Pulsars, often called “cosmic lighthouses”, emit regular radio pulses. As these signals traverse the turbulent interstellar space, they experience scintillation - similar to the twinkling of starlight. This phenomenon serves as a powerful probe to study the physical properties of the interstellar medium.

Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), Dr. Zhigang Wen from Xinjiang Astronomical Observatory, Chinese Academy of Sciences, together with collaborators, revealed detailed scintillation characteristics of the millisecond pulsar B1937+21.

In a three-year observational campaign, the researchers have systematically characterized how the pulsar's signals are scattered when traveling through the ionized interstellar medium. By analyzing data from 24 observational epochs, theyobtained unprecedented insights into the extreme environments traversed by thesepulsar signals.

Using autocorrelation function analysis and secondary spectrum techniques, the researchers precisely measured key scintillation parameters. The average scintillation timescale was determined to be 7.67 minutes, with a decorrelation bandwidth of approximately 0.56 MHz. The study notably captured persistent parabolic scintillation arcs across all observational frequencies.

Moreover ,a particularly significant finding is the annual variation in arc curvature. By developing refined scattering screen models, the researchers constrained the dominant scattering material to be located approximately 2.73 kiloparsecs from the pulsar. This finding offers new methods for precisely locating interstellar scattering media.

This work significantly advances the accuracy of pulsar timing arrays. Such advancements are crucial in the detection of gravitational waves and the establishment of more precise space-time references, potentially opening new avenues in fundamental physics research.

                                          Dynamic spectrum (a), autocorrelation function (b), and secondary spectrum (c) of the millisecond pulsar B1937+21 at a frequency of 1250 MHz.