Youling Yue, Di Li
Nov 13, 2019·astro-ph.IM·PDF We present the big-data challenges posed by the science operation of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Unlike the common usage of the word `big-data', which tend to emphasize both quantity and diversity, the main characteristics of FAST data stream is its single-source data rate at more than 6 GB/s and the resulting data volume at about 20 PB per year. We describe here the main culprit of such a high data rate and large volume, namely pulsar search, and our solution.
Rendong Nan, Di Li, Chengjin Jin, Qiming Wang, Lichun Zhu, Wenbai Zhu, Haiyan Zhang, Youling Yue, Lei Qian
May 19, 2011·astro-ph.IM·PDF Five-hundred-meter Aperture Spherical radio Telescope (FAST) is a Chinese mega-science project to build the largest single dish radio telescope in the world. Its innovative engineering concept and design pave a new road to realize a huge single dish in the most effective way. FAST also represents Chinese contribution in the international efforts to build the square kilometer array (SKA). Being the most sensitive single dish radio telescope, FAST will enable astronomers to jump-start many science goals, for example, surveying the neutral hydrogen in the Milky Way and other galaxies, detecting faint pulsars, looking for the first shining stars, hearing the possible signals from other civilizations, etc. The idea of sitting a large spherical dish in a karst depression is rooted in Arecibo telescope. FAST is an Arecibo-type antenna with three outstanding aspects: the karst depression used as the site, which is large to host the 500-meter telescope and deep to allow a zenith angle of 40 degrees; the active main reflector correcting for spherical aberration on the ground to achieve a full polarization and a wide band without involving complex feed systems; and the light-weight feed cabin driven by cables and servomechanism plus a parallel robot as a secondary adjustable system to move with high precision. The feasibility studies for FAST have been carried out for 14 years, supported by Chinese and world astronomical communities. The project time is 5.5 years from the commencement of work in March of 2011 and the first light is expected to be in 2016. This review intends to introduce FAST project with emphasis on the recent progress since 2006. In this paper, the subsystems of FAST are described in modest details followed by discussions of the fundamental science goals and examples of early science projects.
Youling Yue, Di Li, Rendong Nan
The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is under construction and will be commissioned in September 2016. A low frequency 7-beam receiver working around 400 MHz is proposed for FAST early science. It will be optimized for a whole FAST sky drift-scan pulsar survey. Simulations show that about 1500 new normal pulsars will be discovered, as while as about 200 millisecond pulsars.
Youling Yue, Renxin Xu
Sep 18, 2007·astro-ph·PDF A recent observation has shown that PSR B1257+12 could have quite small X-ray emitting area, only about 2000 m$^2$, which is more than three orders smaller than the canonical polar cap size. We suggest here that PSR B1257+12 could be a low-mass quark star with radius of $R \simeq 0.6$ km and mass of $M \simeq 3\times10^{-4}\msun$. Such a low-mass quark star system may form in an accretion induced collapse process or a collision process of two quark stars.
Lin Wang, Bo Peng, B. W. Stappers, Kuo Liu, M. J. Keith, A. G. Lyne, Jiguang Lu, Ye-Zhao Yu, Feifei Kou, Jun Yan, Peng Jiang, Chengjin Jin, Di Li, Qi Li, Lei Qian, Qiming Wang, Youling Yue, Haiyan Zhang, Shuxin Zhang, Yan Zhu
Feb 14, 2020·astro-ph.HE·PDF We report the discovery of a binary millisecond pulsar (namely PSR J1641+3627F or M13F) in the globular cluster M13 (NGC 6205) and timing solutions of M13A to F using observations made with the Five-hundred-metre Aperture Spherical radio Telescope (FAST). PSR J1641+3627F has a spin period of 3.00 ms and an orbital period of 1.4 days. The most likely companion mass is 0.16 M$_{\odot}$. M13A to E all have short spin periods and small period derivatives. We also confirm that the binary millisecond pulsar PSR J1641$+$3627E (also M13E) is a black widow with a companion mass around 0.02 M$_{\odot}$. We find that all the binary systems have low eccentricities compared to those typical for globular cluster pulsars and that they decrease with distance from the cluster core. This is consistent with what is expected as this cluster has a very low encounter rate per binary.
