We present an analysis of the Imaging X-ray Polarimetry Explorer observation from a newly discovered transient source:Swift J151857.0-572147.The obtained polarization degree(PD)and angle are 0.3%±0.3% and -24...We present an analysis of the Imaging X-ray Polarimetry Explorer observation from a newly discovered transient source:Swift J151857.0-572147.The obtained polarization degree(PD)and angle are 0.3%±0.3% and -24°±26°respectively in 2-8 keV within 68%confidence level errors,and polarization results are below MDP99in all energy bins,with the upper limit on PD of 0.8% in the 2-8 keV energy range.No quasi-periodic oscillations(QPOs)are detected in this observation.The polarization and QPO analyses support the hypothesis that the source was in the high soft state,and the results are consistent with predictions for a thin accretion disk model.展开更多
Fast radio bursts(FRBs)are short pulses observed in radio frequencies usually originating from cosmological distances.The discovery of FRB 200428 and its X-ray counterpart from the Galactic magnetar SGR J1935+2154sugg...Fast radio bursts(FRBs)are short pulses observed in radio frequencies usually originating from cosmological distances.The discovery of FRB 200428 and its X-ray counterpart from the Galactic magnetar SGR J1935+2154suggests that at least some FRBs can be generated by magnetars.However,the majority of X-ray bursts from magnetars are not associated with radio emission.The fact that only in rare cases can an FRB be generated raises the question regarding the special triggering mechanism of FRBs.Here we report long time spin evolution of SGR J1935+2154 until the end of 2022.According to v and v,the spin evolution of SGR J1935+2154 could be divided into two stages.The first stage evolves relatively steady evolution until 2020 April 27.After the burst activity in2020,the spin of SGR J1935+2154 shows strong variations,especially for v.After the burst activity in 2022October,a new spin-down glitch with△v/v=(-7.2±0.6)×10^(-6)is detected around MJD 59876,which is the second event in SGR J1935+2154.At the end,spin frequency and pulse profile do not show variations around the time of FRB 200428 and radio bursts 221014 and 221021,which supply strong clues to constrain the trigger mechanism of FRBs or radio bursts.展开更多
Owing to the broad energy coverage of Insight-HXMT in the hard X-ray band,we detected the highest energy of pulsation exceeding 200 keV around the 2017–2018 outburst peak of the first Galactic pulsating ultraluminous...Owing to the broad energy coverage of Insight-HXMT in the hard X-ray band,we detected the highest energy of pulsation exceeding 200 keV around the 2017–2018 outburst peak of the first Galactic pulsating ultraluminous X-ray source (PULX) Swift J0243.6+6124,which is the highest energy detected from PULXs to date.We also obtained the highest energy of pulsation of every exposure during the outburst in 2017–2018,and found the highest energy is roughly positively correlated with luminosity.Using our newly developed method,we identified the critical luminosity being 4×10^(38)erg s^(-1) when the main peaks of the low and high energy pulse profiles became aligned,which separates the fan-beam dominated and pencil-beam dominated accretion regimes.Above the critical luminosity,the phase of the main peak shifted gradually from 0.5 to 0.8 until the outburst peak in al energy bands is reached,which is in agreement with the phase shift found previously at low energies.Our result is consistent with what is derived from spectral analysis.展开更多
In October 2022,the magnetar SGR J1935+2154 entered the active outburst state.During the episode,the InsightHXMT satellite carried out a long observation that lasted for 20 days.More than 300 bursts were detected,and ...In October 2022,the magnetar SGR J1935+2154 entered the active outburst state.During the episode,the InsightHXMT satellite carried out a long observation that lasted for 20 days.More than 300 bursts were detected,and a certain amount of persistent radiation signals were also accumulated.This paper mainly introduces the results of persistent radiation profile folding and period search based on Insight-HXMT data.At the same time,the burst phase distribution characteristics,spectral lag results of burst,the spectral characteristics of zero-lag bursts and the time-resolved spectral evolution characteristics of high-flux bursts are reported.We found that there is no significant delay feature during different energy bands for the bursts of SGR J1935+2154.The observed zero-lag burst does not have a unique spectrum.The time-resolved spectrum of the individual burst has consistent spectral types and spectral parameters at different time periods of the burst.We also find that the burst number phase distribution and the burst photon phase distribution have the same tendency to concentrate in specific regions of the persistent emission profile.展开更多
We report on X-ray emission properties of the Crab pulsar(PSR B0531+21) using observations by Insight-HXMT during its first year after launch. We obtained high signal-to-noise profiles in the X-ray energy band 11–250...We report on X-ray emission properties of the Crab pulsar(PSR B0531+21) using observations by Insight-HXMT during its first year after launch. We obtained high signal-to-noise profiles in the X-ray energy band 11–250 keV. We have confirmed an increase in the flux ratio of the second peak over the main peak with increasing energy, consistent with other missions. The separation of the two peaks shows no significant trend with increasing energy. The phase-averaged spectrum, fitted by a logpar model, and the phase-resolved spectra of the Crab pulsar, fitted by a powerlaw in the different energy bands of HXMT, are consistent with RXTE and NuSTAR in that photon indices evolve as a function of phase as well as a function of energy, contributing to a broadband modeling.展开更多
