The Follow-up X-ray Telescope(FXT)is one of the main scientific instruments on board the Einstein Probe astronomical satellite,which was launched in 2024 January.FXT consists of two Wolter I type nested telescopes(FXT...The Follow-up X-ray Telescope(FXT)is one of the main scientific instruments on board the Einstein Probe astronomical satellite,which was launched in 2024 January.FXT consists of two Wolter I type nested telescopes(FXT-A and FXT-B)with a focal length of 1600 mm.The focal plane detector employs a PNCCD with 384×384 pixels.The timing mode of FXT serves as the primary operating mode for fast X-ray timing observations.To evaluate and validate the timing performance of FXT prior to launch,a comprehensive timing calibration was performed at the 100 m X-ray test facility.By simulating various periodic Crab-like profiles using the Grid Controlled X-ray Tube(GCXT)in conjunction with a pulsar simulation module,it was verified that the relative time accuracy of FXT exceeds 5×10^(−9).Furthermore,employing GCXT with a voltage pulse generation module enabled the determination of the time resolutions for FXT-A and FXT-B,recorded as 45.6±2.7μs and 47.1±2.8μs,respectively.An absolute timing calibration for FXT-B was carried out using the GCXT and a time interval analyzer,revealing a measured time delay of 3.9±2.1μs for FXT-B.展开更多
Background:The Einstein Probe mission is an astronomical satellite developed in China,focusing on time-domain astronomy in the soft X-ray energy band.A key payload of this mission is the follow-up X-ray telescope(FXT)...Background:The Einstein Probe mission is an astronomical satellite developed in China,focusing on time-domain astronomy in the soft X-ray energy band.A key payload of this mission is the follow-up X-ray telescope(FXT),which is the result of international collaboration between China and Europe.The FXT features gold-coated nickel Wolter-I-type focusing mirrors and utilizes PNCCD detectors for imaging and spectroscopy in the focal plane.Methods:We reviewed the seven-year development history of the FXT.Initially,the configuration of the FXT consisted of a single telescope unit in 2017,but it later evolved into a dual-unit setup.Building on the successful design of eROSITA,the FXT team has innovatively introduced new operational modes for the PNCCD.FXT team also developed an ultra-compact helium pulse tube refrigerator,which cools the PNCCD down to-90℃.Additionally,various passive shielding measures have been implemented to protect against high-energy charged particles and enhance radiation resistance.These advancements have significantly improved the overall performance and reliability of the FXT.Results and conclusion:The ground calibrations and tests of the FXT demonstrate that its primary performance meets the established design goals.The FXT has exhibited outstanding performance in orbit,establishing itself as one of the space X-ray telescopes with considerable international influence.展开更多
Purpose The Einstein Probe(EP)satellite is a science mission of the Chinese Academy of Sciences,which is dedicated to time-domain astronomy and high-energy astrophysics.The X-ray baffle is a crucial component of follo...Purpose The Einstein Probe(EP)satellite is a science mission of the Chinese Academy of Sciences,which is dedicated to time-domain astronomy and high-energy astrophysics.The X-ray baffle is a crucial component of follow-up X-ray telescope(FXT),which is an important payload onboard EP.It was designed to efficiently reduce stray light,especially single reflection on the hyperboloid of Wolter-I Mirrors.Methods In this paper,based on the parameters of FXT's mirror module and the detector,the design parameters of the X-ray baffle are optimized through preliminary design and detailed ray-tracing simulation.Fabrication involved precision laser cutting,roll forming,laser welding and integration processes.The thermal stability and mechanical environment adaptability were validated through thermal cycling and mechanical vibration tests.Finally,the X-ray baffle was mounted onto the mirror module with alignment precisely controlled using optical methods.Results The height of the X-ray baffle ranges from 60 to 120 mm from the outside to the inside;the aperture corresponds to each layer of the mirror module.In order to reduce weight and reduce light occlusion,the thickness of each thin shell is 0.125 mm.The ray-tracing simulation results with X-ray baffle are shown that the stray light is effectively reduced in the effective region of the detector.The Eigen-frequency change of the X-ray baffle after the thermal cycle test and mechanical vibration tests is only 0.52%and 0.77%,respectively.The results proved that X-ray baffle has a high thermo-mechanical reliability.The half power diameter(HPD)of the mirror module remained unchanged on-axis with/without X-ray baffle.Conclusion The introduction of X-ray baffle is expected to be highly significantly reduce stray light.展开更多
