Fast radio bursts are decidedly mysterious astronomical phenomena. Every time researchers believe they have reached their goal and finally understand the secrets of their origins, a new observation arrives to throw everything into doubt. This is once again the case today.
First fast radio burst – a fast radio burst or FRB, as English speakers call them, was observed in 2007. A powerful cosmic explosion that, in just a few milliseconds, launches into space the equivalent of the energy produced by our Sun in a whole year. Therefore, astronomers have been searching for no less than fifteen years to understand the origins and physical mechanisms behind this extraordinary phenomenon. Fifteen years his assumptions are constantly challenged by new observations.
One more time today. With observations made in late spring 2021. In 82 hours spread over 54 days, the spherical radio telescope with an aperture of five hundred meters (Fast) installed in China recorded some 1,863 bursts from a source called FRB 20201124 A. “The largest FRB data sample to date, with bias information from a single source”says Kejia Lee, a researcher at Peking University, in a university of nevada statement (USA).
Recall that recent observations of a fast radio burst in our Milky Way They suggest that the source of the phenomenon lies in the magnetars. It comprises, neutron stars accompanied by an incredibly strong magnetic field. However, the origin of the more distant FRBs remains a mystery. “And these observations bring us back to square one. It is clear that FRBs are more mysterious than we imagine. More multi-wavelength observing campaigns will be needed to further unravel the nature of these objects.”says Bing Zhang, an astrophysicist at the University of Nevada.
A complex and dynamic environment.
In fact, astronomers have noted irregular and short-lived variations in the magnetic field and the evolving particle densities near FRB 20201124 A. Variations that increased and then decreased during the first 36 days of observation. Variations that then abruptly stopped before, 18 days later, the source finally died out.
“Our work revealed a complex and dynamically changing magnetized environment that had never before been imagined for a fast radio burst. Such an environment is not directly expected for an isolated magnetar. Something else could be near the engine of this FRB. Perhaps a fellow signing the existence of a binary system »explains Bing Zhang.
Another surprise is the fact that FRB 20201124A appears to sit in a region of a metal-rich barred spiral galaxy, much like our own Milky Way, in which there is no significant activity from star formation has not been registered so far. A location that is also not very compatible with the idea of a magnetar type source. Which, therefore, definitively relaunches the mystery of fast radio bursts and their sources in galaxies far from our own.