Flicker noise pulsar radio spectra

Abstract

We present new results of fitting 108 spectra of radio pulsars with the flicker noise model proposed by Löhmer et al. (2008) and compare them with the spectral indices of power-law fits published by Maron et al. (2000). The fits to the model were carried out using the Markov chain Monte Carlo (MCMC) method appropriate for the non-linear fits. Our main conclusion is that pulsar radio spectra can be statistically very well described by the flicker noise model over wide frequency range from a few tens of MHz up to tens of GHz. Moreover, our dataset allows us to conduct statistical analysis of the model parameters. As our results show, there is a strong negative correlation between the flicker noise spectrum model parameters log S 0 and n and a strong positive relationship between n and the power-law spectral index α. The latter implies that their physical meaning is similar, however the flicker noise model has an advantage over broken power-law model. Not only it describes the spectra in higher frequency range with only two parameters, not counting scaling factor S 0 , but also it shows smooth transition from flat to steep behaviour at lower and higher frequencies, respectively. On the other hand, there are no correlations of the flicker noise model parameters S 0 , τ and n with any of pulsar physical properties.