The observations of the gigahertz-peaked spectra pulsars

In this short overview, we summarize the current knowledge of the pulsar spectra that exhibit turnovers between 0.5 and 1.5 GHz. We focus on the observations of pulsars, for which the analysis of their spectra allowed a formulation of the hypothesis that external mechanisms are responsible for the high-frequency turnovers. Among these, we discuss the cases of the binary pulsar B1259-63, the Sagittarius A* radiomagnetar (SGR J1745-2900), the variable spectrum of pulsar (PSR) B1800-21, and PSR J1740 + 1000.