Quasi-periodic oscillation(QPO)signals are discovered in some fast radio bursts(FRBs)such as FRB 20191221A,as well as in the X-ray burst associated with the galactic FRB from SGR 1935+2154.We revisit the intermediatef...Quasi-periodic oscillation(QPO)signals are discovered in some fast radio bursts(FRBs)such as FRB 20191221A,as well as in the X-ray burst associated with the galactic FRB from SGR 1935+2154.We revisit the intermediatefield FRB model where the radio waves are generated as fast-magnetosonic waves through magnetic reconnection near the light cylinder.The current sheet in the magnetar wind is compressed by a low frequency pulse emitted from the inner magnetosphere to trigger magnetic reconnection.By incorporating the wave dynamics of the magnetosphere,we demonstrate how the FRB frequency,the single pulse width,and luminosity are determined by the period,magnetic field,QPO frequency and quake energetics of the magnetar.We find that this model can naturally and self-consistently interpret the X-ray/radio event from SGR 1935+2154 and the QPO in FRB20191221A.It can also explain the observed wide energy range of repeating FRBs in a narrow bandwidth.展开更多
The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray varia...The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5-4 keV,at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions.EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard.In this paper,the science objectives of the EP mission are presented.EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales.Among them,fast extragalactic transients will be surveyed systematically in soft X-rays,which includeγ-ray bursts and their variants,supernova shock breakouts,and the predicted X-ray transients associated with binary neutron star mergers.EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei,possibly at an early phase of the flares for some.EP will monitor the variability and outbursts of X-rays from white dwarfs,neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments,and is expected to discover new objects.A large sample of stellar X-ray flares will also be detected and characterised.In the era of multi-messenger astronomy,EP has the potential of detecting the possible X-ray counterparts of gravitational wave events,neutrino sources,and ultra-high energyγ-ray and cosmic ray sources.EP is expected to help advance the studies of extreme objects and phenomena revealed in the dynamic X-ray universe,and their underlying physical processes.Besides EP's strength in time-domain science,its follow-up telescope,with excellent performance,will also enable advances in many areas of X-ray astronomy.展开更多
Fast radio bursts(FRBs)are bright,millisecond-duration radio emissions originating from cosmological distances.In this study,we report multi-year polarization measurements of four repeating FRBs initially discovered b...Fast radio bursts(FRBs)are bright,millisecond-duration radio emissions originating from cosmological distances.In this study,we report multi-year polarization measurements of four repeating FRBs initially discovered by the Canadian Hydrogen Intensity Mapping Experiment(CHIME):FRBs 20190117A,20190208A,20190303A,and 20190417A.We observed the four repeating FRBs with the Five-hundred-meter Aperture Spherical Radio Telescope(FAST),detecting a total of 66 bursts.Two bursts from FRB 20190417A exhibit a circular polarization signal-to-noise ratio greater than 7,with the highest circular polarization fraction recorded at 35.7%.While the bursts from FRBs 20190208A and 20190303A are highly linearly polarized,those from FRBs 20190117A and 20190417A show depolarization due to multi-path propagation,with σ_(RM)=2.78±0.05and 5.19±0.09 rad m^(-2),respectively.The linear polarization distributions among five repeating FRBs—FRBs 20190208A,20190303A,20201124A,20220912A,and 20240114A—are nearly identical but show distinct differences from those of nonrepeating FRBs.FRBs 20190117A,20190303A,and 20190417A exhibit substantial rotation measure(RM)variations between bursts,joining other repeating FRBs in this behavior.Combining these findings with published results,64% of repeating FRBs show RM variations greater than 50 rad m^(-2),and 21% exhibit RM reversals.A significant proportion of repeating FRBs reside in a dynamic magneto-ionic environment.The structure function of RM variations shows a power-law index of γ~(0-0.8),corresponding to a shallow power spectrum α=-(γ+2)~-(2.0-2.8)of turbulence,if the RM variations are attributed to turbulence.This suggests that the variations are dominated by small-scale RM density fluctuations.We perform K-S tests to compare the RMs of repeating and non-repeating FRBs,which reveal a marginal dichotomy in the distribution of their RMs.We caution that the observed dichotomy may be due to the small sample size and selection biases.展开更多
