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Fast Radio Bursts (FRB)s are very short pulses of significant energy in the radio spectrum, some emitting more energy than 500 million suns within milliseconds. Most FRBs are one time events, very few are repetitive, mostly irregularly, only one known produces a periodic signal. In 2021 about 500 FRBs were known. FRBs are currently a topic of research as the nature of these phenomenon is so far unknown. Current proposals for their origin range from rotating neutron stars, black holes and extraterrestrial intelligence 😊. The very first FRB was detected in 2007 and FRBs have been detected from sources millions of light years away. Since the sources of the FRBs are mostly so far away, it was not possible to relate them to a known star.But in 2020 a FBR, designation SGR 1935+2154 (Soft gamma repeater - SGR) has been identified to be from within our own galaxy, about 30.000 light-years away, in the constellation of Vulpecula. Meanwhile astronomers assume this star to be a magnetar. Magnetars are basically neutron stars with ultra-strong magnetic fields, until today only 24 magnetars have been confirmed. Currently the most plausible source of FRBs seem to be object mergers or magnetars.Recently astronomers have been able to locate another repeating FRB, designation 20200120, in our galactic neighborhood. It is the closest extra-galactic source so far, about 12 Mly away, near M81.By chance it happens to be in the sky near a much more distant galaxy, but the location is now confirmed by a recent paper to be in the globular cluster [PR95] 30244 in the halo of M81.  The halo of M81 comprises about 210 globular clusters, as elaborated in a 1995 paper. The locations of them can be visualized in AladinLite, search for [PR95] 30244 and find the siblings, restrict this list to GlC.  To find a FRB in a globular cluster is really surprising and somehow contradicting the magnetar theory. =11.0ptGlobular clusters are comprised of tens of thousands or up to millions of stars all packed together in a tight space, orbiting their mutual center of gravity. There are probably lots of neutrons stars in any given globular, but they are very old. Globular clusters are typically 10–12 billion years old, and any neutrons stars in them are likely to be around that age as well; way too old to produce a magnetar. So the theory that a sort of merger is the FRB source is fitting better to this observation of a FRB in a globular cluster, but in merger scenarios you would expect to find radiation on other wavelengths, which could not be found in this case.So the quest for a theory of the source of FRBs goes on. |
