Not long ago, astronomers discovered a highly mysterious periodic packet of fast radio pulses called FRB 20200120E. And further study of the signal and tracing the location of its source has yielded some rather unexpected results, which have only deepened the mystery of these phenomena. The source of the radio pulse FRB 20200120E is located in a galaxy 11.7 million light years away. This, in turn, makes it the closest known source, the previous record-breaker in the field being 40 times farther away from FRB 20200120E.
But the strangest thing is that the source of FRB 20200120E is located inside a globular cluster, a cluster of very old stars, which is the least likely place where such high-energy processes and phenomena can occur. Such a discovery suggests that fast radio pulses can form under a wider range of conditions determined by the cosmic environment than previously thought.
We remind our readers that fast radio pulses were first recorded in 2007. They are extremely powerful radio signals coming from deep in space. Some of the fast radio pulses, although only a millisecond long, contain energy 500 million times greater than that of the Sun.
By analysing the structure and other parameters of the fast radio pulses, scientists have gradually worked out the nature of their origin and linked them to extremely compact and extremely dense space objects known as neutron stars and magnetars, which are the same as neutron stars but have magnetic fields of unimaginable strength.
Now, the radio pulse profile of FRB 20200120E is exactly the same as that emitted by a magnetar except for its periodicity. Because this signal is repetitive, astronomers have been able to pinpoint the exact location of its source. And by analysing other parameters of the signal, they were able to determine that it, the signal, had travelled a cosmic distance not too far before reaching the radio telescope detectors.
"Traces" of the investigation led to a globular cluster inside the M81 galaxy, additional investigations carried out a little later only confirmed this fact. But this fact, as mentioned above, is the problem. Globular clusters are compact groups of very old stars, which have a mass approximately equal to that of the Sun. All of these stars will have formed in the depths of the same gas cloud at about the same time and, quietly and unhurriedly, have been living out their lives like small-town dwellers ever since.
Neutron stars, on the other hand, which are sources of rapid radio pulses, tend to form from more massive stars with a shorter cycle, called a hydrogen sequence. According to this fact, the appearance of a neutron star in the bowels of a globular cluster is highly unlikely.
However, scientists have already encountered the presence of millisecond pulsars in globular clusters. Such cases are explained by the fact that, due to the high density of stars, stars may collide to form low-mass X-ray double stars and pulsars. Scientists have also identified a mechanism that allows a magnetar to form in a different way from the traditional way. A magnetar can form from the collision of two white dwarf stars or when one white dwarf star absorbs enough matter mass from its closest companion and collapses into a neutron star.
