Famous fast radio eruption FRB20180916B lets itself get caught just barely

Two international teams of astronomers (with great Dutch involvement) have published two scientific articles with new information about the famous rapid radio eruption FRB20180916B. In a study published in the Astrophysical Journal Letters, they measured the radiation of the bars with the lowest possible frequencies. In a study published in Natural Astronomy, they examined the eruptions in the greatest possible detail. While the articles provide new information, they also raise new questions.

In 2007, the first rapid radio eruption (FRB) was discovered. Exactly what caused the bursts is not yet clear. Since 2020, scientists suspect a connection with strong magnetic neutron stars called magnetars. One of the best known fast radio bursts is FRB20180916B. This FRB was discovered in 2018 and is only 500 million light-years from us in another galaxy. The FRB is the closest so far and has a burst pattern that repeats every 16 days: four days of bursts, 12 days of relative silence. This predictability makes it an ideal object for researchers to study.

Lowest radio signals ever

An international team of researchers led by Ziggy Pleunis (a graduate of the University of Amsterdam, now McGill University, Montreal, Canada) studied the FRB with the European network of LOFAR radio telescopes. They tuned the LOFAR antennas to between 110 and 188 MHz. These are almost the lowest possible frequencies that the telescope can receive. They caught 18 bursts. This was unexpected because FRBs usually transmit in high frequencies. FRB20180916B thus breaks the low frequency record. Incidentally, the researchers suspect that the burst of radiation emits at even lower frequencies and will search for it in the near future.

In addition to records, the observations also offer new insights. The low-level radio emissions were fairly clean and later emerged as bursts with higher radio emissions. Co-author Jason Hessels (Dutch Institute for Radio Astronomy ASTRON and University of Amsterdam) says: “At different times we see radio bars with different radio frequencies. Possibly the FRB is part of a binary star. If so, we would ‘ a different views at different times where these tremendously powerful bursts are generated. ‘

A team of researchers led by Kenzie Nimmo (ASTRON and University of Amsterdam, the Netherlands) used the European VLBI network of radio telescopes, which includes one of ASTRON’s 12 Westerbork telescopes in Drenthe and the 100 meter Effelsberg telescope in Germany. They looked in the finest detail ever at the so-called polarized microstructure of the eruptions. The astronomers saw that the burst pattern of FRB20180916B differs from microsecond to microsecond. The most logical explanation for the variation appears to be a ‘dancing’ magnetosphere enveloping a neutron star.