Pulsars are rapidly rotating neutron stars with exceptionally stable spin rates, making them veritable "cosmic clocks" in the universe. However, some pulsars experience sudden "glitches"—abrupt spin-up events followed by a gradual recovery.

PSR B0919+06 is a radio pulsar with a rotation period of about 431 ms. Long-term observations have shown that its spin-down rate undergoes quasi-periodic oscillations with a period of roughly 570 to 580 days, accompanied by changes in its pulse profile.

By analyzing long-term timing data collected with the Nanshan 25 m radio telescope between 2002 and 2014, together with publicly available international datasets, a research team from the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences found that, following a glitch around MJD 55144, the modulation period of PSR B0919+06 and its spin-down rate abruptly shortened from about 575 days to about 437 days before gradually recovering to about 576 days several hundred days later.

This "shorten–recover" pattern is closely correlated with the glitch, suggesting that the glitch directly disturbed the physical mechanism responsible for the periodic modulation, according to the researchers.

Using wavelet transform and autocorrelation analyses, the team verified the statistical significance of this change and ruled out possible artefacts caused by data gaps or fitting errors. Combined with simulations, the researchers confirmed that the glitch itself does not produce a false period-shortening signal. Therefore, the observed variation reflects genuine changes in the neutron star's internal state or magnetospheric environment.

The researchers also compared PSR B0919+06 with other pulsars that exhibit similar quasi-periodic modulations and glitches, such as PSRs B1828-11 and B0740-28. The comparison suggests that such phenomena may be common and provides new observational constraints on the coupling among the neutron star interior, magnetosphere, and radiation.

The results were published in The Astrophysical Journal.

This work was supported by the National Science Foundation of China, the National Key R&D Program of China, the Major Science and Technology Program of Xinjiang Uygur Autonomous Region, and other funding sources.

In the future, building on these findings, observations with high-sensitivity facilities such as Five-hundred-meter Aperture Spherical radio Telescope are expected to further reveal the relationship between pulsar spin variations and radiative properties.