Large-Scale Asymmetry in the Distribution of Galaxy Spin Directions—Analysis and Reproduction

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

I observed some minor misprints in the text and the author may fix them.

Author Response

Report on “Large-scale asymmetry in the distribution of galaxy

spin directions-analysis and reproduction”

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In this study, the author explored the spin direction of galaxies in the largescale structure of the universe in order to identify possible parity violations between the number of galaxies that spin in different directions. He investigated the observational and methodological aspects of various previous studies and compared their results. In my opinion, the manuscript is well-written and the arguments raised by the author sound clear to potential readers. The manuscript has enough material to be published, and I recommend the paper for possible publication in Symmetry after addressing the following minor corrections.

 

--Author response: Thank you for the time you took to read and comment on the paper, and for the helpful insights. All comments have been addressed, and the responses to each comment with explanation of how it was addressed and what changes were made to the manuscript are below the comments. For convenience, changes made to the manuscript are highlighted in bold font.

 

 

1. In the fifth paragraph of Sec. 2, it seems the author is talking about Ref. [119], but he cited Ref. [118]. In the same paragraph, the number of mirrored counterclockwise galaxies should be 5,425 according to Table 1.

 

--Author response:  The reference is in fact the correct reference, but the wording of the sentence is very bad, and led to confusion. The idea was to note that the crowdsourcing provided more annotated galaxies than the dataset discussed in the previous section. But that sentence does not add any useful knowledge, while it is confusing to the reader. I just removed the comparison to the dataset from the previous section, which does not add anything useful to the paper other the confusing the reader.

 

 

2. In the sixth paragraph of Sec. 2, the number of mirrored clockwise galaxies should be 5,155 according to Table 1.

--Author response: Thank you. There was an error in the description. The purpose was that galaxies these are the numbers of galaxies annotated as counterclockwise and the number of mirrored galaxies annotated as counterclockwise. That has been corrected, and now the description is aligned with the numbers in the Table 1.

 

 

 

3. I suggest moving the web links presented throughout the paper to the references. I did not find it interesting to see these links everywhere in the text.

--Author response: Thank you for the comments. I agree that the style of having a URL inside the text is not perfect. I now changed the paper so that the URLs are all footnotes. They are not in the references because they are not exactly scientific sources, but they are also not part of the text. The URLs are important as they lead to the code and data that allow the reproduction of the work.

 

 

 

4. Why did not the author include other important features of galaxies, such as mass and size in the calculations? Intuitively, it seems to me that the effect of mass and size should be considered in the simulations as well.

--Author response: That’s a good point, and was done in previous papers. The size was tested in previous papers (e.g., Shamir, 2020, ApSS, such as Table 4), and the mass was examined in (e.g., Shamir, 2022, AN, such as Figures 18 and 19). There was no point to repeat the same experiments, especially when the topic of this paper is focused on previous experiments, so I just added a short description to the introduction section, with references to these papers. In any case, the purpose of this paper is to reproduce other experiments in the way they were done. Because none of these previous experiments used the mass and size, the replication/analysis of them also did not include them, not to shift from the original experiments. But I added a note to the Introduction section about the effect of size and mass, with references to the papers where these experiments were made.

 

 

5. Did the studies investigated in this manuscript just consider face-on galaxies? If yes, why they did not include inclined galaxies? If not, how did they include inclination in the computations? The author should at least put a comment on this matter.

 

--Author response: This paper uses data used in previous experiments, and were collected by others, so that obviously out of my control. But from observing Galaxy Zoo galaxies and galaxies annotated by SPARCFIRE these galaxies are face-on galaxies, otherwise it is difficult to annotate them. That is because they are annotated by the shape of their arms, and not by spectroscopy like in the case of edge-on galaxies.

Inclination is not included in the analysis, and it can be assumed that the inclination of the face-on galaxies in not exactly 90 degrees for all of them. But it is also expected that these inclination variations will distribute equally between galaxies that spin clockwise and galaxies that spin counterclockwise. That discussion has been added to Section 6.

 

Reviewer 2 Report

The author presents a comprehensive analysis about the large-scale asymmetry in the distribution of galaxy spin
directions.  The work highlights the importance of reproducibility of science, reproducing the results and analyzing the research aims of different studies show conflicting conclusions about large-scale asymmetry. Overall, the manuscript is well written and concise. However, I believe that few additional references in the Introduction are needed before I can recommend the paper for publication.

51: please add York et al. 2000 reference for SDSS and spell acronym.

65: please also see most recent reference (Mai et al. 2022) about how galaxy rotation is affected by the motion of neighbour galaxies

 

73: SAMI - please add Bryant et al. 2015 and Croom+2021 reference for SAMI survey

73: Please add reference Barsanti et al. 2022 for the most recent work on galaxy spin-filament alignments in the SAMI survey

 

Author Response

The author presents a comprehensive analysis about the large-scale asymmetry in the distribution of galaxy spin directions.  The work highlights the importance of reproducibility of science, reproducing the results and analyzing the research aims of different studies show conflicting conclusions about large-scale asymmetry. Overall, the manuscript is well written and concise. However, I believe that few additional references in the Introduction are needed before I can recommend the paper for publication.

--Author response: Thank you for the time reading and commenting on the manuscript, and for bringing these points to my attention. I make all efforts to mention all previous work, but it is possible that some previous work escaped my attention. So thank you for these comments. All of them have been addressed, and the corrections made based on these comments are specified below each comment.

51: please add York et al. 2000 reference for SDSS and spell acronym.