Pei Wang, Jian Li, Long Ji, Xian Hou, Erbil Gugercinoglu, Di Li, Diego F. Torres, Yutong Chen, Jiarui Niu, Weiwei Zhu, Bing Zhang, En-wei Liang, Li Zhang, Mingyu Ge, Zigao Dai, Lin Lin, Jinlin Han, Yi Feng, Chenhui Niu, Yongkun Zhang, Dengjiang Zhou, Heng Xu, Chunfeng Zhang, Jinchen Jiang, Chenchen Miao, Mao Yuan, Weiyang Wang, Youling Yue, Yunsheng Wu, Yabiao Wang, Chengjie Wang, Zhenye Gan, Yuxi Li, Zhongyi Sun, Mingmin Chi
Aug 17, 2023·astro-ph.HE·PDF Magnetars are neutron stars with extremely strong magnetic fields, frequently powering high-energy activity in X-rays. Pulsed radio emission following some X-ray outbursts have been detected (\citealt{Camilo2006,camilo2007a}), albeit its physical origin is unclear. It has long been speculated that the origin of magnetars' radio signals is different from those from canonical pulsars, although convincing evidence is still lacking. Five months after magnetar SGR 1935+2154's X-ray outburst and its associated Fast Radio Burst (FRB) 20200428, a radio pulsar phase was discovered. Here we report the discovery of X-ray spectral hardening associated with the emergence of periodic radio pulsations from SGR 1935+2154 and a detailed analysis of the properties of the radio pulses. The observations suggest that radio emission originates from the outer magnetosphere of the magnetar, and the surface heating due to the bombardment of inward-going particles from the radio emission region is responsible for the observed X-ray spectral hardening.
Yi Feng, Di Li, Yuan-Pei Yang, Yongkun Zhang, Weiwei Zhu, Bing Zhang, Wenbin Lu, Pei Wang, Shi Dai, Ryan S. Lynch, Jumei Yao, Jinchen Jiang, Jiarui Niu, Dejiang Zhou, Heng Xu, Chenchen Miao, Chenhui Niu, Lingqi Meng, Lei Qian, Chao-Wei Tsai, Bojun Wang, Mengyao Xue, Youling Yue, Mao Yuan, Songbo Zhang, Lei Zhang
Feb 19, 2022·astro-ph.HE·PDF The polarization of fast radio bursts (FRBs), bright astronomical transients, contains crucial information about their environments. We report polarization measurements of five repeating FRBs, the abundant signals of which enable wide-band observations with two telescopes. A clear trend of lower polarization at lower frequencies was found, which can be well characterized by a single parameter rotation-measure-scatter (σRM) and modeled by multi-path scatter. Sources with higher σRM have higher RM magnitude and scattering timescales. The two sources with the most substantial σRM, FRB 20121102A and FRB 20190520B, are associated with a compact persistent radio source. These properties indicate a complex environment near the repeating FRBs, such as a supernova remnant or a pulsar wind nebula, consistent with their arising from young populations.
