The relativistic binary programme on MeerKAT: science objectives and first results

Krämer, M.; Stairs, I. H.; Krishnan, V. Venkatraman; Freire, P. C. C.; Abbate, F.; Bailes, M.; Burgay, M.; Buchner, S.; Champion, D. J.; Cognard, I.; Gautam, T.; Geyer, M.; Guillemot, L.; Hu, H.; Janssen, G. H.; Lower, M. E.; Parthasarathy, A.; Possenti, A.; Ransom, S. M.; Reardon, D. J.; Ridolfi, A.; Serylak, M.; Shannon, R. M.; Spiewak, R.; Theureau, G.; Straten, W. van; Wex, Norbert; Oswald, L S; Posselt, Bettina; Sobey, C.; Barr, E. D.; Camilo, F.; Hugo, B.; Jameson, A.; Johnston, S.; Karastergiou, A.; Keith, Michael; Osłowski, S.

doi:10.1093/mnras/stab375

Cited by 45 publications

(43 citation statements)

References 92 publications

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“…Finally, we can also compare the FAST profile to the recently published MeerKAT data (Kramer et al 2021). The time resolution of the profile shown here is a factor of ∼20 better, so that the MeerKAT PA swing is smeared out in comparison and therefore appears to be different.…”

Section: Pulse Polarisation Resultsmentioning

confidence: 75%

“…We use the 'observer's convention', which is assumed for calculating all kinematic effects in the Damour-Deruelle-Kopeikin (DDK) orbital model in tempo and the T2 orbital model used in tempo2. This is different from the convention described by Damour & Taylor (1992) and used by Kramer et al (2021) (see their Fig. 7).…”

Section: Reference Framementioning

confidence: 79%

“…We determine the geometry of the pulsar by fitting the RVM model using a Bayesian optimisation method as described by Johnston & Kramer (2019) and Kramer et al (2021). Using uniform priors, we derive ζ, β, as well as Φ 0 (the location of the aforementioned fiducial plane relative to an arbitrary reference longitude on the neutron star; see Fig.…”

Section: Pulse Polarisation Resultsmentioning

confidence: 99%

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PSR J2222−0137

Guo

Freire

Guillemot

et al. 2021

A&A

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Context. The PSR J2222−0137 binary system has a set of features that make it a unique laboratory for tests of gravity theories. Aims. To fully exploit the system’s potential for these tests, we aim to improve the measurements of its physical parameters, spin and orbital orientation, and post-Keplerian parameters, which quantify the observed relativistic effects. Methods. We describe an improved analysis of archival very long baseline interferometry (VLBI) data, which uses a coordinate convention in full agreement with that used in timing. We have also obtained much improved polarimetry of the pulsar with the Five hundred meter Aperture Spherical Telescope (FAST). We provide an improved analysis of significantly extended timing datasets taken with the Effelsberg, Nançay, and Lovell radio telescopes; this also includes previous timing data from the Green Bank Telescope. Results. From the VLBI analysis, we have obtained a new estimate of the position angle of the ascending node, Ω = 189−18+19 deg (all uncertainties are 68% confidence limits), and a new reference position for the pulsar with an improved and more conservative uncertainty estimate. The FAST polarimetric results, and in particular the detection of an interpulse, yield much improved estimates for the spin geometry of the pulsar, in particular an inclination of the spin axis of the pulsar of ∼84 deg. From the timing, we obtain a new ∼1% test of general relativity (GR) from the agreement of the Shapiro delay parameters and the rate of advance of periastron. Assuming GR in a self-consistent analysis of all effects, we obtain much improved masses: 1.831(10) M⊙ for the pulsar and 1.319(4) M⊙ for the white dwarf companion; the total mass, 3.150(14) M⊙, confirms this as the most massive double degenerate binary known in the Galaxy. This analysis also yields the orbital orientation; in particular, the orbital inclination is 85.27(4) deg – indicating a close alignment between the spin of the pulsar and the orbital angular momentum – and Ω = 187.7(5.7) deg, which matches our new VLBI estimate. Finally, the timing also yields a precise measurement of the variation in the orbital period, Ṗb = 0.251(8) × 10−12 ss−1; this is consistent with the expected variation in the Doppler factor plus the orbital decay caused by the emission of gravitational waves predicted by GR. This agreement introduces stringent constraints on the emission of dipolar gravitational waves.

