Multiband afterglow observations of gamma-ray bursts(GRBs)are important for studying the central engine.GRB 201223A is a GRB with prompt optical detection by GWAC.Here we report on the early optical afterglow of GRB 2...Multiband afterglow observations of gamma-ray bursts(GRBs)are important for studying the central engine.GRB 201223A is a GRB with prompt optical detection by GWAC.Here we report on the early optical afterglow of GRB 201223A detected by NEXT(only 2.8 minutes after the Swift/BAT trigger),which smoothly connects the prompt optical emission and the afterglow phase.Utilizing Amati diagrams and considering the detection of afterglow emission in the Swift u-band,we suggest a redshift range of 0.26–1.85.Based on our optical data and combined with early optical observation from GWAC and early X-ray data from Swift/XRT,a multiband fitting is performed using PyFRS,and we obtain the best afterglow parameters(assuming a redshift of z=1.0):=5.01+10/_(1.70)^(1.91)×^(54)erg,G=-426.58+_(138.18)/^(148.86),θj=-25.98+_(-10.54)^/(9.67)deg,=-n0=0.30+_(-0.26)^(+3.78)cm^(−3),=-p2.32+_(-0.01)/^(+0.01),εe=-3.31+_(-0.86)/^(+1.59)×10^(-5),εB=-3.47+_(-2.62)/^(+4.12)×10^(-1).The late-time X-ray shows a re-brightening,indicating late-time central engine activities.After comparing the leading two central engine models,i.e.,magnetar model and hyperaccreting black hole model,we find that the fallback accretion onto a newborn black hole provides a better explanation for the X-ray re-brightening with fallback accretion rate Mp≈2.76×10^(-9)M⊙s^(-1)and the total fallback accreted mass Mfb≈1.41×10^(−6)M⊙.展开更多
A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature As...A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature Astronomy on January 23,2025 their discovery of an X-ray flash about 12.5 billion lightyears away.The signals burst out only 1.2 billion years after the Big Bang,when our 13.8-billion-year-old universe was still in its infancy,and a science satellite swiftly recorded them.展开更多
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
The nearest GRB 170817A provided an opportunity to probe the angular structure of the jet of this short gamma-ray burst(SGRB),by using its off-axis observed afterglow emission.It is investigated whether the afterglow-...The nearest GRB 170817A provided an opportunity to probe the angular structure of the jet of this short gamma-ray burst(SGRB),by using its off-axis observed afterglow emission.It is investigated whether the afterglow-constrained jet structures can be consistent with the luminosity of the prompt emission of GRB 170817A.Furthermore,by assuming that all SGRBs,including GRB 170817A,have the same explosive mechanism and jet structure,we apply the different jet structures to the calculation of the flux and redshift distributions of the SGRB population,confronting them with the observational distributions of the Swift and Fermi sources.In comparison,it is found that the power-law and double-Gaussian models could be somewhat more favored than the single-Gaussian structure,as the last one could not be very consistent with the flux distribution of the Fermi data.Nevertheless,in view of the large uncertainty of parameters,we are still unable to make a suffciently conclusive judgement at present.展开更多
After launching a jet,outflows of magnetar were used to account for the achromatic plateau of afterglow and the early X-ray flux plateau known as“internal plateau”.The lack of detecting magnetic dipole emission toge...After launching a jet,outflows of magnetar were used to account for the achromatic plateau of afterglow and the early X-ray flux plateau known as“internal plateau”.The lack of detecting magnetic dipole emission together with the energy injection feature in a single observation poses confusion until the long gamma-ray burst(GRB)210610B is detected.GRB 210610B is presented with an optical bump following an early X-ray plateau during the afterglow phase.The plateau followed by a steep decline flux overlays in the steadily decaying X-ray flux with indexα_(X,1)~2.06,indicating an internal origin and that can be fitted by the spin-down luminosity law with the initial plateau luminosity log_(10)L_(X)~48.29 erg s~(-1)and the characteristic spin-down timescale T~2818 s.A subsequent bump begins at~4000 s in the R band with a rising indexα_(R,1)~-0.30 and peaks at~14125 s,after which a decay indexα_(R,2)~0.87 and finally transiting to a steep decay withα_(R,3)~1.77 achieve the closure relation of the external shock for the normal decay phase as well as the magnetar spin-down energy injection phase,provided that the average value of the photon indexΓ_γ=1.80 derived from the spectral energy distributions(SEDs)between the X-ray and optical afterglow.The closure relation also works for the late X-ray flux.Akin to the traditional picture of GRB,the outflow powers the early X-ray plateau by dissipating energy internally and collides with the leading decelerating blast burst as time goes on,which could interpret the exotic feature of GRB 210610B.We carry out a Markov Chain Monte Carlo simulation and obtain a set of best parameters:■.The artificial light curve can fit the afterglow data well.After that,we estimated the average Lorentz factor and the X-ray radiation efficiency of the later ejecta are 35%and 0.13%,respectively.展开更多
