The discovery of ubiquitous habitable extrasolar planets,combined with revolutionary advances in instrumentation and observational capabilities,has ushered in a renaissance in the search for extraterrestrial intellige...The discovery of ubiquitous habitable extrasolar planets,combined with revolutionary advances in instrumentation and observational capabilities,has ushered in a renaissance in the search for extraterrestrial intelligence(SETI).Large scale SETI activities are now underway at numerous international facilities.The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-aperture radio telescope in the world,and is well positioned to conduct sensitive searches for radio emission indicative of exo-intelligence.SETI is one of the five key science goals specified in the original FAST project plan.A collaboration with the Breakthrough Listen Initiative was initiated in 2016 with a joint statement signed both by Dr.Jun Yan,the then director of National Astronomical Observatories,Chinese Academy of Sciences(NAOC),and Dr.Peter Worden,Chairman of the Breakthrough Prize Foundation.In this paper,we highlight some of the unique features of FAST that will allow for novel SETI observations.We identify and describe three different signal types indicative of a technological source,namely,narrow band,wide-band artificially dispersed and modulated signals.Here,we propose observations with FAST to achieve sensitivities never before explored.For nearby exoplanets,such as TESS targets,FAST will be sensitive to an EIRP of 1.9×1011 W,well within the reach of current human technology.For the Andromeda Galaxy,FAST will be able to detect any Kardashev type II or more advanced civilization there.展开更多
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 i...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.展开更多
We have conducted a comprehensive investigation into the bright single pulse emission from PSR B1133+16using the Giant Metrewave Radio Telescope.High time resolution data(61μs)were obtained at a center frequency of 3...We have conducted a comprehensive investigation into the bright single pulse emission from PSR B1133+16using the Giant Metrewave Radio Telescope.High time resolution data(61μs)were obtained at a center frequency of 322 MHz with a bandwidth of 32 MHz over a continuous observation period of 7.45 hr.A total of 1082 bright pulses were sporadically detected with peak flux densities ranging from 10 to 23 times stronger than the average pulse profile.However,no giant pulse-like emission with a relative pulse energy larger than 10 and extremely short duration was detected,indicating that these bright pulses cannot be categorized as giant pulse emission.The majority of these bright pulses are concentrated in pulse phases at both the leading and trailing windows of the average pulse profile,with an occurrence ratio of approximately 2.74.The pulse energy distribution for all individual pulses can be described by a combination of two Gaussian components and a cutoff power-law with an index of α=-3.2.An updated nulling fraction of 15.35%±0.45% was determined from the energy distribution.The emission of individual pulses follows a log-normal distribution in peak flux density ratio.It is imperative that regular phase drifting in bright pulse sequence is identified in both the leading and trailing components for the first time.Possible physical mechanisms are discussed in detail to provide insights into these observations.展开更多
文摘The discovery of ubiquitous habitable extrasolar planets,combined with revolutionary advances in instrumentation and observational capabilities,has ushered in a renaissance in the search for extraterrestrial intelligence(SETI).Large scale SETI activities are now underway at numerous international facilities.The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-aperture radio telescope in the world,and is well positioned to conduct sensitive searches for radio emission indicative of exo-intelligence.SETI is one of the five key science goals specified in the original FAST project plan.A collaboration with the Breakthrough Listen Initiative was initiated in 2016 with a joint statement signed both by Dr.Jun Yan,the then director of National Astronomical Observatories,Chinese Academy of Sciences(NAOC),and Dr.Peter Worden,Chairman of the Breakthrough Prize Foundation.In this paper,we highlight some of the unique features of FAST that will allow for novel SETI observations.We identify and describe three different signal types indicative of a technological source,namely,narrow band,wide-band artificially dispersed and modulated signals.Here,we propose observations with FAST to achieve sensitivities never before explored.For nearby exoplanets,such as TESS targets,FAST will be sensitive to an EIRP of 1.9×1011 W,well within the reach of current human technology.For the Andromeda Galaxy,FAST will be able to detect any Kardashev type II or more advanced civilization there.
基金partially supported by the National Natural Science Foundation of China(NSFC,Grant Nos.U1631106,U1838109,12133004,12041304 and 12041301)the National SKA Program of China(2020SKA0120100)+5 种基金supported by the 2021 project Xinjiang Uygur Autonomous Region of China for Tianshan elitessupported by the Natural Science Foundation of Shanxi Province(20210302123083)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2021L470)supported by the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2021L480)supported by the CAS Jianzhihua projectsupported by the 2018 project of Xinjiang Uygur Autonomous Region of China for flexibly fetching upscale talents。
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.
基金supported by the open project of the Key Laboratory in Xinjiang Uygur Autonomous Region of China(No.2023D04058)the Major Science and Technology Program of Xinjiang Uygur Autonomous Region(No.2022A03013-1)+12 种基金the National Key Research and Development Program of China(No.2022YFC2205203)the National Natural Science Foundation of China(NSFC,Grant Nos.12303053,12288102,11988101,U1838109,12041304,12041301,11873080,12133004,12203094 and U1631106)the Chinese Academy of Sciences Foundation of the young scholars of western(No.2020XBQNXZ-019)the National SKA Program of China(2020SKA0120100)Z.G.W.is supported by the Tianshan Talent Training Program(NO.2023TSYCCX0100)2021 project Xinjiang Uygur autonomous region of China for Tianshan elitesthe Youth Innovation Promotion Association of CAS under No.2023069J.L.C.is supported by the Natural Science Foundation of Shanxi Province(20210302123083)H.W.is supported by the ScientificTechnological Innovation Programs of Higher Education Institutions in Shanxi(grant No.2021L480)W.M.Y.is supported by the CAS Jianzhihua projectH.G.W.is supported by the 2018 project of Xinjiang Uygur autonomous region of China for flexibly fetching in upscale talentsW.H.is supported by the CAS Light of West China Program No.2019-XBQNXZ-B-019。
文摘We have conducted a comprehensive investigation into the bright single pulse emission from PSR B1133+16using the Giant Metrewave Radio Telescope.High time resolution data(61μs)were obtained at a center frequency of 322 MHz with a bandwidth of 32 MHz over a continuous observation period of 7.45 hr.A total of 1082 bright pulses were sporadically detected with peak flux densities ranging from 10 to 23 times stronger than the average pulse profile.However,no giant pulse-like emission with a relative pulse energy larger than 10 and extremely short duration was detected,indicating that these bright pulses cannot be categorized as giant pulse emission.The majority of these bright pulses are concentrated in pulse phases at both the leading and trailing windows of the average pulse profile,with an occurrence ratio of approximately 2.74.The pulse energy distribution for all individual pulses can be described by a combination of two Gaussian components and a cutoff power-law with an index of α=-3.2.An updated nulling fraction of 15.35%±0.45% was determined from the energy distribution.The emission of individual pulses follows a log-normal distribution in peak flux density ratio.It is imperative that regular phase drifting in bright pulse sequence is identified in both the leading and trailing components for the first time.Possible physical mechanisms are discussed in detail to provide insights into these observations.