Invited Talk - Plenary

Thursday, 15 September 2022, 11:30   (Keksdose / virtual plenum)

Fast Radio Bursts

Franz Kirsten
ASTRON & Chalmers University of Technology

Fast Radio Bursts (FRBs) are millisecond-duration, extremely luminous radio transients of cosmologic origin. They are a very common phenomenon with an event rate of 1000's per sky per day. Despite an already published roughly 650 events, we still do not know the physical origin of these sources, let alone the emission mechanism. The vast majority of FRBs have only ever been seen once but a small sub-population of FRBs is known to burst repeatedly -- the so-called 'repeaters'. At this point it is unclear if the repeaters and the apparent non-repeaters share a common origin; the burst properties seem to indicate otherwise. Clues as to the origin of FRBs are given by their host galaxies, the local environment they reside in, as well as their temporal spectro-polarimetric properties. Over the last decade we have gathered a wealth of information about FRBs, culminating in the notion that FRBs are generated by young magnetars -- the best evidence for this scenario being the Galactic magentar SGR1935+2154. However, there is also a very good case against the magnetar-scenario and the more we learn about these transients the less obvious the solution to the puzzle seems to be. Sometimes one result seems to contradict another, leading to more questions than answers. Still, we have only explored a very small region in FRB parameter space, i.e. we have only been scratching at the surface of what we can discover. Many new, dedicated observing facilities and analysis techniques will come online in the next few years, certainly leading to new surprises and major breakthroughs. Regardless of what the progenitors of FRBs might be, their extragalactic origin and point-like structure make them unique cosmologic probes. Not only is the radiation's trajectory influenced by the fabric of space, but the signals carry the imprints of the intervening magneto-ionic medium, allowing us to study the intergalactic distribution of matter in an unprecedented fashion. In this talk I will summarize our current (non-)understanding of what FRBs are and I will share our sweet frustrations and hopes with these sources.