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Section: Pulse Polarisation Resultsmentioning

confidence: 75%

Section: Reference Framementioning

confidence: 79%

Section: Pulse Polarisation Resultsmentioning

confidence: 99%

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PSR J2222−0137

Guo

Freire

Guillemot

et al. 2021

A&A

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show abstract

“…We will use the "observer's convention", which is assumed for calculating all kinematic effects in the DDK orbital model in tempo and the T2 orbital model used in tempo2. This is different from the convention described by Damour & Taylor (1992) and used by Kramer et al (2021) (see their Fig. 7).…”

Section: Reference Framementioning

confidence: 79%

PSR J2222--0137. I. Improved physical parameters for the system

Guo,

Freire,

Guillemot

et al. 2021

Preprint

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Context. The PSR J2222−0137 binary system has a set of features that make it a unique laboratory for tests of gravity theories. Aims. To fully exploit the system's potential for these tests, we aim to improve the measurements of its physical parameters: spin and orbital orientation and post-Keplerian parameters, which quantify the observed relativistic effects. Methods. We describe improved analysis of archival Very Long Baseline Interferometry (VLBI) data, which uses a coordinate convention in full agreement with that used in timing. We have also obtained much improved polarimetry of the pulsar with the Five hundred meter Aperture Spherical Telescope (FAST). We provide an improved analysis of significantly extended timing datasets taken with the Effelsberg, Nançay and Lovell radio telescopes; this also includes previous timing data from the Green Bank Telescope. Results. From the VLBI analysis, we have obtained a new estimate of the position angle of the ascending node, Ω = 189 +19 −18 deg (all uncertainties are 68% confidence limits), and a new reference position for the pulsar with an improved and more conservative uncertainty estimate. The FAST polarimetric results, and in particular the detection of an interpulse, yield much improved estimates for the spin geometry of the pulsar, in particular an inclination of the spin axis of the pulsar of ∼ 84 deg. From the timing, we obtain a new ∼1% test of general relativity (GR) from the agreement of the Shapiro delay parameters and the rate of advance of periastron. Assuming GR in a self-consistent analysis of all effects, we obtain much improved masses: 1.831(10) M for the pulsar and 1.319(4) M for the white dwarf companion; the total mass, 3.150(14) M confirms this as the most massive double degenerate binary known in the Galaxy. This analysis also yields the orbital orientation; in particular the orbital inclination is 85.27(4) deg -indicating a close alignment between the spin of the pulsar and the orbital angular momentum -and Ω = 187.7(5.7) deg, which matches our new VLBI estimate. Finally, the timing also yields a precise measurement of the variation of the orbital period, Ṗb = 0.251(8) × 10 −12 s s −1 ; this is consistent with the expected variation of the Doppler factor plus the orbital decay caused by the emission of gravitational waves (GWs) predicted by GR. This agreement introduces stringent constraints on the emission of dipolar GWs.

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“…5 An important design goal, which is to perform time domain science, has been largely achieved due to the relatively compact core and recent promising observations. [6][7][8] Some pulsars' stability of the order of 4 ns • h −1 is now projected based on MeerKAT measurements. 9 This is an improvement of prior best state-of-the-art measurements on the Parkes Pulsar Timing Array in 2014.…”

Section: Introductionmentioning

confidence: 99%

Design, implementation, and qualification of high-performance time and frequency reference for the MeerKAT telescope

Burger

Siebrits

Gamatham

et al. 2022

J. Astron. Telesc. Instrum. Syst.

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The details of the MeerKAT radio telescope's time and frequency reference subsystem that enables sampling via low-jitter, low-drift microwave clock signals, and absolute timing (≤5 ns accurate) are discussed. The subsystem's microwave and pulse per second transmission parts are now fully qualified and commissioned for the ultra high frequency (UHF) and L-bands and also provide for a 100-MHz interface and timing interfaces for S-band receivers that were installed. The subsystem includes a cable measurement system called the Karoo array timing system (KATS). Performance and differences on different bands and seasonal drift of the cable delay measurement of KATS are reported. A time scale called the Karoo Telescope Time (KTT) (which is estimated from tracking a few atomic clocks via new software) and the issuing of timing bulletins to users have been largely implemented and verified. Absolute timing calibration and linkage of KTT to the global positioning system time scale and to different UTC(k) realizations of the Coordinated Universal Time (UTC) instances are described. The subsystem uniquely enables high-fidelity sampling and stable tied array configuration. The latter configuration enables timing and transient science over time spans of 5 to 10 years. Simultaneous subarraying is supported. The backend is unique for radio telescopes in terms of being very deterministic as far as timing is concerned.

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The relativistic binary programme on MeerKAT: science objectives and first results

Cited by 45 publications

References 92 publications

PSR J2222−0137

PSR J2222−0137

PSR J2222--0137. I. Improved physical parameters for the system

Design, implementation, and qualification of high-performance time and frequency reference for the MeerKAT telescope

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