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| 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://gffzz656c80eee53645cch9ku6599oqkqc6p6b.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 | Targeted Search for Fast Radio Bursts with Nanshan 26m Radio Telescope显示文摘Fast radio bursts(FRBs)are radio transients that are bright and have short duration,with their physical mechanism not being fully understood.We conducted a targeted search for bursts from FRB 20201124A between 2021 June 2and July 20.High time-resolution data were collected for 104.5 hr using the ROACH2-based digital backend.We introduce the details of our FRB search pipeline which is based on HEIMDALL and FETCH.Testing of the injected mock FRBs search could help us better understand the performance of the pipelines,and improve the search algorithms and classifiers.To study the efficiency of our pipeline,5000 mock FRBs were injected into the data and searched using the pipeline.The results of the mock FRB search show that our pipeline can recover almost all(?90%)the injected mock FRBs above a signal-to-noise ratio(S/N)threshold of 15,and the performance is still acceptable(?80%)for injected S/Ns from 10 to 15.The recovery fraction displays relations with S/N,dispersion measure and pulse width.No bursts were detected from FRB 20201124A in the middle of 2021.The non-detection of FRB 20201124A may be due to its quiet phase window or no emission above the threshold of the Nanshan telescope. | Jian-Wei Mao Jian-Ping Yuan Zhi-Gang Wen Jian Li Na Wang Pei Wang Rai Yuen Yu-Bin Wang Nan-Nan Zhai Zhi-Yong Liu Mao-Zheng Chen Guang-Hui Li | 2022 | Research in Astronomy and Astrophysics2022，22，6： | 0 |
| 3 | The Multiple Images of the Plasma Lensing FRB显示文摘We investigate the formation of multiple images as the radio signals from fast radio bursts(FRBs)pass through the plane of a plasma clump.The exponential model for the plasma clump is adopted to analyze the properties of the multiple images.By comparing with the classical dispersion relations,we find that one image has exhibited specific inverse properties to others,such as their delay times at high frequency is higher than that at low frequency,owing to the lensing effects of the plasma clump.We demonstrate that these inverse effects should be observable in some repeating FRBs.Our results predict deviation in the estimated dispersion measure(DM)across multiple images,consistent with the observations of FRB 121102 and FRB 180916.J0158+65.If other plasma lenses have effects similar to an exponential lens,we find that they should also give rise to a similar dispersion relation in the multiple images.For some repeating FRBs,analysis of the differences in time delay and in DM between multiple images at different frequencies can serve as a method to reveal the plasma distribution. | Yu-Bin Wang Zhi-Gang Wen Rai Yuen Na Wang Jian-Ping Yuan Xia Zhou | 2022 | Research in Astronomy and Astrophysics2022，22，6： | 0 |
| 4 | Spin-down and emission variations for PSR J0742-2822显示文摘PSR J0742-2822 is known for its quasi-periodic changes in the observed pulse profile and spindown rate.In this paper,we analyzed 13 years of timing data obtained with the Nanshan 25-m radio telescope and the Parkes 64-m radio telescope.We found that the average values of the spin-down rate((v))of this pulsar changed in four different states.We investigated the correlation between v and W50,and ascertained that the correlation changed in different states.Moreover,not all the changes in states and correlation can be associated with glitch activities.We examined the long term evolution ofγ-ray flux(0.1-300 GeV)and the pulse profiles corresponding to the four different states using Fermi-LAT Pass8(P8 R3)data from 2008 August 5 to 2019 October 1.We did not detect a significant change inγ-ray flux or the pulse profile.Our results suggest that the connection between pulsar rotation and emission is more complex than previously reported for this pulsar. | Shi-Jun Dang Na Wang Hui-Hui Wang Jian-Ping Yuan Lun-Hua Shang Rai Yuen Ming-Yu Ge Xia Zhou Shuang-Qiang Wang Fei-Fei Kou Wen-Ming Yan Jing-Bo Wang Zhi-Gang Wen Jun-Tao Bai Zhi-Yong Liu Zu-Rong Zhou | 2021 | Research in Astronomy and Astrophysics2021，21，2： | 0 |
