Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from...Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from 17 space-and ground-based telescopes/instruments,covering wavelengths from NIR/optical to X-ray and GeV,and spanning from the prompt emission to the afterglow phase triggered by Swift and Fermi.The early afterglow observations were carried out by SVOM/C-GFT,and spectroscopic observations of the afterglow by GTC,VLT,and TNG determined the redshift of the burst(z=0.659)later.A comprehensive analysis of the prompt emission spectrum observed by Swift-BAT and Fermi-GBM/LAT reveals a rare and significant high-energy cutoff at 76 MeV.Assuming this cutoff is due toγγabsorption allows us to place an upper limit on the initial Lorentz factor,Γ_(0)<245.The optical/NIR and GeV afterglow light curves can be described by the standard external shock model,with early-time emission dominated by a reverse shock(RS)and a subsequent transition to forward shock(FS)emission.Our afterglow modeling yields a consistent estimate of the initial Lorentz factor(Γ_(0)∼234).Furthermore,the RS-to-FS magnetic field ratio(R 302B)indicates that the RS region is significantly more magnetized than the FS region.An isotropic-equivalent kinetic energy of E_(k,iso)=5.25×10^(54) erg is derived,and the correspondingγ-ray radiation efficiency is estimated to beη_(γ)=3.1%.On the other hand,the standard afterglow model cannot reproduce the X-ray light curve of GRB 240825A,calling for improved models to characterize all multiwavelength data.展开更多
In 2024,the Chinese Meridian Project(CMP)completed its construction,deploying 282 instruments across 31 stations.This achievement not only provides a robust foundation but also serves as a reference template for the I...In 2024,the Chinese Meridian Project(CMP)completed its construction,deploying 282 instruments across 31 stations.This achievement not only provides a robust foundation but also serves as a reference template for the International Meridian Circle Program(IMCP).The IMCP aims to integrate and establish a comprehensive network of ground-based monitoring stations designed to track the propagation of space weather events from the Sun to Earth.Additionally,it monitors various disturbances generated within the Earth system that impact geospace.Over the past two years,significant progress has been made on the IMCP.In particular,the second phase of construction for the China-Brazil Joint Laboratory for Space Weather has been completed,and the North Pole and Southeast Asia networks are under active construction.The 2024 IMCP joint observation campaign was successfully conducted.To facilitate these developments,the scientific program committee of IMCP was established,following the success of 2023 IMCP workshop and the space weather school,which was co-hosted with the Asia-Pacific Space Cooperation Organization(APSCO)and sponsored by Chinese Academy of Sciences(CAS)and Scientific Committee on Solar-Terrestrial Physics(SCOSTEP).Preparations are now underway for the 2024 workshop in collaboration with the National Institute for Space Research(INPE)in Brazil.展开更多
The second(O2)observational campaign of gravitational waves(GWs)organized by the LIGO/Virgo Collaborations has led to several breakthroughs such as the detection of GW signals from merger systems involving black holes...The second(O2)observational campaign of gravitational waves(GWs)organized by the LIGO/Virgo Collaborations has led to several breakthroughs such as the detection of GW signals from merger systems involving black holes or neutrons stars.During O2,14 GW alerts were sent to the astronomical community with sky regions mostly covering over hundreds of square degrees.Among them,six were finally confirmed as real astrophysical events.Since 2013,a new set of ground-based robotic telescopes called Ground-based Wide Angle Camera system(GWAC)project and its pathfinder mini-GWAC has been developed to contribute to the various challenges of multi-messenger and time domain astronomy.The GWAC system is built up in the framework of the ground-segment system of the SVOM mission that will be devoted to the study of the multi-wavelength transient sky in the next decade.During O2,only the mini-GWAC telescope network was fully operational.Due to the wide field of view and fast automatic follow-up capabilities of the mini-GWAC telescopes,they were adept to efficiently cover the sky localization areas of GW event candidates.In this paper,we present the mini-GWAC pipeline we have set up to respond to GW alerts and we report our optical follow-up observations of eight GW alerts detected during the O2 run.Our observations provided the largest coverage of the GW localization areas with a short latency made by any optical facility.We found tens of optical transient candidates in our images,but none of those could be securely associated with any confirmed black hole-black hole merger event.Based on this first experience and the near future technical improvements of our network system,we will be more competitive in detecting the optical counterparts from some GW events that will be identified during the upcoming O3 run,especially those emerging from binary neutron star mergers.展开更多
