Seminar

Magnetars constitute one of the exotic parts of the neutron star population. Discovered via their high energy emission, magnetars exhibit persistent but highly variable X-ray emission, very high magnetic fields, young ages, and transient radio emission. The detection of radio emission provides the observational link between the magnetars and radio pulsars. The radio emission, observed only from a handful of magnetars so far, typically follows an X-ray outburst, and is transient in nature. The exact cause of the onset as well as the mechanism of the radio emission has remained unclear, and the observed radio properties are eluding. Given the huge energy reservoir in the form of very strong magnetic fields, magnetars also form the basis of a multitude of models to explain the origin of fast radio bursts (FRBs) --- milliseconds-wide highly luminous, extra-galactic radio transient events. In this talk, I will present several interesting properties of XTE J1810-197, the first-ever magnetar which was found to emit transient radio emission. Particularly, the magnetar emits narrow bursts of emission with, likely intrinsic, spectral structures. These structures might indicate a phenomenological link with the giant pulses from young pulsars and possibly repeating fast radio bursts (FRBs), which also show interesting but more detailed frequency structures. Furthermore, monitoring over more than 800 days has uncovered a gradually evolving radio spectrum as well as the emission beam-size of the magnetar. Such an evolution, seen for the first time, has important implications for the emission processes responsible for radio emission from magnetars as well as for a potential presence of a magnetar wind nebulae. These findings will be discussed in the context of emission components known from pulsars, FRBs and magnetars.