PSRmatch: Cross Matching Binary Pulsars with Gaia Sources to Improve Pulsar Distance Estimates*

Pulsars are highly magnetized, spinning neutron stars that emit electromagnetic radiation out of their off-axis magnetic poles. Distance estimates to pulsars can be obtained through several methods, including radio interferometry, dispersion measure, and timing parallaxes, to name a few. But distance estimates to pulsars are just that—estimates—and for applications such as pulsar timing for nanohertz gravitational wave detection, it is important to constrain the distances to pulsars as best we can. One method of obtaining independent distance estimates to pulsars is via cross matching data from the European Space Agency’s Gaia mission with pulsar data in search of companions to binary pulsars.

I developed a software package to cross match sources from Gaia with the Australia Telescope National Facility (ATNF) Pulsar Catalogue, and ultimately any pulsar catalogue or even non-pulsar survey. By comparing the positions, proper motions, and other characteristics of Gaia sources with pulsars, potential pulsar binary companions in the Gaia catalogue are identified. Gaia parallaxes and proper motions of these identified sources may be used to extract distance and transverse velocity estimates to their associated pulsars.

While such methods have been used for older Gaia data releases, I perform this cross matching with the most recent data release, Gaia Data Release 3 (DR3) from June 2022. DR3 represents a longer timespan of observations, with better calibration, corrections for the orbital motion present in binary systems, and containing fainter pulsar companions than previously observed by Gaia, seeing down to a magnitude of G ≈ 21. In the future I will use these cross-matches with DR3 to further constrain the distance and velocity estimates to pulsars in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) pulsar timing array already determined from DR2 and other estimation methods. This will improve the array’s sensitivity to nanohertz gravitational waves. Additionally, these independent parallaxes can be utilized for analysis in many areas, including tests of galactic electron density models.