arXiv:astro-ph/0105090v1 4 May 2001 iais ps-elra”(K aaeescnas efi.These fit. ˙ be advance, also periastron can of parameters (PK) “post-Keplerian” binaries, parameters. system unknown accomplish only usually the is then fitting are model This fit. phase-co be program a also eccentricity, derivat must para to orbital periastron) period axis, orbital fit of semi-major Keplerian period, then orbital five position, projected , is period, binary TOAs For the of measure. a includes collection dispersion produce which to The observation model, (TOA). the timing arrival of timestamp of starting betwetime the offset to the observation; added hours’ is many from profile up “standard built a question, with cross-correlated is observation individual h aeo ria eiddecay, period orbital of rate the rvttoa hoisi S 11+6 icvrda rcb n19 in Arecibo at discovered B1913+16, PSR is theories gravitational h ytmi vreemndadcnb sdt etteter it m theory are the test more to or used three be if can while and co gravity, overdetermined is of is system theory system the the particular measured, are a function parameters within a PK as mined two written if be Thus can parameter masses. PK each gravity, of theory eea eaiiyt etrta 1%. than better to relativity general rcie hs aaeesaefi nater-needn mann theory-independent a in fit are parameters these practice, S 11+6 u lo eas ftefvual nlnto fth of inclination parameters favourable delay the Shapiro of two because the also, bit, but B1913+16, PSR ytm h ˙ the system, S B1534+12. a PSR radiation gravitational of relativity. emission general the of of theory the proof first the provided Ost ecluae;i a vnulysrasPRB931 nthe in B1913+16 PSR surpass permittin eventually thereby may B1913+16, it calculated; PSR be than to pulse TOAs sharper stronger, a tis umte to submitted stairs: nvriyo acetr orl akOsraoy Maccl Observatory, Bank Jodrell Manchester, of University USRTMN BEVTOSADTSSO GENERAL OF TESTS AND OBSERVATIONS TIMING PULSAR ntecs fcranbnr usrsses oal h double-n the notably systems, pulsar binary certain of case the In obtaine profile pulse the First, process. two-stage a is timing Pulsar h etkoneapeo h s fadul-eto-trsys double-neutron-star a of use the of example best-known The iia obenurnsa ytm icvrda rcb n199 in Arecibo at discovered system, double-neutron-star similar A aaeesaemaual,icuigteobtlpro de period orbital the parameters. delay including Shapiro ”Pos measurable, 5 pulsar, res are latter GR the parameters For of general tests systems. B1534+12 the strong-field and describe of B1913+16 We tests systems. to binary neutron-star applied observatio be timing pulsar may in observations used techniques the describe We EAIIYI OBENURNSA BINARIES DOUBLE-NEUTRON-STAR IN RELATIVITY tempo ω , γ 7 and seht:/usrpictneutmo.Tetoselrmasses stellar two The http://pulsar.princeton.edu/tempo). (see hspla emt h esrmn f˙ of measurement the permits pulsar This P ol Scientific World ˙ b ω aaeesaemaue,adarewt h rdcin of predictions the with agree and measured, are parameters h iedlto n rvttoa-esitparameter, gravitational-redshift and time-dilation the , -al [email protected] E-mail: 6 P ˙ b n h hpr-ea parameters, Shapiro-delay the and , .H STAIRS H. I. 2 , 5 hog h esrmn of measurement the Through U.K. r nNvme 1 2018 21, November on and s utemr,PRB541 has B1534+12 PSR Furthermore, . sed hsieS1 9DL SK11 Cheshire esfield, s n hwhwthese how show and ns, ligfo h PSRs the from ulting iaieadtetwo the and rivative double- for relativity -elra”timing t-Keplerian” ω ogtd n epoch and longitude , er. ntetoprofiles two the en o h usrin pulsar the for ” γ ftetostellar two the of 1 nld h rate the include self. P peeydeter- mpletely ees(orbital meters and oeprecise more g ihnagiven a Within ˙ rdce by predicted s high-precision B 74. hssystem this , iayor- binary e 2 e otest to tem dwt the with ed eutron-star r , 3 P 4 ˙ and precision b easured, o this For sfor as , nan in d v and ive herent ,is 0, s In . γ , 1 of its timing solution. At the present time,ω ˙ , γ and s are measured extremely pre- cisely, and also agree with the predictions of to better than 1%.8 It should be noted that the agreement between these PK parameters represents a test of the purely quasi-static regime of general relativity, complementing the mixed quasi-static and radiative test obtained from PSR B1913+16. The range of Shapiro delay, r, is also in agreement with general relativity despite a large measurement uncertainty; this should improve with further timing observations. The orbital period derivative of PSR B1534+12 merits special discussion. The observed value of P˙b cannot be compared directly to the value predicted by general relativity. The relative acceleration of the Solar System Barycenter and the center of mass of the pulsar system induces a bias in the observed value. In the case of PSR B1534+12, the bias is dominated by a proper motion term dependent on the distance of the pulsar from the earth.9 At present, the only, and rough, estimate of the distance to the pulsar comes from its dispersion measure and a model of the free electron content in the galaxy,10 which yield an estimate of 0.7±0.2 kpc. When the bias is calculated using this value for the distance, the resultant measured −12 intrinsic P˙b is (−0.167 ± 0.018) × 10 , only 87% of the value predicted by GR, −0.192 × 10−12.8 Under the assumption that GR is the correct theory of gravity, the test can in fact be inverted and an improved distance to the pulsar calculated;11 by this method, the distance to PSR B1534+12 is found to be 1.1±0.2 kpc.8 An in- dependent measurement of the pulsar distance, through a timing or interferometric parallax, will automatically lead to a greatly strengthened test of general relativity from this pulsar system.

Acknowledgments

I thank my colleagues in the PSR B1534+12 observations: Zaven Arzoumanian, Fernando Camilo, Andrew Lyne, David Nice, Joe Taylor, and Alex Wolszczan. I also thank Michael Kramer for reading the manuscript.

References

1. Damour, T. & Deruelle, N. 1986, Ann. Inst. H. Poincar´e(Phys. th´eor.), 44, 263 2. Taylor, J. H. & Weisberg, J. M. 1989, Astrophys. J., 345, 434 3. Taylor, J. H. & Wolszczan, A. & Damour, T. & Weisberg, J. M. 1992, Nature, 355, 132 4. Hulse, R. A. & Taylor, J. H. 1975, Astrophys. J., 195, L51 5. Damour, T. & Taylor, J. H. 1991, Astrophys. J., 366, 501 6. Taylor, J. H. 1994, in Les Prix Nobel, (Stockholm: Norstedts Tryckeri), 80 7. Wolszczan, A. 1991, Nature, 350, 688 8. Stairs, I. H., Arzoumanian, Z., Camilo, F., Lyne, A. G., Nice, D. J., Taylor, J. H., Thorsett, S. E., & Wolszczan, A. 1998, Astrophys. J., 505, 352 9. Shklovskii, I. S. 1970, Sov. Astron., 13, 562 10. Taylor, J. H. & Cordes, J. M. 1993, Astrophys. J., 411, 674 11. Bell, J. F. & Bailes, M. 1996, Astrophys. J., 456, L33

stairs: submitted to World Scientific on November 21, 2018 2