Yi Feng, George Hobbs, Di Li, Shi Dai, Weiwei Zhu, Youling Yue, Pei Wang, Songbo Zhang, Lei Qian, Lei Zhang, Shuangqiang Wang, Chenchen Miao, Mao Yuan, Yongkun Zhang
Dec 12, 2020·astro-ph.HE·PDF Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we have recorded 10^5 single pulses from PSR J1022+1001. We studied the polarization properties, their energy distribution and their times of arrival. This is only possible with the high sensitivity available using FAST. There is no indication that PSR~J1022+1001 exhibits giant pulse, nulling or traditional mode changing phenomena. The energy in the leading and trailing components of the integrated profile is shown to be correlated. The degree of both linear and circular polarization increases with the pulse flux density for individual pulses. Our data indicates that pulse jitter leads to an excess noise in the timing residuals of 67 ns when scaled to one hour, which is consistent with Liu et al. (2015). We have unsuccessfully trialled various methods to improve timing precision through the selection of specific single pulses. Our work demonstrates that FAST can detect individual pulses from pulsars that are observed in order to detect and study gravitational waves. This capability enables detailed studies, and parameterisation, of the noise processes that affect the sensitivity of a pulsar timing array.
Kai Zhang, Jingwen Wu, Di Li, Marko Krčo, Lister Staveley-Smith, Ningyu Tang, Lei Qian, Mengting Liu, Chengjin Jin, Youling Yue, Yan Zhu, Hongfei Liu, Dongjun Yu, Jinghai Sun, Gaofeng Pan, Hui Li, Hengqian Gan, Rui Yao
Mar 15, 2019·astro-ph.GA·PDF The Five-hundred-meter Aperture Spherical radio Telescope(FAST) is expected to complete its commissioning in 2019. FAST will soon begin the Commensal Radio Astronomy FasT Survey(CRAFTS), a novel and unprecedented commensal drift scan survey of the entire sky visible from FAST. The goal of CRAFTS is to cover more than 20000 $deg^{2}$ and reach redshift up to about 0.35. We provide empirical measurements of the beam size and sensitivity of FAST across the 1.05 to 1.45 GHz frequency range of the FAST L-band Array of 19-beams(FLAN). Using a simulated HI-galaxy catalogue based on the HI Mass Function(HIMF), we estimate the number of galaxies that CRAFTS may detect. At redshifts below 0.35, over $6\, \times \, 10^{5}$ HI galaxies may be detected. Below the redshift of 0.07, the CRAFTS HIMF will be complete above a mass threshold of $10^{9.5}\,M_{\odot}$. FAST will be able to investigate the environmental and redshift dependence of the HIMF to an unprecedented depth, shedding light onto the missing baryon and missing satellite problems.
Ningyu Tang, Di Li, Pei Zuo, Lei Qian, Tie Liu, Yuefang Wu, Marko Krčo, Mengting Liu, Youling Yue, Yan Zhu, Hongfei Liu, Dongjun Yu, Jinghai Sun, Peng Jiang, Gaofeng Pan, Hui Li, Hengqian Gan, Rui Yao, Shu Liu, FAST Collaboration
We present a pilot HI survey of 17 Planck Galactic Cold Clumps (PGCCs) with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). HI Narrow Self-Absorption (HINSA) is an effective method to detect cold HI being mixed with molecular hydrogen H$_2$ and improves our understanding of the atomic to molecular transition in the interstellar medium. HINSA was found in 58\% PGCCs that we observed. The column density of HINSA was found to have an intermediate correlation with that of $^{13}$CO, following $\rm log( N(HINSA)) = (0.52\pm 0.26) log(N_{^{13}CO}) + (10 \pm 4.1) $. HI abundance relative to total hydrogen [HI]/[H] has an average value of $4.4\times 10^{-3}$, which is about 2.8 times of the average value of previous HINSA surveys toward molecular clouds. For clouds with total column density N$\rm_H >5 \times 10^{20}$ cm$^{-2}$, an inverse correlation between HINSA abundance and total hydrogen column density is found, confirming the depletion of cold HI gas during molecular gas formation in more massive clouds. Nonthermal line width of $^{13}$CO is about 0-0.5 km s$^{-1}$ larger than that of HINSA. One possible explanation of narrower nonthermal width of HINSA is that HINSA region is smaller than that of $^{13}$CO. Based on an analytic model of H$_2$ formation and H$_2$ dissociation by cosmic ray, we found the cloud ages to be within 10$^{6.7}$-10$^{7.0}$ yr for five sources.