After a brief reminder of the mechanism of gravitational lensing of ex- tended sources, the particular case of the host galaxy of QSO RXJ0911, a high red-shift （z - 2.8） quadruply imaged quasar, is explored. The non...After a brief reminder of the mechanism of gravitational lensing of ex- tended sources, the particular case of the host galaxy of QSO RXJ0911, a high red-shift （z - 2.8） quadruply imaged quasar, is explored. The non linearity of the problem, together with the proximity of the source to a cusp of the lens inner caustic, has impor-tant consequences on the dependence of the image appearance on the size and shape of the source. Their expected main features and their interpretation in terms of source extension and shape are investigated in a spirit of simplicity and in preparation for the analysis of high sensitivity and spatial resolution images that will soon be within reach with the completion of the Atacama Large Millimeter/submillimeter Array （ALMA）. In particular, the information on source size carded by relative image brightness is dis-cussed. Extension of the results to other types of quadruply imaged quasars is briefly considered.展开更多
We report the discovery of KMT-2020-BLG-0414 Lb,with a planet-to-host mass ratio q2=0.9-1.2×10-5=3-4 q⊕at 1σ,which is the lowest mass-ratio microlensing planet to date.Together with two other recent discoveries...We report the discovery of KMT-2020-BLG-0414 Lb,with a planet-to-host mass ratio q2=0.9-1.2×10-5=3-4 q⊕at 1σ,which is the lowest mass-ratio microlensing planet to date.Together with two other recent discoveries(4?q/q⊕?6),it fills out the previous empty sector at the bottom of the triangular(log s,log q)diagram,where s is the planet-host separation in units of the angular Einstein radiusθE.Hence,these discoveries call into question the existence,or at least the strength,of the break in the mass-ratio function that was previously suggested to account for the paucity of very low-q planets.Due to the extreme magnification of the event,Amax~1450 for the underlying single-lens event,its light curve revealed a second companion with q3~0.05 and|log s3|~1,i.e.,a factor~10 closer to or farther from the host in projection.The measurements of the microlens parallaxπE and the angular Einstein radiusθE allow estimates of the host,planet and second companion masses,(M1,M2,M3)~(0.3 M⊙,1.0 M⊕,17 MJ),the planet and second companion projected separations,(a⊥,2,a⊥,3)~(1.5,0.15 or 15)au,and system distance DL~1 kpc.The lens could account for most or all of the blended light(I~19.3)and so can be studied immediately with high-resolution photometric and spectroscopic observations that can further clarify the nature of the system.The planet was found as part of a new program of high-cadence follow-up observations of high-magnification events.The detection of this planet,despite the considerable difficulties imposed by COVID-19(two KMT sites and OGLE were shut down),illustrates the potential utility of this program.展开更多
In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to t...In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to terrestrial experiments.By observing a diverse population of neutron stars—including isolated objects,X-ray bursters,and accreting systems—eXTP’s unique combination of timing,spectroscopy,and polarimetry enables high-precision measurements of compactness,spin,surface temperature,polarimetric signals,and timing irregularity.These multifaceted observations,combined with advances in theoretical modeling,pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars.Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences,the eXTP mission is planned to be launched in early 2030.展开更多
