Dwarf pulses are found in the old pulsar

Scientists working on the world’s largest FAST radio telescope have discovered very narrow and weak pulses at the old pulsar. The mechanism of their formation is significantly different from what usually happens on neutron stars.

Dwarf pulses from a pulsar. Source: phys.org

Observations on the largest radio telescope

The world’s largest radio telescope FAST, which is located in China and has an antenna diameter of 500 m, recently presented scientists with a new discovery. It was reported by researchers from the National Astronomical Observatory of the Chinese Academy of Sciences.

They observed the pulsar PSR B2111+46. This is a very old and well-studied neutron star, which, like all similar objects, emits radio pulses with a constant, extremely short period. However, from time to time its pulses stop for a while.

This phenomenon is also not something unusual. It is called “pulse nulling” and has been repeatedly observed in old pulsars. However, the causes of its occurrence are still unknown for certain. Perhaps these are changes in magnetic fields that prevent particles from accelerating, or the plasma simply overflows certain zones. 

The unusual thing happened during two pulsar observation sessions in August and September 2020. Then PSR B2111+46 just had “pulse nulling” and it should have been completely quiet. However, experts working with FAST recorded several dozen very weak and narrow pulses. Then they did not find an explanation and decided to investigate the neutron star again.

Dwarf pulses

In March 2022, Chinese scientists again observed PSR B2111+46 during its dormant period. And again they were able to observe the very pulses that they called “dwarf” because their power was not in any way comparable to the main ones.

Now scientists have no doubt that the “dwarf pulses” of pulsars are quite real. Moreover, they were also detected at other old neutron stars. However, it turned out to be almost impossible to establish their nature. After all, even FAST cannot see what the pulsar’s magnetosphere is when it is in an inactive state.

However, scientists have a theory about the origin of “ordinary” and “dwarf” pulses. The first of them arises when a “thunderstorm” of charged particles bursts out of faults in the polar regions of a neutron star. The second ones have a completely different nature. They are emitted by pairs of particles born near such gaps and falling down like raindrops.

According to phys.org

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