We report the radio observations of the eclipsing black widow pulsar J1720-0534, a 3.26 ms pulsar in orbit with a low mass companion of mass 0.029 to 0.034 M⊙. We obtain the phase-connected timing ephemeris and polar...We report the radio observations of the eclipsing black widow pulsar J1720-0534, a 3.26 ms pulsar in orbit with a low mass companion of mass 0.029 to 0.034 M⊙. We obtain the phase-connected timing ephemeris and polarization profile of this millisecond pulsar(MSP) using the Five-hundred-meter Aperture Spherical radio Telescope(FAST), the Green Bank Telescope(GBT), and the Parkes Telescope. For the first time from such a system, an oscillatory polarization angle change was observed from a particular eclipse egress with partial depolarization, indicating 10-milliGauss-level reciprocating magnetic fields oscillating in a length scale of 5 ×10^(3)km(assuming an orbital inclination angle of 90°) outside the companion's magnetosphere. The dispersion measure variation observed during the ingresses and egresses shows the rapid raising of the electron density in the shock boundary between the companion's magnetosphere and the surrounding pulsar wind. We suggest that the observed oscillatory magnetic fields originate from the pulsar wind outside the companion's magnetosphere.展开更多
On 2020 April 27,the soft gamma-ray repeater SGR J1935+2154 entered its intense outburst episode again.Insight-HXMT carried out about one month observation of the source.A total number of 75 bursts were detected durin...On 2020 April 27,the soft gamma-ray repeater SGR J1935+2154 entered its intense outburst episode again.Insight-HXMT carried out about one month observation of the source.A total number of 75 bursts were detected during this activity episode by Insight-HXMT,and persistent emission data were also accumulated.We report on the spin period search result and the phase distribution of burst start times and burst photon arrival times of the Insight-HXMT high energy detectors and Fermi/Gamma-ray Burst Monitor(GBM).We find that the distribution of burst start times is uniform within its spin phase for both Insight-HXMT and Fermi/GBM observations,whereas the phase distribution of burst photons is related to the type of a burst’s energy spectrum.The bursts with the same spectrum have different distribution characteristics in the initial and decay episodes for the activity of magnetar SGR J1935+2154.展开更多
We analyze the time and energy dependence of the Vela pulsar’s pulse profile using 13 yr observations from the Large Area Telescope on the Fermi Gamma-ray Space Telescope.It is found that the pulse profile of the Vel...We analyze the time and energy dependence of the Vela pulsar’s pulse profile using 13 yr observations from the Large Area Telescope on the Fermi Gamma-ray Space Telescope.It is found that the pulse profile of the Vela pulsar inγ-ray changes with time.We parameterize the pulse profile and find that different shape parameters show fiuctuations rather than gradual changes with time.However,these time variation trends are insignificant due to limited statistics.The pulse profile of the Vela pulsar displays clear energy dependence inγ-ray.Different shape parameters are accurately obtained or updated,especially the phase separations among different pulses.Their energy evolution trends are quantified for the first time,which will provide restrictions on currentγ-ray emission models.For the Vela pulsar,we also find a turning point at phase.Before and after this phase,the relative intensity of the pulse profile evolves with energy with the opposite trend.展开更多
PSR J0742-2822 is known for its quasi-periodic changes in the observed pulse profile and spindown rate.In this paper,we analyzed 13 years of timing data obtained with the Nanshan 25-m radio telescope and the Parkes 64...PSR J0742-2822 is known for its quasi-periodic changes in the observed pulse profile and spindown rate.In this paper,we analyzed 13 years of timing data obtained with the Nanshan 25-m radio telescope and the Parkes 64-m radio telescope.We found that the average values of the spin-down rate((v))of this pulsar changed in four different states.We investigated the correlation between v and W50,and ascertained that the correlation changed in different states.Moreover,not all the changes in states and correlation can be associated with glitch activities.We examined the long term evolution ofγ-ray flux(0.1-300 GeV)and the pulse profiles corresponding to the four different states using Fermi-LAT Pass8(P8 R3)data from 2008 August 5 to 2019 October 1.We did not detect a significant change inγ-ray flux or the pulse profile.Our results suggest that the connection between pulsar rotation and emission is more complex than previously reported for this pulsar.展开更多
We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be class...We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.展开更多
We analyzed the spectral properties and pulse profile of PSR J1811-1925,a pulsar located in the center of composite supernova remnant(SNR)G11.2-0.3,by using high timing resolution archival data from the Nuclear Spectr...We analyzed the spectral properties and pulse profile of PSR J1811-1925,a pulsar located in the center of composite supernova remnant(SNR)G11.2-0.3,by using high timing resolution archival data from the Nuclear Spectroscopic Telescope Array Mission(NuSTAR).Analysis of archival Chandra data over different regions rules out the SNR shell as the site of the hard X-ray emission while spectral analysis indicates that the NuSTAR photons originate in the pulsar and its nebula.The pulse profile exhibits a broad single peak up to 35 keV.The jointed spectrum by combining NuSTAR and Chandra can be well fitted by a power-law model with a photon index ofΓ=1.58±0.04.The integrated flux of jointed spectrum over 1-10 keV is 3.36×10^(-12)erg cm^(-2)s^(-1).The spectrum of pulsar having photon indexΓ=1.33±0.06 and a 1-10 keV flux of 0.91×10^(-12)erg cm^(-2)s^(-1).We also performed the phase-resolved spectral analysis by splitting the whole pulse-on phase into five phase bins.The photon indices of the bins are all around 1.4,indicating that the photon index does not evolve with the phase.展开更多