In an attempt to study the flow bursts in the Earth＇s plasma sheet we select an event that took place on August 7, 2004 in the expansion phase of a substorm, using data from the geomagnetic index, solar wind data, pl...In an attempt to study the flow bursts in the Earth＇s plasma sheet we select an event that took place on August 7, 2004 in the expansion phase of a substorm, using data from the geomagnetic index, solar wind data, plasma and magnetic field observa- tions from C1 Cluster satellite （the Cluster mission has 4 satellites） and from Double Star TC-1 satellite. In MHD approach, TC-1 firstly observed the tailward flow, then the earthward, and finally the flow altemated in two directions. C1 firstly ob- served the earthward plasma flow, and then the tailward plasma flow. Before flow bursts are observed by TC-1 and C1, there are disturbances in local entropy with their tailward local entropy larger than those of the earthward. The kinetic features of the plasma flow observed by C1 are similar to those in MHD. However, kinetic characteristics of the plasma flow observed by TC-1 are far more than the description in MHD. The inadequacy mainly exists in two cases： （i） the firstly enhanced tailward flows given in MHD are found without significant increase of the energetic tailward flux; （ii） the almost stagnant flow in MHD is composed of the enhanced energetic ion flux in both earthward and tailward directions. The earthward flow burst observed by TC-1 might be multiple overshoots and rebounds. The earthward flow burst observed by C1 might be simply rebounded in the near-Earth. The pulsation observed by C1 is earlier than that observed by TC-1 with the former intensity less than that of the latter. After the energetic ion flux in the tailward direction is significantly enhanced, the power spectrum intensity of the ULF wave commences to increase obviously, which may suggest that the stream instability is closely correlated with ULF pulsations.展开更多
The nonadiabatic acceleration of plasma sheet ions is important to the understanding of substorm energetic injections and the formation of ring current. Previous studies show that nonadiabatic acceleration of protons ...The nonadiabatic acceleration of plasma sheet ions is important to the understanding of substorm energetic injections and the formation of ring current. Previous studies show that nonadiabatic acceleration of protons by magnetic field dipolarization is hard to occur at X>–10 RE because the time-scale of dipolarization(several minutes) is much larger than the gyroperiod of protons there(several seconds). In this paper, we present a case of nonadiabatic acceleration of plasma sheet ions observed by Cluster on October 30, 2006 at(XGSM, YGSM)=(-7.7, 4.7) RE. The nonadiabatic acceleration of ions is caused not by previously reported magnetospheric dipolarization but by the ultra low frequency(ULF) waves during magnetospheric dipolarization. The nonadiabatic acceleration of ions generates a new energy flux structure of ions, which is characterized by the usual energy flux increase of ions(28–80 ke V) and a concurrent energy flux decrease of ions in a lower energy range(10 e V–20 ke V). These new observations constitute a complete physical picture: The lower energy ions absorb the wave energy, and thus get accelerated to higher energy. We use a nonadiabatic model to interpret the ion energy flux variations. Both analytic and simulation results are in good agreement with the observations. This indicates that the nonadiabatic acceleration associated with ULF waves superposed on dipolarized magnetic field is an effective mechanism for ion energization in the near-Earth plasma sheet. The presented energy flux structures can be used as a proxy to identify the similar dynamic process.展开更多
In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive bl...In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced "spectral-timing-polarimetry" techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process.展开更多
In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting wh...In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.展开更多
