Abstract
We report 21year timing of one of the most precise pulsars: PSR J1713+0747. Its pulse times of arrival are well modeled by a comprehensive pulsar binary model including its threedimensional orbit and a noise model that incorporates shortand longtimescale correlated noise such as jitter and red noise. Its timing residuals have weighted root mean square similar to 92 ns. The new data set allows us to update and improve previous measurements of the system properties, including the masses of the neutron star (1.31 +/ 0.11 Mcircle dot) and the companion white dwarf (0.286 +/ 0.012 Mcircle dot) as well as their parallax distance 1.15 +/ 0.03 kpc. We measured the intrinsic change in orbital period, (P) over dot(b)(Int), is 0.20 +/ 0.17 ps s(1), which is not distinguishable from zero. This result, combined with the measured (P) over dot(b)(Int) of other pulsars, can place a generic limit on potential changes in the gravitational constant G. We found that (G) over dot/G is consistent with zero [(0.6 +/ 1.1) x 10(12) yr(1), 95% confidence] and changes at least a factor of 31 (99.7% confidence) more slowly than the average expansion rate of the universe. This is the best (G) over dot/G limit from pulsar binary systems. The (P) over dot(b)(Int) of pulsar binaries can also place limits on the putative coupling constant for dipole gravitational radiation kappa(D) = (0.9 +/ 3.3) 10(4) (95% confidence). Finally, the nearly circular orbit of this pulsar binary allows us to constrain statistically the strongfield postNewtonian parameters Delta, which describes the violation of strong equivalence principle, and (alpha) over cap (3), which describes a breaking of both Lorentz invariance in gravitation and conservation of momentum. We found, at 95% confidence, Delta <0.01 and (3) <2 x 10(20) based on PSR J1713+0747.
Original language  English 

Article number  41 
Number of pages  15 
Journal  Astrophysical Journal 
Volume  809 
Issue number  1 
Early online date  7 Aug 2015 
DOIs  
Publication status  Published  10 Aug 2015 
Externally published  Yes 
Profiles

Robert Ferdman
 School of Engineering, Mathematics and Physics  Associate Professor in Physics
Person: Academic, Teaching & Research