The Wide Field Survey Telescope(WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China(USTC) and the Purple Mountain Observatory(PMO). It is equipped w...The Wide Field Survey Telescope(WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China(USTC) and the Purple Mountain Observatory(PMO). It is equipped with a 2.5-meter diameter primary mirror, an active optics system, and a mosaic CCD camera with 0.73 gigapixels on the primary focal plane for highquality image capture over a 6.5-square-degree field of view. The installation of WFST near the summit of Saishiteng mountain in the Lenghu region is scheduled in summer of 2023, and the operation is planned to start three months later. WFST will scan the northern sky in four optical bands(u, g, r and i) at cadences from hourly/daily in the deep high-cadence survey(DHS) program, to semi-weekly in the wide field survey(WFS) program. During a photometric night, a nominal 30 s exposure in the WFS program will reach a depth of 22.27, 23.32, 22.84, and 22.31(AB magnitudes) in these four bands, respectively, allowing for the detection of a tremendous amount of transients in the low-z universe and a systematic investigation of the variability of Galactic and extragalactic objects. In the DHS program, intranight 90 s exposures as deep as 23(u) and 24 mag(g), in combination with target of opportunity follow-ups, will provide a unique opportunity to explore energetic transients in demand for high sensitivities, including the electromagnetic counterparts of gravitational wave events, supernovae within a few hours of their explosions,tidal disruption events and fast, luminous optical transients even beyond redshift of unity. In addition, the final 6-year co-added images, anticipated to reach g■25.8 mag in WFS or 1.5 mags deeper in DHS, will be of fundamental importance to general Galactic and extragalactic science. The highly uniform legacy surveys of WFST will serve as an indispensable complement to those of the Vera C. Rubin Observatory's Legacy Survey of Space and Time(LSST) that monitors the southern sky.展开更多
The LIGO detection of gravitational waves(GW) from merging black holes in 2015 marked the beginning of a new era in observational astronomy. The detection of an electromagnetic signal from a GW source is the critical ...The LIGO detection of gravitational waves(GW) from merging black holes in 2015 marked the beginning of a new era in observational astronomy. The detection of an electromagnetic signal from a GW source is the critical next step to explore in detail the physics involved. The Antarctic Survey Telescopes(AST3),located at Dome A, Antarctica, is uniquely situated for rapid response time-domain astronomy with its continuous night-time coverage during the austral winter. We report optical observations of the GW source(GW 170817) in the nearby galaxy NGC 4993 using AST3. The data show a rapidly fading transient at around 1 day after the GW trigger, with the i-band magnitude declining from 17:23 ± 0:13 magnitude to 17:72 ± 0:09 magnitude in ~1:8 h. The brightness and time evolution of the optical transient associated with GW 170817 are broadly consistent with the predictions of models involving merging binary neutron stars. We infer from our data that the merging process ejected about ~10^(-2) solar mass of radioactive material at a speed of up to 30% the speed of light.展开更多
In 2007, a very bright radio pulse was identified in the archival data of the Parkes Telescope in Australia, marking the beginning of a new research branch in astrophysics. In 2013, this kind of millisecond bursts wit...In 2007, a very bright radio pulse was identified in the archival data of the Parkes Telescope in Australia, marking the beginning of a new research branch in astrophysics. In 2013, this kind of millisecond bursts with extremely high brightness temperature takes a unified name, fast radio burst(FRB). Over the first few years, FRBs seemed very mysterious because the sample of known events was limited. With the improvement of instruments over the last five years, hundreds of new FRBs have been discovered.The field is now undergoing a revolution and understanding of FRB has rapidly increased as new observational data increasingly accumulate. In this review, we will summarize the basic physics of FRBs and discuss the current research progress in this area.We have tried to cover a wide range of FRB topics, including the observational property, propagation effect, population study,radiation mechanism, source model, and application in cosmology. A framework based on the latest observational facts is now under construction. In the near future, this exciting field is expected to make significant breakthroughs.展开更多