基金supported by the National Key R&D Program of China(grant No.2024YFA1611600)the SVOM project(a mission under the Strategic Priority Program on Space Science of the Chinese Academy of Sciences)+23 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0550401)the National Natural Science Foundation of China(NSFC,grant No.12494573)partly supported by Natural Science Foundation of Xinjiang Uygur Autonomous Region(grant No.2024D01D32)Tianshan Talent Training Program(grant No.2023TSYCLJ0053)Tianshan Innovation Team Program(grant No.2024D14015)supported by the Jiangsu Funding Program for Excellent Postdoctoral Talent(grant No.2024ZB110)the Postdoctoral Fellowship Program(grant No.GZC20241916)the General Fund(grant No.2024M763531)of the China Postdoctoral Science Foundationsupported by a Royal Society Dorothy Hodgkin Fellowship(grant Nos.DHF-R1-221175 and DHF-ERE-221005)support by a postdoctoral fellowship from the CNESsupported by the National Key R&D Program of China(grant No.2024YFA1611702)the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0550101)the support of the French Agence Nationale de la Recherche(ANR),under grant ANR-23-CE31-0011(project PEGaSUS)financial support from the GRAWITA Large Program Grant(PI P.D’Avanzo)financial support from the Italian Space Agency,contract ASI/INAF No.I/004/11/6support from the INAF project Premiale Supporto Arizona&Italiasupported by the National Natural Science Foundation of China(NSFC,grant No.12133003)supported by the National Natural Science Foundation of China(NSFC,grant No.12373042)the Bagui Scholars Program(No.GXR-6BG2424001)funded by the European Union(ERC,HEAVYMETAL,101071865,Views and opinions expressed are,however,those of the authors only and do not necessarily reflect those of the European Union or the European Research Council Neither the European Union nor the granting authority can be held responsible for them)the Cosmic Dawn Center(DAWN)is funded by the Danish National Research Foundation under grant No.DNRF140supported by the National Natural Science Foundation of China(NSFC,grant Nos.12225305 and 12321003)supported by the National Natural Science Foundation of China(NSFC,grant No.12473049)supported by the General Fund(grant No.2024M763530)of the China Postdoctoral Science Foundation。
文摘Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from 17 space-and ground-based telescopes/instruments,covering wavelengths from NIR/optical to X-ray and GeV,and spanning from the prompt emission to the afterglow phase triggered by Swift and Fermi.The early afterglow observations were carried out by SVOM/C-GFT,and spectroscopic observations of the afterglow by GTC,VLT,and TNG determined the redshift of the burst(z=0.659)later.A comprehensive analysis of the prompt emission spectrum observed by Swift-BAT and Fermi-GBM/LAT reveals a rare and significant high-energy cutoff at 76 MeV.Assuming this cutoff is due toγγabsorption allows us to place an upper limit on the initial Lorentz factor,Γ_(0)<245.The optical/NIR and GeV afterglow light curves can be described by the standard external shock model,with early-time emission dominated by a reverse shock(RS)and a subsequent transition to forward shock(FS)emission.Our afterglow modeling yields a consistent estimate of the initial Lorentz factor(Γ_(0)∼234).Furthermore,the RS-to-FS magnetic field ratio(R 302B)indicates that the RS region is significantly more magnetized than the FS region.An isotropic-equivalent kinetic energy of E_(k,iso)=5.25×10^(54) erg is derived,and the correspondingγ-ray radiation efficiency is estimated to beη_(γ)=3.1%.On the other hand,the standard afterglow model cannot reproduce the X-ray light curve of GRB 240825A,calling for improved models to characterize all multiwavelength data.
基金Supported by International Meridian Circle Program Headquarters,China-Brazil Joint Laboratory for Space Weather(Y42347A99S)。
文摘In 2024,the Chinese Meridian Project(CMP)completed its construction,deploying 282 instruments across 31 stations.This achievement not only provides a robust foundation but also serves as a reference template for the International Meridian Circle Program(IMCP).The IMCP aims to integrate and establish a comprehensive network of ground-based monitoring stations designed to track the propagation of space weather events from the Sun to Earth.Additionally,it monitors various disturbances generated within the Earth system that impact geospace.Over the past two years,significant progress has been made on the IMCP.In particular,the second phase of construction for the China-Brazil Joint Laboratory for Space Weather has been completed,and the North Pole and Southeast Asia networks are under active construction.The 2024 IMCP joint observation campaign was successfully conducted.To facilitate these developments,the scientific program committee of IMCP was established,following the success of 2023 IMCP workshop and the space weather school,which was co-hosted with the Asia-Pacific Space Cooperation Organization(APSCO)and sponsored by Chinese Academy of Sciences(CAS)and Scientific Committee on Solar-Terrestrial Physics(SCOSTEP).Preparations are now underway for the 2024 workshop in collaboration with the National Institute for Space Research(INPE)in Brazil.
