A Tighter Test of Local Lorentz Invariance using PSR J2317+1439

Gravity being a long-range force, one might {\it a priori} expect the Universe’s global matter distribution to select a preferred rest frame for local gravitational physics. The phenomenology of preferred-frame effects, in the strong-gravitational field context of binary pulsars, is described by two parameters ${\widehat{\alpha }}_1$ and ${\widehat{\alpha }}_2$. These parameters vanish identically in general relativity, and reduce, in the weak-field limit, to the two parametrized post-Newtonian (PPN) parameters ${\alpha }_1$ and ${\alpha }_2$. We derive a limit of $\mathrm{\mid }{\widehat{\alpha }}_1\mathrm{\mid }<1.7\times {10}^{-4}$ (90%~C.L.) using the very low eccentricity binary pulsar PSR J2317+1439, improving by a factor of 3 on previous limits.