Transients - Introduction
Fast transients like RRAT and FRB
The search for pulsars by their individual pulses led to the detection of fast transients such as RRAT (rotating radio transient) and FRB (fast radio burst).
RRAT transients turned out to be pulsars that emit one pulse over a period of ten seconds to several hours. Long-term observations of these objects allowed us to find their periods, and the accuracy of the arrival of pulses allowed us to uniquely identify these objects as pulsars. According to some of the theories, these are "dying pulsars", i.e. pulsars at the last stage of life.
FRB transients also exhibit the properties of pulsars. The duration of their pulses (from fractions of a millisecond to tens of milliseconds) is comparable to the duration of pulses of ordinary pulsars. But FRBs have a large measure of variance. So large that it cannot be explained by passing through the medium in our galaxy. Therefore, it is generally assumed that FRBs have an extragalactic nature. But then the energy of these flashes must be very high. There are various hypotheses to explain the nature of such powerful flashes. These are hypotheses about the merger of black holes, about the merger of neutron stars, about the explosions of primary black holes. There is even a hypothesis that these outbreaks are associated with the activities of extraterrestrial civilizations.
At the moment, there are about 100 transients of the RRAT type and 65 objects of the FRB type.