A research group from Xinjiang Astronomical Observatory (XAO) find a young pulsar located far from the Galactic disk in the Galactic halo, which challenges the long-held view that pulsars are predominantly born in the disk. By measuring its motion across the sky and analyzing the “scintillation” of its radio signal, researchers find that this object may have originated in the halo, while its observed scintillation is closely linked to its surrounding pulsar wind nebula (PWN).

The study focuses on the young pulsar PSR J1740+1000. The findings provide new insights into both the origin of young halo pulsars and the physical mechanisms of pulsar scintillation in PWN settings.

The research was carried out by Associate Professor YAO Jumei at the XAO, Chinese Academy of Sciences, together with her collaborators. The results have been published in The Astrophysical Journal.

Using long-term observations from FAST (the Five-hundred-meter Aperture Spherical radio Telescope) and the Nanshan 26-m radio telescope, the team tracked the tiny positional changes of PSR J1740+1000 on the sky. Combining these data with its distance, the researchers calculated its space velocity as 329 ± 80 km s⁻¹.

Based on its inferred space velocity, PSR J1740+1000 likely formed within the Galactic halo and could be the descendant of a runaway OB star: a massive star ejected from its birth environment by violent astrophysical events and moving at high velocity.

In addition, by combining the observations from FAST and the Parkes telescope in Australia, the research team has for the first time reported multiple adjacent scintillation arcs in the pulsar’s secondary spectrum.

Further analysis indicates that these arcs most likely originate from AU-scale ionized structures within the PWN surrounding the pulsar. A PWN forms through the interaction of the pulsar wind with the ambient medium. The results indicate that its small-scale plasma structures can significantly influence radio wave propagation and dominate the generation of scintillation.

This work not only provides key observational evidence for the origin of young pulsars in the Galactic halo, but also highlights the important role of PWN in shaping scintillation. It opens up a new perspective for probing circumstellar and interstellar environments via pulsar signals.

This research was supported by major science and technology projects of the Xinjiang Uygur Autonomous Region and key programs of the regional Natural Science Foundation.