5.3 Binary pulsars and alternative 5 Stellar System Tests of 5.1 The binary pulsar and

5.2 A population of binary pulsars? 

Since 1990, several new massive binary pulsars similar to PSR 1913+16 were discovered, leading to the possibility of new or improved tests of GR.

Table 7: Parameters of other binary pulsars. From [156, 118Jump To The Next Citation Point In The Article, 119Jump To The Next Citation Point In The Article] and from an online catalogue of pulsars maintained by Stephen Thorsett of the University of California, Santa Cruz, see [128].

PSR 1534+12.
This is a binary pulsar system in our galaxy. Its pulses are significantly stronger and narrower than those of PSR 1913+16, so timing measurements are more precise, reaching 3  tex2html_wrap_inline4033 s accuracy. Its parameters are listed in Table  7  [118, 119]. The orbital plane appears to be almost edge-on relative to the line of sight (tex2html_wrap_inline5383); as a result the Shapiro delay is substantial, and separate values of the parameters r and s have been obtained with interesting accuracy. Assuming general relativity, one infers that the two masses are tex2html_wrap_inline5389 and tex2html_wrap_inline5391 . The rate of orbit decay tex2html_wrap_inline5283 agrees with GR to about 15 percent, the precision limited by the poorly known distance to the pulsar, which introduces a significant uncertainty into the subtraction of galactic acceleration. Independently of tex2html_wrap_inline5283, measurement of the four other post-Keplerian parameters gives two tests of strong-field gravity in the non-radiative regime [124].
PSR 2127+11C.
This system appears to be a clone of the Hulse-Taylor binary pulsar, with very similar values for orbital period and eccentricity (see Table  7). The inferred total mass of the system is tex2html_wrap_inline5397 . Because the system is in the globular cluster M15 (NGC 7078), it suffers Doppler shifts resulting from local accelerations, either by the mean cluster gravitational field or by nearby stars, that are more difficult to estimate than was the case with the galactic system PSR 1913+16. This may make a separate, precision measurement of the relativistic contribution to tex2html_wrap_inline5283 impossible.
PSR 1855+09.
This binary pulsar system is not particularly relativistic, with a long period (12 days) and highly circular orbit. However, because we observe the orbit nearly edge on, the Shapiro delay is large and measurable, as reflected in the post-Keplerian parameters r and s .
PSR 0655+64.
This system consists of a pulsar and a white dwarf companion in a nearly circular orbit. Only an upper limit on tex2html_wrap_inline5283 has been placed.

5.3 Binary pulsars and alternative 5 Stellar System Tests of 5.1 The binary pulsar and

image The Confrontation between General Relativity and Experiment
Clifford M. Will
© Max-Planck-Gesellschaft. ISSN 1433-8351
Problems/Comments to livrev@aei-potsdam.mpg.de