Tidal Forces Around Black-Bounce-Reissner–Nordström Black Hole

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled “Tidal Forces Around Black-Bounce–Reissner–Nordström Black Hole” offers an analytical and numerical examination of tidal phenomena in a modified black hole spacetime aimed at eradicating core singularities. The authors seek to quantify the nature of tidal forces by examining the geodesic structure and deviation equations within the black-bounce-Reissner–Nordström (BB-RN) spacetime, and to compare these findings with the conventional Schwarzschild and Reissner–Nordström scenarios. The subject is pertinent and significant to the examination of conventional black holes and quantum-gravity-influenced alterations to classical general relativity. The study yields some intriguing results and comparative insights; however, significant conceptual, methodological, and presentation-related concerns necessitate explanation or enhancement prior to publication consideration.

1-    Could the authors explain the physical meaning and implications of the bounce parameter a concerning observed astrophysical phenomena?
2-    What is the scientific meaning of the Newtonian radial acceleration presented in Section 4, and how does it quantitatively compare with the conventional Reissner–Nordström or Schwarzschild cases?
3-    What precise boundary or beginning conditions were implemented in the analytical and numerical solutions of the geodesic deviation equations, and how do they influence the results?
4-    In what manner do numerical approaches guarantee accuracy and stability in the progression of geodesic deviation vectors, particularly in proximity to the bounce or throat region?
5-    Could the authors provide some clarification regarding the selection of initial conditions IC-I and IC-II? What physical conditions do these conditions relate to?
6-    How does the finite tidal force behaviour near the center influence the feasibility of this spacetime as a physical black hole model compared to a traversable wormhole?
7-    Do distinct tidal behaviours in black-bounce-RNBH exhibit observable implications when contrasted to classical black holes?
8-    What are the future implications of this work. Authors must specify in the conclusion section.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This work contains some valuable material on charged black bounces regarding the tidal forces experienced by nearby travellers.

I have some minor corrections (mostly revolving around the introduction/motivation):

• The authors should state in the introduction what they mean by a ``singularity”. Through the paper they play with the idea of singularity-removal as being attached to making the curvature finite, though a more fundamental concept is that of geodesic completeness, namely, the necessity for all geodesic paths to be complete in the geometry, something achieved in the black bounce proposal. This should be discussed in the introduction.
• The black bounce proposal by Simpson and Visser is actually based on Elli’s proposal for wormholes, via the radial function later recovered by SV. This fact should be mentioned.
• In the introduction the authors come to discuss the different structures held by charged black bounces according to the values of $a$. Since such a structure can only be read off from the metric components, which appear later at Eq.(2), I think this discussion should happen below such an equation, while a mention to it can still appear in the introduction.
• I think that further citations regarding the analysis of tidal forces in modified black hole solutions in the literature could be needed.
• In the conclusion, maybe the authors could elaborate a bit on the effects/size/magnitude of tidal forces near the wormhole throat (in the case the wormhole is traversable) given its obvious relevance for wormholes as mean of travel for time-like observers.

These are minor and optional recommendations, so after the authors ameliorate their paper accordingly, it can be accepted for publication

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Report on
TIDAL FORCES AROUND
BLACK-BOUNCE-REISSNER–NORDSTROM BLACK HOLE

In this work the author describes the tidal forces on a neutral particle around a Black-bounce-Reissner–Nordström Spacetime.
First, the author revisits the horizon structure of such spacetime and describes the geodesic equation of neutral particles moving in the equatorial plane.
Then, a description of the deviation equation on a black hole scenario is analyzed.
The  resulting equations are solved both numerically and analytically for some particular initial conditions.

The paper is interesting and well written, however there are some issues that should be solved before I would recommend it for publication.

Here I describe the points that need some clarification.

1. After Eq. 4, the sentence  "where r_+ shows the distance.." should be rewritten to correctly describe the nature of the r_+ surface.
2. After Eq. 6,. Given the signature of the metric Eq. 1 the values of e should be 0 and -1 (after the choice of normalization).
Furthermore, Eq. 6 already describes the motion of neutral particles, due to the absence of the Lorentz force, thus the sentence right before of Eq. 7
should be rephrased.
3. Although the author describes the radial and angular parts of the deviation equations, the author should provide more information regarding  the t component of \eta·, is not clear why
"... gives no physically important information as such.." as stated in the manuscript.
4. In line 155, of page 6, it is said that the coordinate r is a parameter giving the same nature as the rest parameters, i.e. a and Q. The same occurs in the description of figure 2.
5. I would strongly suggest that the author include more references that reflect the state of the art of similar problems studied in the past.

I would recommend the publication of the manuscript after the issues mentioned are solved.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author has improved the paper. Now it cna be accepted for publication.