基金supported by the National Natural Science Foundation of China(Grant Nos.11533003,11673006,U1331202,U1931133 and U1938201)the Guangxi Science Foundation(2016GXNSFFA380006,AD17129006and 2018GXNSFGA281007)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB23040000)the Strategic Pioneer Program on Space Science,Chinese Academy of Sciences(XDA15052600)financial support from the Chinese Academy of Sciences PIFI post-doctoral fellowship program(program C)financial support of the Univ Earth S Labex program at Sorbonne Paris Cité(ANR-10-LABX-0023 and ANR-11-IDEX-0005-02)
文摘The second(O2)observational campaign of gravitational waves(GWs)organized by the LIGO/Virgo Collaborations has led to several breakthroughs such as the detection of GW signals from merger systems involving black holes or neutrons stars.During O2,14 GW alerts were sent to the astronomical community with sky regions mostly covering over hundreds of square degrees.Among them,six were finally confirmed as real astrophysical events.Since 2013,a new set of ground-based robotic telescopes called Ground-based Wide Angle Camera system(GWAC)project and its pathfinder mini-GWAC has been developed to contribute to the various challenges of multi-messenger and time domain astronomy.The GWAC system is built up in the framework of the ground-segment system of the SVOM mission that will be devoted to the study of the multi-wavelength transient sky in the next decade.During O2,only the mini-GWAC telescope network was fully operational.Due to the wide field of view and fast automatic follow-up capabilities of the mini-GWAC telescopes,they were adept to efficiently cover the sky localization areas of GW event candidates.In this paper,we present the mini-GWAC pipeline we have set up to respond to GW alerts and we report our optical follow-up observations of eight GW alerts detected during the O2 run.Our observations provided the largest coverage of the GW localization areas with a short latency made by any optical facility.We found tens of optical transient candidates in our images,but none of those could be securely associated with any confirmed black hole-black hole merger event.Based on this first experience and the near future technical improvements of our network system,we will be more competitive in detecting the optical counterparts from some GW events that will be identified during the upcoming O3 run,especially those emerging from binary neutron star mergers.
基金support from the Institute for Nuclear Science and Technology, National Foundation for Science and Technology Development (NAFOSTED)the World Laboratory, the French CNRS, the French Embassy in Hanoi, Rencontres du Vietnam and Odon Vallet fellowships
文摘After a brief reminder of the mechanism of gravitational lensing of ex- tended sources, the particular case of the host galaxy of QSO RXJ0911, a high red-shift （z - 2.8） quadruply imaged quasar, is explored. The non linearity of the problem, together with the proximity of the source to a cusp of the lens inner caustic, has impor-tant consequences on the dependence of the image appearance on the size and shape of the source. Their expected main features and their interpretation in terms of source extension and shape are investigated in a spirit of simplicity and in preparation for the analysis of high sensitivity and spatial resolution images that will soon be within reach with the completion of the Atacama Large Millimeter/submillimeter Array （ALMA）. In particular, the information on source size carded by relative image brightness is dis-cussed. Extension of the results to other types of quadruply imaged quasars is briefly considered.
基金support by the National Natural Science Foundation of China(Grant Nos.11821303 and 11761131004)supported by grants from the National Research Foundation of Korea(2019R1A2C2085965 and 2020R1A4A2002885)+3 种基金supported by JPL grant 1571564supported by JSPS KAK-ENHI(Grant Nos.JSPS24253004,JSPS26247023,JSPS23340064,JSPS15H00781,JP16H06287,JP17H02871 and JP19KK0082)supported by Tsinghua University Initiative Scientific Research Program(Program ID 2019Z07L02017)supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)under the funding(reference#CITA 490888-16)。
文摘We report the discovery of KMT-2020-BLG-0414 Lb,with a planet-to-host mass ratio q2=0.9-1.2×10-5=3-4 q⊕at 1σ,which is the lowest mass-ratio microlensing planet to date.Together with two other recent discoveries(4?q/q⊕?6),it fills out the previous empty sector at the bottom of the triangular(log s,log q)diagram,where s is the planet-host separation in units of the angular Einstein radiusθE.Hence,these discoveries call into question the existence,or at least the strength,of the break in the mass-ratio function that was previously suggested to account for the paucity of very low-q planets.Due to the extreme magnification of the event,Amax~1450 for the underlying single-lens event,its light curve revealed a second companion with q3~0.05 and|log s3|~1,i.e.,a factor~10 closer to or farther from the host in projection.The measurements of the microlens parallaxπE and the angular Einstein radiusθE allow estimates of the host,planet and second companion masses,(M1,M2,M3)~(0.3 M⊙,1.0 M⊕,17 MJ),the planet and second companion projected separations,(a⊥,2,a⊥,3)~(1.5,0.15 or 15)au,and system distance DL~1 kpc.The lens could account for most or all of the blended light(I~19.3)and so can be studied immediately with high-resolution photometric and spectroscopic observations that can further clarify the nature of the system.The planet was found as part of a new program of high-cadence follow-up observations of high-magnification events.The detection of this planet,despite the considerable difficulties imposed by COVID-19(two KMT sites and OGLE were shut down),illustrates the potential utility of this program.