| 5 | Frequency dependence in the emission from subpulse drifting pulsars显示文摘We investigate relations in the emission properties as revealed by drifting subpulses detected at different observing frequencies based on the method that incorporates the rotating carousels in pulsar magnetospheres of multiple emission states.An emission state is associated with particular emission properties as determined by the drifting subpulses at a particular frequency,and different emission states obtained at different frequencies reveal the variation of emission properties across the emission region.The method allows the determination of the essential radio emission properties such as the relative emission height,subpulse number,charge density and the plasma flow relative to corotation in an emission region for a particular frequency.We apply the method to seven pulsars that exhibit subpulse drifting along single drift-band at 326 MHz and 1429 MHz.Our results show that drifting subpulses observed at different frequencies correspond to particular emission states suggesting that the pulsar emission properties are frequency dependent.We show that emission follows the frequency-to-radius mapping for pulsars with obliquity angle?30°regardless of the sign and magnitude of the drift-rate.For pulsars with long rotation periods in our sample,the circulation time for the plasma to revolve once around the magnetosphere relative to corotation increases as the rotation period increases at both frequencies,but exhibits irregularity for pulsars with short rotation periods.Our results suggest that evolution of the obliquity angles in subpulse drifting pulsars is from large to small,and the emission region tends to be’thicker’in younger pulsars. | 韩晓红 Rai Yuen | 2021 | Research in Astronomy and Astrophysics2021，21，9： | 0 |
| 6 | A single pulse study of PSR J1752+2359显示文摘The single pulse observation of PSR J1752+2359 at 1250 MHz made using the Five-hundredmeter Aperture Spherical radio Telescope(FAST)is presented.We show that the pulsar exhibits two distinct emission states:a normal state with continuous normal pulse emission and a rotating radio transient(RRAT)-like state with sporadic emission.This makes PSR J1752+2359 the third pulsar that exhibits switching between RRAT-like and pulsar-like states.Our data show that,during the observation,20 per cent of the time for this pulsar was in the normal state and 80 per cent in the RRAT-like state.A quasiperiodic switching,with a periodicity of around 568 spin periods,between the two states was observed.The pulse energies for the two states both follow log-normal distributions.We demonstrate that the polarization profiles and the linear polarization position angle(PA)swings differ significantly between the two states.There is a phase offset of about 0°.35 between the pulse profile peaks of the two states.We argue that the emission geometry in the magnetosphere may be different for the two states. | 孙盛楠 闫文明 王娜 Rai Yuen | 2021 | Research in Astronomy and Astrophysics2021，21，9： | 0 |
