Improved Bounds on Lorentz Symmetry Violation from High-Energy Astrophysical Sources

Round 1

Reviewer 1 Report

The author presents new constraints on the electron sector LIV parameters from recent  gamma ray data from observations of synchrotron and inverse Compton emissions. The paper also presents a detailed introduction about the mSME in the electron sector. Since the paper is well written and presents novel constraints on LIV parameters I recommend it for publication. 

Author Response

I thank the referee for their positive remarks.

Reviewer 2 Report

In this work, bounds on SME electron coefficients were deduced from synchrotron and inverse Compton emissions from ultrarelativistic electrons in astrophysical sources.  The model used by the author is derived from the minimal SME.  The author disregarded SME coefficients that in principle could contribute to the Lorentz-violating signals because of existing tight constraints on the coefficients.  Other coefficients were removed by assuming a specific coordinate transformation of the Lagrangian. The author concludes the work by discussing the prospects of improving the reported bounds.

The bounds presented in this work are an important improvement from previous bounds and for that reason this work is relevant. The author also has an insightful discussion about the prospects of improving these constraints using astrophysical sources.  He makes a compelling argument that atomic clock experiments have better prospects for improving the bounds on the coefficients, except, for one of the coefficients where the bounds from astrophysical sources still have an advantage.

I recommend publishing this work

The following are some suggestions for clarity purposes

On the right-hand of equation (5), the author uses v_MAX} (p\hat) that is a speed, using a velocity will be more consistent \vec{v}_{MAX} (p\hat).

In the sentence before equation (6), the author defines the gamma Lorentz factor as \gamma=(1-\vec{v}^2)^(-1/2),  using a speed square will be more consistent than using a velocity square.

In the second sentence of the third paragraph in the introduction, I suggest using “the quantization of gravity”

In the last sentence of the fourth paragraph in the introduction, I suggest using “affecting CPT symmetry”

In the third sentence of the fifth paragraph in the introduction,  I suggest using “generic effective field theory”

In the fourth sentence of the fifth paragraph in the introduction,  I suggest using “standard-model extension”

Author Response

I thank the referee for their positive comments and for picking up on a number of small errors, which I have corrected.

Of the six changes mentioned by the referee, I have made the first five.  However, I don't think the last suggested changed—hyphenating "standard model extension"—is stylistically necessary.