Sparrow Roch, “Observatory Position as a Source of Noise in Pulsar Timing Searches for Gravitational Waves”
Mentor: Sarah Vigeland, Physics
Poster #150

Pulsars are extremely dense, highly magnetized neutron stars that rapidly rotate with a reliable period. This rotation produces an intense radiation beam emitted from the star’s magnetic poles. These periodic signals are observed as radio pulses. Millisecond pulsars (MSPs) have rotational periods of around 10 milliseconds or less and their pulse signals are known to have extremely consistent times of arrival when observed from Earth. Timing the unique pulses from MSPs at different locations in the galaxy allows for novel ways to study the universe, including the potential to detect gravitational waves at much lower frequencies than those previously detected. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is a collaboration that aims to detect gravitational waves by timing MSPs. Many factors contribute to accurate pulsar timing; here, the focus is observatory positions, which are assumed to be well-defined and are required in order to reference arrival times to the solar system barycenter. However, incorrect position coordinates could potentially skew or otherwise manipulate the interpulsar correlations in timing residuals. This project reevaluates NANOGrav pulsar data with intentionally imposed positional offsets to assess whether incorrect observatory coordinates could result in a spatially correlated quadrupolar signature as expected from gravitational waves. A new gravitational wave analysis will be done to determine whether or not and to what extent these positional errors could falsely provoke results that mimic gravitational wave signals.