Millisecond and Binary Pulsars as Nature's Frequency Standards. II. Effects of Low-Frequency Timing Noise on Residuals and Measured Parameters

Pulsars are the most stable natural frequency standards. They can be applied to a number of principal problems of modern astronomy and time-keeping metrology. The full exploration of pulsar properties requires obtaining unbiased estimates of the spin and orbital parameters. These estimates depend essentially on the random noise component being revealed in the residuals of time of arrivals (TOA). In the present paper, the influence of low-frequency ("red") timing noise with spectral indices from 1 to 6 on TOA residuals, variances, and covariances of estimates of measured parameters of single and binary pulsars are studied. In order to determine their functional dependence on time, an analytic technique of processing of observational data in time domain is developed which takes into account both stationary and non-stationary components of noise. Our analysis includes a simplified timing model of a binary pulsar in a circular orbit and procedure of estimation of pulsar parameters and residuals under the influence of red noise. We reconfirm that uncorrelated white noise of errors of measurements of TOA brings on gradually decreasing residuals, variances and covariances of all parameters. On the other hand, we show that any red noise causes the residuals, variances, and covariances of certain parameters to increase with time. Hence, the low frequency noise corrupts our observations and reduces experimental possibilities for better tests of General Relativity Theory. We also treat in detail the influence of a polynomial drift of noise on the residuals and fitting parameters. Results of the analitic analysis are used for discussion of a statistic describing stabilities of kinematic and dynamic pulsar time scales.Comment: 40 pages, 1 postscript figure, 1 picture, uses mn.sty, accepted to Mon. Not. Roy. Astron. So

Testing Relativistic Effect of Propagation of Gravity by Very-Long Baseline Interferometry

It is shown that the finite speed of gravity affects very-long baseline interferometric observations of quasars during the time of their line-of-sight close angular encounter with Jupiter. The next such event will take place in 2002, September 8. The present Letter suggests a new experimental test of general relativity in which the effect of propagation of gravity can be directly measured by very-long baseline interferometry as an excess time delay in addition to the logarithmic Shapiro time delay (Shapiro, I. I., 1964, Phys. Rev. Lett., 13, 789).Comment: 11 pages, accepted to ApJ Letter

Beyond the Standard IAU Framework

We discuss three conceivable scenarios of extension and/or modification of the IAU relativistic resolutions on time scales and spatial coordinates beyond the Standard IAU Framework. These scenarios include: (1) the formalism of the monopole and dipole moment transformations of the metric tensor replacing the scale transformations of time and space coordinates; (2) implementing the parameterized post-Newtonian formalism with two PPN parameters - beta and gamma; (3) embedding the post-Newtonian barycentric reference system to the Friedman-Robertson-Walker cosmological model.Comment: 9 pages, no figures, submitted to the proceedings of the IAU 261 Symposium "Relativity in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis"", Virginia Beach, USA; May 200

The Measurement of the Light Deflection from Jupiter: Theoretical Interpretation

Equations of light, propagating from quasar to observer on earth, are integrated in the time-dependent gravitational field of the solar system by making use of either retarded or advanced solutions of the Einstein field equations. This technique allows to separate explicitly the effects associated with the propagation of gravity from those associated with light in the integral expression for the relativistic time delay of light. We prove that the relativistic correction to the Shapiro time delay discovered by Kopeikin (ApJ, 556, L1, 2001) changes sign if one retains direction of the light propagation but replaces retarded with advanced solution of the gravitational field equations. Hence, this correction is due to the propagation of gravity and allows to measure its speed. Relativistic VLBI experiment conducted by Fomalont and Kopeikin in September 2002 proves that the propagation of gravitational field is characterized by the retarded potentials.Comment: 14 pages, 1 figur

The Speed of Gravity in General Relativity and Theoretical Interpretation of the Jovian Deflection Experiment

Recent measurements of the propagation of the quasar's radio signal past Jupiter are directly sensitive to the time-dependent effect from the geometric sector of general relativity which is proportional to the speed of propagation of gravity but not the speed of light. It provides a first confirmative measurement of the fundamental speed of the Einstein general principle of relativity for gravitational field.Comment: 45 pages, 6 figures, publishe