Preferred-Frame Effects in Gravity: Theory and Pulsar Timing Constraints

Einstein-æther gravity is a Lorentz-violating extension of General Relativity in which a dynamical, unit timelike vector field introduces a preferred frame. I will give an overview of the theory, covering new preliminary results on spherical collapse, the emission of extra gravitational modes, and post-Newtonian corrections to the two-body problem. Building on this theoretical framework, I will then present quasi-strong-field constraints on the Einstein-æther coupling constants derived from high-precision timing of PSR J1738+0333.

Our approach combines a full Bayesian timing analysis with a resampling scheme that propagates posteriors on post-Keplerian parameters into theory-specific bounds on the fundamental coupling constants, yielding the most stringent constraints from a single binary pulsar to date. The method is general and applicable to other alternative theories of gravity.