Weiwei Zhu, Heng Xu, Dejiang Zhou, Lin Lin, Bojun Wang, Pei Wang, Chunfeng Zhang, Jiarui Niu, Yutong Chen, Chengkui Li, Lingqi Meng, Kejia Lee, Bing Zhang, Yi Feng, Mingyu Ge, Ersin Göğüş, Xing Guan, Jinlin Han, Jinchen Jiang, Peng Jiang, Chryssa Kouveliotou, Di Li, Chenchen Miao, Xueli Miao, Yunpeng Men, Chenghui Niu, Weiyang Wang, Zhengli Wang, Jiangwei Xu, Renxin Xu, Mengyao Xue, Yuanpei Yang, Wenfei Yu, Mao Yuan, Youling Yue, Shuangnan Zhang, Yongkun Zhang
Jul 30, 2023·astro-ph.HE·PDF The megajansky radio burst, FRB 20200428, and other bright radio bursts detected from the Galactic source SGR J1935+2154 suggest that magnetars can make fast radio bursts (FRBs), but the emission site and mechanism of FRB-like bursts are still unidentified. Here we report the emergence of a radio pulsar phase of the magnetar five months after FRB 20200428. 795 pulses were detected in 16.5 hours over 13 days by the Five-hundred-meter Aperture Spherical Radio telescope, with luminosities about eight decades fainter than FRB 20200428. The pulses were emitted in a narrow phase window anti-aligned with the X-ray pulsation profile observed by the X-ray telescopes. The bursts, conversely, appear in random phases. This dichotomy suggests that radio pulses originate from a fixed region within the magnetosphere, but bursts occur in random locations and are possibly associated with explosive events in a dynamically evolving magnetosphere. This picture reconciles the lack of periodicity in cosmological repeating FRBs within the magnetar engine model.
Yanqing Cai, Ziwei Wu, Weiwei Zhu, Joris P. W. Verbiest, Yulan Liu, Krishnakumar Moochickal Ambalappat, Marcus Brüggen, Benedetta Ciardi, Ralf-Jürgen Dettmar, Ziyao Fang, Qiuyang Fu, Matthias Hoeft, Jiawei Jin, Lars Künkel, Jörn Künsemöller, Caisong Liu, Lingqi Meng, Xueli Miao, Jiarui Niu, Rukiya Rejep, Dominik J. Schwarz, Golam M. Shaifullah, Caterina Tiburzi, Christian Vocks, Olaf Wucknitz, Mengyao Xue, Mao Yuan, Youling Yue, Chunfeng Zhang, Zhen Zhang
The interstellar scintillation observed in radio pulsars arises from interference between electromagnetic waves scattered by electron density fluctuations in the turbulent interstellar plasma, providing a critical tool for probing the small-scale structure of the ionized interstellar medium and the pulsar system itself. The primary aim of this work is to study long-term scintillation variations for a bright and nearby pulsar, PSR J0814$+$7429, carried out from 2013 September to 2023 September with the LOw-Frequency ARray (LOFAR) High Band Antennae in the frequency range of 120 - 170 MHz. We derive the basic scintillation parameters, scintillation bandwidth ($Δν_{\rm d}$) and scintillation timescale ($Δτ_{\rm d}$), from the two-dimensional (2D) auto-covariance function of the dynamic spectra that are a 2D matrix of pulse intensity as a function of time and frequency. We present the long-term monitoring of $Δν_{\rm d}$ and $Δτ_{\rm d}$ for PSR J0814$+7429$, which shows a strong annual variation in the time series of the $Δτ_{\rm d}$. From our modeling of the annual variations of scintillation velocities, the scattering screen is anisotropic and located at $0.23\pm0.02$ kpc from the Earth, likely corresponding to the boundary of the Local Bubble.
