Applying clock comparison methods to pulsar timing observations

TL;DR

This paper applies advanced clock comparison techniques to pulsar timing data, demonstrating how to detect correlated signals like gravitational waves by analyzing pulsar signals with multiple telescopes.

Contribution

It introduces a novel application of frequency metrology methods to pulsar timing, enabling detection of correlated signals such as gravitational waves.

Findings

Detection limit for correlated red noise signals between telescopes

Validation of statistical methods on simulated pulsar data

Potential for improved gravitational wave detection

Abstract

Frequency metrology outperforms any other branch of metrology in accuracy (parts in $10^{-16}$) and small fluctuations ($<10^{-17}$). In turn, among celestial bodies, the rotation speed of millisecond pulsars (MSP) is by far the most stable ($<10^{-18}$). Therefore, the precise measurement of the time of arrival (TOA) of pulsar signals is expected to disclose information about cosmological phenomena, and to enlarge our astrophysical knowledge. Related to this topic, Pulsar Timing Array (PTA) projects have been developed and operated for the last decades. The TOAs from a pulsar can be affected by local emission and environmental effects, in the direction of the propagation through the interstellar medium or universally by gravitational waves from super massive black hole binaries. These effects (signals) can manifest as a low-frequency fluctuation over time, phenomenologically similar to a red noise. While the remaining pulsar intrinsic and instrumental background (noise) are white. This article focuses on the frequency metrology of pulsars. From our standpoint, the pulsar is an accurate clock, to be measured simultaneously with several telescopes in order to reject the uncorrelated white noise. We apply the modern statistical methods of time-and-frequency metrology to simulated pulsar data, and we show the detection limit of the correlated red noise signal between telescopes.