On the patchiness of the individual pulse spectra at the very low radio frequencies

Abstract

We have used sensitive LOw Frequency ARray (LOFAR) observations of PSR B0809+74 at 15-62 MHz to study the anomalously intensive pulses, first reported by Ulyanov et al. (2006) at 18-30 MHz. Similarly to Ulyanov et al., we found that the spectra of strong pulses consist of distinct bright patches. Moreover, these spectral patches were spotted to drift upwards in frequency over the course of several pulse sequences. We established that this drift is not pulsar-intrinsic, but is caused by the broadband ∼20 second…