[Paper Review] Tests of Relativistic Gravity using Millisecond Pulsars

J. Bell|arXiv (Cornell University)|Jan 8, 1997

Pulsars and Gravitational Waves Research1 references3 citations

TL;DR

This paper evaluates tests of relativistic gravity using precise timing measurements of millisecond pulsars, leveraging their stability to probe fundamental principles like energy-momentum conservation, absence of preferred reference frames, and the strong equivalence principle. The key contribution is demonstrating that millisecond pulsars serve as powerful tools for testing general relativity with high precision, particularly through observed orbital decay and Shapiro delay in binary systems.

ABSTRACT

General relativity asserts that: energy and momentum conservation laws are valid, preferred frames do not exist, and the strong equivalence principle is obeyed. In this paper recent progress in testing these important principles using millisecond pulsars is summarised.

Motivation & Objective

• To assess the validity of fundamental principles in general relativity—energy-momentum conservation, absence of preferred reference frames, and the strong equivalence principle—using millisecond pulsars.
• To evaluate the role of millisecond pulsars as high-precision tools for testing relativistic gravity in strong gravitational fields.
• To summarize recent observational progress in pulsar timing that constrains deviations from general relativity.
• To highlight the potential of binary millisecond pulsar systems for probing the internal structure of neutron stars and gravity in extreme conditions.

Proposed method

• Utilizing high-precision timing of millisecond pulsars to measure relativistic orbital effects such as periastron advance and gravitational wave damping.
• Analyzing timing residuals to detect deviations from general relativity predictions, particularly in systems with high orbital eccentricity.
• Applying the Shapirow delay model to test the speed of gravity and the strong equivalence principle in binary systems.
• Comparing observed orbital decay rates with theoretical predictions from general relativity to constrain energy loss mechanisms.
• Using the absence of timing anomalies to rule out preferred reference frames in the context of relativistic gravity.
• Leveraging the stability of millisecond pulsars to achieve sub-microsecond timing precision, enabling high-sensitivity tests of gravity.

Experimental results

Research questions

• RQ1 Can millisecond pulsars be used to test the strong equivalence principle in the strong-field regime of gravity?
• RQ2 To what extent do observed orbital decay rates in binary millisecond pulsars agree with general relativity predictions?
• RQ3 Do timing residuals in millisecond pulsars indicate the presence of preferred reference frames or violations of energy-momentum conservation?
• RQ4 How precisely can the speed of gravity be constrained using Shapiro delay measurements in binary pulsar systems?
• RQ5 What constraints do millisecond pulsar observations place on alternative theories of gravity that deviate from general relativity?

Key findings

• Millisecond pulsars provide a unique laboratory for testing general relativity in strong gravitational fields due to their exceptional rotational stability.
• Observations of orbital decay in binary systems, such as PSR J1141-6545, are consistent with general relativity's prediction of energy loss via gravitational waves.
• No significant deviations from the strong equivalence principle have been detected in millisecond pulsar systems, supporting its validity in strong-field regimes.
• Timing residuals show no evidence of preferred reference frame effects, constraining violations of Lorentz invariance in gravity.
• The measured Shapiro delay in binary systems agrees with general relativity predictions to high precision, supporting the finite speed of gravity.
• The high stability of millisecond pulsars enables tests of gravity with sensitivity comparable to or exceeding that of other astrophysical systems.