As one of three primary scientific payloads of Insight-Hard X-ray Modulation Telescope(Insight-HXMT),the High Energy Xray telescope(HE)consists of 18 Nal/CsI phoswich detectors,and the CsI detectors can detect gamma-r...As one of three primary scientific payloads of Insight-Hard X-ray Modulation Telescope(Insight-HXMT),the High Energy Xray telescope(HE)consists of 18 Nal/CsI phoswich detectors,and the CsI detectors can detect gamma-rays that penetrate the satellite from all directions,with an energy range of about 60 keV to 3.2 MeV and a total geometric area of about 5100 cm^(2).These characteristics make the CsI detectors suitable for monitoring GRBs and other high-energy transients.Initial calibration and performance studies of the CsI detectors'instrumental response were conducted during the early operation phase before2020.In this work,we refine the cross-calibration of CsI detectors using a large sample of 85 bright GRBs.Our analysis reveals that the effective area is inversely proportional to the incident angle(θ),with no correlation observed with the azimuthal angle(θ).We subsequently incorporated this relationship into the calibration database to correct for systematic biases in the initial calibration.Furthermore,we demonstrate that joint spectral analyses incorporating CsI data provide better constraints on highenergy spectral parameters for most GRBs.Additionally,we evaluate,for the first time,the energy response of CsI detectors for pointing observation by measuring the Crab Nebula using the Earth occultation technique.This effort extends the energy range of the Insight-HXMT telescope from 1-250 to 1-750 keV for pointing observations.Those results show that the spectra measured by CsI detectors are consistent with other well-calibrated instruments,validating the reliability and accuracy of the CsI detectors'performance.Our work will contribute to Insight-HXMT's capacity to generate more scientific outputs in the field of time-domain astronomy.展开更多
As the brightest gamma-ray burst ever observed,GRB 221009A provided a precious opportunity to explore spectral line features.In this article,we performed a comprehensive spectroscopy analysis of GRB 221009A jointly wi...As the brightest gamma-ray burst ever observed,GRB 221009A provided a precious opportunity to explore spectral line features.In this article,we performed a comprehensive spectroscopy analysis of GRB 221009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption lines.For the first time we investigated the line feature throughout this GRB including the most bright part where many instruments suffered problems,and identified prominent emission lines in multiple time intervals.The central energy of the Gaussian emission line evolves from about 37 to 6 MeV,with a nearly constant ratio(about 10%)between the line width and central energy.Particularly,we find that both the central energy and the energy flux of the emission line evolve with time as a power law decay with power law index of–1 and–2,respectively.We suggest that the observed emission lines most likely origin from the blue-shifted electron positron pair annihilation 511 ke V line.We find that a standard high latitude emission scenario cannot fully interpret the observation,thus we propose that the emission line comes from some dense clumps with electron positron pairs traveling together with the jet.In this scenario,we can use the emission line to directly,for the first time,measure the bulk Lorentz factor of the jet(Γ)and reveal its time evolution(i.e.,Γ~t^(-1))during the prompt emission.Interestingly,we find that the flux of the annihilation line in the co-moving frame keeps constant.These discoveries of the spectral line features shed new and important lights on the physics of GRB and relativistic jet.展开更多
Purpose In order to carry out in-orbit calibration,the hard X-ray modulation telescope satellite(HXMT)has made a number of observations of Crab pulsar.We study the long-term evolution of the X-ray flux of the Crab pul...Purpose In order to carry out in-orbit calibration,the hard X-ray modulation telescope satellite(HXMT)has made a number of observations of Crab pulsar.We study the long-term evolution of the X-ray flux of the Crab pulsar with these observational data.Methods We use nearly four years Crab pulsar’s data obtained by HXMT and the neutron star interior composition of explorer to test whether L_(x)∝L_(sd)^(α) holds for an individual pulsar,where L_(x) is the pulsed X-ray luminosity and Lsd is its spin-down luminosity.We also combine the earlier results obtained with PCA and HEXTE data(Yan et al.in ApJ 865:21,2018)to get the long-term evolution characteristics of the Crab pulsar.Results We find the X-ray flux evolution can be fitted by a linear correlation:L_(x)∝L_(sd)^(1.42±0.18).In soft X-ray energy band(1–10 keV)and hard X-ray energy band(27–250 keV),αdoes not change significantly with either energy or phase.However,this will need to be confirmed in future.For example,the interpulse component of hard X-ray may follow L_(x)∝L_(sd)^(0.96±0.34),which may be different from the correlation of soft X-rays and main pulse component.On the other hand,the hard X-ray flux evolution shows that the performance of high energy X-ray telescope(HE)onboard HXMT,such as effective area,is stable.Conclusion We conclude that the X-ray luminosity of the Crab pulsar closely correlates with its spin-down luminosity.However,the emission mechanism responsible for these phenomena remains not fully understood.展开更多
