Binary Pulsar B1259-63 Spectrum Evolution and Classification of Pulsar Spectra

TL;DR

This paper investigates the spectral evolution of the binary pulsar B1259-63, proposing models involving environmental effects like free-free absorption and cyclotron resonance, to explain its spectrum changes and their relation to gigahertz-peaked spectra.

Contribution

It introduces a qualitative model explaining spectrum evolution due to orbital motion and environmental factors, linking binary pulsar spectra to gigahertz-peaked spectra of isolated pulsars.

Findings

Spectrum evolution is influenced by orbital motion.

Environmental conditions affect pulsar spectral shapes.

Binary pulsar spectra resemble gigahertz-peaked spectra.

Abstract

Recently published results \citep{kijak2011b} indicated the evidence for a new aspect in radio pulsars spectra. We studied the radio spectrum of PSR B1259-63 in an unique binary with Be star LS 2883 and showed that this pulsar undergoes a spectrum evolution due to orbital motion. We proposed a qualitative model which explains this evolution. We considered two mechanisms that might influence the observed radio emission: free-free absorption and cyclotron resonance. According to published results \citep{kijak2011a}, there were found objects with a new type of pulsar radio spectra, called gigahertz-peaked spectra (GPS) pulsars. Most of them were found to exist in very interesting environments. Therefore, it is suggested that the turnover phenomenon is associated with the environment than being related intrinsically to the radio emission mechanism. Having noticed the apparent resemblance between the B1259-63 spectrum and the GPS, we suggested that the same mechanisms should be responsible for both cases. Thus, we believe that this binary system can hold the clue to the understanding of gigahertz-peaked spectra of isolated pulsars. Using the same database we constructed spectra for chosen observing days and obtained different types of spectra. Comparing to current classification of pulsar spectra, there occurs a suggestion that the appearance of various spectra shapes, different from a simple power law which is typical for radio pulsars, is possibly caused by environmental conditions around neutron stars.