Qiuyu Yu, Zhichen Pan, Lei Qian, Shen Wang, Youling Yue, Menglin Huang, Qiaoli Hao, Shanping You, Bo Peng, Yan Zhu, Lei Zhang, Zhijie Liu
Dec 30, 2019·astro-ph.IM·PDF We developed a pulsar search pipeline based on PRESTO (PulsaR Exploration and Search Toolkit). This pipeline simply runs dedispersion, FFT (Fast Fourier Transformation), and acceleration search in process-level parallel to shorten the processing time. With two parallel strategies, the pipeline can highly shorten the processing time in both the normal searches or acceleration searches. This pipeline was first tested with PMPS (Parkes Multibeam Pulsar Survery) data and discovered two new faint pulsars. Then, it was successfully used in processing the FAST (Five-hundred-meter Aperture Spherical radio Telescope) drift scan data with tens of new pulsar discoveries up to now. The pipeline is only CPU-based and can be easily and quickly deployed in computing nodes for testing purposes or data processes.
Pei Wang, Di Li, Colin J. Clark, Pablo Saz Parkinson, Xian Hou, Weiwei Zhu, Lei Qian, Youling Yue, Zhichen Pan, Zhijie Liu, Xuhong Yu, Xiaoyao Xie, Qijun Zhi, Hui Zhang, Jumei Yao, Jun Yan, Chengmin Zhang, Paul S. Ray, Matthew Kerr, David A. Smith, Peter F. Michelson, Elizabeth C. Ferrara, David J. Thompson, Zhiqiang Shen, Na Wang, FAST-FermiLAT Collaboration
High sensitivity radio searches of unassociated $γ$-ray sources have proven to be an effective way of finding new pulsars. Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) during its commissioning phase, we have carried out a number of targeted deep searches of \textit{Fermi} Large Area Telescope (LAT) $γ$-ray sources. On Feb. 27$^{th}$, 2018 we discovered an isolated millisecond pulsar (MSP), PSR J0318+0253, coincident with the unassociated $γ$-ray source 3FGL J0318.1+0252. PSR J0318+0253 has a spin period of $5.19$ milliseconds, a dispersion measure (DM) of $26$ pc cm$^{-3}$ corresponding to a DM distance of about $1.3$ kpc, and a period-averaged flux density of $\sim$11 $\pm$ 2 $μ$Jy at L-band (1.05-1.45 GHz). Among all high energy MSPs, PSR J0318+0253 is the faintest ever detected in radio bands, by a factor of at least $\sim$4 in terms of L-band fluxes. With the aid of the radio ephemeris, an analysis of 9.6 years of \textit{Fermi}-LAT data revealed that PSR J0318+0253 also displays strong $γ$-ray pulsations. Follow-up observations carried out by both Arecibo and FAST suggest a likely spectral turn-over around 350 MHz. This is the first result from the collaboration between FAST and the \textit{Fermi}-LAT teams as well as the first confirmed new MSP discovery by FAST, raising hopes for the detection of many more MSPs. Such discoveries will make a significant contribution to our understanding of the neutron star zoo while potentially contributing to the future detection of gravitational waves, via pulsar timing array (PTA) experiments.
Yonghua Xu, Kejia Lee, Longfei Hao, Hongguang Wang, Zhiyong Liu, Youling Yue, Jianping Yuan, Zhixuan Li, Min Wang, Jiang Dong, Jiajun Tan, Wen Chen, Jinming Bai
In this paper, we report our investigation of pulsar scintillation phenomena by monitoring PSR B0355$+$54 at 2.25 GHz for three successive months using \emph{Kunming 40-m radio telescope}. We have measured the dynamic spectrum, the two-dimensional correlation function, and the secondary spectrum. In those observations with high signal-to-noise ratio ($S/N\ge100$), we have detected the scintillation arcs, which are rarely observable using such a small telescope. The sub-microsecond scale width of the scintillation arc indicates that the transverse scale of structures on scattering screen is as compact as AU size. Our monitoring has also shown that both the scintillation bandwidth, timescale, and arc curvature of PSR B0355$+$54 were varying temporally. The plausible explanation would need to invoke multiple-scattering-screen or multiple-scattering-structure scenario that different screens or ray paths dominate the scintillation process at different epochs.
