Improving millisecond pulsar timing accuracy using polarization – .

Pulsar timing enables the most rigorous tests of fundamental physics. By monitoring the pulse arrival times (ToAs) of a set of stable millisecond pulsars (MSPs), known as a pulsar timing array (PTA), it is possible to detect nanohertz gravitational waves (GW) . Successful GW detection with PTAs requires the highest possible temporal precision.

The temporal precision of a pulsar is limited by many sonic contributions, including those introduced by the pulsar itself, the interstellar medium along the line of sight, and the measurement process. On short time scales, noise is generally dominated by white noise, which includes radiometer noise, jitter noise, and scintillation noise.

In a study published in The Astrophysics JournalWang Shuangqiang of the Xinjiang Astronomical Observatory (XAO) of the Chinese Academy of Sciences and colleagues used data obtained from the Five Hundred Meter Aperture Spherical Radio Telescope (FAST) to conduct a study of white noise in MSPs.

The researchers presented measurements of radiometer noise, jitter noise, and scintillation noise from 12 MSPs that are part of the International Pulsar Timing Array sample.

They found that different pulsars exhibit different levels of jitter noise. The contribution of scintillation noise is probably negligible and jitter noise is more important than radiometer noise, making it the dominant component of white noise. Therefore, mitigating jitter noise is important for GW detection.

Furthermore, the researchers applied a new method, namely matrix template matching, which generates ToAs using all four Stokes parameters rather than just Stokes I, in order to mitigate jitter noise.

They found that jitter noise can be reduced by 6.7% to 39.6% using this method. Therefore, matrix template matching is a valuable method to improve the accuracy of pulsar timing.

In the future, this method will be applied to a large dataset of MSPs with FAST.