A nebular origin for the persistent radio emission of fast radio bursts

Autor: Bruni, Gabriele, Piro, Luigi, Yang, Yuan-Pei, Quai, Salvatore, Zhang, Bing, Palazzi, Eliana, Nicastro, Luciano, Feruglio, Chiara, Tripodi, Roberta, O’Connor, Brendan, Gardini, Angela, Savaglio, Sandra, Rossi, Andrea, Nicuesa Guelbenzu, Ana M., Paladino, Rosita
Zdroj: Nature; 20240101, Issue: Preprints p1-3, 3p
Abstrakt: Fast radio bursts (FRBs) are millisecond-duration, bright (approximately Jy) extragalactic bursts, whose production mechanism is still unclear1. Recently, two repeating FRBs were found to have a physically associated persistent radio source of non-thermal origin2,3. These two FRBs have unusually large Faraday rotation measure values2,3, probably tracing a dense magneto-ionic medium, consistent with synchrotron radiation originating from a nebula surrounding the FRB source4–8. Recent theoretical arguments predict that, if the observed Faraday rotation measure mostly arises from the persistent radio source region, there should be a simple relation between the persistent radio source luminosity and the rotation measure itself7,9. Here we report the detection of a third, less luminous persistent radio source associated with the repeating FRB source FRB 20201124A at a distance of 413 Mpc, substantially expanding the predicted relation into the low luminosity–low Faraday rotation measure regime (<1,000 rad m−2). At lower values of the Faraday rotation measure, the expected radio luminosity falls below the limit-of-detection threshold for present-day radio telescopes. These findings support the idea that the persistent radio sources observed so far are generated by a nebula in the FRB environment and that FRBs with low Faraday rotation measure may not show a persistent radio source because of a weaker magneto-ionic medium. This is generally consistent with models invoking a young magnetar as the central engine of the FRB, in which the surrounding ionized nebula—or the interacting shock in a binary system—powers the persistent radio source.
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