Di Li, Pei Wang, Lei Qian, Marko Krco, Alex Dunning, Peng Jiang, Youling Yue, Chenjin Jin, Yan Zhu, Zhichen Pan, Rendong Nan
Feb 11, 2018·astro-ph.IM·PDF Having achieved 'first-light' right before the opening ceremony on September 25, 2016, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is being busily commissioned. Its innovative design requires ~1000 points to be measured and driven instead of just the two axes of motion, e.g. Azimuth and Elevation for most of the conventional antennae, to realize pointing and tracking. We have devised a survey plan to utilized the full sensitivity of FAST, while minimizing the complexities in operation the system. The 19-beam L band focal plan array will be rotated to specific angles and taking continuous data streams while the surface shape and the focal cabin stay fixed. Such a survey will cover the northern sky in about 220 full days. Our aim is to obtain data for pulsar search, HI (neutral hydrogen) galaxies, HI imaging, and radio transients, simultaneously, through multiple backends. These data sets could be a significant contribution to all related fields in radio astronomy and remain relevant for decades.
Weiwei Zhu, Di Li, Rui Luo, Chenchen Miao, Bing Zhang, Laura Spitler, Duncan Lorimer, Michael Kramer, David Champion, Youling Yue, Andrew Cameron, Marilyn Cruces, Ran Duan, Yi Feng, Jun Han, George Hobbs, Chenhui Niu, Jiarui Niu, Zhichen Pan, Lei Qian, Dai Shi, Ningyu Tang, Pei Wang, Hongfeng Wang, Mao Yuan, Lei Zhang, Xinxin Zhang, Shuyun Cao, Li Feng, Hengqian Gan, Long Gao, Xuedong Gu, Minglei Guo, Qiaoli Hao, Lin Huang, Menglin Huang, Peng Jiang, Chengjin Jin, Hui Li, Qi Li, Qisheng Li, Hongfei Liu, Gaofeng Pan, Bo Peng, Hui Qian, Xiangwei Shi, Jinyuo Song, Liqiang Song, Caihong Sun, Jinghai Sun, Hong Wang, Qiming Wang, Yi Wang, Xiaoyao Xie, Jun Yan, Li Yang, Shimo Yang, Rui Yao, Dongjun Yu, Jinglong Yu, Chengmin Zhang, Haiyan Zhang, Shuxin Zhang, Xiaonian Zheng, Aiying Zhou, Boqin Zhu, Lichun Zhu, Ming Zhu, Wenbai Zhu, Yan Zhu
Apr 29, 2020·astro-ph.HE·PDF We report the discovery of a highly dispersed fast radio burst, FRB~181123, from an analysis of $\sim$1500~hr of drift-scan survey data taken using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The pulse has three distinct emission components, which vary with frequency across our 1.0--1.5~GHz observing band. We measure the peak flux density to be $>0.065$~Jy and the corresponding fluence $>0.2$~Jy~ms. Based on the observed dispersion measure of 1812~cm$^{-3}$~pc, we infer a redshift of $\sim 1.9$. From this, we estimate the peak luminosity and isotropic energy to be $\lesssim 2\times10^{43}$~erg~s$^{-1}$ and $\lesssim 2\times10^{40}$~erg, respectively. With only one FRB from the survey detected so far, our constraints on the event rate are limited. We derive a 95\% confidence lower limit for the event rate of 900 FRBs per day for FRBs with fluences $>0.025$~Jy~ms. We performed follow-up observations of the source with FAST for four hours and have not found a repeated burst. We discuss the implications of this discovery for our understanding of the physical mechanisms of FRBs.
