|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | The FAST Galactic Plane Pulsar Snapshot survey:I.Project design and pulsar discoveries显示文摘Discovery of pulsars is one of the main goals for large radio telescopes.The Five-hundredmeter Aperture Spherical radio Telescope(FAST),that incorporates an L-band 19-beam receiver with a system temperature of about 20 K,is the most sensitive radio telescope utilized for discovering pulsars.We designed the snapshot observation mode for a FAST key science project,the Galactic Plane Pulsar Snapshot(GPPS)survey,in which every four nearby pointings can observe a cover of a sky patch of 0.1575 square degrees through beam-switching of the L-band 19-beam receiver.The integration time for each pointing is 300 seconds so that the GPPS observations for a cover can be made in 21 minutes.The goal of the GPPS survey is to discover pulsars within the Galactic latitude of±10∘from the Galactic plane,and the highest priority is given to the inner Galaxy within±5∘.Up to now,the GPPS survey has discovered 201 pulsars,including currently the faintest pulsars which cannot be detected by other telescopes,pulsars with extremely high dispersion measures(DMs)which challenge the currently widely used models for the Galactic electron density distribution,pulsars coincident with supernova remnants,40 millisecond pulsars,16 binary pulsars,some nulling and mode-changing pulsars and rotating radio transients(RRATs).The follow-up observations for confirmation of new pulsars have polarization-signals recorded for polarization profiles of the pulsars.Re-detection of previously known pulsars in the survey data also leads to significant improvements in parameters for 64 pulsars.The GPPS survey discoveries are published and will be updated at http://gffzz656c80eee53645cch5ow0nnkfn5bo6uuw.ffgz.tsg.suse.edu.cn/GPPS/. | J.L.Han Chen Wang P.F.Wang Tao Wang D.J.Zhou Jing-Hai Sun Yi Yan Wei-Qi Su Wei-Cong Jing Xue Chen X.Y.Gao Li-Gang Hou Jun Xu K.J.Lee Na Wang Peng Jiang Ren-Xin Xu Jun Yan Heng-Qian Gan Xin Guan Wen-Jun Huang Jin-Chen Jiang Hui Li Yun-Peng Men Chun Sun Bo-Jun Wang H.G.Wang Shuang-Qiang Wang Jin-Tao Xie Heng Xu Rui Yao Xiao-Peng You D.J.Yu Jian-Ping Yuan Rai Yuen Chun-Feng Zhang Yan Zhu | 2021 | Research in Astronomy and Astrophysics2021，21，5： | 4 |
| 2 | FAST Observations of an Extremely Active Episode of FRB 20201124A:Ⅰ.Burst Morphology显示文摘We report the properties of more than 600 bursts(including cluster-bursts)detected from the repeating fast radio burst(FRB)source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode on UTC 2021 September 25–28,in a series of four papers.The observations were carried out in the band of 1.0–1.5 GHz by using the center beam of the L-band 19-beam receiver.We monitored the source in sixteen1 hr sessions and one 3 hr session spanning 23 days.All the bursts were detected during the first four days.In this first paper of the series,we perform a detailed morphological study of 624 bursts using the two-dimensional frequencytime“waterfall”plots,with a burst(or cluster-burst)defined as an emission episode during which the adjacent emission peaks have a separation shorter than 400 ms.The duration of a burst is therefore always longer than 1 ms,with the longest up to more than 120 ms.The emission spectra of the sub-bursts are typically narrow within the observing band with a characteristic width of~277 MHz.The center frequency distribution has a dominant peak at about 1091.9 MHz and a secondary weak peak around 1327.9 MHz.Most bursts show a frequencydownwarddrifting pattern.Based on the drifting patterns,we classify the bursts into five main categories:downward drifting(263)bursts,upward drifting(3)bursts,complex(203),no drifting(35)bursts,and no evidence for drifting(121)bursts.Subtypes are introduced based on the emission frequency range in the band(low,middle,high and wide)as well as the number of components in one burst(1,2,or multiple).We measured a varying scintillation bandwidth from about 0.5 MHz at 1.0 GHz to 1.4 MHz at 1.5 GHz with a spectral index of 3.0. | D.J.Zhou J.L.Han B.Zhang K.J.Lee W.W.Zhu D.Li W.C.Jing W.-Y.Wang Y.K.Zhang J.C.Jiang J.R Niu R Luo H.Xu C.F.Zhang B.J.Wang J.W.Xu P.Wang Z.L.Yang Y.Feng | 2022 | Research in Astronomy and Astrophysics2022，22，12： | 0 |
