Radio pulsars exhibit significant emission variations in many different forms, such as the profile mode-changing. Study of these variations is important for unlocking the emission characteristics and the radiation mechanism of radio pulsars. 

TU Zuoying, a PhD student at the Xinjiang Astronomical Observatory (XAO) of the Chinese Academy of Sciences (CAS), together with her supervisors and collaborators, used data obtained from the NanShan 25-m Radio Telescope (NSRT) to carry out a single-pulse study for the emission from the pulsar PSR B0329+54. They identified an extra low emission mode in the pulsar, and investigated its emission properties.

Their study was published in Monthly Notices of the Royal Astronomical Society. 

"The low emission mode, or low-mode, is characterized by the intensity drop in the central component below that of the other two components of the average pulse profile," said TU.

The low-modes accounted for 3.6% of the observations and had an average duration of three pulse periods. They occurred in both the normal and abnormal modes, but more frequently in the normal mode. 

 "We also found correlation between the pulsed emission in the normal mode and the low-mode, in the way that, after a low-mode, the former emission resembled the abnormal mode emission and returned to the normal mode after about three pulse periods," said TU. 

Through the energy analysis of the single pulses, the researchers found that the cause of energy decline in the central component may have nothing to do with the emission in the other two components. 

The results suggest that the plasma density in different parts of the profile changes when the mode-change occurs.