In Tian Qin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic pro...In Tian Qin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic properties. Here we present a single frequency modulation method based on a torsion pendulum to measure the remanent magnetic moment mr of 1.1 kg dummy copper test mass, and the measurement result is(6.45 ± 0.04(stat) ± 0.07(syst)) × 10^(-8)A · m^(2). The measurement precision of the mr is about 0.9 n A · m^(2), well below the present measurement requirement of Tian Qin. The method is particularly useful for measuring extremely low magnetic properties of the materials for use in the construction of space-borne gravitational wave detection and other precision scientific apparatus.展开更多
The space-borne gravitational wave detectors will observe a large population of double white dwarf binaries in the Milky Way.However,the search for double white dwarfs in the gravitational wave data will be time-consu...The space-borne gravitational wave detectors will observe a large population of double white dwarf binaries in the Milky Way.However,the search for double white dwarfs in the gravitational wave data will be time-consuming due to the large number of templates involved and antenna response calculation.In this paper,we implement an iterative combinatorial algorithm to search for double white dwarfs in MLDC-3.1 data.To quickly determine the rough parameters of the target sources,the following algorithms are adopted in a coarse search process:(1)using the downsampling method to reduce the number of original data points;(2)using the undersampling method to speed up the generation of a single waveform template;(3)using the stochastic template bank method to quickly construct the waveform template bank while achieving high coverage of the parameter space;(4)combining the FFT acceleration algorithm with the stochastic template bank to reduce the calculation time of a single template.A fine search process is applied to further determine the parameters of the signals based on the coarse search,for which we adopt the particle swarm optimization.Finally,we detect O(10^(4))double white dwarf signals,validating the feasibility of our method.展开更多
As the signal reflected by the corner-cube reflector arrays is very weak and easily submerged during the full moon,we analyze the influence of the thermal effect of corner-cube reflector arrays on the intensity of lun...As the signal reflected by the corner-cube reflector arrays is very weak and easily submerged during the full moon,we analyze the influence of the thermal effect of corner-cube reflector arrays on the intensity of lunar laser ranging echo.Laser ranging measurements during the penumbra lunar eclipse verify suspected thermal deformation in the Lunakhod 2 reflectors.Signal levels vary over two orders of magnitude as the penumbra eclipse progresses.This can be explained by the change in the dihedral angle of the corner-cube reflectors caused by the temperature.The results show that when the dihedral angle errors reach 1,the energy is reduced by 100 times compared with the ideal corner-cube reflector.In the experiment,our findings suggest that when the corner-cube reflector arrays enter the penumbra of the earth,the effective echo signal level which reaches 0.18 photons/s far exceeds the historical level of the full moon.However,11 minutes after the penumbra lunar eclipse,the effective echo rate of Lunakhod 2 will drop two orders of magnitude.The mechanism can explain the acute signal deficit observed at full moon.展开更多
The axion or axion-like particle motivated from a natural solution of strong CP problem or string theory is a promising dark matter candidate.We study the new observational effects of ultralight axion-like particles b...The axion or axion-like particle motivated from a natural solution of strong CP problem or string theory is a promising dark matter candidate.We study the new observational effects of ultralight axion-like particles by the space-borne gravitational wave detector and the radio telescope.Taking the neutron star-black hole binary as an example,we demonstrate that the gravitational waveform could be obviously modified by the slow depletion of the axion cloud around the black hole formed through the superradiance process.We compare these new effects on the binary with the well-studied effects from dynamical friction with dark matter and dipole radiation in model-independent ways.Finally,we discuss the constraints from LIGO/Virgo and study the detectability of the ultralight axion particles at LISA and TianQin.展开更多
In this paper,we present a suppression method for the thermal drift of an ultra-stable laser interferometer.The detailed analysis on the Michelson interferometer indicates that the change in optical path length induce...In this paper,we present a suppression method for the thermal drift of an ultra-stable laser interferometer.The detailed analysis on the Michelson interferometer indicates that the change in optical path length induced by temperature variation can be effectively reduced by choosing proper thickness and/or incident angle of a compensator.Taking the optical bench of the Laser Interferometer Space Antenna Pathfinder as an example,we analyze the optical bench model with a compensator and show that the temperature coefficient of this laser interferometer can be reduced down to 1 pm/K with an incident angle of 0.267828 rad.The method presented in this paper can be used in the design of ultra-stable laser interferometers,especially for space-based gravitational waves detection.展开更多
