SciPost Submission Page

Gravity waves in a rainbow universe

by Mustafa Salti, Oktay Aydogdu

Submission summary

As Contributors: Mustafa Salti
Preprint link: scipost_202105_00029v1
Date submitted: 2021-05-19 12:55
Submitted by: Salti, Mustafa
Submitted to: SciPost Physics
Academic field: Physics
Specialties:
  • Gravitation, Cosmology and Astroparticle Physics
  • Mathematical Physics
Approach: Theoretical

Abstract

The dawn of the epoch of gravitational wave (GW) astronomy, which initiated with the detection of a fundamental noise, was the period when the search for a theory in which gravity could be quantized began to increase significantly. In this paper, we have mainly intended to focus on the polar modes of GWs in the formalism of gravity’s rainbow, which is based largely on the product of the disparity between quantum mechanics (QM) and general relativity (GR). For this purpose, we have perturbed the spatially flat conformal Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, material distribution and the components of four-velocity by making use of the polar Regge-Wheeler gauge and formulated the corresponding field equations for both the zeroth-order (unperturbed) and the first-order (perturbed) cases of the metric. Subsequently, these field equations have been taken into account simultaneously to get exact expressions of the gauge functions. From a graphical perspective, we have studied the impact of rainbow parameters on the amplitude of GWs. At the final step, we have discussed the Huygens Principle and concluded that the GWs obey the principle only in the radiation-dominated era and the principle is broken otherwise.

Current status:
Editor-in-charge assigned



Reports on this Submission

Anonymous Report 4 on 2021-9-2 (Invited Report)

Report

I do not recommend publication in the present form. Please see the attached pdf for further details.

Attachment


  • validity: low
  • significance: ok
  • originality: ok
  • clarity: low
  • formatting: acceptable
  • grammar: acceptable

Anonymous Report 3 on 2021-8-25 (Invited Report)

Strengths

This article has analyzed gravitational waves in the context of rainbow gravity by using Regge-Wheeler formalism, which is new thinking at this time.

Weaknesses

No mention

Report

The authors have addressed all the issues satisfactorily. I will recommend the article in favour of publication in SciPost Physics Core if all the issues are incorporated in the final version of the manuscript.

Requested changes

No changes at this stage except all the issues are incorporated in the original manuscript.

  • validity: high
  • significance: high
  • originality: high
  • clarity: high
  • formatting: good
  • grammar: excellent

Anonymous Report 2 on 2021-8-25 (Invited Report)

Strengths

Very good article

Weaknesses

Nothing

Report

The authors have addressed all the issues satisfactorily. I will recommend the article in favour of publication in SciPost Physics if all the issues are incorporated in the final version of the manuscript.

  • validity: high
  • significance: high
  • originality: high
  • clarity: high
  • formatting: excellent
  • grammar: excellent

Anonymous Report 1 on 2021-7-4 (Invited Report)

Strengths

This article has analyzed gravitational waves in the context of rainbow gravity by using Regge-Wheeler formalism, which is new thinking at this time.

Weaknesses

The paper should be well written and justify the more physical reasons for various portions.

Report

The paper entitled “Gravity waves in a rainbow universe” deals with the polar modes of GWs employing the formalism of gravity’s rainbow, which is based largely on the product of the disparity between quantum mechanics (QM) and general relativity (GR). They have adopted the perturbation of the spatially flat conformal Friedmann-Lemaitre-Robertson-Walker (FLRW) metric using the Regge-Wheeler formalism.

There are some serious questions:

1. Is the Planck length fundamental?
2. In rainbow gravity [Joao Magueijo and Lee Smolin, Class. Quantum Grav., 21, 1725, (2004).], the geometry of spacetime is energy (E) dependent and then quanta of different energies may support different classical geometries. In this context, is the fundamental length energy dependent?
3. Justify the choices of the rainbow functions (eq. 3), since this type of rainbow functions can not be seen in Ref. 29, as stated in your paper.
4. Justify the relation between the last paragraph of page 24 and the Fig-1 of page 25 i.e., with experimental (Planck data) result.
5. Does the value of the H0 change in the presence of Rainbow functions?
6. Briefly explain how the equation 85 obeys Huygens’ principle.
7. In equation 89, the authors have used the new parameters /tao and /xi. Then the equation 89 becomes free from rainbow functions explicitly, how is it physically justified?
This paper will be worthy of further reviewing if the authors can manage to address the above points

Requested changes

1. Is the Planck length fundamental?
2. In rainbow gravity [Joao Magueijo and Lee Smolin, Class. Quantum Grav., 21, 1725, (2004).], the geometry of spacetime is energy (E) dependent and then quanta of different energies may support different classical geometries. In this context, is the fundamental length energy dependent?
3. Justify the choices of the rainbow functions (eq. 3), since this type of rainbow function can not see in Ref. 29, as stated in your paper.
4. Justify the relation between the last paragraph of page 24 and Fig-1 of page 25 i.e., with experimental (Planck data) result.
5. Does the value of the H0 change in the presence of Rainbow functions?
6. Briefly explain how equation 85 obeys Huygens’ principle.
7. In equation 89, the authors have used the new parameters /tao and /xi. Then the equation 89 becomes free from rainbow functions explicitly, how is it physically justified?

  • validity: good
  • significance: good
  • originality: good
  • clarity: good
  • formatting: good
  • grammar: good

Author:  Mustafa Salti  on 2021-08-03

(in reply to Report 1 on 2021-07-04)
Category:
answer to question

We have presented our responses in a separate PDF file.

Attachment:

response.pdf

Author:  Mustafa Salti  on 2021-08-03

(in reply to Report 1 on 2021-07-04)
Category:
answer to question

We have presented our responses in a separate PDF file.

Attachment:

Revised.pdf

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