We derive the gravitational-wave(GW)strain upper limits from resolvable supermassive black-hole binaries using the data from the Five-hundred-meter Aperture Spherical radio Telescope,in the context of the Chinese Puls...We derive the gravitational-wave(GW)strain upper limits from resolvable supermassive black-hole binaries using the data from the Five-hundred-meter Aperture Spherical radio Telescope,in the context of the Chinese Pulsar Timing Array project.We focus on circular orbits in theμHz GW frequency band between 10^(−7)and 3×10^(−6)Hz.This frequency band is higher than the traditional pulsar timing array band and is less explored.We used the data of the millisecond pulsar PSR J1713+5307 observed between 2019 August and 2021 April.A dense observation campaign was carried out in 2020 September to allow for theμHz band coverage.Our sky-averaged continuous source upper limit at the 95%confidence level at 1μHz is 1.26×10^(−12),while the same limit in the direction of the pulsar is 4.77×10^(−13).展开更多
A time-synchronization strategy for packetized transmission of target position about a large-aperture telescope observation control system has been proposed in this study.Compared with the existing telescope tracking ...A time-synchronization strategy for packetized transmission of target position about a large-aperture telescope observation control system has been proposed in this study.Compared with the existing telescope tracking strategy,the target position packing and sending strategy based on the time synchronization method proposed in this paper has the advantages of high stability and reliability.First,the telescope tracking observation control method was elaborated in this paper,including the motion pattern during telescope tracking.Then,the strategy for packetizes transmission of target positions based on time-synchronization is established and lists the detailed steps.Finally,the performance of the tracking strategy is verified using the 2.5 m telescope for the simulated uniform speed star and the blind-tracking fixed star HIP 31216,respectively.The test results show that the accuracy root mean square of the tracking strategy proposed in this paper is less than 0".02 at 30 minutes,and the performance is much better than the design requirement of 0".3.The most important advantage of this tracking strategy is that the telescope can guarantee normal tracking for a certain period of time even if the hardware or software of the host computer is abnormal.展开更多
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 Ju...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.展开更多
基金supported by the FAST Key projectsupported by the National SKA Program of China (2020SKA0120100)+4 种基金the National Natural Science Foundation of China (NSFC, Grant Nos. 12041303 and 12250410246)the CAS-MPG LEGACY projectfunding from the Max-Planck Partner Groupsupport from the XPLORER PRIZE and 20 yr long-term support from Dr. Guojun Qiaosupported by Major Science and Technology Program of Xinjiang Uygur Autonomous Region No. 2022A03013-4
文摘We derive the gravitational-wave(GW)strain upper limits from resolvable supermassive black-hole binaries using the data from the Five-hundred-meter Aperture Spherical radio Telescope,in the context of the Chinese Pulsar Timing Array project.We focus on circular orbits in theμHz GW frequency band between 10^(−7)and 3×10^(−6)Hz.This frequency band is higher than the traditional pulsar timing array band and is less explored.We used the data of the millisecond pulsar PSR J1713+5307 observed between 2019 August and 2021 April.A dense observation campaign was carried out in 2020 September to allow for theμHz band coverage.Our sky-averaged continuous source upper limit at the 95%confidence level at 1μHz is 1.26×10^(−12),while the same limit in the direction of the pulsar is 4.77×10^(−13).
基金supported by the National Natural Science Foundation of China(grant Nos.11973065 and U1931207)Jiangsu Funding Program for Excellent Postdoctoral Talent(2022ZB449)to this paper+1 种基金financial support from China Scholarship Council(No.CSC201904910254)Chinese Academy of Sciences Public Study Abroad Fund(Lingzhe Xu)。
文摘A time-synchronization strategy for packetized transmission of target position about a large-aperture telescope observation control system has been proposed in this study.Compared with the existing telescope tracking strategy,the target position packing and sending strategy based on the time synchronization method proposed in this paper has the advantages of high stability and reliability.First,the telescope tracking observation control method was elaborated in this paper,including the motion pattern during telescope tracking.Then,the strategy for packetizes transmission of target positions based on time-synchronization is established and lists the detailed steps.Finally,the performance of the tracking strategy is verified using the 2.5 m telescope for the simulated uniform speed star and the blind-tracking fixed star HIP 31216,respectively.The test results show that the accuracy root mean square of the tracking strategy proposed in this paper is less than 0".02 at 30 minutes,and the performance is much better than the design requirement of 0".3.The most important advantage of this tracking strategy is that the telescope can guarantee normal tracking for a certain period of time even if the hardware or software of the host computer is abnormal.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11873080,12041304,U1838109 and 12041301)the CAS Jianzhihua project+3 种基金supported by the Key Laboratory of Xinjiang Uygur Autonomous Region No.2020D04049the National SKA Program of China No.2020SKA0120200the 2018 Project of Xinjiang Uygur Autonomous Region of China for Flexibly Fetching Upscale Talentspartly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)。
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.