GRB 200612A could be classified as an ultralong gamma-ray burst due to its prompt emission lasting up to~1020 s and the true timescale of the central engine activity t_(burst)≥4×10^(4) s.The late X-ray light cur...GRB 200612A could be classified as an ultralong gamma-ray burst due to its prompt emission lasting up to~1020 s and the true timescale of the central engine activity t_(burst)≥4×10^(4) s.The late X-ray light curve with a decay index ofα=7.53 is steeper than the steepest possible decay from an external shock model.We propose that this X-ray afterglow can be driven by dipolar radiation from the magnetar spindown during its early stage,while the magnetar collapsed into the black hole before its spindown,resulting in a very steep decay of the late X-ray light curve.The optical data show that the light curve is still rising after 1.1 ks,suggesting a late onset.We show that GRB 200612A’s optical afterglow light curve is fitted with the forward shock model by Gaussian structured off-axis jet.This is a special case among GRBs,as it may be an ultralong gamma-ray burst powered by a magnetar in an off-axis observation scenario.展开更多
Theoretically,a supra-massive neutron star or magnetar may be formed after the merger of binary neutron stars.GRB210323A is a short-duration gamma-ray burst(GRB)with a duration of lasting~1 s.The light curve of the pr...Theoretically,a supra-massive neutron star or magnetar may be formed after the merger of binary neutron stars.GRB210323A is a short-duration gamma-ray burst(GRB)with a duration of lasting~1 s.The light curve of the prompt emission of GRB 210323A shows a signal-peaked structure and a cutoff power-law model can adequately fit the spectra with E_p=1826±747.More interestingly,it has an extremely long-lasting plateau emission in the X-ray afterglow with a duration of~10^(4)s,and then follows a rapid decay with a decay slope~3.2.This temporal feature is challenging by invoking the external shock mode.In this paper,we suggest that the observed long-lasting X-ray plateau emission is caused by the energy injection of dipole radiation from supra-massive magnetar,and the abrupt decay following the longlasting X-ray plateau emission is explained by supra-massive magnetar collapsing into a black hole.It is the short GRB(SGRB)with the longest X-ray internal plateau emission powered by a supra-massive neutron star.If this is the case,one can estimate the physical parameters of a supra-massive magnetar,and compare with other SGRBs.We also discuss the possible gravitational-wave emission,which is powered by a supra-massive magnetar and its detectability,and the possible kilonova emission,which is powered by r-process and magnetar spin-down to compare with the observed data.展开更多
目的:观察人结直肠癌组织磷酸化哺乳动物雷帕霉素靶蛋白(phosphorylated mammalian target of rapamycin,p-mTOR)、表皮生长因子受体(EGFR)、生长因子受体结合蛋白2(Grb2)和血管内皮生长因子(VEGF)等的表达,并探讨其可能的临床意义。方...目的:观察人结直肠癌组织磷酸化哺乳动物雷帕霉素靶蛋白(phosphorylated mammalian target of rapamycin,p-mTOR)、表皮生长因子受体(EGFR)、生长因子受体结合蛋白2(Grb2)和血管内皮生长因子(VEGF)等的表达,并探讨其可能的临床意义。方法:构建含有185例结直肠癌标本的组织芯片,免疫组化法检测结直肠癌组织及癌旁组织中EGFR、Grb2、p-mTOR和VEGF的表达,并分析不同结直肠癌临床病理学特征下(如年龄、性别、浸润深度、淋巴转移、临床分期和分化程度)各自的表达情况,探讨可能的临床意义。结果:EGFR、Grb2、p-mTOR和VEGF在结直肠癌旁组织中呈少量表达或不表达,在结直肠癌组织中的表达率分别为21.1%、44.9%、42.2%和54.1%,明显高于癌旁组织(P<0.05)。结直肠癌患者不同性别、年龄、肿瘤分化程度下EGFR、Grb2、p-mTOR和VEGF表达率无统计学差异;不同浸润深度和临床分期下EGFR的表达率有统计学差异(P<0.05);不同浸润深度、淋巴转移和临床分期下p-mTOR、VEGF表达率均有统计学差异(P<0.05)。结直肠癌组织EGFR/Grb2/p-mTOR/VEGF蛋白两两间均有一定的相关性(r=0.245～0.567,P<0.05)。结论:EGFR、Grb2、p-mTOR和VEGF表达与结直肠癌的发生、发展相关,值得进一步研究以作为结直肠癌肿瘤靶向治疗新的作用靶点。展开更多
基金supported by the MINECO/FEDER through grant AyA2017-84089.7the science research grants from the China Manned Space Project with NO.CMSCSST-2021-A13CMS-CSST-2021-B11.W.H.Lei acknowledges support by the National Key R&D Program of China(No.2020YFC2201400)。
