Fast Radio Bursts ( FRBs ) are transient sources that emit a single radio pulse with a duration of only a few milliseconds .
Since the discovery of the first FRB in 2007 , tens of similar events have been detected .
However , their physical origin remains unclear , and a number of scenarios even larger than the number of known FRBs has been proposed during these years .
The detection of multiple bursts in FRB 121102 excluded all cataclysmic scenarios , at least for this particular FRB .
The presence of these repeating bursts allowed us to perform a precise localization of the source with the Karl G. Jansky Very Large Array ( VLA ) and the European VLBI Network ( EVN ) .
Optical observations with Keck , Gemini and HST unveiled the host to be a low-metallicity star-forming dwarf galaxy located at a redshift of 0.193 .
The EVN results showed that the bursts are co-located ( within a projected separation of < 40 pc ) to a compact and persistent radio source with a size of < 0.7 pc and located within a star-forming region .
This environment resembles the ones where superluminous supernovae or long-duration gamma-ray bursts are produced .
Although the nature of this persistent source and the origin of the bursts remain unknown , the scenarios considering a neutron star/magnetar energizing a young superluminous supernova , or a system with a pulsar/magnetar in the vicinity of a massive black hole are the most plausible ones to date .
More recent observations have shown that the bursts from FRB 121102 are almost 100 % linearly polarized at an unexpectedly high and variable Faraday rotation measure , that has been observed to date only in vicinities of massive/supermassive black holes .
The bursts are thus likely produced from a neutron star in such environment , although the system can still be explained by a young neutron star embedded in a highly magnetized pulsar wind nebula or supernova remnant .
New FRB localizations would unveil if this source is representative of the whole population or a particular case .
Upcoming interferometric searches are expected to report tens of these localizations in the coming years , dramatically boosting the field of FRBs .