| 7 | A Search Technique Based on Deep Learning for Fast Radio Bursts and Initial Results for FRB 20201124A with the NSRT显示文摘The origin and phenomenology of Fast Radio Bursts(FRBs) remain unknown. Fast and efficient search technology for FRBs is critical for triggering immediate multi-wavelength follow-up and voltage data dump. This paper proposes a dispersed dynamic spectra search(DDSS) pipeline for FRB searching based on deep learning, which performs the search directly from observational raw data, rather than relying on generated FRB candidates from single-pulse search algorithms that are based on de-dispersion. We train our deep learning network model using simulated FRBs as positive and negative samples extracted from the observational data of the Nanshan 26 m radio telescope(NSRT)at Xinjiang Astronomical Observatory. The observational data of PSR J1935+1616 are fed into the pipeline to verify the validity and performance of the pipeline. Results of the experiment show that our pipeline can efficiently search single-pulse events with a precision above 99.6%, which satisfies the desired precision for selective voltage data dump. In March 2022, we successfully detected the FRBs emanating from the repeating case of FRB 20201124A with the DDSS pipeline in L-band observations using the NSRT. The DDSS pipeline shows excellent sensitivity in identifying weak single pulses, and its high precision greatly reduces the need for manual review. | Yan-Ling Liu Jian Li Zhi-Yong Liu Mao-Zheng Chen Jian-Ping Yuan Na Wang Rai Yuen Hao Yan | 2022 | Research in Astronomy and Astrophysics2022，22，10： | 0 |
| 8 | Investigation of Mode Changing,Pulse Nulling and Subpulse Drifting Properties in the Asymmetric Conal Triple Radio Pulsar B2319+60显示文摘We report on a detailed analysis of the mode changing,nulling and subpulse drifting behavior of the conal triple pulsar B2319+60 at 1.5 GHz observed with the Nanshan 25 m radio telescope.The pulsar’s profile can be interpreted as resulting from a sightline traverse which cuts across an outer cone and tangentially grazes an inner cone.About 30 per cent of nulls are found to create alternating bunches of nulls and emission in a quasi-periodic manner with an averaged fluctuation rate of about four rotation periods(P_(1)).The presence of two distinct drift modes(A and ABN)plus a phase-stationary non-drift emission mode(B)is confirmed,and each corresponds to a different pulse profile.The mode A is dominated by a phase modulation in the trailing component with a circulation time of around 7P_(1).In addition to a 3P_(1)phase modulation in the leading component,mode ABN presents an amplitude modulation in the leading and trailing components with a period of around 40P_(1).The emission region and geometry remain constant during mode changing.The diversity seen in the individual pulse behavior of the pulsar B2319+60 provides a unique window into the emission physics. | Jian-Ling Chen Zhi-Gang Wen Hong-Guang Wang Na Wang Rai Yuen Vishal Gajjar Jian-Ping Yuan Zhen Wang Wen-Ming Yan Jin-Peng Wang Cheng-Bing Lyu Hui Wang Xue-Feng Duan | 2022 | Research in Astronomy and Astrophysics2022，22，11： | 0 |
| 9 | PSR B1237+25的强脉冲辐射特性的观测与研究显示文摘强脉冲是一种特殊的单脉冲辐射,表现为较强的射电爆发.利用新疆天文台南山25 m射电望远镜研究了PSR B1237+25的强脉冲辐射特性.发现探测到的793个强脉冲出现在积分轮廓的所有辐射成分中,峰值流量密度是平均脉冲的10.2至82.5倍.用对数正态分布对强脉冲的峰值流量密度比、信噪比和脉冲宽度的分布进行了拟合.在1540 MHz频率下首次发现PSR B1237+25有新的、微弱的辐射成分.新发现的最内锥辐射属于部分锥,前导成分非常微弱,因此很难被探测到.对3层锥结构进行的详细研究发现新成分非常靠近核区,辐射区高度以约300 km为步长逐步升高,中心锥和外锥辐射可能来自同一套磁力线. | 麦麦提艾力·米吉提 温志刚 王娜 王兆军 袁建平 YUEN Rai 闫文明 | 2021 | 天文学报2021，62，1： | 0 |
| 10 | 脉冲星射电轮廓中高斯成分在主脉冲和中间脉冲的不同分布显示文摘研究了高斯辐射成分在可视点所画出轨迹上的分布,这个可视点因脉冲星的转动而作非匀速度运动.通过假设辐射区域围绕磁轴均匀分布,一个高斯辐射成分便对应于可视轨迹划过的一个辐射区域.因为演示辐射区域在可视轨迹上是不均匀的分布,因此高斯成分沿轨迹也是不均匀的,而高斯成分的密度在磁轴与视线距离最近时为最大.高斯成分的分布取决于脉冲星的两个角度:旋转轴和视线之间的夹角,以及磁轴和旋转轴之间的倾角.基于此模型,一个脉冲星平均轮廓中观察到的多个高斯成分便对应于可视轨迹在特定的转动相位范围内的辐射区域.演示了脉冲星旋转的近侧和远侧的相位,分别对应的主脉冲和中间脉冲,两者高斯成分的数量和分布是不同的.而且还发现,沿可视轨迹上的辐射区域总数与围绕磁轴的辐射区域的总数是不同,并且预测的辐射区域数目会因忽略可见点的运动而明显不同.拟合表明脉冲星轮廓的高斯成分的形状和数量可能与实际构成轮廓的成分的形状和数量不同.以PSR B0826-34的辐射为例,并假设辐射来自单一磁极. | 韩晓红 YUEN Rai | 2022 | 天文学报2022，63，3： | 0 |
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