Purpose This study aimed to optimize the pre-treatment process for electroless nickel-phosphorus plating in the Einstein Probe project,addressing technical challenges encountered with 6061 aluminum alloy substrates to...Purpose This study aimed to optimize the pre-treatment process for electroless nickel-phosphorus plating in the Einstein Probe project,addressing technical challenges encountered with 6061 aluminum alloy substrates to enhance coating quality and operational efficiency.Methods Verification experiments were conducted using 6061 aluminum alloy sheets as substitutes for large aluminum mandrels.The effects of surface roughness,rinsing methods,and the necessity of acid pickling were systematically evaluated.The samples were characterized by scanning electron microscopy,atomic force microscopy,and energy-dispersive X-ray spectroscopy to analyze surface morphology and elemental composition.Results and Conclusion Excessive surface roughness should be avoided,with a roughness below 338 nm ensuring uniform coatings.Flowing water rinsing after each step was critical to prevent contamination from residual solutions,whereas stagnant water immersion proved inadequate.Acid pickling was determined to be non-essential,as it had minimal impact on coating quality.The zinc layer formed during immersion exhibited weak adhesion and should be rinsed gently to avoid detachment.These findings offer valuable insights for pre-treatment process refinement in the Einstein Probe project and related applications.展开更多
Purpose The follow-up X-ray telescope(FXT)is one of the two payloads of the Einstein Probe(EP),consisting of the upper composite with the X-ray mirror module as the core,the lower composite with the pnCCD module as th...Purpose The follow-up X-ray telescope(FXT)is one of the two payloads of the Einstein Probe(EP),consisting of the upper composite with the X-ray mirror module as the core,the lower composite with the pnCCD module as the core,and the interface structure.The FXT thermal control subsystem is responsible for the thermal design,thermal implementations,and testing of the entire FXT payload thermal control.Methods A design approach is adopted with passive thermal control technology as the main method and active thermal control technology as a supplement for common components.The X-ray mirror modules are high-precision optical components,utilizing active closed-loop temperature control to ensure high precision and stability.The pnCCD detectors operate at a stable low temperature,with refrigerators used to cool the detector houses,ensuring they can operate under stable low-temperature conditions.The hot ends of the refrigerators are connected to the external radiator panels through heat pipes for heat dissipation.Results The thermal control subsystem of FXT is operating properly in-orbit.All component temperatures meet the design requirements.Conclusion After multiple rounds of design and test verification,FXT was successfully launched with EP and completed in-orbit testing.During the in-orbit testing phase of EP,the function of the FXT thermal control subsystem works well.The temperatures of the components and units are normal.This paper introduces the design of FXT thermal control and the in-orbit performance of the thermal control subsystem.展开更多
Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positio...Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positioning accuracy of the Follow-up X-ray Telescope(FXT),playing a crucial role in achieving the on-orbit scientific objectives of the FXT.Higher positioning accuracy makes it easier to identify corresponding bodies for the discovery and positioning of transient sources.Accurate positioning is beneficial for follow-up observations in other bands,such as optical spectroscopy.Methods This article mainly introduces the precision control methods and processes of the FXT optical structure,which have been tested and verified through satellite test.The on-orbit source positioning accuracy of the FXT telescope is within 20 arcseconds(90% confidence level),meeting the requirements of the FXT mission.Results and Conclusion To ensure the accuracy of the EP satellite’s FXT optical structure,measures such as component processing control,installation control,and posttest adjustments are taken on the ground to ensure that the detector mounting position,optical axis deviation,and other precision indicators before and after the satellite lever test meet the design requirements.After a successful launch,through on-orbit calibration,the FXT-A and FXT-B optical axis pointing direction deviation is 39 arcseconds,and the source positioning error is better than 3'' at 68% confidence level.FXT optical structure meets all the requirements from design,processing,installation,etc.,successfully meeting scientific needs.展开更多
Purpose:In order to evaluate the mechanical feasibility of the domestic baffle made by wire electrode cutting for the mirror assembly of the Follow-up X-ray Telescope(FXT)onboard the Einstein Probe(EP)mission.Methods:...Purpose:In order to evaluate the mechanical feasibility of the domestic baffle made by wire electrode cutting for the mirror assembly of the Follow-up X-ray Telescope(FXT)onboard the Einstein Probe(EP)mission.Methods:Finite element analysis was performed to compare the structural differences between the domestic baffle made by wire electrode cutting and the eROSITA baffle made by bonding.The finite element models were verified by test data in advance to avoid significant deviations.Finally,the differences in dynamical performances between the FXT mirror assemblies with the two baffles were investigated through modal analysis and frequency response analysis using the pre-verified models.Results and conclusions:The results show that,from the perspective of the entire mirror assembly,their eigenfrequencies remain similar,except for the second lateral eigenfrequency,which shifts forward by approximately 24 Hz in the mirror assembly equipped with the domestic baffle.However,for the X-ray baffles themselves,the axial and lateral eigenfrequencies of the two baffles differ by approximately 49 Hz and 185 Hz,respectively.These eigenfrequencies are staggered,ensuring that over-response is avoided.In terms of response amplification,the domestic baffle,compared to the eROSITA baffle,exhibits inferior axial mechanical characteristics but superior lateral characteristics.In summary,from a mechanical perspective,the domestic baffle is feasible.展开更多