基金supported by China’s Space Origins Exploration Programsupported by the National Natural Science Foundation of China (Grant No.12273028)+36 种基金support from ERC Consolidator (Grant No.865768) AEONSsupport from NWO grant ENW-XL OCENW.XL21.XL21.038the support of the CNESsupported by the National Natural Science Foundation of China (Grant No.12333007)the International Partnership Program of Chinese Academy of Sciences (Grant No.113111KYSB20190020)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA15020100)supported by the China National Postdoctoral Program for Innovation Talents (Grant No.BX20240223)the China Postdoctoral Science Foundation Funded Project (Grant No.2024M761948)support from a Ramon y Cajal fellowship (Grant No.RYC2021-032718-I) financed by MCIN/AEI/10.13039/501100011033 and the European Union Next Generation EU/PRTRsupported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region (Grant No.2023D01E20)the National SKA Program of China (Grant No.2020SKA0120300)supported by the National Natural Science Foundation of China (Grant Nos.12033001,and 12473039)supported by Zhejiang Provincial Natural Science Foundation of China (Grant No.LQ24A030002)supported by the National Natural Science Foundation of China (Grant No.12003009)supported by the National SKA Program of China (Grant No.2020SKA0120200)the National Natural Science Foundation of China (Grant No.12041303)supported by the National Natural Science Foundation of China (Grant No.1227303)supported by the National SKA Program of China (Grant No.2020SKA0120300)the Beijing Natural Science Foundation (Grant No.1242018)the Max Planck Partner Group Program funded by the Max Planck Societysupported by JSPS KAKENHI (the Japan Society for the Promotion of Science,Grantsin-Aid for Scientific Research) (Grant Nos.23K19056,and 25K17403)supported by the National Natural Science Foundation of China (Grant No.12175109)support from FCT (Fundacao para a Ciência e a Tecnologia,I.P.,Portugal) (Grant Nos.UIDB/04564/2020,and 2022.06460.PTDC)supported from the program Unidad de Excelencia María de Maeztu CEX2020-001058-Mfrom the project PID2022-139427NB-I00 financed by the Spanish MCIN/AEI/10.13039/501100011033/FEDER,UE (FSE+)by the CRC-TR 211 “Strong-interaction matter under extreme conditions” -project Nr.315477589-TRR 211support from grant PID2021-124581OB-I0,PID2024-155316NB-I00,and 2021SGR00426supported by the National Natural Science Foundation of China (Grant No.12122513)supported in part by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant No.101020842)by the Deutsche Forschungsgemeinschaft (DFG,German Research Foundation)-Project-ID 279384907-SFB 1245support from the ERC Consolidator (Grant No.101002352) (LOVENEST)supported by the European Research Council (ERC) via the Consolidator Grant “MAGNESIA” (Grant No.817661)the Proof of Concept “Deep Space Pulse” (Grant No.101189496)the Catalan grant SGR2021-01269the Spanish grant ID2023-153099NA-I00the program Unidad de Excelencia Maria de Maeztu CEX2020-001058-Msupported by the Research Council of Finland (Grant No.354533).
文摘In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to terrestrial experiments.By observing a diverse population of neutron stars—including isolated objects,X-ray bursters,and accreting systems—eXTP’s unique combination of timing,spectroscopy,and polarimetry enables high-precision measurements of compactness,spin,surface temperature,polarimetric signals,and timing irregularity.These multifaceted observations,combined with advances in theoretical modeling,pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars.Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences,the eXTP mission is planned to be launched in early 2030.
