Radio signals from space, it’s a record: the mystery deepens

Unnamed FRB121102, the cause would not be a single source. A team of scientists has identified an unprecedented number of fast radio flashes.

Fast radio flashes, or FRBs, have fascinated scientists since 2007, when the first one was identified. Now, however, an international team has recorded 1,652 radio flashes from a mysterious source in just 47 days. The study was published in Nature in October, but the analysis dates back to 2019. After the radio signal found at the center of our galaxy, comes another surprising observation that has baffled the scientific community. Dubbed FRB121102, these radio signals set a record with the highest activity ever recorded and 122 flashes projected in a single hour.

What we know about the 1,652 radio signals from space

According to scientists, no sign of periodicity was found among the 1,652 radio signals in space, which could mean that FRBs would not be caused by a single source, but several different sources. The observations were made between Aug. 29 and Oct. 29, 2019 using the FAST (Five-hundred-meter Aperture Spherical Telescope) radio telescope in China.

According to Bing Zhang, professor of physics and astronomy at the University of Nevada at Las Vegas and co-author of the research, "there could be more than one mechanism behind a fast radio flash, but observations on other repeated sources need to be made to confirm this hypothesis." The researchers are therefore still studying where these FRBs originated and whether or not they all have the same source.

How the discovery changes theories about the origin of FRBs

Zhang, in an email, pointed out that the main model for interpreting FRBs calls into question magnetars, neutron stars with a very strong magnetic field, of which there are two theories, one of which would lose value after the recording of 1.652 radio signals.  "There are two versions - he wrote - in the first, the magnetosphere of the magnetar would be responsible for the emission of FRB; in the second, to generate them would be instead the shocks coming from a point far from the magnetosphere. The new observations penalize the second model, which does not have a high efficiency in generating flashes."

According to the study's co-author, it is essentially impossible, given the high number of flashes in a short period of time, for the second model to work because it would not be able to generate so many signals in a short time. "Our results suggest that the flashes were more likely produced by the magnetosphere of the magnetars, assuming and not granting that magnetars are indeed the source of the repeated FRBs," Zhang wrote.

In any case, so far, the only things known about the 1,652 radio signals is that an active phase was followed by an inactivity phase lasting 67 days and that they would come from a dwarf galaxy in a star-forming region three billion light-years from Earth. The mysteries about FRB121102 therefore remain numerous and the team of scholars is continuing to accumulate data to solve all the riddles about their origin.

Recently, then, another mysterious signal that strikes the Earth every 16 days has been recorded and even from Venus has arrived another radio signal, transformed by NASA into a space melody.

Stefania Bernardini