The Tianhui-202(TH02-02)satellite formation,as a supplement to the microwave mapping satellite system Tianhui-201(TH02-01),is the first Interferometric Synthetic Aperture Radar(InSAR)satellite formation-flying system ...The Tianhui-202(TH02-02)satellite formation,as a supplement to the microwave mapping satellite system Tianhui-201(TH02-01),is the first Interferometric Synthetic Aperture Radar(InSAR)satellite formation-flying system that supports the tracking of BeiDou global navigation Satellite system(BDS3)new B1C and B2a signals.Meanwhile,the twin TH02-02 satellites also support the tracking of Global Positioning System(GPS)L1&L2 and BDS B1I&B3I signals.As the spaceborne receiver employs two independent boards to track the Global Navigation Satellite System(GNSS)satellites,we design an orbit determination strategy by estimating independent receiver clock offsets epoch by epoch for each GNSS to realize the multi-GNSS data fusion from different boards.The performance of the spaceborne receiver is evaluated and the contribution of BDS3 to the kinematic and reduced-dynamic Precise Orbit Determination(POD)of TH02-02 satellites is investigated.The tracking data onboard shows that the average number of available BDS3 and GPS satellites are 8.7 and 9.1,respectively.The carrier-to-noise ratio and carrier phase noise of BDS3 B1C and B2a signals are comparable to those of GPS.However,strong azimuth-related systematic biases are recognized in the pseudorange multipath errors of B1C and B3I.The pseudorange noise of BDS3 signals is better than that of GPS after eliminating the multipath errors from specific signals.Taking the GPS-based reduced-dynamic orbit with single-receiver ambiguity fixing technique as a reference,the results of BDS3-only and BDS3+GPS combined POD are assessed.The Root Mean Square(RMS)of orbit comparison of BDS3-based kinematic and reduced-dynamic POD with reference orbit are better than 7 cm and 3 cm in three-Dimensional direction(3D).The POD performance based on B1C&B2a data is comparable to that based on B1I&B3I.The precision of BDS3+GPS combined kinematic orbit can reach up to 3 cm(3D RMS),which has a more than 25%improvement relative to the GPS-only solution.In addition,the consistency between the BDS3+GPS combined reduced-dynamic orbit and the GPS-based ambiguity-fixed orbit is better than 1.5 cm(3D RMS).展开更多
基金supported by the National Key R&D Program of China (Grant No. 2020YFC2200500)the National Natural Science Foundation of China (Grant Nos. 12075325, 12005308, and 11605065)。
文摘In Tian Qin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic properties. Here we present a single frequency modulation method based on a torsion pendulum to measure the remanent magnetic moment mr of 1.1 kg dummy copper test mass, and the measurement result is(6.45 ± 0.04(stat) ± 0.07(syst)) × 10^(-8)A · m^(2). The measurement precision of the mr is about 0.9 n A · m^(2), well below the present measurement requirement of Tian Qin. The method is particularly useful for measuring extremely low magnetic properties of the materials for use in the construction of space-borne gravitational wave detection and other precision scientific apparatus.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2019B030302001)the National Natural Science Foundation of China(NSFC,Grant No.12173104)+2 种基金the fellowship of China Postdoctoral Science Foundation(Grant No.2021M703769)the Natural Science Foundation of Guangdong Province of China(Grant No.2022A1515011862)the support by National Supercomputer Center in Guangzhou。
文摘The space-borne gravitational wave detectors will observe a large population of double white dwarf binaries in the Milky Way.However,the search for double white dwarfs in the gravitational wave data will be time-consuming due to the large number of templates involved and antenna response calculation.In this paper,we implement an iterative combinatorial algorithm to search for double white dwarfs in MLDC-3.1 data.To quickly determine the rough parameters of the target sources,the following algorithms are adopted in a coarse search process:(1)using the downsampling method to reduce the number of original data points;(2)using the undersampling method to speed up the generation of a single waveform template;(3)using the stochastic template bank method to quickly construct the waveform template bank while achieving high coverage of the parameter space;(4)combining the FFT acceleration algorithm with the stochastic template bank to reduce the calculation time of a single template.A fine search process is applied to further determine the parameters of the signals based on the coarse search,for which we adopt the particle swarm optimization.Finally,we detect O(10^(4))double white dwarf signals,validating the feasibility of our method.
