somewhat difficult to describe, and using a dipole magnetic field as a first approximation is quite reasonable. However, an inevitable question for a reader is: what would happen to the cascade of secondary photons as a function of the intensity of this field, mentioned in line 97?

7) The flow anomaly mentioned in the text after figure 8, page 12 (in my version of the article there is no number of lines in this part), is one of the keys to this work. Having in hand the measurement of the photon flux CRE/year, it would be possible (in theory) to quantize the increase in the flux measured in references 19 and 20. Mentioning this possibility in the conclusion would give more weight to the work.

Minor corrections:

Figures need to be adjusted:

Figures 1 and 2 have very small letters and the three-dimensional position does not make it much easier for the reader to identify the positions of the primary and secondary photons. In figure 2, only by reading the text it is possible to identify the tiny purple arrow, which is almost black. Maybe switching to magenta will help. But the best would be to enlarge the figure and the text.

Figures 5, 6 and 7 have problems with the alignment and overlapping of the points on the axes or on the tickness. The size of the dots could be bigger. Figure 5 has very small letters too Figure 6 could start with the y-axis a little below zero so that the points are not overlapping by the x-axis. Same for figure 7.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The article "Simulation of the isotropic ultra-high energy photons flux
in the solar magnetic field" by Poncyljusz et al. is a nice report on the possibilities of simulations of UHE photons in the solar magnetic field using the PRESHOWER program. I therefore only have a few small remarks from which the article would profit in my opinion:

1. Please define the term "ultra high energy" explicitly. Since it is used in different ways by different authors, it would be good to know which regime eactly you use by that.
2. I am somehow confused by the definition of "Cosmic Rays" in the article: In lines 65-66 it says "ultra-high energy cosmic ray flux composed mainly of photons", which implies that photons are, in fact, cosmic rays, which is wrong, as cosmic rays are the nuclear component of the overall flux arriving at Earth. Please correct the corresponding statement here and in other sections of the article.
3. In the discussion section I am missing a comment on how the results and methods presented here may be connected with the results of simulations of the interstellar, galactic and intergalactic propagation of UHE photons (using, for example, DRAGON, GAPROP or CRPropa). Are there plans, or has it already been done? Please comment on that.
4. The text overall would profit from a thorough language proofreading of the whole text. In the following, I only list the mistakes I found on first glance, but even more could be present:
- line 21: "res" -> "results"
- line 32: "such approach" -> "such an approach"
- line 40: "for us" -> "to us"
- page 3: "hν - photon energy, me - electron mass" -> "hν is the photon energy, me is the electron mass"
- page 4: "is modified Bessel function" -> "is the modified Bessel function"
- page 4: please define the term "fractional pair-member energy"
- page 4: "For short time interval" -> "For a short time interval"
- page 4: "with Taylor series expansion" -> "with the Taylor series expansion"
- page 4: "with parametrization ..., where E is electron/positron energy, and" -> "with the parametrization ..., where E is the electron/positron energy, and"
- page 4: "is emitted photon energy" -> "is the emitted photon energy"
- page 5: "where P is radiation power and r0 is classical electron radius" -> "where P is the radiation power and r0 is the classical electron radius"
- page 5: "and dN - the number" -> "and dN is the number"
- page 6: "at ultra-relativistic regime, synchrotron photons are emitted in half opening angle" -> "in the ultra-relativistic regime, synchrotron photons are emitted in a half opening angle"
- line 94: "about charge particle direction" -> "around the direction of the charged particle"
- line 104: "like it was done in" -> "as it was done in"
- line 117: "start point" -> "starting point"
- line 134: "start point" -> "starting point"
- line 148: "start point" -> "starting point"
- line 166: "or created particles" -> "or the created particles"
- page 8: "start point" -> "starting point"
- page 8: "to local Cartesian system" -> "to the local Cartesian system"
- line 232: "First simulations" -> "The first simulations"
- line 233: "on the Earth" -> "on Earth"
- line 238: "land point" -> "arrival point"
- line 240: "on the Earth" -> "on Earth"
- page 11: "on the Earth" -> "on Earth"
- page 13: "However, prepared method" -> "However, the presented method"

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The explanations introduced by the authors in the abstract does not change the quality of the results (the lines 21-23 make no sense - incomplete sentence ?).

In my opinion, this manuscript is a preliminary stage of a work which should produce more quantitative results. The optimization of a simulation code is an important achievement, but the readers are expecting some realistic results i.e. the density and energy spectrum of secondary photons at the top of the atmosphere and a realistic rate of CRE potentially observed at cosmic ray experiments like Auger of TA (which should take into account the experimental capabilities). After that we can think about constraining the UHE photons limits which would be a great result.

Therefore, I consider that the present manuscript is not suitable for publication in this form.

Author Response

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Author Response File: Author Response.pdf