We report the discovery of PSR J1909+0122 by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)as part of the Commensal Radio Astronomy FAST Survey.PSR J1909+0122 has a spin period of 1.257 s and a disper...We report the discovery of PSR J1909+0122 by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)as part of the Commensal Radio Astronomy FAST Survey.PSR J1909+0122 has a spin period of 1.257 s and a dispersion measure of 186.2 pc cm^(-3).The averaged pulse profile shows two distinct components.We performed a single-pulse study based on a one-hour observation at 1.25 GHz on 2021 August 23.We used a threshold of 5σ_(ep) to measure the nulling fraction(NF)as 63%±1.5%.The longitude-resolved fluctuation spectra and fast Fourier transform spectra of the binary sequences revealed the quasi-periodicity of nulling with a period of 30 rotation periods.We examined the reliability of the periodicity by comparing it to random noise injection.The NF,E,and modulation periodicity P_(M) of PSR J1909+0122 were compared with other periodic nulling pulsars,showing that the source of J1909+0122 has the second largest NF in the population.Long-term timing observations over six months were used to derive the phase-connected ephemeris of this pulsar.The measured P and P values disfavor dipolar geometry for polar gap models,and the prediction for a space-charge-limited flow model in the case of inverse Compton scattering is only just above the death line.In this work,PSR J1909+0122 has revealed possible correlations between nulling behavior and pulsar properties,which will help to shed light on the pulsar emission mechanism and its temporal evolution in future observations.展开更多
Globular clusters harbor numerous millisecond pulsars,but long-period pulsars(P 100 ms)are rarely found.In this study,we employed a fast folding algorithm to analyze observational data from multiple globular clusters ...Globular clusters harbor numerous millisecond pulsars,but long-period pulsars(P 100 ms)are rarely found.In this study,we employed a fast folding algorithm to analyze observational data from multiple globular clusters obtained by the Five-hundredmeter Aperture Spherical radio Telescope(FAST),aiming to detect the existence of long-period pulsars.We estimated the impact of the median filtering algorithm in eliminating red noise on the minimum detectable flux density(S_(min))of pulsars.Subsequently,we successfully discovered two isolated long-period pulsars in M15 with periods approximately equal to 1.928451 and3.960716 s,respectively.On the P-˙P diagram,both pulsars are positioned below the spin-up line,suggesting a possible history of partial recycling in X-ray binary systems disrupted by dynamical encounters later on.According to timing results,these two pulsars exhibit remarkably strong magnetic fields.If the magnetic fields were weakened during the accretion process,then a short duration of accretion might explain the strong magnetic fields of these pulsars.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)Grant Nos.11988101,1172531312041303,12041304,12203045,12203070,12103013,T2241020the National SKA Program of China(Nos.2020SKA0120200,2022SKA0130100,2022SKA0130104)+5 种基金the Foundation of Science and Technology of Guizhou Province(No.(2021)023)the Foundation of Guizhou Provincial Education Department(Nos.KY(2021)303,KY(2020)003)support from the National Natural Science Foundation of China under grant U2031117the Youth Innovation Promotion Association CAS(id.2021055)CAS Project for Young Scientists in Basic Research(grant YSBR006)the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CAS。
文摘We report the discovery of PSR J1909+0122 by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)as part of the Commensal Radio Astronomy FAST Survey.PSR J1909+0122 has a spin period of 1.257 s and a dispersion measure of 186.2 pc cm^(-3).The averaged pulse profile shows two distinct components.We performed a single-pulse study based on a one-hour observation at 1.25 GHz on 2021 August 23.We used a threshold of 5σ_(ep) to measure the nulling fraction(NF)as 63%±1.5%.The longitude-resolved fluctuation spectra and fast Fourier transform spectra of the binary sequences revealed the quasi-periodicity of nulling with a period of 30 rotation periods.We examined the reliability of the periodicity by comparing it to random noise injection.The NF,E,and modulation periodicity P_(M) of PSR J1909+0122 were compared with other periodic nulling pulsars,showing that the source of J1909+0122 has the second largest NF in the population.Long-term timing observations over six months were used to derive the phase-connected ephemeris of this pulsar.The measured P and P values disfavor dipolar geometry for polar gap models,and the prediction for a space-charge-limited flow model in the case of inverse Compton scattering is only just above the death line.In this work,PSR J1909+0122 has revealed possible correlations between nulling behavior and pulsar properties,which will help to shed light on the pulsar emission mechanism and its temporal evolution in future observations.
基金supported by the National Natural Science Foundation of China(Grant Nos.11988101,12103013,12041303,U2031117,12373109,and 12103069)the National SKA Program of China(Grant Nos.2020SKA0120200,2022SKA0130100,and2022SKA0130104)+2 种基金the National Key Research and Development Program of China(Grant No.2023YFB4503300)the Foundation of Science and Technology of Guizhou Province(Grant No.(2021)023)the Foundation of Guizhou Provincial Education Department(Grant Nos.KY(2020)003,and KY(2023)059)。
文摘Globular clusters harbor numerous millisecond pulsars,but long-period pulsars(P 100 ms)are rarely found.In this study,we employed a fast folding algorithm to analyze observational data from multiple globular clusters obtained by the Five-hundredmeter Aperture Spherical radio Telescope(FAST),aiming to detect the existence of long-period pulsars.We estimated the impact of the median filtering algorithm in eliminating red noise on the minimum detectable flux density(S_(min))of pulsars.Subsequently,we successfully discovered two isolated long-period pulsars in M15 with periods approximately equal to 1.928451 and3.960716 s,respectively.On the P-˙P diagram,both pulsars are positioned below the spin-up line,suggesting a possible history of partial recycling in X-ray binary systems disrupted by dynamical encounters later on.According to timing results,these two pulsars exhibit remarkably strong magnetic fields.If the magnetic fields were weakened during the accretion process,then a short duration of accretion might explain the strong magnetic fields of these pulsars.
