A New Method of Investigation of the Orientation of Galaxies in Clusters in the Absence of Information on Their Morphological Types
Round 1
Reviewer 1 Report
The article suggests a new way to study the galaxy orientation in clusters. According to the authors, this method can also be used in the case when the galaxy morphological types are unknown. In the article, the authors apply this method to well-known small galaxy groups and show qualitative consistency with the expected absence of galaxy alignment. It is a significant scientific result and can be published in Applied Sciences.
My main insistent recommendation to the authors is to describe in detail the proposed method, the construction of simulated galaxy distributions, and the results of applying the method to galaxy groups. In the present text, not enough is paid to the description of the new method and the most important parameter, as the estimated frequency of occurrences of given morphological types. Therefore, it is difficult to understand the actual usability and advantages of the new method.
Section 3.2.
* The authors did not specify how the known occurrence frequencies for the given galaxy types were used. Why not use these frequencies in the distribution of the parameter q immediately instead of setting q by isotropic random distribution? Is it justified to initially set an isotropic distribution q? Will the q distribution correspond to an isotropic one if we simulate a galaxy cluster at the known occurrence frequency of morphological types and the isotropic distribution for the angle i?
* Even if each morphological type gives a uniform q-distribution, then this distribution is within different limits, for example, for E0 q=1, for E1, the minimum q-value is greater than the minimum q for spiral galaxies. And accounting for the different occurrence frequencies of morphological types, the statement that q-distribution will be isotropic needs to be checked.
* For the transition to deltaD and eta, you need to set the locations of the galaxies in space. How was this done in your simulation?
Section 4.
* It would be helpful to explain what Tully groups are.
* Please explain for what aim the analysis is carried out first without the FP photometric correction and then with it. Since there is a reference to the corresponding article, it has already been proven that photometric correction is necessary to obtain a correct result.
*Lines 258-260: It is unclear from the text how the galaxy morphological type was accounted for.
* Line 260: What did you mean under "correct result"? Is it the isotropy of the angle distribution? If so, it would be useful to give arguments that there should be an isotropic distribution.
* Lines 262-263: On the one hand, this conclusion is evident from formulae (1)-(5). On the other hand, it opens up the possibility to study in more detail the influence of i on statistical tests by comparing distributions of i calculated in 3 ways for Tully groups with varying and unchanging statistical test results. Perhaps this is the subject of a future article, but in this context, it would also be interesting to note this.
* I strongly recommend considering a way (table or histogram) of presenting the results of comparing statistical tests, because it is difficult to visually compare several tables, containing 18 groups.
* In all tables containing the results of statistical tests, it would be good to give in the title the conditions under which the tests are considered satisfactory or to make separate marks, for example, +/-, indicating the test result. In the present state, it is very inconvenient to search for critical value in the text of section 3.1, especially since the critical value is not specified there for all tests. It is particularly important when comparing the results obtained using the new method (Tables 7-10).
* Please indicate if the results of statistical tests in Tables 7-10 are the average for 10,000 simulations, or are the results for any one selected simulation?
* From the text on page 15, it is not clear how the compared distributions for which the statistical test results are listed in Tables 7-10 and 11-12 differ. Please explain.
* Line 281: What is meant by classical methods? Are methods for calculating i based on the catalog, from which deltaD and eta are calculated? Then the "new method" is modeling an isotropic distribution and performing statistical tests for that. Again, it is not clear how the simulation was carried out.
* Please explain what is meant by "three cluster poles". Why does the galaxy cluster have three poles?
* The text does not explain the choice of 4 groups out of 18 to display in Fig. 1-8.
* It is not described how the simulated distributions of fictitious galaxies are used and whether they are used in statistical analysis accounting for the FP correction.
My other suggestions for improving the manuscript are as follows.
* In the introduction, there is the term “positional angle”, whereas the “position angle” is used in the rest text. Maybe use a uniform designation.
* In some places, there is the text overloading by the preposition "of", for example, in the title “method of investigation of the orientation of galaxies”, further “the frequency of the appearance of galaxies of particular morphological types”, “version of the method of analysis of the orientation of galaxies”, “lists of members of individual galaxy groups” and so on.
* Sometimes articles are omitted, for example, on line 69 “(the) practical application”, “(the) new variant”, (line 79) “(the) magnitude limit”.
* Lines 95-97: Why is the Einstein de Sitter cosmological model mentioned, whereas, on line 26, the ΛCDM model is mentioned and is now generally accepted?
* Lines 107-108: What is the main plane? In each study, this plane and the coordinate system are different, or is some specific choice of this plane and coordinate system generally accepted? Please explain.