文摘Multiband afterglow observations of gamma-ray bursts(GRBs)are important for studying the central engine.GRB 201223A is a GRB with prompt optical detection by GWAC.Here we report on the early optical afterglow of GRB 201223A detected by NEXT(only 2.8 minutes after the Swift/BAT trigger),which smoothly connects the prompt optical emission and the afterglow phase.Utilizing Amati diagrams and considering the detection of afterglow emission in the Swift u-band,we suggest a redshift range of 0.26–1.85.Based on our optical data and combined with early optical observation from GWAC and early X-ray data from Swift/XRT,a multiband fitting is performed using PyFRS,and we obtain the best afterglow parameters(assuming a redshift of z=1.0):=5.01+10/_(1.70)^(1.91)×^(54)erg,G=-426.58+_(138.18)/^(148.86),θj=-25.98+_(-10.54)^/(9.67)deg,=-n0=0.30+_(-0.26)^(+3.78)cm^(−3),=-p2.32+_(-0.01)/^(+0.01),εe=-3.31+_(-0.86)/^(+1.59)×10^(-5),εB=-3.47+_(-2.62)/^(+4.12)×10^(-1).The late-time X-ray shows a re-brightening,indicating late-time central engine activities.After comparing the leading two central engine models,i.e.,magnetar model and hyperaccreting black hole model,we find that the fallback accretion onto a newborn black hole provides a better explanation for the X-ray re-brightening with fallback accretion rate Mp≈2.76×10^(-9)M⊙s^(-1)and the total fallback accreted mass Mfb≈1.41×10^(−6)M⊙.
文摘A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature Astronomy on January 23,2025 their discovery of an X-ray flash about 12.5 billion lightyears away.The signals burst out only 1.2 billion years after the Big Bang,when our 13.8-billion-year-old universe was still in its infancy,and a science satellite swiftly recorded them.
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 the National Key R&D Program of China(2021YFA0718500)the China Manned Spaced Project(CMS-CSST-2021-A12)+1 种基金the National Natural Science Foundation of China(grant Nos.12393811,U1838203,and11803007)Hubei Provincial Outstanding Young and Middle-aged Science and Technology Innovation Team Project of China(T2021026)。
文摘The nearest GRB 170817A provided an opportunity to probe the angular structure of the jet of this short gamma-ray burst(SGRB),by using its off-axis observed afterglow emission.It is investigated whether the afterglow-constrained jet structures can be consistent with the luminosity of the prompt emission of GRB 170817A.Furthermore,by assuming that all SGRBs,including GRB 170817A,have the same explosive mechanism and jet structure,we apply the different jet structures to the calculation of the flux and redshift distributions of the SGRB population,confronting them with the observational distributions of the Swift and Fermi sources.In comparison,it is found that the power-law and double-Gaussian models could be somewhat more favored than the single-Gaussian structure,as the last one could not be very consistent with the flux distribution of the Fermi data.Nevertheless,in view of the large uncertainty of parameters,we are still unable to make a suffciently conclusive judgement at present.
基金funded by the National Natural Science Foundation of China(Nos.12373042,U1938201,12273005 and 12133003)the Programme of Bagui Scholars Programme(WXG)support of the China Space Station Telescope(CSST)。
文摘After launching a jet,outflows of magnetar were used to account for the achromatic plateau of afterglow and the early X-ray flux plateau known as“internal plateau”.The lack of detecting magnetic dipole emission together with the energy injection feature in a single observation poses confusion until the long gamma-ray burst(GRB)210610B is detected.GRB 210610B is presented with an optical bump following an early X-ray plateau during the afterglow phase.The plateau followed by a steep decline flux overlays in the steadily decaying X-ray flux with indexα_(X,1)~2.06,indicating an internal origin and that can be fitted by the spin-down luminosity law with the initial plateau luminosity log_(10)L_(X)~48.29 erg s~(-1)and the characteristic spin-down timescale T~2818 s.A subsequent bump begins at~4000 s in the R band with a rising indexα_(R,1)~-0.30 and peaks at~14125 s,after which a decay indexα_(R,2)~0.87 and finally transiting to a steep decay withα_(R,3)~1.77 achieve the closure relation of the external shock for the normal decay phase as well as the magnetar spin-down energy injection phase,provided that the average value of the photon indexΓ_γ=1.80 derived from the spectral energy distributions(SEDs)between the X-ray and optical afterglow.The closure relation also works for the late X-ray flux.Akin to the traditional picture of GRB,the outflow powers the early X-ray plateau by dissipating energy internally and collides with the leading decelerating blast burst as time goes on,which could interpret the exotic feature of GRB 210610B.We carry out a Markov Chain Monte Carlo simulation and obtain a set of best parameters:■.The artificial light curve can fit the afterglow data well.After that,we estimated the average Lorentz factor and the X-ray radiation efficiency of the later ejecta are 35%and 0.13%,respectively.
