From the Janis–Newman–Winicour Naked Singularities to the Einstein–Maxwell Phantom Wormholes
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis is an interesting study on the physics of the JNW naked singularity solution, in particular of the physical meaning of the two parameters entering this solution. Several interesting black hole and wormhole solutions with a rich structure are obtained by applying specific transformations, whereby a contribution of a massless phantom field to the corresponding energy-momentum tensor is found, amongst other things. Strong similarities between the quintessence potential and the dilaton potential are pointed out. Of special interest is the embedding of the JNW solution into a de Sitter or anti-de Sitter universe. Based on the assumptions used, the authors conclude that one of the aforementioned parameters of the JNW metric leads to a negative black hole mass which is not allowed for non-exotic black holes in the context of general relativity. However, such a negative mass (and a non-trivial topology) is allowed in other contexts, see e.g. R. Mann, CQG 14(10) 2927 (1997), or B.R. Hull and R. Mann, Phys. Rev. D107, 064027 (2023) in the context of Lovelock gravity. The authors could comment on such cases in their conclusions.
Comments for author File: 
Comments.pdf
There is urgent need for many corrections in the use of English in order to improve the quality of the paper. See attached pdf-file for suggested corrections.
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsIn this paper, the authors start with the analysis of the Janis-Newman-Winicour solution and some of its misunderstood features. Then, starting from this solution, they construct a traversable WH solution by means of a complex transformation. In practice, the WH solution obtained is a phantom WH.
The paper is interesting and merits publication. I just have two minor comments:
1. The WH is proved to be traversable, as the authors show that the flaring-out condition is satisfied near the throat. However, they do not address the stability. I would like that the author study this point. They might use the method based on the analysis of the adiabatic sound velocity (see e.g. Eqs (25) and (26) in arXiv:2309.01976).
2. In the introduction, many details of Janis-Newman-Winicour solution are given, but a proper reference to existing WH solutions in the literature is missing. The authors should mention some WH solutions in the introduction. They can start with the following papers:
-"Phantom fluid supporting traversable wormholes in alternative gravity with extra material terms" Int.J.Mod.Phys.D 27 (2018) 16, 1950004
-"Wormhole solutions with a polynomial equation-of-state and minimal violation of the null energy condition", Eur.Phys.J.C 80 (2020) 5, 366
-"Novel black-bounce spacetimes: wormholes, regularity, energy conditions, and causal structure", Phys.Rev.D 103 (2021) 8, 084052
-"Spin, torsion and violation of null energy condition in traversable wormholes" Eur.Phys.J.Plus 132 (2017) 12, 537
In the revised version of the paper, I would like to see a section regarding the point 1 (WH stability). Regarding the point 2, this is up to the authors. They might also decide to ignore this second comment, as the paper with or without an answer to point 2 can be accepted for publication.
Comments on the Quality of English LanguageMinor editing (typos) of English language required.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