基金supported by the National Natural Science Foundation of China(Grant Nos.40931054,41174141 and 40904042)the National Basic Research Program of China("973"Project)(Grant No.2011CB811404)Specialized Research Fund for State Key Laboratories of China(Grant No.KP201104)
文摘In an attempt to study the flow bursts in the Earth＇s plasma sheet we select an event that took place on August 7, 2004 in the expansion phase of a substorm, using data from the geomagnetic index, solar wind data, plasma and magnetic field observa- tions from C1 Cluster satellite （the Cluster mission has 4 satellites） and from Double Star TC-1 satellite. In MHD approach, TC-1 firstly observed the tailward flow, then the earthward, and finally the flow altemated in two directions. C1 firstly ob- served the earthward plasma flow, and then the tailward plasma flow. Before flow bursts are observed by TC-1 and C1, there are disturbances in local entropy with their tailward local entropy larger than those of the earthward. The kinetic features of the plasma flow observed by C1 are similar to those in MHD. However, kinetic characteristics of the plasma flow observed by TC-1 are far more than the description in MHD. The inadequacy mainly exists in two cases： （i） the firstly enhanced tailward flows given in MHD are found without significant increase of the energetic tailward flux; （ii） the almost stagnant flow in MHD is composed of the enhanced energetic ion flux in both earthward and tailward directions. The earthward flow burst observed by TC-1 might be multiple overshoots and rebounds. The earthward flow burst observed by C1 might be simply rebounded in the near-Earth. The pulsation observed by C1 is earlier than that observed by TC-1 with the former intensity less than that of the latter. After the energetic ion flux in the tailward direction is significantly enhanced, the power spectrum intensity of the ULF wave commences to increase obviously, which may suggest that the stream instability is closely correlated with ULF pulsations.
基金supported by the China Postdoctoral Science Foundation(Grant No.2013M531344)the Fundamental Research Funds for the Central Universities(Grant No.56YAH12039)+1 种基金the National Natural Science Foundation of China(Grant No.41174141)the National Basic Research Program of China("973"Project)(Grant No.2011CB811404)
文摘The nonadiabatic acceleration of plasma sheet ions is important to the understanding of substorm energetic injections and the formation of ring current. Previous studies show that nonadiabatic acceleration of protons by magnetic field dipolarization is hard to occur at X>–10 RE because the time-scale of dipolarization(several minutes) is much larger than the gyroperiod of protons there(several seconds). In this paper, we present a case of nonadiabatic acceleration of plasma sheet ions observed by Cluster on October 30, 2006 at(XGSM, YGSM)=(-7.7, 4.7) RE. The nonadiabatic acceleration of ions is caused not by previously reported magnetospheric dipolarization but by the ultra low frequency(ULF) waves during magnetospheric dipolarization. The nonadiabatic acceleration of ions generates a new energy flux structure of ions, which is characterized by the usual energy flux increase of ions(28–80 ke V) and a concurrent energy flux decrease of ions in a lower energy range(10 e V–20 ke V). These new observations constitute a complete physical picture: The lower energy ions absorb the wave energy, and thus get accelerated to higher energy. We use a nonadiabatic model to interpret the ion energy flux variations. Both analytic and simulation results are in good agreement with the observations. This indicates that the nonadiabatic acceleration associated with ULF waves superposed on dipolarized magnetic field is an effective mechanism for ion energization in the near-Earth plasma sheet. The presented energy flux structures can be used as a proxy to identify the similar dynamic process.
基金financial contribution from the agreement ASI-INAF n.2017-14-H.Osupport of the Chinese Academy of Sciences through the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the Polish National Science Centre(Grant No.2013/10/M/ST9/00729)
文摘In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced "spectral-timing-polarimetry" techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process.
基金supported by the Royal Society,ERC Starting(Grant No.639217)he European Union Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Global Fellowship(Grant No.703916)+10 种基金the National Natural Science Foundation of China(Grant Nos.11233001,11773014,11633007,11403074,11333005,11503008,and 11590781)the National Basic Research Program of China(Grant No.2015CB857100)NASA(Grant No.NNX13AD28A)an ARC Future Fellowship(Grant No.FT120100363)the National Science Foundation(Grant No.PHY-1430152)the Spanish MINECO(Grant No.AYA2016-76012-C3-1-P)the ICCUB(Unidad de Excelencia’Maria de Maeztu’)(Grant No.MDM-2014-0369)EU’s Horizon Programme through a Marie Sklodowska-Curie Fellowship(Grant No.702638)the Polish National Science Center(Grant Nos.2015/17/B/ST9/03422,2015/18/M/ST9/00541,2013/10/M/ST9/00729,and 2015/18/A/ST9/00746)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the NWO Veni Fellowship(Grant No.639.041.647)
文摘In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.