Purpose We present the five-year in-orbit background evolution of Insight-HXMT since the launch,as well as the effects of the background model in data analysis.Methods The backgrounds of the three main payloads,i.e.,l...Purpose We present the five-year in-orbit background evolution of Insight-HXMT since the launch,as well as the effects of the background model in data analysis.Methods The backgrounds of the three main payloads,i.e.,low-energy telescope,medium-energy telescope,and high-energy telescope,are described.The evolution of the background over time is obtained by simply comparing the background in every year during the in-orbit operation of Insight-HXMT.Results The major observational characteristics of the Insight-HXMT in-orbit background are presented,including the light curve,spectrum,geographical distribution,and long-term evolution.The systematic error in background estimation is investigated for every year.Conclusion The observational characteristics of the five-year in-orbit background are consistent with our knowledge of the satellite design and the space environment,and the background model is still valid for the latest observations of Insight-HXMT.展开更多
Purpose The high-energy X-ray telescope(HE),one of the three main payloads of the Insight-HXMT mission,is composed of eighteen NaI(Tl)/CsI(Na)phoswich detectors,where NaI(Tl)serves as the primary detector covering 20...Purpose The high-energy X-ray telescope(HE),one of the three main payloads of the Insight-HXMT mission,is composed of eighteen NaI(Tl)/CsI(Na)phoswich detectors,where NaI(Tl)serves as the primary detector covering 20–250 keV,and CsI(Na)is used as an active shield detector to suppress the background of NaI(Tl)and also serves as an all-sky gammaray burst monitor covering 0.2–3MeV.In this paper,we review the in-orbit performance of HE in the first 5 years since Insight-HXMT was launched on June 15,2017.Methods The major performances we concern include the gain and energy resolution of NaI(Tl)and CsI(Na)detectors,the performance of pulse shape discriminator(PSD)and system dead time.In this work,we investigate these performances mainly using the data of blank-sky observations and the data when the telescope is in earth occultation.Results The overall performance of HE/NaI(Tl)is very stable in the first 5 years,whereas the gain of HE/CsI(Na)shows a continuously increasing trend and should be calibrated regularly.Conclusion In general,HE is still in good health and well-calibrated status after five-year’s operation.The in-orbit performance of HE has no significant deviation from expectation.HE is expected to be in operation healthily for another several years of extended mission life.展开更多
基金supported by the National Key R&D Program of China(grant No.2023YFE0117200)the National Natural Science Foundation of China(NSFC,grant Nos.12373041 and 12373051)+1 种基金special funding for Guangxi distinguished professors(Bagui Xuezhe)the Guangxi Talent Program(Highland of Innovation Talents)。
文摘We present an analysis of the Imaging X-ray Polarimetry Explorer observation from a newly discovered transient source:Swift J151857.0-572147.The obtained polarization degree(PD)and angle are 0.3%±0.3% and -24°±26°respectively in 2-8 keV within 68%confidence level errors,and polarization results are below MDP99in all energy bins,with the upper limit on PD of 0.8% in the 2-8 keV energy range.No quasi-periodic oscillations(QPOs)are detected in this observation.The polarization and QPO analyses support the hypothesis that the source was in the high soft state,and the results are consistent with predictions for a thin accretion disk model.
基金supported by the National Key R&D Program of China(2021YFA0718500)from the Minister of Science and Technology of China(MOST)supports from the National Natural Science Foundation of China under grants 12173103,12003028,U2038101,U2038102 and 11733009+2 种基金supported by International Partnership Program of Chinese Academy of Sciences(grant No.113111KYSB20190020)the National SKA Program of China(2022SKA0130100)the China Manned Spaced Project(CMS-CSST-2021-B11)。
文摘Fast radio bursts(FRBs)are short pulses observed in radio frequencies usually originating from cosmological distances.The discovery of FRB 200428 and its X-ray counterpart from the Galactic magnetar SGR J1935+2154suggests that at least some FRBs can be generated by magnetars.However,the majority of X-ray bursts from magnetars are not associated with radio emission.The fact that only in rare cases can an FRB be generated raises the question regarding the special triggering mechanism of FRBs.Here we report long time spin evolution of SGR J1935+2154 until the end of 2022.According to v and v,the spin evolution of SGR J1935+2154 could be divided into two stages.The first stage evolves relatively steady evolution until 2020 April 27.After the burst activity in2020,the spin of SGR J1935+2154 shows strong variations,especially for v.After the burst activity in 2022October,a new spin-down glitch with△v/v=(-7.2±0.6)×10^(-6)is detected around MJD 59876,which is the second event in SGR J1935+2154.At the end,spin frequency and pulse profile do not show variations around the time of FRB 200428 and radio bursts 221014 and 221021,which supply strong clues to constrain the trigger mechanism of FRBs or radio bursts.