基金supported by the National Natural Science Foundation of China(Nos.U1938201 and 12373042)。
文摘GRB 200612A could be classified as an ultralong gamma-ray burst due to its prompt emission lasting up to~1020 s and the true timescale of the central engine activity t_(burst)≥4×10^(4) s.The late X-ray light curve with a decay index ofα=7.53 is steeper than the steepest possible decay from an external shock model.We propose that this X-ray afterglow can be driven by dipolar radiation from the magnetar spindown during its early stage,while the magnetar collapsed into the black hole before its spindown,resulting in a very steep decay of the late X-ray light curve.The optical data show that the light curve is still rising after 1.1 ks,suggesting a late onset.We show that GRB 200612A’s optical afterglow light curve is fitted with the forward shock model by Gaussian structured off-axis jet.This is a special case among GRBs,as it may be an ultralong gamma-ray burst powered by a magnetar in an off-axis observation scenario.
基金supported by the Guangxi Science Foundation(grant No.2023GXNSFDA026007)the Program of Bagui Scholars Program(LHJ)。
文摘Theoretically,a supra-massive neutron star or magnetar may be formed after the merger of binary neutron stars.GRB210323A is a short-duration gamma-ray burst(GRB)with a duration of lasting~1 s.The light curve of the prompt emission of GRB 210323A shows a signal-peaked structure and a cutoff power-law model can adequately fit the spectra with E_p=1826±747.More interestingly,it has an extremely long-lasting plateau emission in the X-ray afterglow with a duration of~10^(4)s,and then follows a rapid decay with a decay slope~3.2.This temporal feature is challenging by invoking the external shock mode.In this paper,we suggest that the observed long-lasting X-ray plateau emission is caused by the energy injection of dipole radiation from supra-massive magnetar,and the abrupt decay following the longlasting X-ray plateau emission is explained by supra-massive magnetar collapsing into a black hole.It is the short GRB(SGRB)with the longest X-ray internal plateau emission powered by a supra-massive neutron star.If this is the case,one can estimate the physical parameters of a supra-massive magnetar,and compare with other SGRBs.We also discuss the possible gravitational-wave emission,which is powered by a supra-massive magnetar and its detectability,and the possible kilonova emission,which is powered by r-process and magnetar spin-down to compare with the observed data.
文摘目的:观察人结直肠癌组织磷酸化哺乳动物雷帕霉素靶蛋白(phosphorylated mammalian target of rapamycin,p-mTOR)、表皮生长因子受体(EGFR)、生长因子受体结合蛋白2(Grb2)和血管内皮生长因子(VEGF)等的表达,并探讨其可能的临床意义。方法:构建含有185例结直肠癌标本的组织芯片,免疫组化法检测结直肠癌组织及癌旁组织中EGFR、Grb2、p-mTOR和VEGF的表达,并分析不同结直肠癌临床病理学特征下(如年龄、性别、浸润深度、淋巴转移、临床分期和分化程度)各自的表达情况,探讨可能的临床意义。结果:EGFR、Grb2、p-mTOR和VEGF在结直肠癌旁组织中呈少量表达或不表达,在结直肠癌组织中的表达率分别为21.1%、44.9%、42.2%和54.1%,明显高于癌旁组织(P<0.05)。结直肠癌患者不同性别、年龄、肿瘤分化程度下EGFR、Grb2、p-mTOR和VEGF表达率无统计学差异;不同浸润深度和临床分期下EGFR的表达率有统计学差异(P<0.05);不同浸润深度、淋巴转移和临床分期下p-mTOR、VEGF表达率均有统计学差异(P<0.05)。结直肠癌组织EGFR/Grb2/p-mTOR/VEGF蛋白两两间均有一定的相关性(r=0.245～0.567,P<0.05)。结论:EGFR、Grb2、p-mTOR和VEGF表达与结直肠癌的发生、发展相关,值得进一步研究以作为结直肠癌肿瘤靶向治疗新的作用靶点。
