Tests of gravitational symmetries with pulsar binary J1713+0747

Abstract

Symmetries play a fundamental role in modern theories of gravity. The strong equivalence principle (SEP) constitutes a collection of gravitational symmetries which are all implemented by general relativity. Alternative theories, however, are generally expected to violate some aspects of SEP. We test three aspects of SEP using observed change rates in the orbital period and eccentricity of binary pulsar J1713+0747: (1) the gravitational constant's constancy as part of locational invariance of gravitation; (2) the universality of free fall (UFF) for strongly self-gravitating bodies; (3) the post-Newtonian parameterα 3 in gravitational Lorentz invariance. Based on the pulsar timing result of the combined data set from the North American Nanohertz Gravitational Observatory and the European Pulsar Timing Array, we findĠ/G = (−0.1 ± 0.9) × 10 −12 yr −1 , which is weaker than Solar system limits, but applies for strongly self-gravitating objects. Furthermore, we obtain an improved test for a UFF violation by a strongly self-gravitating mass falling in the gravitational field of our Galaxy, with a limit of | | < 0.002 (95 per cent C.L.). Finally, we derive an improved limit on the self-acceleration of a gravitationally bound rotating body, to a preferred reference frame in the Universe, with −3 × 10 −20 <α 3 < 4 × 10 −20 (95 per cent C.L.). These results are based on direct UFF and α 3 tests using pulsar binaries, and they overcome various limitations of previous tests of this kind.

Secular effects of ultralight dark matter on binary pulsars

“…For systems with nearly circular orbits the strongest effect is the drift of eccentricity occurring at the N = 1 resonance. To illustrate the ensuing constraints, we consider the system J1713+0747 that has been timed for more than two decades, T obs ∼ 20 y [79][80][81] with a white dwarf companion of mass M 2 0.29 M . The residual drifts of its orbital period and eccentricity parameters (after subtracting the known standard contributions) have been constrained at the level [81]:…”

Testing Fifth Forces from the Galactic Dark Matter

“…Due to its narrow pulse profile and stable rotation, PSR J1713+0747 is monitored by the North American Nanohertz Gravitational Observatory (NANOGrav), the European Pulsar Timing Array (EPTA), and the Parkes Pulsar Timing Array (PPTA). Splaver et al [12], Zhu et al [13], and Desvignes et al [14] have published timing solutions for this pulsar, and the latest timing parameters from combined datasets are given in Zhu et al [9]. Some relevant parameters for this proceeding are collected in Table I.…”

“…It renders a previous timing model for small-eccentricity binary pulsars, ELL1 [15], not accurate enough. Zhu et al [9] developed an extended model, ELL1+, by including higherorder contributions from the eccentricity. The ELL1+ model includes terms up to O (e 2 ) in the Römer delay [9].…”

“…Zhu et al [9] developed an extended model, ELL1+, by including higherorder contributions from the eccentricity. The ELL1+ model includes terms up to O (e 2 ) in the Römer delay [9]. The measured values for e x and e y are listed in Table I.…”

“…The proceeding is organized as follows. In the next section the relevant observational characteristics of PSR J1713+0747 are introduced [9]. In section III, we review the EPviolating signal in the orbital dynamics of a binary pulsar [10,11].…”