基金project funded by China National Space Administration(CNSA)the Chinese Academy of Sciences(CAS)+2 种基金supported by the National Key R&D Program of China(2021YFA0718500 and 2023YFE0101200)from the Minister of Science and Technology of China(MOST)supports from the National Natural Science Foundation of China under grants 12373051 and 12333007supported by International Partnership Program of Chinese Academy of Sciences(grant No.113111KYSB20190020)。
文摘Owing to the broad energy coverage of Insight-HXMT in the hard X-ray band,we detected the highest energy of pulsation exceeding 200 keV around the 2017–2018 outburst peak of the first Galactic pulsating ultraluminous X-ray source (PULX) Swift J0243.6+6124,which is the highest energy detected from PULXs to date.We also obtained the highest energy of pulsation of every exposure during the outburst in 2017–2018,and found the highest energy is roughly positively correlated with luminosity.Using our newly developed method,we identified the critical luminosity being 4×10^(38)erg s^(-1) when the main peaks of the low and high energy pulse profiles became aligned,which separates the fan-beam dominated and pencil-beam dominated accretion regimes.Above the critical luminosity,the phase of the main peak shifted gradually from 0.5 to 0.8 until the outburst peak in al energy bands is reached,which is in agreement with the phase shift found previously at low energies.Our result is consistent with what is derived from spectral analysis.
基金supported by International Partnership Program of Chinese Academy of Sciences(grant No.113111KYSB20190020)by the National Key R&D Program of China(2021YFA0718500)from the Minister of Science and Technology of China(MOST)supports from the National Natural Science Foundation of China under Grants U1938109,12333007,12173103,U2038101,U1938103,12333007,12303045,U1938201 and 11733009。
文摘In October 2022,the magnetar SGR J1935+2154 entered the active outburst state.During the episode,the InsightHXMT satellite carried out a long observation that lasted for 20 days.More than 300 bursts were detected,and a certain amount of persistent radiation signals were also accumulated.This paper mainly introduces the results of persistent radiation profile folding and period search based on Insight-HXMT data.At the same time,the burst phase distribution characteristics,spectral lag results of burst,the spectral characteristics of zero-lag bursts and the time-resolved spectral evolution characteristics of high-flux bursts are reported.We found that there is no significant delay feature during different energy bands for the bursts of SGR J1935+2154.The observed zero-lag burst does not have a unique spectrum.The time-resolved spectrum of the individual burst has consistent spectral types and spectral parameters at different time periods of the burst.We also find that the burst number phase distribution and the burst photon phase distribution have the same tendency to concentrate in specific regions of the persistent emission profile.
基金supported by the National Key R&D Program of China (2016YFA0400800)the National Natural Science Foundation of China (Grant Nos. 11503027, 11673023, U1838201 and U1838104)the HXMT mission, a project funded by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS)
文摘We report on X-ray emission properties of the Crab pulsar(PSR B0531+21) using observations by Insight-HXMT during its first year after launch. We obtained high signal-to-noise profiles in the X-ray energy band 11–250 keV. We have confirmed an increase in the flux ratio of the second peak over the main peak with increasing energy, consistent with other missions. The separation of the two peaks shows no significant trend with increasing energy. The phase-averaged spectrum, fitted by a logpar model, and the phase-resolved spectra of the Crab pulsar, fitted by a powerlaw in the different energy bands of HXMT, are consistent with RXTE and NuSTAR in that photon indices evolve as a function of phase as well as a function of energy, contributing to a broadband modeling.
