Timing models for the long-orbital period binary pulsar PSR B1259-63
N. Wex (Max-Planck Society, Research Unit Theory of Gravitation, Germany),
S. Johnston (RCfTA, University of Sydney, Australia),
R. N. Manchester (ATNF, CSIRO, Australia),
A. G. Lyne (NRAL, University of Manchester, Jodrell Bank, UK.),
B. W. Stappers (MSSSO, ANU, Australia),
M. Bailes (University of Melbourne, Australia).

(1998) MNRAS, 298, 997-1004.

Abstract
The pulsar PSR B1259-63 is in a highly eccentric 3.4-yr orbit with the Be star SS 2883. Timing observations of this pulsar, made over a 7-yr period using the Parkes 64-m radio telescope, cover two periastron passages, in 1990 August and 1994 January. The timing data cannot be fitted by the normal pulsar and Keplerian binary parameters. A timing solution including a (non-precessing) Keplerian orbit and timing noise (represented as a polynomial of fifth order in time) provide a satisfactory fit to the data. However, because the Be star probably has a significant quadrupole moment, we prefer to interpret the data by a combination of timing noise, dominated by a cubic phase term, and omega-dot and x-dot terms. We show that the omega-dot and x-dot are likely to be a result of a precessing orbit caused by the quadrupole moment of the tilted companion star. We further rule out a number of possible physical effects which could contribute to the timing data of PSR B1259-63 on a measurable level.

Key words:pulsar timing -- timing noise -- binary pulsars -- classical spin-orbit coupling -- pulsars: individual (PSR B1259-63)

simonj@physics.usyd.edu.au