We model the evolution of the spin frequency's second derivative ν¨ and the braking index n of radio pulsars with simulations within the phenomenological model of their surface magnetic field evolution, which c...We model the evolution of the spin frequency's second derivative ν¨ and the braking index n of radio pulsars with simulations within the phenomenological model of their surface magnetic field evolution, which contains a long-term power-law decay modulated by short-term oscillations. For the pulsar PSR B0329+54, a model with three oscillation components can reproduce its ν¨ variation. We show that the "averaged" n is different from the instantaneous n, and its oscillation magnitude decreases abruptly as the time span increases, due to the "averaging" effect. The simulated timing residuals agree with the main features of the reported data. Our model predicts that the averaged ν¨ of PSR B0329+54 will start to decrease rapidly with newer data beyond those used in Hobbs et al. We further perform Monte Carlo simulations for the distribution of the reported data in |ν¨| and |n| versus characteristic age τcdiagrams.It is found that the magnetic field oscillation model with decay index α = 0 can reproduce the distributions quite well. Compared with magnetic field decay due to the ambipolar diffusion(α = 0.5) and the Hall cascade(α = 1.0), the model with no long term decay(α = 0) is clearly preferred for old pulsars by the p-values of the two-dimensional Kolmogorov-Smirnov test.展开更多
We have used the unique low frequency sensitivity of the Large Phased Array (LPA) radio telescope of Pushchino Radio Astronomy Observatory to collect a dataset consisting of single pulse observations of second perio...We have used the unique low frequency sensitivity of the Large Phased Array (LPA) radio telescope of Pushchino Radio Astronomy Observatory to collect a dataset consisting of single pulse observations of second period pulsars in the Northern Hemisphere. During observation sessions in 2011- 2017, we collected data on 71 pulsars at a frequency of 111 MHz using a digital pulsar receiver. We have discovered Giant Radio Pulses (GRPs) from pulsars B0301+09 and B 1237+25, and confirmed earlier reported generation of anomalously strong (probable giant) pulses from B 1133+16 in a statistically significant dataset. Data for these pulsars and from B0950+08 and B 1112+50, earlier reported as pulsars generating GRPs, were analyzed to evaluate their behavior over long time intervals. It was found that the statistical criterion (power-law spectrum of GRP distribution of energy and peak flux density) seems not to be strict for pulsars with a low magnetic field at their light cylinder. Moreover, spectra of some of these pulsars demonstrate unstable behavior with time and have a complex multicomponent shape. In the dataset for B0950+08, we have detected the strongest GRP from a pulsar with a low magnetic field at its light cylinder ever reported, having a peak flux density as strong as 16.8 kJy.展开更多
基金Supported by the National Natural Science Foundation of China
文摘We model the evolution of the spin frequency's second derivative ν¨ and the braking index n of radio pulsars with simulations within the phenomenological model of their surface magnetic field evolution, which contains a long-term power-law decay modulated by short-term oscillations. For the pulsar PSR B0329+54, a model with three oscillation components can reproduce its ν¨ variation. We show that the "averaged" n is different from the instantaneous n, and its oscillation magnitude decreases abruptly as the time span increases, due to the "averaging" effect. The simulated timing residuals agree with the main features of the reported data. Our model predicts that the averaged ν¨ of PSR B0329+54 will start to decrease rapidly with newer data beyond those used in Hobbs et al. We further perform Monte Carlo simulations for the distribution of the reported data in |ν¨| and |n| versus characteristic age τcdiagrams.It is found that the magnetic field oscillation model with decay index α = 0 can reproduce the distributions quite well. Compared with magnetic field decay due to the ambipolar diffusion(α = 0.5) and the Hall cascade(α = 1.0), the model with no long term decay(α = 0) is clearly preferred for old pulsars by the p-values of the two-dimensional Kolmogorov-Smirnov test.
基金supported in part by the Program of the Presidium of Russian Academy of Sciences“Nonstationary processes in the Universe”
文摘We have used the unique low frequency sensitivity of the Large Phased Array (LPA) radio telescope of Pushchino Radio Astronomy Observatory to collect a dataset consisting of single pulse observations of second period pulsars in the Northern Hemisphere. During observation sessions in 2011- 2017, we collected data on 71 pulsars at a frequency of 111 MHz using a digital pulsar receiver. We have discovered Giant Radio Pulses (GRPs) from pulsars B0301+09 and B 1237+25, and confirmed earlier reported generation of anomalously strong (probable giant) pulses from B 1133+16 in a statistically significant dataset. Data for these pulsars and from B0950+08 and B 1112+50, earlier reported as pulsars generating GRPs, were analyzed to evaluate their behavior over long time intervals. It was found that the statistical criterion (power-law spectrum of GRP distribution of energy and peak flux density) seems not to be strict for pulsars with a low magnetic field at their light cylinder. Moreover, spectra of some of these pulsars demonstrate unstable behavior with time and have a complex multicomponent shape. In the dataset for B0950+08, we have detected the strongest GRP from a pulsar with a low magnetic field at its light cylinder ever reported, having a peak flux density as strong as 16.8 kJy.