In a recently study published in The Astrophysical Journal, Prof. ZHOU Xia from the Xinjiang Astronomical Observatory (XAO) of the Chinese Academy of Sciences, in collaboration with Dr. WANG Yubin from Sichuan University of Science & Engineering, Dr. Abdusattar Kurban from XAO, and Professor WAMG Fayin from Nanjing University, for the first time derived the dispersion relation for photons with non-zero mass propagating in plasma . 

Using data collected by ultra-wideband (UWB) receivers from pulsar timing and fast radio bursts (FRBs), the researchers established a stringent upper limit for the photon mass at 9.52 × 10^-46 kg (5.34 × 10^-10 eV c^-2).

Photons are typically considered massless particles, a hypothesis based on Maxwell's electromagnetic theory and Einstein's special relativity. However, if photons possess nonzero mass, it would have profound implications for existing physical theories. This study provided a novel theoretical framework for understanding the propagation characteristics of massive photons in plasma, offering a new method to verify photon mass. 

The researchers used high-precision timing data from the Parkes Pulsar Timing Array (PPTA) and dedispersed pulse data from FRBs. Leveraging the wide frequency range covered by UWB receivers, they improved the signal-to-noise ratio and the accuracy of dispersion measurements. The high time resolution of UWB technology allowed for precise determination of signal arrival times, effectively reducing the dispersion effects caused by the interstellar medium.