Gravitational signal propagation in the double pulsar studied with the MeerKAT telescope

Abstract

The Double Pulsar, PSR J0737−3039A/B, has offered a wealth of gravitational experiments in the strong-field regime, all of which general relativity has passed with flying colours. In particular, among current gravity experiments that test photon propagation, the Double Pulsar probes the strongest spacetime curvature. Observations with MeerKAT and, in future, the Square Kilometre Array (SKA) can greatly improve the accuracy of current tests and facilitate tests of next-to-leading-order (NLO) contributions in both orbital motion and signal propagation.We present our timing analysis of new observations of PSR J0737−3039A, made using the MeerKAT telescope over the last three years. The increased timing precision offered by MeerKAT yields a 2 times better measurement of Shapiro delay parameter s and improved mass measurements compared to previous studies. In addition, our results provide an independent confirmation of the NLO signal propagation effects and already surpass the previous measurement from 16-yr data by a factor of 1.65. These effects include the retardation effect due to the movement of the companion and the deflection of the signal by the gravitational field of the companion. We also investigate novel effects which are expected. For instance, we search for potential profile variations near superior conjunctions caused by shifts of the line-of-sight due to latitudinal signal deflection and find insignificant evidence with our current data. With simulations, we find that the latitudinal deflection delay is unlikely to be measured with timing because of its correlation with Shapiro delay. Furthermore, although it is currently not possible to detect the expected lensing correction to the Shapiro delay, our simulations suggest that this effect may be measured with the full SKA. Finally, we provide an improved analytical description for the signal propagation in the Double Pulsar system that meets the timing precision expected from future instruments such as the full SKA.

The Relativistic Spin Precession in the Compact Double Neutron Star System PSR J1946+2052

“…Based on the companion mass we derive, we infer that the second SN of the PSR J1946+2052 system is likely similar to that of the double pulsar system. Ferdman et al (2013) did not find obvious profile evolution of PSR J0737-3039A from 2005-2011, confirmed more recently by Hu et al (2022). The reason why we nevertheless observe profile evolution in PSR J1946+2052 is likely that our line of sight is closer to the edge of the circular emission beam than that in PSR J0737-3039A; thus, the variation of the peak separation is significant.…”

A study of the light bending phenomenon under full general relativity for a pulsar in a binary with a Schwarzschild black hole

“…15a, we see that the profile variation due to the bending is insignificant for a pulsar−black hole binary with 𝑖 = 89.7 • . This also explains the null detection of the bending induced profile variation for the double pulsar for which 𝑖 = 89.35 • or 90.65 • (Hu et al 2022).…”

“…Similar to the Shapiro delay (another manifestation of the spacetime curvature around the companion), the total bending delay is also stronger for edge-on systems, especially at the orbital phases near the superior conjunction. So, it might be difficult to decouple these delays (Hu et al 2022). However, the value of the Shapiro delay depends only on the masses of the pulsar and the companions as well as the orbital parameters, e.g., 𝑒, 𝑃 𝑏 , 𝑖, 𝜔, and 𝐴 𝑇 .…”

Measuring the Lense–Thirring Orbital Precession and the Neutron Star Moment of Inertia with Pulsars

“…Moreover, the rotation of A has been confirmed to be prograde using the modulation of B's emission by the interaction with A's pulsar wind [94]. The unique high inclination angle between the orbital angular momentum and the line of sight towards the pulsar system (i = 89.36 • ± 0.03 • or 180 • − i from timing analysis) enabled the studies of an aberrational light bending effect [58,79], thus independently confirming the prograde rotation of A and providing additional evidence for a low-kick SN.…”

“…A schematic comparison of these compact binary systems with the the Hulse-Taylor pulsar PSR B1913+16 and the Sun is shown in Figure 6. [78], J0737−3039 [79], J1757−1854 [34], J1946+2052 [80], and J1141−6545 [75]) compared to the size of the Sun. The left orbit of each pair corresponds to the pulsar, whereas the right orbit corresponds to the companion (pulsar A and pulsar B in the case of the Double Pulsar).…”