PSR B1237+25,whose mean pulse profile has five components,is a well-known star to study pulsar emission geometries.We conducted mode changing and modulation analysis on this pulsar using FAST data at 1.25 GHz with a b...PSR B1237+25,whose mean pulse profile has five components,is a well-known star to study pulsar emission geometries.We conducted mode changing and modulation analysis on this pulsar using FAST data at 1.25 GHz with a bandwidth of 400 MHz.We observed and identified three emission modes of this pulsar:a quiet normal mode that has little or no core activity with distinctive 2.8-period subpulse modulation on its outer cone,a flare normal mode in which the core is highly active and an abnormal mode in which the core is active and the last component is weak.We found that the core activity cuts off the position angle traverse in flare normal mode and leads to a position angle jumping in abnormal mode.We also found that there exists a quasi-periodical modulation on the outer conal components.Such modulation shows an irregular wave-like pattern,and has a weak correlation with the core component.We discuss the likely origin of such a modulation,and argue that this modulation can be interpreted as precession of the emission cones around the magnetic axis.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 Key R&D Program of China under grant number 2018YFA0404703the Open Project Program of the CAS Key Laboratory of FAST, NAOC,Chinese Academy of Sciences。
文摘PSR B1237+25,whose mean pulse profile has five components,is a well-known star to study pulsar emission geometries.We conducted mode changing and modulation analysis on this pulsar using FAST data at 1.25 GHz with a bandwidth of 400 MHz.We observed and identified three emission modes of this pulsar:a quiet normal mode that has little or no core activity with distinctive 2.8-period subpulse modulation on its outer cone,a flare normal mode in which the core is highly active and an abnormal mode in which the core is active and the last component is weak.We found that the core activity cuts off the position angle traverse in flare normal mode and leads to a position angle jumping in abnormal mode.We also found that there exists a quasi-periodical modulation on the outer conal components.Such modulation shows an irregular wave-like pattern,and has a weak correlation with the core component.We discuss the likely origin of such a modulation,and argue that this modulation can be interpreted as precession of the emission cones around the magnetic axis.
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.