In this paper,we present the current status of the enhanced X-ray Timing and Polarimetry mission,which has been fully approved for launch in 2030.eXTP is a space science mission designed to study fundamental physics u...In this paper,we present the current status of the enhanced X-ray Timing and Polarimetry mission,which has been fully approved for launch in 2030.eXTP is a space science mission designed to study fundamental physics under extreme conditions of matter density,gravity,and magnetism.The mission aims at determining the equation of state of matter at supra-nuclear density,measuring the effects of quantum electro-dynamics,and understanding the dynamics of matter in strong-field gravity.In addition to investigating fundamental physics,the eXTP mission is poised to become a leading observatory for time-domain and multi-messenger astronomy in the 2030s,as well as providing observations of unprecedented quality on a variety of galactic and extragalactic objects.After briefly introducing the history and a summary of the scientific objectives of the eXTP mission,this paper presents a comprehensive overview of:(1)the cutting-edge technology,technical specifications,and anticipated performance of the mission’s scientific instruments;(2)the full mission profile,encompassing spacecraft design,operational capabilities,and ground segment infrastructure.展开更多
Background The Einstein probe(EP)is an X-ray astronomical satellite dedicated to time-domain astronomy and high-energy astrophysics.Initiated at the end of 2017,it was successfully launched on January 9,2024.The follo...Background The Einstein probe(EP)is an X-ray astronomical satellite dedicated to time-domain astronomy and high-energy astrophysics.Initiated at the end of 2017,it was successfully launched on January 9,2024.The follow-up X-ray telescope(FXT)is a key payload on the EP satellite.The FXT employs PNCCD as its focal plane detector.Its electronic components include the electronic control box(EC-Box),the detector electronics boxes(DE-Box),the refrigerator controller,the movement mechanisms controller,and the temperature control instrument.Methods The FXT conducted functional performance tests in-orbit as planned,including three operating modes of the detector,energy detection range,and energy resolution.Results Since FXT became operational in orbit,all electronic equipment has been working stably.The FXT has an energy detection range of 0.3-10 keV,with an energy resolution of approximately 92 eV@1.25 keV,and an electronic noise of about 3.3e^(-).展开更多
Purpose To meet the stringent requirements for high-quality processing of focusing mirror molds and reproduction mirrors,specific cleaning procedures must be both accurate and efficient.Methods This study examines the...Purpose To meet the stringent requirements for high-quality processing of focusing mirror molds and reproduction mirrors,specific cleaning procedures must be both accurate and efficient.Methods This study examines the stability and consistency of the removal rate throughout the polishing process by analyzing changes in the composition of the polishing slurry at various stages.Infrared spectroscopy was used to measure the chemical groups of compounds on the mandrel surface and assess its stress state.Additionally,the adsorption mechanism at the interface was explored in detail.Results and Conclusion The study investigates ultra-precision polishing of nickel–phosphorus alloy,focusing on factors influencing the water film formation ability on the workpiece surface.X-ray electron spectroscopy was employed to analyze the mandrel before and after the cleaning process.The effectiveness of the cleaning process was evaluated by comparing its surface removal effect with that of the polishing process.展开更多
We report the discovery of a peculiar X-ray transient,EP240408a,by Einstein Probe(EP)and follow-up studies made with EP,Swift,NICER,GROND,ATCA and other ground-based multiwavelength telescopes.The new transient was fi...We report the discovery of a peculiar X-ray transient,EP240408a,by Einstein Probe(EP)and follow-up studies made with EP,Swift,NICER,GROND,ATCA and other ground-based multiwavelength telescopes.The new transient was first detected with Wide-field X-ray Telescope(WXT)on board EP on April 8th,2024,manifested in an intense yet brief X-ray flare lasting for 12 s.The flare reached a peak flux of 3:9×10^(−9) erg cm^(−2) s^(−1) in 0.5-4 keV,∼300 times brighter than the underlying X-ray emission detected throughout the observation.Rapid and more precise follow-up observations by EP/FXT,Swift and NICER confirmed the finding of this new transient.Its X-ray spectrum is non-thermal in 0.5-10 keV,with a power-law photon index varying within 1.8-2.5.The X-ray light curve shows a plateau lasting for∼4 d,followed by a steep decay till becoming undetectable∼10 d after the initial detection.Based on its temporal property and constraints from previous EP observations,an unusual timescale in the range of 7-23 d is found for EP240408a,which is intermediate between the commonly found fast and long-term transients.No counterparts have been found in optical and near-infrared,with the earliest observation at 17 h after the initial X-ray detection,suggestive of intrinsically weak emission in these bands.We demonstrate that the remarkable properties of EP240408a are inconsistent with any of the transient types known so far,by comparison with,in particular,jetted tidal disruption events,gamma-ray bursts,X-ray binaries and fast blue optical transients.The nature of EP240408a thus remains an enigma.We suggest that EP240408a may represent a new type of transients with intermediate timescales of the order of∼10 d.The detection and follow-ups of more of such objects are essential for revealing their origin.展开更多