* Lines 114-115: Please explain why there are only four ways galaxies can be aligned relative to the observer. It is natural to expect any arbitrary orientation.
* What are the “two possible settings of galaxies” on line 117?
* Maybe the authors will think about adding a figure to illustrate the geometric parameters used in formulae (1)-(5).
* Lines 191-192: there is an incomprehensible phrase “… with the allows the coefficient …”.
* Line 296 and captions of Fig. 9 and 10: There is no explanation for the acronym FP in the text, although the full term the Authors used earlier.
* Line 303: The meaning of the phrase is unclear.
* Line 303: For the understanding of Figures 9 and 10 by broad specialists, it would be helpful to explain the physical/geometric/mathematical meaning of the parameter s to describe what their positive, negative, and zero values mean.
* Caption of fig. 9: There are unexplained acronyms HHD, S, and NS.
* There are no article titles for references 55 and 56.
* Typos. Line 93: must be a point after “catalog”; line 112: redundant space after L; second “i” on line 125 is in italics; line 136: redundant space after Heidmann; line 215: “was” must be replaced with “were”. Line 216: the first "w" must be capitalized. Line 153: n must be in italics. Line 302: it -> It. Line 286: One point out of two and closing parenthesis are redundant. Line 409: 2015193 -> 2015 193.
Author Response
"Please see the attachment"
Author Response File: 
Author Response.docx
Reviewer 2 Report
Reviewer`s comment
Dear editor/authors
In this work authors use a numerical method to investigation of orientation of galaxies in clusters without to need to information on their morphology. In fact most of the astronomical data available today does not contain information about the morphological types of galaxies. From the latter point of view this work can be important and possibly have sound. Their method is based on the statistical analysis of the distribution of the angles giving the spatial orientation of galaxies in space. To be have a physical correspondence they take into account the Holmberg effect and the fact that galaxies are oblate spheroids with the real axis ratio depending on the morphological type. Their method is extension of works given by one of author at 2012 and other researchers. As observational data they test the presented method for Tully Near by Galaxies (NBG) Catalog. To have the distances of galaxies which are determined by velocity, They choose the Einstein de Sitter model or the flat dust model with (q0 = 1 / 2) and H0 = 75kms−1 Mpc−1 and the velocity perturbation model near the Virgo Cluster. In their statistical method and simulations they check: The statistical χ2 test, the First Autocorrelation test and the Fourier test, and additionally the Kolmogorov-Smirnov test, Cramer-von Mises test and Watson test. Then they compared obtained results from each test with other tests. The results are collected in the several tables and the diagrams. At last numerical analysis of the work predicts in small groups and clusters of galaxies, (Tully clusters), that there is no galaxy alignment which corresponds to observational data. In short I should point that:
English is good written throughout the paper and understandable for all readers in my opinion. Discussion about the tables and figures are enough and acceptable.
But I have essential questions about the manuscript as follows.
a) In my opinion weight of paper is low and it is better to improve via extension to other large groups of galaxies. In that case results of the work may changed
b) 10 references from total 59 are self-citation however some of them are inevitable.
c) Why anisotropy in cosmology as a observational effect is not considered here ?
d) What say the model about the dark matter or its possible alternatives which is an important effect on correction of galaxy rotations?
At last In my opinion, this version of the article is not suitable for publication unless suitable and convincing answers are given to the above questions.
Sincerely yours
Reviewer`s comment
Dear editor/authors
In this work authors use a numerical method to investigation of orientation of galaxies in clusters without to need to information on their morphology. In fact most of the astronomical data available today does not contain information about the morphological types of galaxies. From the latter point of view this work can be important and possibly have sound. Their method is based on the statistical analysis of the distribution of the angles giving the spatial orientation of galaxies in space. To be have a physical correspondence they take into account the Holmberg effect and the fact that galaxies are oblate spheroids with the real axis ratio depending on the morphological type. Their method is extension of works given by one of author at 2012 and other researchers. As observational data they test the presented method for Tully Near by Galaxies (NBG) Catalog. To have the distances of galaxies which are determined by velocity, They choose the Einstein de Sitter model or the flat dust model with (q0 = 1 / 2) and H0 = 75kms−1 Mpc−1 and the velocity perturbation model near the Virgo Cluster. In their statistical method and simulations they check: The statistical χ2 test, the First Autocorrelation test and the Fourier test, and additionally the Kolmogorov-Smirnov test, Cramer-von Mises test and Watson test. Then they compared obtained results from each test with other tests. The results are collected in the several tables and the diagrams. At last numerical analysis of the work predicts in small groups and clusters of galaxies, (Tully clusters), that there is no galaxy alignment which corresponds to observational data. In short I should point that:
English is good written throughout the paper and understandable for all readers in my opinion. Discussion about the tables and figures are enough and acceptable.