--Author response: Thank you for the comment. SDSS is now spelled out (in the first time it is mentioned in the paper), and the reference has been added to the part where SDSS is briefly described (line 51 in the original version). 

65: please also see most recent reference (Mai et al. 2022) about how galaxy rotation is affected by the motion of neighbour galaxies

--Author response: I was not aware of this newer work, and now added it to the manuscript. Thank you. It discusses spin alignment in smaller scales, and is now mentioned in the part where smaller scale studies are discussed.

 
73: SAMI - please add Bryant et al. 2015 and Croom+2021 reference for SAMI survey

--Author response: Yes. These references have been added to where SAMI is mentioned first.

 

73: Please add reference Barsanti et al. 2022 for the most recent work on galaxy spin-filament alignments in the SAMI survey

--Author response: I make efforts to add all relevant previous studies, but can surely often miss something. So thank you for bringing it to my attention. The reference has been added with a very brief description. The new work includes some interesting work on the link between spin alignment and morphology, and that has been added.

 

Reviewer 3 Report

see the pdf file

Comments for author File: Comments.pdf

Author Response

REVIEWER COMMENTS.

General.

The author shows through many statistical and realized studies dataset arguments that no exists a symmetry in the galaxies spin in the space that shows a privileged direction in the universe, that is to say, in large-scale level, at least in a deep study of the galaxies structure and related with possibly the microscopic aspects of the field. For it the author analyses a big sample of galaxies and establishes a possibility of error in the galaxy annotation. The contention that the Universe is oriented around a major axis shifts from the standard cosmological models could be false.

--Author response: I would like to thank the knowledgeable anonymous reviewer (I noticed that the reviewer elected to sign their report, but the identity of the reviewer is anonymous until the paper is published) for the time you spent reading and commenting on the manuscript, and for the useful comments. The paper indeed suggests that the standard model might be incomplete. That claim is aligned with other recent (and some not-so-recent) observations, also mentioned in the paper. I addressed all comments, and the point-by-point responses to the comments are listed under each comment, with the description of the changes made to the manuscript. For convenience, changes in the manuscript are highlighted in bold font.

Weakness

1.    Mention more the role of the QFT, and microscopic phenomena and causes.

--Author response: A paragraph about QFT and microscopic phenomena has been added to the Introduction section. In particular, QFT predicts gravitational dipoles, and that can be directly relevant to observation reported here. Cosmological theories relate to CP and CPT violations have also been added. I obviously cannot be sure, but the observation described in this paper might play a role in the related theories of black hole cosmology, holographic universe, and QFT. I hope that it will trigger interest from theorists to further understand such possible link.

2. The abstract must be changed and shorted. The author must mention clearly which is the
fundamental or mean result of this research.

--Author response: Thank you for the comment. The abstract could have indeed been shorter, and it was shortened substantially in the revised version. More importantly, it makes the main statement of the research, which is the cosmological-scale axis formed by the galaxies rotation.

 

2.    Mention in the conclusions the perspective to new works starting from this.

--Author response:  A description of the new work starting from this point has been added to the end of the conclusion section as suggested. Probably the most exciting additions are the two new powerful instruments: The Vera Rubin observatory will provide much more, better, and deeper data that will allow an accurate identification of the peak of the dipole. That will allow to compare it with other observations to identify its nature. The other work from here is with DESI, that will provide spectra for an unprecedented number of galaxies, allowing to study how the asymmetry changes with the redshift. That has been added to the end of the conclusion section.

Strengthens
1. Citation and references.
Suggested Improvement
1. For example, when is mentioned by the author that the privileged direction (that is the symmetry existence) in agreement with other theories such as ellipsoidal universe or Einsteinian models, rotating Universe, and all symmetric, for example spherical black hole cosmology where is assumed the existence of a cosmological-scale axis, results interesting analyse for example some field theory tools and others related to curvature from microscopic level. In many aspects on galaxies structures the torsion is implicit in from breaking of CPT and another fundamental symmetries.

--Author response: I hope I fully understand the comment. Generally speaking, I try to mention as many theories as I am aware of, but can definitely miss something. A short description of CP violation, CPT violation, and some references making links between these violations and cosmological anisotropies and cosmological dipoles have been added to the part of the Introduction section where the theories are discussed. Other theories have also been added such as spin foam cosmology, dipole big bang, cosmological big bounce, and LCDM dipole cosmology. What I found especially interesting is that a black hole universe is expected to violate CPT symmetry, and that note has also been added. CP and CPT violations are now discussed, and I hope that’s what the comment meant. I noticed that the reviewer elected to sign their report, which can help to better understand the comment, but in the system the reviewer is anonymous. In any case, I made my best effort to include more theories that can be related to the observation, including some related to the particle physics level.

 

2. The author could consider the role of the torsion in large-scale.

--Author response: Yes. Torsion and its link to the LSS were discussed in much more details in a previous paper (http://doi.org/10.1093/mnras/stac2372). A paragraph about that has been added to the Introduction section of the revised version of the paper.

 

3. The poles as gravitational sources in the Universe, can change the large-scale symmetry, provoking fluctuations that contribute in the evolution of the Universe and its geometrical aspect doing asymmetric possibly. The author must consider this.

--Author response: Yes. Gravitational poles can be related to the observation, and definitely an option. The statement has been added to the Introduction section.

Decision
Accepted under suggested improvements realized to the author.
--Author response: Thank you again for the time and efforts you invested in preparing this report, and for the useful comments.

 

Round 2

Reviewer 3 Report

The author realized the corrections, additions, and improvements suggested. Even the author enriched of a relevant way his research paper by adding new references to field theory aspects, gravitational waves, and CPT breaking.