A pulsar-based time-scale from the International Pulsar Timing Array

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.

Modelling double neutron stars: radio and gravitational waves

“…For some binary pulsars, their orbital properties (orbital period, eccentricity and masses) are also well-measured quantities. Pulsar timing is comparable in precision to terrestrial atomic clocks (Hobbs et al 2012;Hobbs et al 2019). An aggregation of pulsars, with spin periods of the order of milliseconds (called millisecond pulsars, MSPs), scattered across the Milky Way can be analysed to detect low frequency gravitational waves from merging supermassive black-holes at the centre of galaxies (e.g.…”

Bayesian Solar Wind Modeling with Pulsar Timing Arrays

“…Many pulsars are used since the unique noise properties of individual pulsars necessitates the corroboration of common 2 astrophysical signals across multiple sources and because lower-amplitude common signals can be drawn out of the noise of more pulsars. Additionally, PTAs allow us to search for other common signals, for instance the motion of the solar system barycenter (Vallisneri et al 2020) or errors in terrestrial time standards (Hobbs et al 2020).…”

Gravity Tests with Radio Pulsars

“…Fast rotating pulsars with smallṖ, the so-called millisecond pulsars (MSP; bottom left corner of Figure 1), appear to be particularly stable in their rotation. In terms of stability on long time-scales, some of them can compare with the best atomic clocks on Earth [8]. MSPs are the result of a previous, stable mass transfer from the companion, which leads to a "recycling" of an old pulsar, often spinning it up to millisecond periods [9].…”

“…Over the next few years these two telescopes are expected to greatly benefit the field of gravity tests with pulsars. Of great importance here is the fact that the MeerKAT interferometer will soon be extended to MeerKAT+ in a collaboration between the South African Radio Astronomy (SARAO) and the Max-Planck Society (MPG) 8 and eventually to SKA1. How this will improve our gravity tests has recently be demonstrated in [146] on the basis of extensive mock data simulations for the Double Pulsar.…”

“…In GR, where there is no variation of the local gravitational constant, one has δγ E = 0. The modification of the gravitational field of the companion also affects the signal propagation, i.e., the Shapiro delay Equation (8). If the spacetime metric of the companion in the first post-Minkowskian approximation has the form (i, j = 1, 2, 3)…”