Double Pulsar: 16 Year Study Validates Relativity

[fresh_42]

I'm not sure if this belongs to astronomy or GR. But as it - once again - proves Einstein right, I posted it here for all who need another paper to conquer all who doubt. And I think it is an interesting paper (53 pages), at least from my layman's point of view.

Continued timing observations of the double pulsar $\text{PSR J0737–3039A/B},$ which consists of two active radio pulsars ($A$ and $B$) that orbit each other with a period of $2.45 \,h$ in a mildly eccentric ($e=0.088$) binary system, have led to large improvements in the measurement of relativistic effects in this system. With a $16$-yr data span, the results enable precision tests of theories of gravity for strongly self-gravitating bodies and also reveal new relativistic effects that have been expected but are now observed for the first time. These include effects of light propagation in strong gravitational fields which are currently not testable by any other method. In particular, we observe the effects of retardation and aberrational light bending that allow determination of the spin direction of the pulsar. In total, we detect seven post-Keplerian parameters in this system, more than for any other known binary pulsar. For some of these effects, the measurement precision is now so high that for the first time we have to take higher-order contributions into account. These include the contribution of the A pulsar’s effective mass loss (due to spin-down) to the observed orbital period decay, a relativistic deformation of the orbit, and the effects of the equation of state of superdense matter on the observed post-Keplerian parameters via relativistic spin-orbit coupling. We discuss the implications of our findings, including those for the moment of inertia of neutron stars, and present the currently most precise test of general relativity’s quadrupolar description of gravitational waves, validating the prediction of general relativity at a level of $1.3 \cdot 10^{-4}$ with $95\%$ confidence. We demonstrate the utility of the double pulsar for tests of alternative theories of gravity by focusing on two specific examples and also discuss some implications of the observations for studies of the interstellar medium and models for the formation of the double pulsar system. Finally, we provide context to other types of related experiments and prospects for the future.

https://journals.aps.org/prx/pdf/10.1103/PhysRevX.11.041050
https://journals.aps.org/prx/abstract/10.1103/PhysRevX.11.041050

And here is a pop-science summary:
https://www.sciencealert.com/16-year-study-of-extreme-stars-has-once-again-validated-relativity

 

[Ambitwistor]

Thank you for sharing this fascinating paper on the double pulsar system and its implications for theories of gravity. it is always exciting to see new evidence supporting established theories and pushing the boundaries of our understanding.

It is indeed a difficult question whether this belongs to astronomy or general relativity, as both fields are crucial in studying this system and its behavior. However, I would argue that the study of celestial bodies and their interactions, such as in this binary system, falls under the realm of astronomy.

The results of this 16-year study are truly impressive and provide important tests for general relativity. It is also exciting to see the detection of new relativistic effects that were previously only theorized. The precision of the measurements also highlights the importance of continued observations and taking into account higher-order contributions.

The implications of these findings, such as for the moment of inertia of neutron stars and the validation of general relativity's predictions, are significant. Additionally, the potential for using this system to test alternative theories of gravity is promising.

Thank you again for sharing this paper and providing a pop-science summary for those who may not be familiar with the technical details. I look forward to seeing further research and discoveries from this fascinating double pulsar system.