基金The Parkes Radio Telescope (Murriyang) is part of the Australia Telescope National Facility, which is funded by the Australian Government for operation as a National Facility managed by CSIROsupported by the National Natural Science Foundation of China (NSFC) grant Nos. 12041303, 12041304, 11873067, 12133004, 12203045, 12203070, 12203072, 12103013, U2031117 and T2241020+11 种基金the CAS-MPG LEGACY project and the National SKA Program of China No. 2020SKA0120200the Foundation of Science and Technology of Guizhou Province No. ((2021)023)the Foundation of Guizhou Provincial Education Department (No.KY(2021)303)the National Key Research and Development Program of China Nos. 2022YFC2205202 and 2022YFC2205203the Major Science and Technology Program of Xinjiang Uygur Autonomous Region Nos. 2022A03013-1, 2022A03013-3 and 2022A03013-4the National Key Research and Development Program of China No. 2022YFC2205203the 2021 project Xinjiang Uygur autonomous region of China for Tianshan elites and the Youth Innovation Promotion Association of CAS under No. 2023069support from the Youth Innovation Promotion Association CAS (id. 2021055)CAS Project for Young Scientists in Basic Research (grant YSBR-006)the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CASsupport from Zhejiang Provincial Natural Science Foundation of China under grant No. LY23A030001supported by the NSF Physics Frontiers Center award number 2020265。
文摘We report the radio observations of the eclipsing black widow pulsar J1720-0534, a 3.26 ms pulsar in orbit with a low mass companion of mass 0.029 to 0.034 M⊙. We obtain the phase-connected timing ephemeris and polarization profile of this millisecond pulsar(MSP) using the Five-hundred-meter Aperture Spherical radio Telescope(FAST), the Green Bank Telescope(GBT), and the Parkes Telescope. For the first time from such a system, an oscillatory polarization angle change was observed from a particular eclipse egress with partial depolarization, indicating 10-milliGauss-level reciprocating magnetic fields oscillating in a length scale of 5 ×10^(3)km(assuming an orbital inclination angle of 90°) outside the companion's magnetosphere. The dispersion measure variation observed during the ingresses and egresses shows the rapid raising of the electron density in the shock boundary between the companion's magnetosphere and the surrounding pulsar wind. We suggest that the observed oscillatory magnetic fields originate from the pulsar wind outside the companion's magnetosphere.
基金partially supported by International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020)the National Key R&D Program of China(2021YFA0718500)from the Minister of Science and Technology of China(MOST)The authors thank supports from the National Natural Science Foundation of China under Grants U1938109,U1838201,U1838202,12173103,U2038101,U1938103,12133007,U1938201 and 11733009。
文摘On 2020 April 27,the soft gamma-ray repeater SGR J1935+2154 entered its intense outburst episode again.Insight-HXMT carried out about one month observation of the source.A total number of 75 bursts were detected during this activity episode by Insight-HXMT,and persistent emission data were also accumulated.We report on the spin period search result and the phase distribution of burst start times and burst photon arrival times of the Insight-HXMT high energy detectors and Fermi/Gamma-ray Burst Monitor(GBM).We find that the distribution of burst start times is uniform within its spin phase for both Insight-HXMT and Fermi/GBM observations,whereas the phase distribution of burst photons is related to the type of a burst’s energy spectrum.The bursts with the same spectrum have different distribution characteristics in the initial and decay episodes for the activity of magnetar SGR J1935+2154.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11903001,U1938109,U1838201,U1838202 and 42004004)the Key Research Foundation of Education Ministry of Anhui Province(KJ2019A0787)the Doctor Foundation of Anhui Jianzhu University 2019(2019QDZ14)。
文摘We analyze the time and energy dependence of the Vela pulsar’s pulse profile using 13 yr observations from the Large Area Telescope on the Fermi Gamma-ray Space Telescope.It is found that the pulse profile of the Vela pulsar inγ-ray changes with time.We parameterize the pulse profile and find that different shape parameters show fiuctuations rather than gradual changes with time.However,these time variation trends are insignificant due to limited statistics.The pulse profile of the Vela pulsar displays clear energy dependence inγ-ray.Different shape parameters are accurately obtained or updated,especially the phase separations among different pulses.Their energy evolution trends are quantified for the first time,which will provide restrictions on currentγ-ray emission models.For the Vela pulsar,we also find a turning point at phase.Before and after this phase,the relative intensity of the pulse profile evolves with energy with the opposite trend.
基金supported by the National Key Research and Development Program of China(2016YFA0400804,2017YFA0402602,2018YFA0404603 and 2018YFA0404703)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administered by the Chinese Academy of Sciences(CAS),the National Natural Science Foundation of China(Grant Nos.11873080,U1831102,U1731238,U1938109,U1838104,11873040,11573010,11661161010,U1631103 and U1838102)+4 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences,the CAS“Light of West China”Program(Nos.2018-XBQNXZ-B-023,2018-XBQNXZ-B-025 and 2016-QNXZ-B-24)the Tianshan Youth Program No.2018Q039the Open Project Program of the Key Laboratory of FAST,NAOC,Chinese Academy of Sciences,the China Postdoctoral Science Foundation grant(2019M650847)the 2016 and 2018 Project of Xinjiang Uygur Autonomous Region of China for Flexibly Fetching in Upscale Talents and the Science and Technology Fund of Guizhou Province(Grant Nos.(2016)–4008 and(2017)5726–37)part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO。
文摘PSR J0742-2822 is known for its quasi-periodic changes in the observed pulse profile and spindown rate.In this paper,we analyzed 13 years of timing data obtained with the Nanshan 25-m radio telescope and the Parkes 64-m radio telescope.We found that the average values of the spin-down rate((v))of this pulsar changed in four different states.We investigated the correlation between v and W50,and ascertained that the correlation changed in different states.Moreover,not all the changes in states and correlation can be associated with glitch activities.We examined the long term evolution ofγ-ray flux(0.1-300 GeV)and the pulse profiles corresponding to the four different states using Fermi-LAT Pass8(P8 R3)data from 2008 August 5 to 2019 October 1.We did not detect a significant change inγ-ray flux or the pulse profile.Our results suggest that the connection between pulsar rotation and emission is more complex than previously reported for this pulsar.
