The Resonant Bremsstrahlung of Ultrarelativistic Electrons on a Nucleus with Radiation of Hard Gamma-Quanta in the Presence of a Pulsed Field of the X-ray Pulsar

Round 1

Reviewer 1 Report

Astrophysical radiations, jets and cosmic rays from neutron stars, magnetars, X-ray pulsars, and black holes etc. have been well studied in theoretical and experimental physics. The authors study spontaneous bremsstrahlung processes of ultrarelativistic electrons with hard gamma-quanta radiations under subsequent resonant conditions and obtain high resonant differential cross-sections of such processes which could explain anomalous emissions of high-energy gamma-quanta from astrophysical compact objects. I find this work interesting but I recommend the authors to consider following points:
i) "Roshhupkin" in page 1 would be replaced with "Roshchupkin".
ii) Third diapason with $\delta '_{f} ^{2} > \delta '_{+(r)} ^{2}$ is not discussed in pages 6-7. Then the authors may add some sentences to explain third diapason.
iii) Curves 1' and 2' in Fig. 3, a curve 1 in Fig. 5 (b) and curves 1 and 2 in Fig. 6 (b) are broken in the middle. Then the authors may correct these curves or explain the reason why these curves are broken.
iv) There are following papers by present authors in arXiv:
a) S. P. Roshchupkin, A. I.Voroshilo, arXiv:cond-mat/9911369.
b) Sergei P. Roshchupkin, Alexander Dubov, Victor V. Dubov, arXiv:2004.02247.
For example, figures in above paper b) are similar to those in a present paper. Then the authors may add discussions to explain differences between these two papers and a present paper in detail.

Author Response

Dear Reviewer and MDPI editor colleage,

Thank you for your work,
Please see the attachment to this letter with the answer to the review.

Regards,
Authors

Author Response File: Author Response.pdf

Reviewer 2 Report

An interesting paper. It should be published, eventually. However, I am afraid that without improving the presentation, 90% of the readership will not get the main points of the paper. Let me ask some questions: Where, precisely, do I find the precise definitions of all the M^0 and F_mu symbols used in Eqs. (14) and (15)? How, precisely, are the incoming and outgoing states being described? As Dirac-Volkov states? Which approximations are made for the internal propagator? How does the treatment compare to the one described in Refs. [41] and [42], where all summations over the virtual excitations (Dirac-Volkov propagators can be written as such) are carried out to all orders? Is it possible to compare the work to the ones by Ritus, who considered the mutual relation of cascade processes and radiative corrections to synchrotron radiation in the 1970s? Are the authors sure that the reader precisely understands what "resonant" means in the current context? Is it "resonant" with respect to the relation of the emitted photon frequency and the driving laser frequency, and/or also "resonant" in regard to the emission direction? [ I think I know the answer, but many readers will be fully confused. ] In general, the introduction and the general presentation could be drastically improved. The same applies to the typesetting (line breaks) in the mathematical formulas, and (in part) to the conclusions.

Author Response

Dear Reviewer and MDPI editor colleage,

Thank you for your work,
Please see the attachment to this letter with the answer to the review.

Regards,
Authors

Author Response File: Author Response.pdf

Reviewer 3 Report

This is an excellent document. The only criticism I have of it after looking at it for a week is that this is an extension of the following document

 

See the attached file. 1907.10431.pdf

 

I request that the authors specifically at the beginning of the document go through in detail what is different in their present document from the ARXIV 1907.10431.pdf document and to elaborate how their present document builds upon the ARXIV document , improves and expands on it.

Aside from this nit, the document is professional and well worth publishing. Having this clearly stated and then talking about the subsequent build up to the new document is a minor but useful exercise for the record

I do NOT have a criticism of the research itself. But if one goes to figure 6  of page 12 of the ARXIV PDF below and compare it with the document sent in for UNIVERSE, this is a paper worth having in this journal

 

It is by no means an issue of self plagarization. But if an article is in ARXIV as 1907.10431.pdf then one has to be dotting the i and crossing the t in the manuscript

 

Aside from that, well done!

 

Author Response

Dear Reviewer and MDPI editor colleage,

Thank you for your work,
Please see the attachment to this letter with the answer to the review.

Regards,
Authors

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have addressed many of my concerns. I would like to leave further improvements to the authors, such as an improved typesetting of Eq. (6), the correction of the incomplete sentences around Eqs. (40) to (43), the missing full stop after Eq. (45), etc. etc. etc. In the caption of Fig. 3, I would suggest to explain better, in physical terms, what the curves 1', 2', and 3' mean, in terms of their physical interpretation. A reader might be interested in understanding the curves without having to read the entire article in precise detail.

Author Response

Dear Reviewer,

Thank you for your work and attention,

The indicated changes were implemented into the paper, please see the attachment with description of changes.

Regards,
Authors

Author Response File: Author Response.pdf