But I have essential questions about the manuscript as follows.
a) In my opinion weight of paper is low and it is better to improve via extension to other large groups of galaxies. In that case results of the work may changed
b) 10 references from total 59 are self-citation however some of them are inevitable.
c) Why anisotropy in cosmology as a observational effect is not considered here ?
d) What say the model about the dark matter or its possible alternatives which is an important effect on correction of galaxy rotations?
At last In my opinion, this version of the article is not suitable for publication unless suitable and convincing answers are given to the above questions.
Sincerely yours
Reviewer`s comment
Dear editor/authors
In this work authors use a numerical method to investigation of orientation of galaxies in clusters without to need to information on their morphology. In fact most of the astronomical data available today does not contain information about the morphological types of galaxies. From the latter point of view this work can be important and possibly have sound. Their method is based on the statistical analysis of the distribution of the angles giving the spatial orientation of galaxies in space. To be have a physical correspondence they take into account the Holmberg effect and the fact that galaxies are oblate spheroids with the real axis ratio depending on the morphological type. Their method is extension of works given by one of author at 2012 and other researchers. As observational data they test the presented method for Tully Near by Galaxies (NBG) Catalog. To have the distances of galaxies which are determined by velocity, They choose the Einstein de Sitter model or the flat dust model with (q0 = 1 / 2) and H0 = 75kms−1 Mpc−1 and the velocity perturbation model near the Virgo Cluster. In their statistical method and simulations they check: The statistical χ2 test, the First Autocorrelation test and the Fourier test, and additionally the Kolmogorov-Smirnov test, Cramer-von Mises test and Watson test. Then they compared obtained results from each test with other tests. The results are collected in the several tables and the diagrams. At last numerical analysis of the work predicts in small groups and clusters of galaxies, (Tully clusters), that there is no galaxy alignment which corresponds to observational data. In short I should point that:
English is good written throughout the paper and understandable for all readers in my opinion. Discussion about the tables and figures are enough and acceptable.
But I have essential questions about the manuscript as follows.
a) In my opinion weight of paper is low and it is better to improve via extension to other large groups of galaxies. In that case results of the work may changed
b) 10 references from total 59 are self-citation however some of them are inevitable.
c) Why anisotropy in cosmology as a observational effect is not considered here ?
d) What say the model about the dark matter or its possible alternatives which is an important effect on correction of galaxy rotations?
At last In my opinion, this version of the article is not suitable for publication unless suitable and convincing answers are given to the above questions and they are shown in the revised manuscript.
Sincerely yours
Author Response
"Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
I am grateful to the authors for answering my questions. The authors have improved the text by adding a detailed description of the proposed method and elucidative figures. I am glad to recommend the article for publication in Applied Sciences . Additionally, I request the authors to take into account the following comments.
Lines 274, 276, and 279 has typos, I think it is must be “it is difficult”, “Cumulative”, and “autocorellation”. What is “i” on the line 279? Line 365: “It means”; line 386: “angel”-> “angle”.
Line 379: It is probably meant another group instead of 35, which is not in the tables at all.
Author Response
The paper was corrected according to reviewer's suggestions. The detailed answers are as follows:
I am grateful to the authors for answering my questions. The authors have improved the text by adding a detailed description of the proposed method and elucidative figures. I am glad to recommend the article for publication in Applied Sciences . Additionally, I request the authors to take into account the following comments.
Lines 274, 276, and 279 has typos, I think it is must be “it is difficult”, “Cumulative”, and “autocorellation”. What is “i” on the line 279? Line 365: “It means”; line 386: “angel”-> “angle”.
The typos were corrected.
Line 379: It is probably meant another group instead of 35, which is not in the tables at all.
Yes, it should be group 31 not 35.
Best regards
Włodzimierz Godłowski,
Błażej Mrzygłód
Author Response File: Author Response.docx
Reviewer 2 Report
Dear Editor/authors i satisfied with responses to reviewer`s comments which intended inside of the paper and so i feel that this version is appropriate to publication but it is need to edited its English
for instance see page 9 line 274:
`irt` should be written as `it`...in my opinion
sincerely
Author Response
The paper was corrected according to reviewer's suggestions. The detailed answers are as follows:
Dear Editor/authors i satisfied with responses to reviewer`s comments which intended inside of the paper and so i feel that this version is appropriate to publication but it is need to edited its English
for instance see page 9 line 274:
`irt` should be written as `it`...in my opinion
sincerely
The typos were corrected.
Sincerely yours
Włodzimierz Godłowski,
Błażej Mrzygłód
Author Response File: Author Response.docx
