We report the properties of more than 800 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 25th-28th in a series of four papers.In this fourth paper of the series,we present a systematic search of the spin period and linear acceleration of the source object from both 996 individual pulse peaks and the dedispersed time series.No credible spin period was found from this data set.We rule out the presence of significant periodicity in the range between 1 ms and 100 s with a pulse duty cycle＜0.49±0.08(when the profile is defined by a von-Mises function,not a boxcar function)and linear acceleration up to 300 m s-2 in each of the four one-hour observing sessions,and up to 0.6 m s-2 in all 4 days.These searches contest theoretical scenarios involving a 1 ms-100 s isolated magnetar/pulsar with surface magnetic field＜1015 G and a small duty cycle(such as in a polar-cap emission mode)or a pulsar with a companion star or black hole up to 100 M⊙ and Pb＞10 hr.We also perform a periodicity search of the fine structures and identify 53 unrelated millisecond-timescale"periods"in multi-components with the highest significance of 3.9σ.The"periods"recovered from the fine structures are neither consistent nor harmonically related.Thus they are not likely to come from a spin period.We caution against claiming spin periodicity with significance below～4σ with multi-components from one-off FRBs.We discuss the implications of our results and the possible connections between FRB multi-components and pulsar microstructures.

Jia-Rui Niu;Wei-Wei Zhu;Bing Zhang;Mao Yuan;De-Jiang Zhou;Yong-Kun Zhang;Jin-Chen Jiang;J.L.Han;Di Li;Ke-Jia Lee;Pei Wang;Yi Feng;Dong-Zi Li;Rui Luo;Fa-Yin Wang;Zi-Gao Dai;Chen-Chen Miao;Chen-Hui Niu;Heng Xu;Chun-Feng Zhang;Wei-Yang Wang;Bo-Jun Wang;Jiang-Wei Xu

National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China;Institute for Frontier in Astronomy and Astrophysics,Beijing Normal University,Beijing 102206,China;Department of Physics and Astronomy,University of Nevada,Las Vegas,NV 89154,USA;Department of Astronomy,Peking University,Beijing 100871,China;NAOC-UKZN Computational Astrophysics Centre,University of KwaZulu-Natal,Durban 4000,South Africa;Kavli Institute for Astronomy and Astrophysics,Peking University,Beijing 100871,China;Research Center for Intelligent Computing Platforms,Zhejiang Laboratory,Hangzhou 311100,China;Cahill Center for Astronomy and Astrophysics,MC 249-17 California Institute of Technology,Pasadena CA 91125,USA;CSIRO Space and Astronomy,PO Box 76,Epping,NSW 1710,Australia;School of Astronomy and Space Science,Nanjing University,Nanjing 210093,China;Key Laboratory of Modern Astronomy and Astrophysics,Nanjing University,Ministry of Education,Nanjing 210093,China;Department of Astronomy,University of Science and Technology of China,Hefei 230026,China

天文和天体物理学研究

[1]Jia-Rui Niu;Wei-Wei Zhu;Bing Zhang;Mao Yuan;De-Jiang Zhou;Yong-Kun Zhang;Jin-Chen Jiang;J.L.Han;Di Li;Ke-Jia Lee;Pei Wang;Yi Feng;Dong-Zi Li;Rui Luo;Fa-Yin Wang;Zi-Gao Dai;Chen-Chen Miao;Chen-Hui Niu;Heng Xu;Chun-Feng Zhang;Wei-Yang Wang;Bo-Jun Wang;Jiang-Wei Xu-.FAST Observations of an Extremely Active Episode of FRB 20201124A.Ⅳ.Spin Period Search)[J].天文和天体物理学研究,2022(12):99-122

20201124A,dedispersed,boxcar,magnetar,harmonically,FRBs

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