As China’s first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band(1-250 ke V) slat-collimator-based X-ray as...As China’s first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band(1-250 ke V) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 Me V. It was designed to perform pointing, scanning and gamma-ray burst(GRB)observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed.Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results.展开更多
In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The m...In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources.The paper provides a detailed description of:(1) the technological and technical aspects, and the expected performance of the instruments of the scientific payload;(2) the elements and functions of the mission, from the spacecraft to the ground segment.展开更多
Finding the electromagnetic （EM） counterpart of binary compact star merger, especially the binary neutron star （BNS） merger, is critically important for gravitational wave （GW） astronomy, cosmology and fundament...Finding the electromagnetic （EM） counterpart of binary compact star merger, especially the binary neutron star （BNS） merger, is critically important for gravitational wave （GW） astronomy, cosmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and Fermi/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope （HE） onboard Insight-HXMT （Hard X-ray Modulation Telescope） is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart （SSS17a/AT2017gfo） with very large collection area （M000 cm2） and microsecond time resolution in 0.2-5 MeV. In addition, Insight-HXMT quickly implemented a Target of Opportunity （TOO） observation to scan the GW localization area for potential X-ray emission from the GW source. Although Insight-HXMT did not detect any significant high energy （0.2-5 MeV） radiation from GW170817, its observation helped to confirm the unexpected weak and soft nature of GRB 170817A. Meanwhile, Insight-HXMT/HE provides one of the most stringent constraints （-10-7 to 104 erg/cm2/s） for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of Insight-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event.展开更多
The Low Energy X-ray telescope(LE) is one of the three main instruments of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT). It is equipped with Swept Charge Device(SCD) sensor arrays with a total geometrical...The Low Energy X-ray telescope(LE) is one of the three main instruments of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT). It is equipped with Swept Charge Device(SCD) sensor arrays with a total geometrical area of 384 cm^2 and an energy band from 0.7 to 13 ke V. In order to evaluate the particle induced X-ray background and the cosmic X-ray background simultaneously, LE adopts collimators to define four types of Field Of Views(FOVs), i.e., 1.6°×6°, 4°×6°, 50°-60°×2°-6 oand the blocked ones which block the X-ray by an aluminum cover. LE is constituted of three detector boxes(LEDs) and an electric control box(LEB) and achieves a good energy resolution of 140 e V@5.9 ke V, an excellent time resolution of 0.98 ms, as well as an extremely low pileup(<1%@18000 cts/s). Detailed performance tests and calibration on the ground have been performed,including energy-channel relation, energy response, detection efficiency and time response.展开更多
Purpose The low-energy X-ray telescope(LE)is a main instrument of the Insight-HXMT mission and consists of 96 swept charge devices covering the 1–10 keV energy band.The energy gain and resolution are continuously cal...Purpose The low-energy X-ray telescope(LE)is a main instrument of the Insight-HXMT mission and consists of 96 swept charge devices covering the 1–10 keV energy band.The energy gain and resolution are continuously calibrated by analyzing Cassiopeia A(Cas A)and blank sky data,while the effective areas are also calibrated with the observations of the Crab Nebula.In this paper,we present the evolution of the in-orbit performances of LE in the first 5 years since launch.Methods The Insight-HXMT data analysis software package(HXMTDAS)is utilized to extract the spectra of Cas A,blank sky,and Crab Nebula using different good time interval selections.We fit a model with a power-law continuum and several Gaussian lines to different ranges of Cas A and blank sky spectra to get peak energies of their lines through xspec.After updating the energy gain calibration in CALibration DataBase(CALDB),we rerun the Cas A data to obtain the energy resolution.An empirical function is used to modify the simulated effective areas so that the background-subtracted spectrum of the Crab Nebula can best match the standard model of the Crab Nebula.Results The energy gain,resolution,and effective areas are calibrated every month.The corresponding calibration results are duly updated in CALDB,which can be downloaded and used for the analysis of Insight-HXMT data.Simultaneous observations with NuSTAR and NICER can also be used to verify our derived results.Conclusion LE is a well-calibrated X-ray telescope working in 1–10 keV band.The uncertainty of LE gain is less than 20eV in 2–9 keV band,and the uncertainty of LE resolution is less than 15eV.The systematic errors of LE,compared to the model of the Crab Nebula,are lower than 1.5%in 1–10 keV.展开更多
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences,grant No.XDA15310103.