Fast radio bursts(FRBs)are millisecond-duration flashes of Giga-Hertz radio emission.Since Lorimer and his collaborators[1]claimed their discovery in 2007,FRBs have remained one of the hottest fields in astronomy.In t...Fast radio bursts(FRBs)are millisecond-duration flashes of Giga-Hertz radio emission.Since Lorimer and his collaborators[1]claimed their discovery in 2007,FRBs have remained one of the hottest fields in astronomy.In this research field,the physical origin,radiation mechanism and ambient environment are three of the key questions that have been unsolved[2,3].展开更多
Short-duration gamma-ray bursts (SGRBs) are mysterious gamma-ray flashes with durations less than two seconds, which occur at the cosmological distances. Some of them usually not only have very tenuous medium gases an...Short-duration gamma-ray bursts (SGRBs) are mysterious gamma-ray flashes with durations less than two seconds, which occur at the cosmological distances. Some of them usually not only have very tenuous medium gases and old host galaxies but also are in the outskirts of the galaxies, suggesting an origin of binary neutron star (NS) mergers (1)This origin was confirmed undoubtedly thanks to the discoveries of a gravitational wave event namedGW170817 and its electromagnetic counterparts (an SGRB, a multiwavelengthkilo-nova, and a broadband afterglow) [2].展开更多
Gamma-ray bursts(GRBs)are flashes of ganima-rays occurring at cosmological distances(for a recent review see^([1])).They are divided into two classes based on their prompt emission durations:short-duration(<2 secon...Gamma-ray bursts(GRBs)are flashes of ganima-rays occurring at cosmological distances(for a recent review see^([1])).They are divided into two classes based on their prompt emission durations:short-duration(<2 seconds)hard-spectrum bursts and long-duration soft-spectmm bursts(>2 seconds).The observations(including discoveries of both the gravitational wave event GW170817 from an inspiral of two neutron stars and its electromagnetic counterparts)indicate that long-duration GRBs result from core collapses of massive stars and short-duration GRBs are produced from mergers of neutron star-neutron star binaries or black hole-neutron star binaries.展开更多
The Chinese Space Station Survey Telescope(CSST)is an upcoming Stage-IV sky survey telescope,distinguished by its large field of view(Fo V),high image quality,and multi-band observation capabilities.It can simultaneou...The Chinese Space Station Survey Telescope(CSST)is an upcoming Stage-IV sky survey telescope,distinguished by its large field of view(Fo V),high image quality,and multi-band observation capabilities.It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys.The CSST is equipped with five scientific instruments,i.e.,Multi-band Imaging and Slitless Spectroscopy Survey Camera(SC),Multi-Channel Imager(MCI),Integral Field Spectrograph(IFS),Cool Planet Imaging Coronagraph(CPI-C),and THz Spectrometer(TS).Using these instruments,CSST is expected to make significant contributions and discoveries across various astronomical fields,including cosmology,galaxies and active galactic nuclei(AGN),the Milky Way and nearby galaxies,stars,exoplanets,Solar System objects,astrometry,and transients and variable sources.This review aims to provide a comprehensive overview of the CSST instruments,observational capabilities,data products,and scientific potential.展开更多
基金J.S.W.acknowledges the support from the Alexander von Humboldt FoundationX.L.is supported by NSERC,funding reference#CITA 490888–16+7 种基金the Jeffrey L.Bishop FellowshipResearch at Perimeter Institute is supported in part by the Government of Canada through the Department of Innovation,Science and Economic Development Canadathe Province of Ontario through the Ministry of Colleges and UniversitiesZ.G.D.is supported by the National Key Research and Development Program of China(Grant No.2017YFA0402600)the National SKA Program of China(Grant No.2020SKA0120300)the National Natural Science Foundation of China(Grant No.11833003)X.F.W.is supported by the National Natural Science Foundation of China(Grant Nos.11725314,12041306)the National SKA Program of China(2022SKA0130101)。
文摘Quasi-periodic oscillation(QPO)signals are discovered in some fast radio bursts(FRBs)such as FRB 20191221A,as well as in the X-ray burst associated with the galactic FRB from SGR 1935+2154.We revisit the intermediatefield FRB model where the radio waves are generated as fast-magnetosonic waves through magnetic reconnection near the light cylinder.The current sheet in the magnetar wind is compressed by a low frequency pulse emitted from the inner magnetosphere to trigger magnetic reconnection.By incorporating the wave dynamics of the magnetosphere,we demonstrate how the FRB frequency,the single pulse width,and luminosity are determined by the period,magnetic field,QPO frequency and quake energetics of the magnetar.We find that this model can naturally and self-consistently interpret the X-ray/radio event from SGR 1935+2154 and the QPO in FRB20191221A.It can also explain the observed wide energy range of repeating FRBs in a narrow bandwidth.