基金the HXMT mission,a project funded by China National Space Administration(CNSA)and the Chinese Academy of Sciences(CAS)supported by the National Key R&D Program of China(2016YFA0400800)the National Natural Science Foundation of China(Grant Nos.11673023,U1838201,U1838115,U1838111,U1838202,11733009 and U1838108)。
文摘We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.
基金supported by the National Natural Science Foundation of China(NSFC,grant No.U1838203)International Partnership Program of Chinese Academy of Sciences(grant No.113111KYSB20190020)。
文摘We analyzed the spectral properties and pulse profile of PSR J1811-1925,a pulsar located in the center of composite supernova remnant(SNR)G11.2-0.3,by using high timing resolution archival data from the Nuclear Spectroscopic Telescope Array Mission(NuSTAR).Analysis of archival Chandra data over different regions rules out the SNR shell as the site of the hard X-ray emission while spectral analysis indicates that the NuSTAR photons originate in the pulsar and its nebula.The pulse profile exhibits a broad single peak up to 35 keV.The jointed spectrum by combining NuSTAR and Chandra can be well fitted by a power-law model with a photon index ofΓ=1.58±0.04.The integrated flux of jointed spectrum over 1-10 keV is 3.36×10^(-12)erg cm^(-2)s^(-1).The spectrum of pulsar having photon indexΓ=1.33±0.06 and a 1-10 keV flux of 0.91×10^(-12)erg cm^(-2)s^(-1).We also performed the phase-resolved spectral analysis by splitting the whole pulse-on phase into five phase bins.The photon indices of the bins are all around 1.4,indicating that the photon index does not evolve with the phase.
基金the support from the National Key Research and Development Program of China(Grant No.2021YFA0718500)the Strategic Priority Research Program+1 种基金the Chinese Academy of Sciences(Grant Nos.XDB0550300 and XDA30050000)the National Natural Science Foundation of China(Grant Nos.12273042,12494572,12373047,12273043,and 12103055)。
文摘As one of three primary scientific payloads of Insight-Hard X-ray Modulation Telescope(Insight-HXMT),the High Energy Xray telescope(HE)consists of 18 Nal/CsI phoswich detectors,and the CsI detectors can detect gamma-rays that penetrate the satellite from all directions,with an energy range of about 60 keV to 3.2 MeV and a total geometric area of about 5100 cm^(2).These characteristics make the CsI detectors suitable for monitoring GRBs and other high-energy transients.Initial calibration and performance studies of the CsI detectors'instrumental response were conducted during the early operation phase before2020.In this work,we refine the cross-calibration of CsI detectors using a large sample of 85 bright GRBs.Our analysis reveals that the effective area is inversely proportional to the incident angle(θ),with no correlation observed with the azimuthal angle(θ).We subsequently incorporated this relationship into the calibration database to correct for systematic biases in the initial calibration.Furthermore,we demonstrate that joint spectral analyses incorporating CsI data provide better constraints on highenergy spectral parameters for most GRBs.Additionally,we evaluate,for the first time,the energy response of CsI detectors for pointing observation by measuring the Crab Nebula using the Earth occultation technique.This effort extends the energy range of the Insight-HXMT telescope from 1-250 to 1-750 keV for pointing observations.Those results show that the spectra measured by CsI detectors are consistent with other well-calibrated instruments,validating the reliability and accuracy of the CsI detectors'performance.Our work will contribute to Insight-HXMT's capacity to generate more scientific outputs in the field of time-domain astronomy.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFA0718500,and 2023YFE0101200)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA15360102,XDA15360300,and XDA15052700)+3 种基金the National Natural Science Foundation of China(Grant Nos.12273042,61234003,61434004,61504141,11673062,12393813,2333007,12027803,and 12303045)the CAS Interdisciplinary Project(Grant No.KJZD-EW-L11-04)supported by the Strategic Priority Research Program on Space Science(Grant No.XDA15360000)of the Chinese Academy of Sciencessupported by the Yunnan Revitalization Talent Support Program(Yun Ling Scholar Award)。
文摘As the brightest gamma-ray burst ever observed,GRB 221009A provided a precious opportunity to explore spectral line features.In this article,we performed a comprehensive spectroscopy analysis of GRB 221009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption lines.For the first time we investigated the line feature throughout this GRB including the most bright part where many instruments suffered problems,and identified prominent emission lines in multiple time intervals.The central energy of the Gaussian emission line evolves from about 37 to 6 MeV,with a nearly constant ratio(about 10%)between the line width and central energy.Particularly,we find that both the central energy and the energy flux of the emission line evolve with time as a power law decay with power law index of–1 and–2,respectively.We suggest that the observed emission lines most likely origin from the blue-shifted electron positron pair annihilation 511 ke V line.We find that a standard high latitude emission scenario cannot fully interpret the observation,thus we propose that the emission line comes from some dense clumps with electron positron pairs traveling together with the jet.In this scenario,we can use the emission line to directly,for the first time,measure the bulk Lorentz factor of the jet(Γ)and reveal its time evolution(i.e.,Γ~t^(-1))during the prompt emission.Interestingly,we find that the flux of the annihilation line in the co-moving frame keeps constant.These discoveries of the spectral line features shed new and important lights on the physics of GRB and relativistic jet.
