GENERIC GRAVITY TESTS WITH THE DOUBLE PULSAR

Abstract

Among the most well-known uses of pulsars has been their role in tests of theories of gravity, in particular in the experimental verification of general relativity (GR). In 2003 a binary system was discovered where both members were identified as radio pulsars. Both pulsars, now known as PSR J0737–3039A (23ms) and PSR J0737–3039B (2.8 s), A and B hereafter, orbit each other in 2.45 hours in a slightly eccentric orbit. As a result, the system is not only the first and, thus far, only double neutron star system where both neutron stars are visible as active radio pulsars, but it is also the most relativistic binary pulsar known to date. By measuring the radial motion of the two pulsars, we obtain a precise measurement of the mass ratio mA/mB . 4 In addition, a total of six post-Keplerian (PK) parameters has been measured. Five arise from four different relativistic effects visible in pulsar timing (Ref. 5), while a sixth one can be determined from the effects of geodetic precession on the observed radio eclipses (Ref. 6). The measurement of the mass ratio and six PK parameters, including the relativistic spin precession of B, makes the double pulsar (DP) the most constrained binary pulsar known. This allows for much more general statements about alternative theories of gravity than it has been possible before the discovery of this system.