分类： 天文学 >> 天体物理学 提交时间： 2023-12-17
Yuxiao Wu
Zhichen Pan
Lei Qian
Scott Ransom
BoJun Wang
Zhen Yan
Jintao Luo
Liyun Zhang
Minghui Li
Dejiang Yin
Baoda Li
Yifeng Li
Yinfeng Dai
Yaowei Li
Xinnan Zhang
Tong Liu
Yu Pan
摘要： We present the discovery of three pulsars in Globular Cluster M15 (NGC 7078) by the Five-hundred-meter Aperture Spherical radio Telescope (FAST).In the three pulsars, PSR~J2129+1210J (M15J) is a millisecond pulsar with a spinning period of 11.84 ms and a dispersion measure of 66.68 pc cm$^{-3}$.Both PSR~J2129+1210K and L (M15K and L) are long period pulsars with spinning periods of 1928 ms and 3961 ms, respectively,while M15L is the GC pulsar with the longest spinning period till now.The discoveries of M15K and L support the theory that core-collapsed Globular Clusters may contain partially recycled long period pulsars citep{verbunt-2014-slowpulsar}.With the same dataset, the timing solutions of M15A to H were updated,and the timing parameter P1 of M15F is different from the previous results, which is approximately 0.027$ times 10^{-18} ss^{-1}$ from our work and $0.032 times 10^{-18} ss^{-1}$ from Anderson's citep{anderson-1993}.As predicted by Rodolfi et al. citep{ridolfi-2017},the luminosity of M15C kept decreasing and the latest detection in our dataset is on December 20$^{ rm th}$, 2022.We also detected M15I for one more time.The different barycentric spin periods indicate that this pulsar should locate in a binary system,manifesting itself as the exceptional one in such a core-collapsing GC.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Lei Qian
Zhichen Pan
Hongfei Liu
Hengqian Gan
Jinglong Yu
Lei Zhao
Jiguang Lu
Cun Sun
Jingye Yan
Peng Jiang
摘要： We present the estimation of the solar observation with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). For both the quite Sun and the Sun with radio bursts, when pointing directly to the Sun, the total power received by FAST would be out of the safe operational range of the signal chain, even resulting in the damage to the receiver. As a conclusion, the Sun should be kept at least $\sim 2^{\circ}$ away from the main beam during the observing at $\sim 1.25 {\ \rm GHz}$. The separation for lower frequency should be larger. For simplicity, the angular separation between the FAST beam and the Sun is suggested to be $\sim 5^{\circ}$ for observations on 200 MHz or higher bands.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Lei Qian
Zhichen Pan
Hongfei Liu
Hengqian Gan
Jinglong Yu
Lei Zhao
Jiguang Lu
Cun Sun
Jingye Yan
Peng Jiang
摘要： We present the estimation of the solar observation with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). For both the quite Sun and the Sun with radio bursts, when pointing directly to the Sun, the total power received by FAST would be out of the safe operational range of the signal chain, even resulting in the damage to the receiver. As a conclusion, the Sun should be kept at least $\sim 2^{\circ}$ away from the main beam during the observing at $\sim 1.25 {\ \rm GHz}$. The separation for lower frequency should be larger. For simplicity, the angular separation between the FAST beam and the Sun is suggested to be $\sim 5^{\circ}$ for observations on 200 MHz or higher bands.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Zhichen Pan
Lei Qian
Xiaoyun Ma
Kuo Liu
Lin Wang
Jintao Luo
Zhen Yan
Scott Ransom
Duncan Lorimer
Di Li
Peng Jiang
摘要： We present the discovery of 24 pulsars in 15 Globular Clusters (GCs) using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These include the first pulsar discoveries in M2, M10, and M14. Most of the new systems are either confirmed or likely members of binary systems. M53C, NGC6517H and I are the only three pulsars confirmed to be isolated. M14A is a black widow pulsar with an orbital period of 5.5 hours and a minimum companion mass of 0.016 \Ms. M14E is an eclipsing binary pulsar with an orbital period of 20.3 hours. With the other 8 discoveries that have been reported elsewhere, in total 32 GC pulsars have been discovered by FAST so far. In addition, We detected M3A twice. This was enough to determine that it is a black widow pulsar with an orbital period of 3.3 hours and a minimum companion mass of 0.0125 \Ms.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Shanping You
Pei Wang
Xuhong Yu
Xiaoyao Xie
Di Li
Zhijie Liu
Zhichen Pan
Youling Yue
Lei Qian
Bin Zhang
Zonghao Chen
摘要： 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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We present a pulsar candidate identification and confirmation procedure based on a position-switch mode during the pulsar search observations. This method enables the simultaneous search and confirmation of a pulsar in a single observation, by utilizing the different spatial features of a pulsar signal and a radio frequency interference (RFI). Based on this method, we performed test pulsar search observations in globular clusters M3, M15, and M92. We discovered and confirmed a new pulsar, M3F, and detected the known pulsars M3B, M15 A to G (except C), and M92A.
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