基金supported by Strategic Priority Program on Space Science of Chinese Academy of Sciences,in collaboration with ESA,MPE and CNES(Grant Nos.XDA15310000,and XDA15052100)supported by the National Natural Science Foundation of China(Grant Nos.61234003,61434004,and 61504141)CAS Interdisciplinary Project(Grant No.KJZD-EW-L11-04)。
文摘The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5-4 keV,at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions.EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard.In this paper,the science objectives of the EP mission are presented.EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales.Among them,fast extragalactic transients will be surveyed systematically in soft X-rays,which includeγ-ray bursts and their variants,supernova shock breakouts,and the predicted X-ray transients associated with binary neutron star mergers.EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei,possibly at an early phase of the flares for some.EP will monitor the variability and outbursts of X-rays from white dwarfs,neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments,and is expected to discover new objects.A large sample of stellar X-ray flares will also be detected and characterised.In the era of multi-messenger astronomy,EP has the potential of detecting the possible X-ray counterparts of gravitational wave events,neutrino sources,and ultra-high energyγ-ray and cosmic ray sources.EP is expected to help advance the studies of extreme objects and phenomena revealed in the dynamic X-ray universe,and their underlying physical processes.Besides EP's strength in time-domain science,its follow-up telescope,with excellent performance,will also enable advances in many areas of X-ray astronomy.
基金supported by the National Natural Science Foundation of China(Grant Nos.12588202,12203045,12233002,12403100,12103069,and 12403042)the Leading Innovation and Entrepreneurship Team of Zhejiang Province of China(Grant No.2023R01008)+3 种基金the Key R&D Program of Zhejiang(Grant No.2024SSYS0012)supported by the National Natural Science Foundation of China(Grant No.12473047)the National SKA Program of China(Grant No.2022SKA0130100)the support from the Xinjiang Tianchi Program。
文摘Fast radio bursts(FRBs)are bright,millisecond-duration radio emissions originating from cosmological distances.In this study,we report multi-year polarization measurements of four repeating FRBs initially discovered by the Canadian Hydrogen Intensity Mapping Experiment(CHIME):FRBs 20190117A,20190208A,20190303A,and 20190417A.We observed the four repeating FRBs with the Five-hundred-meter Aperture Spherical Radio Telescope(FAST),detecting a total of 66 bursts.Two bursts from FRB 20190417A exhibit a circular polarization signal-to-noise ratio greater than 7,with the highest circular polarization fraction recorded at 35.7%.While the bursts from FRBs 20190208A and 20190303A are highly linearly polarized,those from FRBs 20190117A and 20190417A show depolarization due to multi-path propagation,with σ_(RM)=2.78±0.05and 5.19±0.09 rad m^(-2),respectively.The linear polarization distributions among five repeating FRBs—FRBs 20190208A,20190303A,20201124A,20220912A,and 20240114A—are nearly identical but show distinct differences from those of nonrepeating FRBs.FRBs 20190117A,20190303A,and 20190417A exhibit substantial rotation measure(RM)variations between bursts,joining other repeating FRBs in this behavior.Combining these findings with published results,64% of repeating FRBs show RM variations greater than 50 rad m^(-2),and 21% exhibit RM reversals.A significant proportion of repeating FRBs reside in a dynamic magneto-ionic environment.The structure function of RM variations shows a power-law index of γ~(0-0.8),corresponding to a shallow power spectrum α=-(γ+2)~-(2.0-2.8)of turbulence,if the RM variations are attributed to turbulence.This suggests that the variations are dominated by small-scale RM density fluctuations.We perform K-S tests to compare the RMs of repeating and non-repeating FRBs,which reveal a marginal dichotomy in the distribution of their RMs.We caution that the observed dichotomy may be due to the small sample size and selection biases.
