Investigating the spectral nature of gigahertz-peaked spectra pulsar candidates

Abstract

We report the measurements of low radio frequency spectra of fourteen gigahertz-peaked spectra (GPS) pulsar candidates, between 300~MHz and 700~MHz, using the upgraded Giant Meterwave Radio Telescope. Combining newly collected measurements with archival results the spectral nature of each pulsar was examined using four different physical models: simple power law, broken power law, low-frequency turn-over power law and free-free thermal absorption. Based on this analysis, we confirm the GPS nature of five pulsars, three of them being new detections. In addition, one pulsar can be classified as having a broken power law spectrum, and we found the typical power law spectra in four other cases. In the remaining four pulsars the spectra showed tendencies of low frequency turn-over that require further investigations at lower frequency ranges. These results demonstrate the effectiveness of wideband measurements at low frequencies, below 1 GHz, in characterizing the spectral nature in pulsars. Our results also underline the need for more systematic theoretical studies to refine existing models and better interpret pulsar emission properties.