A pulsar-based timescale from the International Pulsar Timing Array

TL;DR

This paper presents a new pulsar-based timescale, TT(IPTA16), constructed from IPTA data, which agrees with existing atomic timescales and offers an independent check, though limited by solar-system knowledge.

Contribution

The paper introduces TT(IPTA16), a pulsar-based timescale derived from IPTA data, demonstrating its agreement with TT(BIPM17) and its potential for independent validation of atomic timescales.

Findings

TT(IPTA16) agrees with TT(BIPM17) within uncertainties.

Pulsar timescales are unlikely to improve atomic clock stability in the next decade.

Errors in solar-system models limit pulsar timescale stability.

Abstract

We have constructed a new timescale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from the International Pulsar Timing Array (IPTA). We used two analysis techniques with independent estimates of the noise models for the pulsar observations and different algorithms for obtaining the pulsar timescale. The two analyses agree within the estimated uncertainties and both agree with TT(BIPM17), a post-corrected timescale produced by the Bureau International des Poids et Mesures (BIPM). We show that both methods could detect significant errors in TT(BIPM17) if they were present. We estimate the stability of the atomic clocks from which TT(BIPM17) is derived using observations of four rubidium fountain clocks at the US Naval Observatory. Comparing the power spectrum of TT(IPTA16) with that of these fountain clocks suggests that pulsar-based timescales are unlikely to contribute to the stability of the best timescales over the next decade, but they will remain a valuable independent check on atomic timescales. We also find that the stability of the pulsar-based timescale is likely to be limited by our knowledge of solar-system dynamics, and that errors in TT(BIPM17) will not be a limiting factor for the primary goal of the IPTA, which is to search for the signatures of nano-Hertz gravitational waves.