A Pulsar Time Scale Based on Parkes Observations in 1995--2010

TL;DR

This paper constructs an ensemble pulsar time scale using Parkes telescope data from 1995 to 2010, demonstrating high stability and setting limits on gravitational wave background energy density.

Contribution

It introduces a new pulsar-based time scale with enhanced accuracy using Wiener filters and compares it to terrestrial time standards over 15 years.

Findings

Time-scale difference does not exceed 0.8 microseconds.

Fractional instability over 15 years is approximately 0.6×10^{-15}.

Sets upper limits on gravitational wave background energy density.

Abstract

Timing of highly stable millisecond pulsars provides the possibility of independently verifying terrestrial time scales on intervals longer than a year. An ensemble pulsar time scale is constructed based on pulsar timing data obtained on the 64-m Parkes telescope (Australia) in 1995--2010. Optimal Wiener filters were applied to enhance the accuracy of the ensemble time scale. The run of the time--scale difference PT$_{ens}$ $-$ TT(BIPM2011) does not exceed $0.8 {\pm} 0.4$ $\mu s$ over the entire studied time interval. The fractional instability of the difference $_{ens}$ $-$ TT(BIPM2011) over 15 years is ${\sigma_z} = (0.6\pm 1.6){\cdot}10^{-15}$, which corresponds to an upper limit for the energy density of the gravitational--wave background ${\Omega_g}h^2 {\sim} 10^{-10}$ and variations in the gravitational potential ${\sim} 10^{-15}$ Hz at the frequency $2{\cdot}10^{-9}$.