基金support from the National Program on Key Research and Development Project(Grant No.2021YFA0718500)from the Minister of Science and Technology of China(MOST)supports from the National Natural Science Foundation of China under Grants U1938102,12273043,U1838201,U1838202,U1938109 and U1938108supported by International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020).
文摘Purpose In order to carry out in-orbit calibration,the hard X-ray modulation telescope satellite(HXMT)has made a number of observations of Crab pulsar.We study the long-term evolution of the X-ray flux of the Crab pulsar with these observational data.Methods We use nearly four years Crab pulsar’s data obtained by HXMT and the neutron star interior composition of explorer to test whether L_(x)∝L_(sd)^(α) holds for an individual pulsar,where L_(x) is the pulsed X-ray luminosity and Lsd is its spin-down luminosity.We also combine the earlier results obtained with PCA and HEXTE data(Yan et al.in ApJ 865:21,2018)to get the long-term evolution characteristics of the Crab pulsar.Results We find the X-ray flux evolution can be fitted by a linear correlation:L_(x)∝L_(sd)^(1.42±0.18).In soft X-ray energy band(1–10 keV)and hard X-ray energy band(27–250 keV),αdoes not change significantly with either energy or phase.However,this will need to be confirmed in future.For example,the interpulse component of hard X-ray may follow L_(x)∝L_(sd)^(0.96±0.34),which may be different from the correlation of soft X-rays and main pulse component.On the other hand,the hard X-ray flux evolution shows that the performance of high energy X-ray telescope(HE)onboard HXMT,such as effective area,is stable.Conclusion We conclude that the X-ray luminosity of the Crab pulsar closely correlates with its spin-down luminosity.However,the emission mechanism responsible for these phenomena remains not fully understood.
基金supports from the National Key R&D Program of China(2021YFA0718500)the National Natural Science Foundation of China under Grants Nos.U1838202 and U1838201This work was partially supported by International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020).
文摘Purpose We present the five-year in-orbit background evolution of Insight-HXMT since the launch,as well as the effects of the background model in data analysis.Methods The backgrounds of the three main payloads,i.e.,low-energy telescope,medium-energy telescope,and high-energy telescope,are described.The evolution of the background over time is obtained by simply comparing the background in every year during the in-orbit operation of Insight-HXMT.Results The major observational characteristics of the Insight-HXMT in-orbit background are presented,including the light curve,spectrum,geographical distribution,and long-term evolution.The systematic error in background estimation is investigated for every year.Conclusion The observational characteristics of the five-year in-orbit background are consistent with our knowledge of the satellite design and the space environment,and the background model is still valid for the latest observations of Insight-HXMT.
基金support from the National Program on Key Research and Development Project(Grant No.2021YFA0718500)from the Minister of Science and Technology of China(MOST)The authors thank supports from the National Natural Science Foundation of China under Grants 12273043,U1838201,U1838202,U1938109,U1938102,U1938108This work was partially supported by International Partnership Program of ChineseAcademy of Sciences(Grant No.113111KYSB20190020).
文摘Purpose The high-energy X-ray telescope(HE),one of the three main payloads of the Insight-HXMT mission,is composed of eighteen NaI(Tl)/CsI(Na)phoswich detectors,where NaI(Tl)serves as the primary detector covering 20–250 keV,and CsI(Na)is used as an active shield detector to suppress the background of NaI(Tl)and also serves as an all-sky gammaray burst monitor covering 0.2–3MeV.In this paper,we review the in-orbit performance of HE in the first 5 years since Insight-HXMT was launched on June 15,2017.Methods The major performances we concern include the gain and energy resolution of NaI(Tl)and CsI(Na)detectors,the performance of pulse shape discriminator(PSD)and system dead time.In this work,we investigate these performances mainly using the data of blank-sky observations and the data when the telescope is in earth occultation.Results The overall performance of HE/NaI(Tl)is very stable in the first 5 years,whereas the gain of HE/CsI(Na)shows a continuously increasing trend and should be calibrated regularly.Conclusion In general,HE is still in good health and well-calibrated status after five-year’s operation.The in-orbit performance of HE has no significant deviation from expectation.HE is expected to be in operation healthily for another several years of extended mission life.