Jiguang Lu, Bo Peng, Renxin Xu, Meng Yu, Shi Dai, Weiwei Zhu, Ye-Zhao Yu, Peng Jiang, Youling Yue, Lin Wang, FAST Collaboration
Mar 15, 2019·astro-ph.HE·PDF With the largest dish Five-hundred-meter Aperture Spherical radio Telescope (FAST), both the mean and single pulses of PSR B2016$+$28, especially including the single-pulse structure, are investigated in detail in this study. The mean pulse profiles at different frequencies can be well fitted in a conal model, and the peak separation of intensity-dependent pulse profiles increases with intensity. The integrated pulses are obviously frequency dependent (pulse width decreases by $\sim\,20\%$ as frequency increases from 300 MHz to 750 MHz), but the structure of single pulses changes slightly (the corresponding correlation scale decreases by only $\sim\,1\%$). This disparity between mean and single pulses provides independent evidence for the existence of the RS-type vacuum inner gap, indicating a strong bond between particles on the pulsar surface. Diffused drifting sub-pulses are analyzed. The results show that the modulation period along pulse series ($P_3$) is positively correlated to the separation between two adjacent sub-pulses ($P_2$). This correlation may hint a rough surface on the pulsar, eventually resulting in the irregular drift of sparks. All the observational results may have significant implications in the dynamics of pulsar magnetosphere and are discussed extensively in this paper.
Shanping You, Pei Wang, Xuhong Yu, Xiaoyao Xie, Di Li, Zhijie Liu, Zhichen Pan, Youling Yue, Lei Qian, Bin Zhang, Zonghao Chen
Oct 25, 2021·astro-ph.IM·PDF We developed a GPU based single-pulse search pipeline (GSP) with candidate-archiving database. Largely based upon the infrastructure of Open source pulsar search and analysis toolkit (PRESTO), GSP implements GPU acceleration of the de-dispersion and integrates a candidate-archiving database. We applied GSP to the data streams from the commensal radio astronomy FAST survey (CRAFTS), which resulted in a quasi-real-time processing. The integrated candidate database facilitates synergistic usage of multiple machine-learning tools and thus improves efficient identification of radio pulsars such as rotating radio transients (RRATs) and Fast Radio Bursts (FRBs). We first tested GSP on pilot CRAFTS observations with the FAST Ultra-Wide Band (UWB) receiver. GSP detected all pulsars known from the the Parkes multibeam pulsar survey in the respective sky area covered by the FAST-UWB. GSP also discovered 13 new pulsars. We measured the computational efficiency of GSP to be ~120 times faster than the original PRESTO and ~60 times faster than a MPI-parallelized version of PRESTO.
Mao Yuan, Weiwei Zhu, Haiyan Zhang, Shijie Huang, Mengyao Xue, Di Li, Youling Yue, Pei Wang, 1 Jiarui Niu, Yuxuan Hu, Chunjiang Li, Chenchen Miao, Yu Wang, Lingqi Meng, Bo Peng
May 18, 2022·astro-ph.IM·PDF Radio frequency interference (RFI) is a significant challenge faced by today's radio astronomers. While most past efforts were devoted to cleaning the RFI from the data, we develop a novel method for categorizing and cataloguing RFI for forensic purpose. We present a classifier that categorizes RFI into different types based on features extracted using Principal Component Analysis (PCA) and Fourier analysis. The classifier can identify narrowband non-periodic RFI above 2 sigma, narrowband periodic RFI above 3 sigma, and wideband impulsive RFI above 5 sigma with F1 scores between 0.87 and 0.91 in simulation. This classifier could be used to identify the sources of RFI as well as to clean RFI contamination (particularly in pulsar search). In the long-term analysis of the categorized RFI, we found a special type of drifting periodic RFI that is detrimental to pulsar search. We also found evidences of an increased rate of impulsive RFI when the telescope is pointing toward the cities. These results demonstrate this classifier's potential as a forensic tool for RFI environment monitoring of radio telescopes.