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Peer-Review Record

Impact of Charge on Strange Compact Stars in Rastall Theory

by Malick Sallah 1,2 and Muhammad Sharif 1,*
Reviewer 1: Anonymous
Reviewer 2:
Reviewer 3: Anonymous
Submission received: 24 October 2024 / Revised: 13 January 2025 / Accepted: 14 January 2025 / Published: 16 January 2025
(This article belongs to the Special Issue Gravity and Cosmology: Exploring the Mysteries of f(T) Gravity)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors studied the spherical symmetric, anisotropic quark stars in the (so named) Rastall Gravity, under the electric field. The author employs the MIT bag Model as the input EOS, drawing on observational data of strange stellar systems, to construct five anisotropic stellar models and subsequently illustrates their physical properties, including their stability. 

While the overarching research design is sound, I would not advise the publication of this manuscript in Universe due to a fundamental flaw in the framework, namely the Rastall gravity. 

As previously indicated by Refs. [1] and [2], Rastall gravity is equivalent to Einstein's relativistic gravity. In particular, Rastall's non-conserved "energy-momentum" tensor (Eq. 1) is simply derived from the redefinition of the standard conserved energy-momentum tensor related to the Einstein tensor (see, e.g,  Eq.(2) of Ref.[2]). In other words, there is no reason to assume that {tilde T}_{psi chi} in Eq.(1) represents physical energy and momentum and is therefore equivalent to a charged anisotropic matter distribution as in Eq.(3). This assumption is erroneous. 

To illustrate, the stability analysis outlined in Section 4.5 is flawed since the system sound speed cannot be given by V_{sr} = d  {\tilde P}_r / d {\tilde \rho} in the Rastall gravity. Consequently, the adiabatic index in Eq. (32) cannot be compared with 4/3 to claim stability as is usually done in Newtonian/Relativistic stellar dynamics.

I'd like to suggest to the authors that they familiarise themselves with Sec.2 and 3 of Ref. [2] to gain insight into the technical shortcomings of the Rasrall gravity and its application to the physical problem. 

REFERENCES: 
[1] Rastall gravity is equivalent to Einstein gravity
Matt Visser
https://arxiv.org/abs/1711.11500

[2]
More on the fact that Rastall = GR
Alexey Golovnev
https://arxiv.org/abs/2311.00131

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

Rastall theory of gravity was introduced in 1972. More than 50 years have passed and it has not had official recognition from the scientific community. For this reason, I am not very attracted to it. Despite this, I must admit that it is currently undergoing a significant surge in popularity. Rastall hypothesized to modify gravity with a non-conserved stress-energy tensor, and an unusual non-minimal coupling between matter and geometry. In the framework of this theory, the authors study the impact of charge on the structural development of different types of five spherically symmetric anisotropic stars. They used MIT bag model with the Rastall’s field equations analyzing the differences compared to the usual approach. I consider the work very professional and I believe that it adds new results compared to the scientific literature on this topic. It appears to be mathematically correct and well referenced. The abstract, introduction and conclusions clearly describe the results obtained in the sections of the work. Since there are numerous research groups working on Rastall's gravitational theory, I believe that this paper could be of interest to them. I believe that the manuscript can be published in its present form.

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Reviewer 3 Report

Comments and Suggestions for Authors

Please check the attached file.

Comments for author File: Comments.pdf

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Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Please check the attached file.

Comments for author File: Comments.pdf

Author Response

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