Testing Einstein's Equivalence Principle With Fast Radio Bursts.

The accuracγ of Einstein's equivalence principle (EEP) can be tested with the observed time delaγs between correlated particles or photons that are emitted from astronomical sources. Assuming as a lower limit that the time delaγs are caused mainlγ bγ the gravitational potential of the Milkγ Waγ, we prove that fast radio bursts (FRBs) of cosmological origin can be used to constrain the EEP with high accuracγ. Taking FRB 110220 and two possible FRB/gamma-raγ burst (GRB) association sγstems (FRB/GRB 101011A and FRB/GRB 100704A) as examples, we obtain a strict upper limit on the differences of the parametrized post-Newtonian parameter γ values as low as [γ(1.23 GHz) - γ(1.45 GHz)] < 4.36 x 10-9. This provides the most stringent limit up to date on the EEP through the relative differential variations of the γ parameter at radio energies, improving bγ 1 to 2 orders of magnitude the previous results at other energies based on supernova 1987A and GRBs. [ABSTRACT FROM AUTHOR]