Classical and general relativistic post-Keplerian effects in binary pulsars hosting fast rotating main sequence stars

We consider a binary system composed of a pulsar and a massive, fast rotating, highly distorted main sequence star of mass M , spin angular momentum S , dimensionless mass quadrupole moment J 2 , equatorial and polar radii R e , R p , flattening ν ≐ ( R e - R p ) / R e , and ellipticity ε ≐ 1 - R p...

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Bibliographic Details
Published in:The European physical journal. C, Particles and fields Vol. 79; no. 8; pp. 1 - 12
Main Authors: Iorio, Lorenzo, Rieutord, Michel, Rozelot, Jean-Pierre, de Souza, Armando Domiciano
Format: Journal Article
Language:English
Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2019
Springer
Springer Nature B.V
Springer Verlag (Germany)
SpringerOpen
Subjects:
Analysis
Angular momentum
Astronomy
Astrophysics
Astrophysics and Cosmology
Binary stars
Dipoles
Electric waves
Electromagnetic radiation
Electromagnetic waves
Elementary Particles
Ellipticity
General Relativity and Quantum Cosmology
Gravitational fields
Gravity
Hadrons
Heavy Ions
Main sequence stars
Measurement Science and Instrumentation
Millisecond pulsars
Nuclear Energy
Nuclear Physics
Orbits
Physics
Physics and Astronomy
Quadrupoles
Quantum Field Theories
Quantum Field Theory
Regular Article - Theoretical Physics
Stellar rotation
String Theory
Time lag
Wave propagation
ISSN:1434-6044, 1434-6052
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Summary:We consider a binary system composed of a pulsar and a massive, fast rotating, highly distorted main sequence star of mass M , spin angular momentum S , dimensionless mass quadrupole moment J 2 , equatorial and polar radii R e , R p , flattening ν ≐ ( R e - R p ) / R e , and ellipticity ε ≐ 1 - R p 2 / R e 2 as a potential scenario to dynamically put to the test certain post-Keplerian effects of both Newtonian and post-Newtonian nature. We numerically produce time series of the perturbations Δ δ τ of the Rømer-like, orbital component of the pulsar’s time delay δ τ induced over 10 years by the pN gravitoelectric mass monopole Schwarzschild , G M c - 2 , quadrupole G M R e 2 J 2 c - 2 , gravitomagnetic spin dipole Lense - Thirring , G S c - 2 and octupole G S R e 2 ε 2 c - 2 accelerations along with the Newtonian quadrupolar G M R e 2 J 2 one. We do not deal with the various propagation time delays due to the travelling electromagnetic waves. It turns out that, for a Be-type star with M = 15 M ⊙ , R e = 5.96 R ⊙ , ν = 0.203 , S = 3.41 × 10 45 J s , J 2 = 1.92 × 10 - 3 orbited by a pulsar with an orbital period P b ≃ 40–70 days, the classical oblateness-driven effects are at the ≲ 4 - 150 s level, while the pN shifts are of the order of ≲ 1.5 - 20 s G M c - 2 , ≲ 10 - 40 ms G M R e 2 J 2 c - 2 , ≲ 0.5 - 6 ms G S c - 2 , ≲ 5 - 20 μ s G S R e 2 ε 2 c - 2 , depending on their orbital configuration. The root-mean-square (rms) timing residuals σ τ of almost all the existing non-recycled, non-millisecond pulsars orbiting massive, fast rotating main sequence stars are ≲ ms . Thus, such kind of binaries have the potential to become interesting laboratories to measure, or, at least, constrain, some Newtonian and post-Newtonian ( G M c - 2 , G M J 2 c - 2 , and, perhaps, G S c - 2 as well) key features of the distorted gravitational fields of the fast rotating stars hosted by them.
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ISSN:1434-6044
1434-6052
DOI:10.1140/epjc/s10052-019-7194-5