文摘The Follow-up X-ray Telescope(FXT)is one of the main scientific instruments on board the Einstein Probe astronomical satellite,which was launched in 2024 January.FXT consists of two Wolter I type nested telescopes(FXT-A and FXT-B)with a focal length of 1600 mm.The focal plane detector employs a PNCCD with 384×384 pixels.The timing mode of FXT serves as the primary operating mode for fast X-ray timing observations.To evaluate and validate the timing performance of FXT prior to launch,a comprehensive timing calibration was performed at the 100 m X-ray test facility.By simulating various periodic Crab-like profiles using the Grid Controlled X-ray Tube(GCXT)in conjunction with a pulsar simulation module,it was verified that the relative time accuracy of FXT exceeds 5×10^(−9).Furthermore,employing GCXT with a voltage pulse generation module enabled the determination of the time resolutions for FXT-A and FXT-B,recorded as 45.6±2.7μs and 47.1±2.8μs,respectively.An absolute timing calibration for FXT-B was carried out using the GCXT and a time interval analyzer,revealing a measured time delay of 3.9±2.1μs for FXT-B.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA 15310103).
文摘Background:The Einstein Probe mission is an astronomical satellite developed in China,focusing on time-domain astronomy in the soft X-ray energy band.A key payload of this mission is the follow-up X-ray telescope(FXT),which is the result of international collaboration between China and Europe.The FXT features gold-coated nickel Wolter-I-type focusing mirrors and utilizes PNCCD detectors for imaging and spectroscopy in the focal plane.Methods:We reviewed the seven-year development history of the FXT.Initially,the configuration of the FXT consisted of a single telescope unit in 2017,but it later evolved into a dual-unit setup.Building on the successful design of eROSITA,the FXT team has innovatively introduced new operational modes for the PNCCD.FXT team also developed an ultra-compact helium pulse tube refrigerator,which cools the PNCCD down to-90℃.Additionally,various passive shielding measures have been implemented to protect against high-energy charged particles and enhance radiation resistance.These advancements have significantly improved the overall performance and reliability of the FXT.Results and conclusion:The ground calibrations and tests of the FXT demonstrate that its primary performance meets the established design goals.The FXT has exhibited outstanding performance in orbit,establishing itself as one of the space X-ray telescopes with considerable international influence.
基金supported by the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBMS-532)the Natural Science Basic Research Program of Shaanxi Province(2023-JC-ZD-40)+1 种基金the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBQN-0003)the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBQN-0686).
文摘Purpose The Einstein Probe(EP)satellite is a science mission of the Chinese Academy of Sciences,which is dedicated to time-domain astronomy and high-energy astrophysics.The X-ray baffle is a crucial component of follow-up X-ray telescope(FXT),which is an important payload onboard EP.It was designed to efficiently reduce stray light,especially single reflection on the hyperboloid of Wolter-I Mirrors.Methods In this paper,based on the parameters of FXT's mirror module and the detector,the design parameters of the X-ray baffle are optimized through preliminary design and detailed ray-tracing simulation.Fabrication involved precision laser cutting,roll forming,laser welding and integration processes.The thermal stability and mechanical environment adaptability were validated through thermal cycling and mechanical vibration tests.Finally,the X-ray baffle was mounted onto the mirror module with alignment precisely controlled using optical methods.Results The height of the X-ray baffle ranges from 60 to 120 mm from the outside to the inside;the aperture corresponds to each layer of the mirror module.In order to reduce weight and reduce light occlusion,the thickness of each thin shell is 0.125 mm.The ray-tracing simulation results with X-ray baffle are shown that the stray light is effectively reduced in the effective region of the detector.The Eigen-frequency change of the X-ray baffle after the thermal cycle test and mechanical vibration tests is only 0.52%and 0.77%,respectively.The results proved that X-ray baffle has a high thermo-mechanical reliability.The half power diameter(HPD)of the mirror module remained unchanged on-axis with/without X-ray baffle.Conclusion The introduction of X-ray baffle is expected to be highly significantly reduce stray light.
基金supported by the National Natural Science Foundation of China(Grant Nos.42327802 and 22479035).
文摘Purpose This study aimed to optimize the pre-treatment process for electroless nickel-phosphorus plating in the Einstein Probe project,addressing technical challenges encountered with 6061 aluminum alloy substrates to enhance coating quality and operational efficiency.Methods Verification experiments were conducted using 6061 aluminum alloy sheets as substitutes for large aluminum mandrels.The effects of surface roughness,rinsing methods,and the necessity of acid pickling were systematically evaluated.The samples were characterized by scanning electron microscopy,atomic force microscopy,and energy-dispersive X-ray spectroscopy to analyze surface morphology and elemental composition.Results and Conclusion Excessive surface roughness should be avoided,with a roughness below 338 nm ensuring uniform coatings.Flowing water rinsing after each step was critical to prevent contamination from residual solutions,whereas stagnant water immersion proved inadequate.Acid pickling was determined to be non-essential,as it had minimal impact on coating quality.The zinc layer formed during immersion exhibited weak adhesion and should be rinsed gently to avoid detachment.These findings offer valuable insights for pre-treatment process refinement in the Einstein Probe project and related applications.
