Issue |
A&A
Volume 654, October 2021
|
|
---|---|---|
Article Number | A16 | |
Number of page(s) | 17 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/202141450 | |
Published online | 01 October 2021 |
PSR J2222−0137
I. Improved physical parameters for the system
1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: yjguo@mpifr-bonn.mpg.de
2
Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Université d’Orléans/CNRS, 45071 Orléans Cedex 02, France
3
Station de radioastronomie de Nançay, Observatoire de Paris, CNRS/INSU, 18330 Nançay, France
4
CAS Key Laboratory of FAST, NAOC, Chinese Academy of Sciences, Beijing 100101, PR China
5
Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada
6
Centre for Astrophysics and Supercomputing, Swinburne University of Technology John St, Hawthorn, VIC 3122, Australia
7
ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), Hawthorn, Australia
8
Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee, PO Box 413 Milwaukee, WI 53201, USA
9
Jodrell Bank Center for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK
10
School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, PR China
11
National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA
12
LUTH, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, 92195 Meudon, France
Received:
1
June
2021
Accepted:
17
July
2021
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.
Key words: binaries: close / gravitational waves / pulsars: general / pulsars: individual: J2222−0137 / stars: neutron / white dwarfs
© Y. J. Guo et al. 2021
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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