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12th of September 2023
Testing General Relativity with the PSR J1757-1854 double neutron star system
by Cameron et al.
PSR J1757−1854 is one of the most relativistic double neutron star binary systems known in our Galaxy, with an orbital period of 4.4 hr and an orbital eccentricity of 0.61. As such, it has promised to be an outstanding laboratory for conducting tests of relativistic gravity. Cameron et al. present the results of a 6-yr campaign with the 100-m Green Bank Telescope and the 64-m Parkes telescope, Murriyang, designed to capitalise on this potential. They identify secular changes in the profile morphology and polarisation of PSR J1757−1854, confirming the presence of geodetic precession and allowing the constraint of viewing geometry solutions consistent with General Relativity. They also update PSR J1757−1854’s timing, including new constraints of the pulsar’s proper motion, post-Keplerian parameters and component masses. They conclude that the radiative test of gravity provided by PSR J1757−1854 is fundamentally limited to a precision of 0.3 per cent due to the pulsar’s unknown distance. A search for pulsations from the companion neutron star is also described, with negative results.

The figure shows the mass-mass diagram for PSR J1757–1854. Each coloured triplet of lines shows the constraints (with 1-𝜎 uncertainty) placed by each of the measured post-Keplarian parameters on the mass of the pulsar and the companion NS under the assumption of General Relativity. The measured uncertainty of w is so small that it cannot be seen at this scale. The grey region in the bottom right is excluded due to orbital geometry. The divergence of the orbital period curve (black) from the common intersection of the other parameters arises from the current uncertainties in the pulsar's distance.

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