基金supported by the Einstein-Probe(EP)Program which is funded by the Strategic Priority Research Program of the Chinese Academy of Sciences Grant No.XDA15310103.
文摘Purpose The follow-up X-ray telescope(FXT)is one of the two payloads of the Einstein Probe(EP),consisting of the upper composite with the X-ray mirror module as the core,the lower composite with the pnCCD module as the core,and the interface structure.The FXT thermal control subsystem is responsible for the thermal design,thermal implementations,and testing of the entire FXT payload thermal control.Methods A design approach is adopted with passive thermal control technology as the main method and active thermal control technology as a supplement for common components.The X-ray mirror modules are high-precision optical components,utilizing active closed-loop temperature control to ensure high precision and stability.The pnCCD detectors operate at a stable low temperature,with refrigerators used to cool the detector houses,ensuring they can operate under stable low-temperature conditions.The hot ends of the refrigerators are connected to the external radiator panels through heat pipes for heat dissipation.Results The thermal control subsystem of FXT is operating properly in-orbit.All component temperatures meet the design requirements.Conclusion After multiple rounds of design and test verification,FXT was successfully launched with EP and completed in-orbit testing.During the in-orbit testing phase of EP,the function of the FXT thermal control subsystem works well.The temperatures of the components and units are normal.This paper introduces the design of FXT thermal control and the in-orbit performance of the thermal control subsystem.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA 15310103).
文摘Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positioning accuracy of the Follow-up X-ray Telescope(FXT),playing a crucial role in achieving the on-orbit scientific objectives of the FXT.Higher positioning accuracy makes it easier to identify corresponding bodies for the discovery and positioning of transient sources.Accurate positioning is beneficial for follow-up observations in other bands,such as optical spectroscopy.Methods This article mainly introduces the precision control methods and processes of the FXT optical structure,which have been tested and verified through satellite test.The on-orbit source positioning accuracy of the FXT telescope is within 20 arcseconds(90% confidence level),meeting the requirements of the FXT mission.Results and Conclusion To ensure the accuracy of the EP satellite’s FXT optical structure,measures such as component processing control,installation control,and posttest adjustments are taken on the ground to ensure that the detector mounting position,optical axis deviation,and other precision indicators before and after the satellite lever test meet the design requirements.After a successful launch,through on-orbit calibration,the FXT-A and FXT-B optical axis pointing direction deviation is 39 arcseconds,and the source positioning error is better than 3'' at 68% confidence level.FXT optical structure meets all the requirements from design,processing,installation,etc.,successfully meeting scientific needs.
基金supported by the Einstein Probe(EP)Program which is funded by the"Strategic Priority Research Program"of the Chinese Academy of Sciences(Grant No.XDA15310103).
文摘Purpose:In order to evaluate the mechanical feasibility of the domestic baffle made by wire electrode cutting for the mirror assembly of the Follow-up X-ray Telescope(FXT)onboard the Einstein Probe(EP)mission.Methods:Finite element analysis was performed to compare the structural differences between the domestic baffle made by wire electrode cutting and the eROSITA baffle made by bonding.The finite element models were verified by test data in advance to avoid significant deviations.Finally,the differences in dynamical performances between the FXT mirror assemblies with the two baffles were investigated through modal analysis and frequency response analysis using the pre-verified models.Results and conclusions:The results show that,from the perspective of the entire mirror assembly,their eigenfrequencies remain similar,except for the second lateral eigenfrequency,which shifts forward by approximately 24 Hz in the mirror assembly equipped with the domestic baffle.However,for the X-ray baffles themselves,the axial and lateral eigenfrequencies of the two baffles differ by approximately 49 Hz and 185 Hz,respectively.These eigenfrequencies are staggered,ensuring that over-response is avoided.In terms of response amplification,the domestic baffle,compared to the eROSITA baffle,exhibits inferior axial mechanical characteristics but superior lateral characteristics.In summary,from a mechanical perspective,the domestic baffle is feasible.
基金the support of the National Natural Science Foundation of China(Grant No.12333007)the International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020)+4 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)support by ASI,under the dedicated eXTP agreements and agreement ASI-INAF n.2017-14-H.O.by INAF and INFN under project REDSOXsupport from the Deutsche Zentrum für Luft-und Raumfahrt,the German Aerospace Center(DLR)support from MINECO grant ESP2017-82674-R and FEDER funds.
文摘In this paper,we present the current status of the enhanced X-ray Timing and Polarimetry mission,which has been fully approved for launch in 2030.eXTP is a space science mission designed to study fundamental physics under extreme conditions of matter density,gravity,and magnetism.The mission aims at determining the equation of state of matter at supra-nuclear density,measuring the effects of quantum electro-dynamics,and understanding the dynamics of matter in strong-field gravity.In addition to investigating fundamental physics,the eXTP mission is poised to become a leading observatory for time-domain and multi-messenger astronomy in the 2030s,as well as providing observations of unprecedented quality on a variety of galactic and extragalactic objects.After briefly introducing the history and a summary of the scientific objectives of the eXTP mission,this paper presents a comprehensive overview of:(1)the cutting-edge technology,technical specifications,and anticipated performance of the mission’s scientific instruments;(2)the full mission profile,encompassing spacecraft design,operational capabilities,and ground segment infrastructure.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences Grant No.XDA15310103.
