Optimal Filtration and a Pulsar Time Scale

TL;DR

This paper introduces an optimal Wiener filter-based algorithm to construct a pulsar time scale, effectively separating atomic and pulsar rotation variations, and uses it to compare terrestrial and pulsar-based times, setting limits on gravitational-wave background energy density.

Contribution

It presents a novel algorithm for creating a pulsar time scale using optimal Wiener filters, enabling precise comparison with terrestrial time standards.

Findings

Discrepancy between terrestrial and pulsar time is within 0.4 microseconds.

Established a new upper limit for gravitational-wave background energy density.

Demonstrated the effectiveness of the method on two pulsars.

Abstract

An algorithm is proposed for constructing a group (ensemble) pulsar time based on the application of optimal Wiener filters. This algorithm makes it possible to separate the contributions of variations of the atomic time scale and of the pulsar rotation to barycentric residual deviations of the pulse arrival times. The method is applied to observations of the pulsars PSR B1855+09 and PSR B1937+21, and is used to obtain corrections to UTC relative to the group pulsar time PT$_{\rm ens}$. Direct comparison of the terrestrial time TT(BIPM06) and the group pulsar time PT$_{\rm ens}$ shows that they disagree by no more than $0.4\pm 0.17\; \mu$s. Based on the fractional instability of the time difference TT(BIPM06) -- PT$_{\rm ens}$, a new limit for the energy density of the gravitational-wave background is established at the level $\Omega_g {h}^2\sim 10^{-9}$.