基金supported by the Cyrus Chun Ying Tang Foundationsthe Major Science and Technology Project of Qinghai Province(Grant No.2019ZJ-A10)+4 种基金the 111 Project for“Observational and Theoretical Research on Dark Matter and Dark Energy”(Grant No.B23042)the National Natural Science Foundation of China(Grant Nos.11833007,12073078,12173088,12192221,12192224,12233008,12273036,and 12273113)the Frontier Scientific Research Program of Deep Space Exploration Laboratory(Grant No.2022-QYKYJH-HXYF-012)the support from the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2030002009)Project for Young Scientists in Basic Research of the Chinese Academy of Sciences(Grant No.YSBR-061),respectively。
文摘The Wide Field Survey Telescope(WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China(USTC) and the Purple Mountain Observatory(PMO). It is equipped with a 2.5-meter diameter primary mirror, an active optics system, and a mosaic CCD camera with 0.73 gigapixels on the primary focal plane for highquality image capture over a 6.5-square-degree field of view. The installation of WFST near the summit of Saishiteng mountain in the Lenghu region is scheduled in summer of 2023, and the operation is planned to start three months later. WFST will scan the northern sky in four optical bands(u, g, r and i) at cadences from hourly/daily in the deep high-cadence survey(DHS) program, to semi-weekly in the wide field survey(WFS) program. During a photometric night, a nominal 30 s exposure in the WFS program will reach a depth of 22.27, 23.32, 22.84, and 22.31(AB magnitudes) in these four bands, respectively, allowing for the detection of a tremendous amount of transients in the low-z universe and a systematic investigation of the variability of Galactic and extragalactic objects. In the DHS program, intranight 90 s exposures as deep as 23(u) and 24 mag(g), in combination with target of opportunity follow-ups, will provide a unique opportunity to explore energetic transients in demand for high sensitivities, including the electromagnetic counterparts of gravitational wave events, supernovae within a few hours of their explosions,tidal disruption events and fast, luminous optical transients even beyond redshift of unity. In addition, the final 6-year co-added images, anticipated to reach g■25.8 mag in WFS or 1.5 mags deeper in DHS, will be of fundamental importance to general Galactic and extragalactic science. The highly uniform legacy surveys of WFST will serve as an indispensable complement to those of the Vera C. Rubin Observatory's Legacy Survey of Space and Time(LSST) that monitors the southern sky.
基金supported by the National Basic Research Program(973 Program)of China(2013CB834900)the Chinese Polar Environment Comprehensive Investigation&Assessment Program(CHINARE2016-02-03)+21 种基金the National Natural Science Foundation of China(11573014,11673068,11325313,11633002,11433009,11725314)the Key Research Program of Frontier Sciences(QYZDY-SSW-SLH010,QYZDB-SSW-SYS005)the Strategic Priority Research Program"multi-waveband gravitational wave Universe”(XDB23040000)the Youth Innovation Promotion Association(2011231)of Chinese Academy of Sciencesfunds from Tsinghua UniversityNanjing UniversityBeijing Normal UniversityUniversity of New South WalesTexas A&M Universitythe Australian Antarctic Divisionthe National Collaborative Research Infrastructure Strategy(NCRIS)of Australiafunding from the Chinese Academy of Sciences through the Center for Astronomical Mega-Science and National Astronomical Observatory of China(NAOC)made possible through the use of the AAVSO Photometric All-Sky Survey(APASS)funded by the Robert Martin Ayers Sciences Fundfunded by the Australian Research Council(ARC)Centre of Excellence for Gravitational Wave Discovery(OzGrav),CE170100004the ARC Centre of Excellence for All-sky Astrophysics(CAASTRO),CE110001020the Centre of Excellence for All-sky Astrophysics in 3-Dimensions(ASTRO-3D),CE170100013provided by the Australian Astronomical Observatory(AAO)the ARC Future Fellowship grant,FT130101219supported by the National Basic Research Program(Project 973)of China(2014CB845800)the National Natural Science Foundation of China(11633001 and 11373014)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB23000000)
文摘The LIGO detection of gravitational waves(GW) from merging black holes in 2015 marked the beginning of a new era in observational astronomy. The detection of an electromagnetic signal from a GW source is the critical next step to explore in detail the physics involved. The Antarctic Survey Telescopes(AST3),located at Dome A, Antarctica, is uniquely situated for rapid response time-domain astronomy with its continuous night-time coverage during the austral winter. We report optical observations of the GW source(GW 170817) in the nearby galaxy NGC 4993 using AST3. The data show a rapidly fading transient at around 1 day after the GW trigger, with the i-band magnitude declining from 17:23 ± 0:13 magnitude to 17:72 ± 0:09 magnitude in ~1:8 h. The brightness and time evolution of the optical transient associated with GW 170817 are broadly consistent with the predictions of models involving merging binary neutron stars. We infer from our data that the merging process ejected about ~10^(-2) solar mass of radioactive material at a speed of up to 30% the speed of light.