基金Project supported by the National Natural Science Foundation of China(Grant No.12033009)。
文摘As the signal reflected by the corner-cube reflector arrays is very weak and easily submerged during the full moon,we analyze the influence of the thermal effect of corner-cube reflector arrays on the intensity of lunar laser ranging echo.Laser ranging measurements during the penumbra lunar eclipse verify suspected thermal deformation in the Lunakhod 2 reflectors.Signal levels vary over two orders of magnitude as the penumbra eclipse progresses.This can be explained by the change in the dihedral angle of the corner-cube reflectors caused by the temperature.The results show that when the dihedral angle errors reach 1,the energy is reduced by 100 times compared with the ideal corner-cube reflector.In the experiment,our findings suggest that when the corner-cube reflector arrays enter the penumbra of the earth,the effective echo signal level which reaches 0.18 photons/s far exceeds the historical level of the full moon.However,11 minutes after the penumbra lunar eclipse,the effective echo rate of Lunakhod 2 will drop two orders of magnitude.The mechanism can explain the acute signal deficit observed at full moon.
基金supported by the National Natural Science Foundation of China(Grant No.12205387)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2019B030302001)。
文摘The axion or axion-like particle motivated from a natural solution of strong CP problem or string theory is a promising dark matter candidate.We study the new observational effects of ultralight axion-like particles by the space-borne gravitational wave detector and the radio telescope.Taking the neutron star-black hole binary as an example,we demonstrate that the gravitational waveform could be obviously modified by the slow depletion of the axion cloud around the black hole formed through the superradiance process.We compare these new effects on the binary with the well-studied effects from dynamical friction with dark matter and dipole radiation in model-independent ways.Finally,we discuss the constraints from LIGO/Virgo and study the detectability of the ultralight axion particles at LISA and TianQin.
基金supported by the Natural Science Foundation of Guangdong Province (No. 2021A1515010198)the Guangzhou Science and Technology Plan Project (No. 202102020794)the National Key R&D Program of China (No. 2020YFC2200500)
文摘In this paper,we present a suppression method for the thermal drift of an ultra-stable laser interferometer.The detailed analysis on the Michelson interferometer indicates that the change in optical path length induced by temperature variation can be effectively reduced by choosing proper thickness and/or incident angle of a compensator.Taking the optical bench of the Laser Interferometer Space Antenna Pathfinder as an example,we analyze the optical bench model with a compensator and show that the temperature coefficient of this laser interferometer can be reduced down to 1 pm/K with an incident angle of 0.267828 rad.The method presented in this paper can be used in the design of ultra-stable laser interferometers,especially for space-based gravitational waves detection.
基金funded by the National Natural Science Foundation of China(Nos.61803018 and 41874028)the Key Laboratory Found,China(No.6142210200105)the National Key R&D Program of China(No.2020YFA0713502).
文摘The Tianhui-202(TH02-02)satellite formation,as a supplement to the microwave mapping satellite system Tianhui-201(TH02-01),is the first Interferometric Synthetic Aperture Radar(InSAR)satellite formation-flying system that supports the tracking of BeiDou global navigation Satellite system(BDS3)new B1C and B2a signals.Meanwhile,the twin TH02-02 satellites also support the tracking of Global Positioning System(GPS)L1&L2 and BDS B1I&B3I signals.As the spaceborne receiver employs two independent boards to track the Global Navigation Satellite System(GNSS)satellites,we design an orbit determination strategy by estimating independent receiver clock offsets epoch by epoch for each GNSS to realize the multi-GNSS data fusion from different boards.The performance of the spaceborne receiver is evaluated and the contribution of BDS3 to the kinematic and reduced-dynamic Precise Orbit Determination(POD)of TH02-02 satellites is investigated.The tracking data onboard shows that the average number of available BDS3 and GPS satellites are 8.7 and 9.1,respectively.The carrier-to-noise ratio and carrier phase noise of BDS3 B1C and B2a signals are comparable to those of GPS.However,strong azimuth-related systematic biases are recognized in the pseudorange multipath errors of B1C and B3I.The pseudorange noise of BDS3 signals is better than that of GPS after eliminating the multipath errors from specific signals.Taking the GPS-based reduced-dynamic orbit with single-receiver ambiguity fixing technique as a reference,the results of BDS3-only and BDS3+GPS combined POD are assessed.The Root Mean Square(RMS)of orbit comparison of BDS3-based kinematic and reduced-dynamic POD with reference orbit are better than 7 cm and 3 cm in three-Dimensional direction(3D).The POD performance based on B1C&B2a data is comparable to that based on B1I&B3I.The precision of BDS3+GPS combined kinematic orbit can reach up to 3 cm(3D RMS),which has a more than 25%improvement relative to the GPS-only solution.In addition,the consistency between the BDS3+GPS combined reduced-dynamic orbit and the GPS-based ambiguity-fixed orbit is better than 1.5 cm(3D RMS).