文摘Background The Einstein probe(EP)is an X-ray astronomical satellite dedicated to time-domain astronomy and high-energy astrophysics.Initiated at the end of 2017,it was successfully launched on January 9,2024.The follow-up X-ray telescope(FXT)is a key payload on the EP satellite.The FXT employs PNCCD as its focal plane detector.Its electronic components include the electronic control box(EC-Box),the detector electronics boxes(DE-Box),the refrigerator controller,the movement mechanisms controller,and the temperature control instrument.Methods The FXT conducted functional performance tests in-orbit as planned,including three operating modes of the detector,energy detection range,and energy resolution.Results Since FXT became operational in orbit,all electronic equipment has been working stably.The FXT has an energy detection range of 0.3-10 keV,with an energy resolution of approximately 92 eV@1.25 keV,and an electronic noise of about 3.3e^(-).
基金the Strategic Priority Program on Space Science China,the Chinese Academy of Science,(Grant No.XDA15020106 and XDA15020501)the National Natural Science Foundation of China,grant number 42327802.
文摘Purpose To meet the stringent requirements for high-quality processing of focusing mirror molds and reproduction mirrors,specific cleaning procedures must be both accurate and efficient.Methods This study examines the stability and consistency of the removal rate throughout the polishing process by analyzing changes in the composition of the polishing slurry at various stages.Infrared spectroscopy was used to measure the chemical groups of compounds on the mandrel surface and assess its stress state.Additionally,the adsorption mechanism at the interface was explored in detail.Results and Conclusion The study investigates ultra-precision polishing of nickel–phosphorus alloy,focusing on factors influencing the water film formation ability on the workpiece surface.X-ray electron spectroscopy was employed to analyze the mandrel before and after the cleaning process.The effectiveness of the cleaning process was evaluated by comparing its surface removal effect with that of the polishing process.
基金based on data obtained with Einstein Probe,a space mission supported by Strategic Priority Program on Space Science of Chinese Academy of Sciences,in collaboration with ESA,MPE and CNES(Grant No.XDA15310000)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0550200)+5 种基金the National Key R&D Program of China(Grant No.2022YFF0711500)the support by the National Natural Science Foundation of China(Grant Nos.12333004,12321003,12103065,12373040,12021003,12025303,12393814,and 12203071)the China Manned Space Project(Grant Nos.CMS-CSST-2021-A13,and CMS-CSST-2021-B11)the Youth Innovation Promotion Association of the Chinese Academy of Sciencessupported by a Ramón y Cajal fellowship(Grant No.RYC2021-030888-I)financial support from AGAUR,CSIC,MCIN and AEI 10.13039/501100011033(Grant Nos.PID2023-151307NB-I00,PIE 20215AT016,CEX2020-001058-M,and 2021-SGR-01270)。
文摘We report the discovery of a peculiar X-ray transient,EP240408a,by Einstein Probe(EP)and follow-up studies made with EP,Swift,NICER,GROND,ATCA and other ground-based multiwavelength telescopes.The new transient was first detected with Wide-field X-ray Telescope(WXT)on board EP on April 8th,2024,manifested in an intense yet brief X-ray flare lasting for 12 s.The flare reached a peak flux of 3:9×10^(−9) erg cm^(−2) s^(−1) in 0.5-4 keV,∼300 times brighter than the underlying X-ray emission detected throughout the observation.Rapid and more precise follow-up observations by EP/FXT,Swift and NICER confirmed the finding of this new transient.Its X-ray spectrum is non-thermal in 0.5-10 keV,with a power-law photon index varying within 1.8-2.5.The X-ray light curve shows a plateau lasting for∼4 d,followed by a steep decay till becoming undetectable∼10 d after the initial detection.Based on its temporal property and constraints from previous EP observations,an unusual timescale in the range of 7-23 d is found for EP240408a,which is intermediate between the commonly found fast and long-term transients.No counterparts have been found in optical and near-infrared,with the earliest observation at 17 h after the initial X-ray detection,suggestive of intrinsically weak emission in these bands.We demonstrate that the remarkable properties of EP240408a are inconsistent with any of the transient types known so far,by comparison with,in particular,jetted tidal disruption events,gamma-ray bursts,X-ray binaries and fast blue optical transients.The nature of EP240408a thus remains an enigma.We suggest that EP240408a may represent a new type of transients with intermediate timescales of the order of∼10 d.The detection and follow-ups of more of such objects are essential for revealing their origin.