基金supported by the National Key Research and Development Program of China (Grant No.2017YFA0402600)the National Natural Science Foundation of China (Grant Nos.11833003,U1831207,11903018,and 11851305)supported by the Natural Science Foundation for the Youth of Jiangsu Province (Grant No.BK20180324)。
文摘In 2007, a very bright radio pulse was identified in the archival data of the Parkes Telescope in Australia, marking the beginning of a new research branch in astrophysics. In 2013, this kind of millisecond bursts with extremely high brightness temperature takes a unified name, fast radio burst(FRB). Over the first few years, FRBs seemed very mysterious because the sample of known events was limited. With the improvement of instruments over the last five years, hundreds of new FRBs have been discovered.The field is now undergoing a revolution and understanding of FRB has rapidly increased as new observational data increasingly accumulate. In this review, we will summarize the basic physics of FRBs and discuss the current research progress in this area.We have tried to cover a wide range of FRB topics, including the observational property, propagation effect, population study,radiation mechanism, source model, and application in cosmology. A framework based on the latest observational facts is now under construction. In the near future, this exciting field is expected to make significant breakthroughs.
文摘Fast radio bursts(FRBs)are millisecond-duration flashes of Giga-Hertz radio emission.Since Lorimer and his collaborators[1]claimed their discovery in 2007,FRBs have remained one of the hottest fields in astronomy.In this research field,the physical origin,radiation mechanism and ambient environment are three of the key questions that have been unsolved[2,3].
文摘Short-duration gamma-ray bursts (SGRBs) are mysterious gamma-ray flashes with durations less than two seconds, which occur at the cosmological distances. Some of them usually not only have very tenuous medium gases and old host galaxies but also are in the outskirts of the galaxies, suggesting an origin of binary neutron star (NS) mergers (1)This origin was confirmed undoubtedly thanks to the discoveries of a gravitational wave event namedGW170817 and its electromagnetic counterparts (an SGRB, a multiwavelengthkilo-nova, and a broadband afterglow) [2].
文摘Gamma-ray bursts(GRBs)are flashes of ganima-rays occurring at cosmological distances(for a recent review see^([1])).They are divided into two classes based on their prompt emission durations:short-duration(<2 seconds)hard-spectrum bursts and long-duration soft-spectmm bursts(>2 seconds).The observations(including discoveries of both the gravitational wave event GW170817 from an inspiral of two neutron stars and its electromagnetic counterparts)indicate that long-duration GRBs result from core collapses of massive stars and short-duration GRBs are produced from mergers of neutron star-neutron star binaries or black hole-neutron star binaries.
基金support of the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-092)the National Key R&D Program of China(Grant Nos.2022YFF0503404,and 2020SKA0110402)+1 种基金the National Natural Science Foundation of China(Grant No.12473002)supported by science research grants from the China Manned Space Project(Grant Nos.CMS-CSST-2025-A02,CMS-CSST-2021-B01,CMSCSST-2021-A01,CMS-CSST-2021-A03,CMS-CSST-2021-A12,and CMSCSST-2021-B10)。
文摘The Chinese Space Station Survey Telescope(CSST)is an upcoming Stage-IV sky survey telescope,distinguished by its large field of view(Fo V),high image quality,and multi-band observation capabilities.It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys.The CSST is equipped with five scientific instruments,i.e.,Multi-band Imaging and Slitless Spectroscopy Survey Camera(SC),Multi-Channel Imager(MCI),Integral Field Spectrograph(IFS),Cool Planet Imaging Coronagraph(CPI-C),and THz Spectrometer(TS).Using these instruments,CSST is expected to make significant contributions and discoveries across various astronomical fields,including cosmology,galaxies and active galactic nuclei(AGN),the Milky Way and nearby galaxies,stars,exoplanets,Solar System objects,astrometry,and transients and variable sources.This review aims to provide a comprehensive overview of the CSST instruments,observational capabilities,data products,and scientific potential.
