"China's Sky Eye" has made new discoveries!

The "big pot" in Guizhou has made new discoveries. Using the China Sky Eye (FAST), Chinese astronomers discovered a new form of pulsar radiation - dwarf pulse radiation, and revealed the physical fact that the magnetosphere structure of pulsars remains basically unchanged when pulsar radiation is about to go out. More importantly, this pulsar radiation form is difficult to observe with other radio telescopes in the world. The relevant research results were published online in the journal Nature Astronomy on August 18.

Panoramic view of the "China Sky Eye" (file photo). Photographed by Xinhua News Agency reporter Ou Dongqu

Generally speaking, pulsars periodically emit radio signals when they rotate. However, in certain periods, the radiation of some pulsars will completely extinguish, a phenomenon astronomers call pulse nulling. "Since there is no radiation after the pulsar radiation is extinguished, its magnetosphere structure and physical characteristics are difficult to detect, so the physical mechanism of pulse nulling has been difficult to determine," said Han Jinlin, corresponding author of the paper and researcher at the National Astronomical Observatory of the Chinese Academy of Sciences.

Coincidentally, when using FAST to search for pulsars, the research team discovered a very special pulsar, B2111+46, in the massive data. "We originally thought that the pulses of this pulsar had disappeared, but after careful study, we found that it still has sporadic, weak and narrow pulses. We call such pulses dwarf pulses," Han Jinlin explained.

Then, the research team conducted a two-hour verification observation of the pulsar and obtained more than 100 dwarf pulses. These pulses are significantly different from normal pulses in terms of pulse intensity and width distribution, and they constitute an independent radiation group. At the same time, FAST performed precise polarization measurements on these dwarf pulses. The results show that compared with normal pulses, the magnetosphere structure of the dwarf pulse radiation region has basically not changed, but dwarf pulses are more likely to become very strong in the high-frequency band.

"Pulsar B2111+46 is relatively old and is already located in the 'death valley' of pulsars, so the reason for the pulse disappearance is most likely the radiation instability caused by the insufficient induced potential and particle acceleration energy of the old pulsar." Han Jinlin said that the normal pulses of a pulsar are radiated by the stable acceleration of a large number of charged particles and the production of a large number of "thunderstorm" particle droplets, while the dwarf pulses are produced by one or a few particle droplets formed in the fragile and unstable state of this dying pulsar.

The research team also detected a small number of dwarf pulses in the pulse nulling state of several other pulsars. The discovery of this extremely weak radiation mode has opened a new window for studying the difficult problem of pulsar radiation, and has important scientific significance for revealing the physics of pulsar magnetosphere and its extreme plasma environment. (Science and Technology Daily reporter Lu Chengkuan)