基金project funded by China National Space Administration(CNSA)and the Chinese Academy of Sciences(CAS)support from the National Key Research and Development Program of China(Grant No.2016YFA0400800)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA04010202,XDA04010300,and XDB23040400)the National Natural Science Foundation of China(Grant Nos.U1838201,and U1838102).
文摘As China’s first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band(1-250 ke V) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 Me V. It was designed to perform pointing, scanning and gamma-ray burst(GRB)observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed.Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results.
基金support of the Chinese Academy of Sciences through the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA15020100)support by ASI, under the dedicated eXTP agreements and agreement ASI-INAF (Grant No. 2017-14-H.O.)+3 种基金by INAF and INFN under project REDSOXsupport from the Deutsche Zentrum für Luft- und Raumfahrt, the German Aerospce Center (DLR)support of Science Centre (Grant No. 2013/10/M/ST9/00729)support from MINECO (Grant No. ESP2017-82674-R) and FEDER funds
文摘In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources.The paper provides a detailed description of:(1) the technological and technical aspects, and the expected performance of the instruments of the scientific payload;(2) the elements and functions of the mission, from the spacecraft to the ground segment.
基金supported by the National Program on Key Research and Development Project(Grant No.2016YFA0400800)from the Ministry of Science and Technology of China(MOST)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB23040400)the Hundred Talent Program of Chinese Academy of Sciences,the National Natural Science Foundation of China(Grant Nos.11233001,11503027,11403026,11473027,and11733009)
文摘Finding the electromagnetic （EM） counterpart of binary compact star merger, especially the binary neutron star （BNS） merger, is critically important for gravitational wave （GW） astronomy, cosmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and Fermi/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope （HE） onboard Insight-HXMT （Hard X-ray Modulation Telescope） is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart （SSS17a/AT2017gfo） with very large collection area （M000 cm2） and microsecond time resolution in 0.2-5 MeV. In addition, Insight-HXMT quickly implemented a Target of Opportunity （TOO） observation to scan the GW localization area for potential X-ray emission from the GW source. Although Insight-HXMT did not detect any significant high energy （0.2-5 MeV） radiation from GW170817, its observation helped to confirm the unexpected weak and soft nature of GRB 170817A. Meanwhile, Insight-HXMT/HE provides one of the most stringent constraints （-10-7 to 104 erg/cm2/s） for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of Insight-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event.
基金the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA040102).
文摘The Low Energy X-ray telescope(LE) is one of the three main instruments of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT). It is equipped with Swept Charge Device(SCD) sensor arrays with a total geometrical area of 384 cm^2 and an energy band from 0.7 to 13 ke V. In order to evaluate the particle induced X-ray background and the cosmic X-ray background simultaneously, LE adopts collimators to define four types of Field Of Views(FOVs), i.e., 1.6°×6°, 4°×6°, 50°-60°×2°-6 oand the blocked ones which block the X-ray by an aluminum cover. LE is constituted of three detector boxes(LEDs) and an electric control box(LEB) and achieves a good energy resolution of 140 e V@5.9 ke V, an excellent time resolution of 0.98 ms, as well as an extremely low pileup(<1%@18000 cts/s). Detailed performance tests and calibration on the ground have been performed,including energy-channel relation, energy response, detection efficiency and time response.
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,U1938102,and U1938108This work was partially supported by the International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020).
文摘Purpose The low-energy X-ray telescope(LE)is a main instrument of the Insight-HXMT mission and consists of 96 swept charge devices covering the 1–10 keV energy band.The energy gain and resolution are continuously calibrated by analyzing Cassiopeia A(Cas A)and blank sky data,while the effective areas are also calibrated with the observations of the Crab Nebula.In this paper,we present the evolution of the in-orbit performances of LE in the first 5 years since launch.Methods The Insight-HXMT data analysis software package(HXMTDAS)is utilized to extract the spectra of Cas A,blank sky,and Crab Nebula using different good time interval selections.We fit a model with a power-law continuum and several Gaussian lines to different ranges of Cas A and blank sky spectra to get peak energies of their lines through xspec.After updating the energy gain calibration in CALibration DataBase(CALDB),we rerun the Cas A data to obtain the energy resolution.An empirical function is used to modify the simulated effective areas so that the background-subtracted spectrum of the Crab Nebula can best match the standard model of the Crab Nebula.Results The energy gain,resolution,and effective areas are calibrated every month.The corresponding calibration results are duly updated in CALDB,which can be downloaded and used for the analysis of Insight-HXMT data.Simultaneous observations with NuSTAR and NICER can also be used to verify our derived results.Conclusion LE is a well-calibrated X-ray telescope working in 1–10 keV band.The uncertainty of LE gain is less than 20eV in 2–9 keV band,and the uncertainty of LE resolution is less than 15eV.The systematic errors of LE,compared to the model of the Crab Nebula,are lower than 1.5%in 1–10 keV.