| 3 | The FAST Galactic Plane Pulsar Snapshot Survey.II.Discovery of 76 Galactic Rotating Radio Transients and the Enigma of RRATs显示文摘We have carried out the Galactic Plane Pulsar Snapshot(GPPS)survey by using the Five-hundred-meter Aperture Spherical radio Telescope(FAST),the most sensitive systematic pulsar survey in the Galactic plane.In addition to more than 500 pulsars already discovered through normal periodical search,we report here the discovery of 76 new transient radio sources with sporadic strong pulses,detected by using the newly developed module for a sensitive single-pulse search.Their small DM values suggest that they all are Galactic rotating radio transients(RRATs).They show different properties in the follow-up observations.More radio pulses have been detected from 26 transient radio sources but no periods can be found due to a limited small number of pulses from all FAST observations.The followup observations show that 16 transient sources are newly identified as being the prototypes of RRATs with a period already determined from more detected sporadic pulses,and 10 sources are extremely nulling pulsars,and 24 sources are weak pulsars with sparse strong pulses.On the other hand,48 previously known RRATs have been detected by the FAST,either during verification observations for the GPPS survey or through targeted observations of applied normal FAST projects.Except for one RRAT with four pulses detected in a session of 5-minute observation and four RRATs with only one pulse detected in a session,sensitive FAST observations reveal that 43 RRATs are just generally weak pulsars with sporadic strong pulses or simply very nulling pulsars,so that the previously known RRATs always have an extreme emission state together with a normal hardly detectable weak emission state.This is echoed by the two normal pulsars J1938+2213 and J1946+1449 with occasional brightening pulses.Though strong pulses of RRATs are very outstanding in the energy distribution,their polarization angle variations follow the polarization angle curve of the averaged normal pulse profile,suggesting that the predominant sparse pulses of RRATs are emitted in the same region with the same geometry as normal weak pulsars. | D.J.Zhou J.L.Han Jun Xu Chen Wang P.F.Wang Tao Wang Wei-Cong Jing Xue Chen Yi Yan Wei-QiSu Heng-Qian Gan Peng Jiang Jing-Hai Sun Hong-Guang Wang Na Wang Shuang-Qiang Wang Ren-Xin Xu Xiao-Peng You | 2023 | Research in Astronomy and Astrophysics2023，23，10： | 0 |
| 4 | FAST Pulsar Database.I.Polarization Profiles of 682 Pulsars显示文摘Pulsar polarization profiles form a very basic database for understanding the emission processes in a pulsar magnetosphere.After careful polarization calibration of the 19-beam L-band receiver and verification of beamoffset observation results,we obtain polarization profiles of 682 pulsars from observations by the Five-hundredmeter Aperture Spherical radio Telescope(FAST)duringthe Galactic Plane Pulsar Snapshot survey and other normal FAST projects.Among them,polarization profiles of about 460 pulsars are observed for the first time.The profiles exhibit diverse features.Some pulsars have a polarization position angle curve with a good S-shaped swing,some with orthogonal modes;some have components with highly linearly polarized components or strong circularly polarized components;some have a very wide profile,coming from an aligned rotator,and some have an interpulse from a perpendicular rotator;some wide profiles are caused by interstellar scattering.We derive geometric parameters for 190 pulsars from the S-shaped position angle curves or with orthogonal modes.We find that the linear and circular polarization or the widths of pulse profiles have various frequency dependencies.Pulsars with a large fraction of linear polarization are more likely to have a large Edot. | P.F.Wang J.L.Han J.Xu C.Wang Y.Yan W.C.Jing W.Q.Su D.J.Zhou T.Wang | 2023 | Research in Astronomy and Astrophysics2023，23，10： | 0 |
| 5 | Cleaning Radio Frequency Interference in Pulsar-Folded Data Based on the Conditional Random Fields with an Adaptive Prior显示文摘Radio astronomy observations are frequently impacted by radio frequency interference(RFI).We propose a novel method,named 2σCRF,for cleaning RFI in the folded data of pulsar observations,utilizing a Bayesian-based model called conditional random fields(CRFs).This algorithm minimizes the“energy”of every pixel given an initial label.The standard deviations(i.e.,rms values)of the folded pulsar data are utilized as pixels for all subintegrations and channels.Non-RFI data without obvious interference is treated as“background noise,”while RFI-affected data have different classes due to their exceptional rms values.This initial labeling can be automated and is adaptive to the actual data.The CRF algorithm optimizes the label category for each pixel of the image with the prior initial labels.We demonstrate the efficacy of the proposed method on pulsar folded data obtained from Five-hundred-meter Aperture Spherical radio Telescope observations.It can effectively recognize and tag various categories of RFIs,including broadband or narrowband,constant or instantaneous,and even weak RFIs that are unrecognizable in some pixels but picked out based on their neighborhoods.The results are comparable to those obtained via manual labeling but without the need for human intervention,saving time and effort. | Xue Chen J.L.Han W.Q.Su Z.L.Yang D.J.Zhou | 2023 | Research in Astronomy and Astrophysics2023，23，10： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员