It has been a half-decade since the first direct detection of gravitational waves, which signifies the coming of the era of the gravitational-wave astronomy and gravitational-wave cosmology. The increasing number of t...It has been a half-decade since the first direct detection of gravitational waves, which signifies the coming of the era of the gravitational-wave astronomy and gravitational-wave cosmology. The increasing number of the detected gravitational-wave events has revealed the promising capability of constraining various aspects of cosmology, astronomy, and gravity. Due to the limited space in this review article, we will briefly summarize the recent progress over the past five years, but with a special focus on some of our own work for the Key Project "Physics associated with the gravitational waves" supported by the National Natural Science Foundation of China. In particular,(1) we have presented the mechanism of the gravitational-wave production during some physical processes of the early Universe, such as inflation, preheating and phase transition, and the cosmological implications of gravitational-wave measurements;(2) we have put constraints on the neutron star maximum mass according to GW170817 observations;(3) we have developed a numerical relativity algorithm based on the finite element method and a waveform model for the binary black hole coalescence along an eccentric orbit.展开更多
Recently,pulsar timing array(PTA)experiments have provided compelling evidence for the existence of the nanohertz stochastic gravitational wave background(SGWB).In this work,we demonstrated that cosmic string loops ge...Recently,pulsar timing array(PTA)experiments have provided compelling evidence for the existence of the nanohertz stochastic gravitational wave background(SGWB).In this work,we demonstrated that cosmic string loops generated from cosmic global strings offer a viable explanation for the observed nanohertz SGWB data,requiring a cosmic string tension parameter of log(Gμ)~-12 and a loop number density of log N~4.Additionally,we revisited the impact of cosmic string loops on the abundance of massive galaxies at high redshifts.However,our analysis revealed challenges in identifying a consistent parameter space that can concurrently explain both the SGWB data and observations from the James Webb Space Telescope.This indicates the necessity for either extending the existing model employed in this research or acknowledging distinct physical origins for these two phenomena.展开更多
The pulsar timing array(PTA)collaborations have recently reported compelling evidence for a stochastic signal consistent with a gravitational-wave background.In this paper,we combine the latest data sets from NANOGrav...The pulsar timing array(PTA)collaborations have recently reported compelling evidence for a stochastic signal consistent with a gravitational-wave background.In this paper,we combine the latest data sets from NANOGrav,PPTA,and EPTA to explore cosmological interpretations for the PTA signal from first-order phase transitions,domain walls,and cosmic strings,respectively.We find that the domain wall model is strongly disfavored with the Bayes factors compared with the first-order phase transitions and cosmic strings being 1/90 and 1/189,respectively,breaking the degeneracy among these models in individual data set.We also find that:(1)a strong phase transition at temperatures below the electroweak scale is favored,and the bubble collisions make the dominant contribution to the energy density spectrum;(2)a small reconnection probability p<1.55×10^(-1)allowed by strings in(super)string theory is favored at the 95%confidence level,and ground-based detectors can further constrain the parameter space.展开更多
In the frequency band of the Laser Interferometer Space Antenna(LISA),extensive research has been conducted on the impact of foreground confusion noise generated by galactic binaries within the Milky Way Galaxy.Additi...In the frequency band of the Laser Interferometer Space Antenna(LISA),extensive research has been conducted on the impact of foreground confusion noise generated by galactic binaries within the Milky Way Galaxy.Additionally,recent evidence of a stochastic signal,announced by the NANOGrav,EPTA,PPTA,CPTA,and InPTA,indicates that the stochastic gravitational-wave background(SGWB)generated by supermassive black hole binaries(SMBHBs)can contribute strong background noise within the LISA band.Given the presence of such strong noise,it is expected to have significant impacts on LISA's scientific missions.In this study,we investigate the impacts of the SGWB generated by SMBHBs on the detection of individual massive black hole binaries,verified galactic binaries,and extreme mass ratio inspirals in the context of LISA.We find it essential to resolve and eliminate the excess noise from the SGWB to guarantee the success of LISA's missions.展开更多
The effective one-body method provides a framework to apply the black hole perturbation theory to the binary system where two masses can be comparable.We study the gravitational-wave equation in the background of the ...The effective one-body method provides a framework to apply the black hole perturbation theory to the binary system where two masses can be comparable.We study the gravitational-wave equation in the background of the effective one-body system for the spinless binary,which is in general available with the spherically symmetric background as well.We obtain the gauge conditions for the decoupled wave equation,and also give the solutions to the gauge conditions in terms of the metric perturbation for a special case,which extends the result by Jing et al.(Sci.China-Phys.Mech.Astron.65,260411(2022)).Finally we obtain the gravitational-wave equation which is the generalization of the Teukolsky equation.展开更多
Future space-based gravitational-wave detectors will detect gravitational waves with high sensitivity in the millihertz frequency band,providing more opportunities to test theories of gravity than ground-based detecto...Future space-based gravitational-wave detectors will detect gravitational waves with high sensitivity in the millihertz frequency band,providing more opportunities to test theories of gravity than ground-based detectors.The study of quasinormal modes(QNMs)and their application in gravity theory testing have been an important aspect in the field of gravitational physics.In this study,we investigate the capability of future space-based gravitational wave detectors,such as LISA,TaiJi,and TianQin,to constrain the dimensionless deviating parameter for Einsteindilaton-Gauss-Bonnet(EdGB)gravity with ringdown signals from the merger of binary black holes.The ringdown signal is modeled by the two strongest QNMs in EdGB gravity.Considering time-delay interferometry,we calculate the signal-to-noise ratio of different space-based detectors for ringdown signals to analyze their capabilities.The Fisher information matrix is employed to analyze the accuracy of parameter estimation,with particular focus on the dimensionless deviating parameter for EdGB gravity.The impact of the parameters of gravitational wave sources on the estimation accuracy of the dimensionless deviating parameter is also studied.We find that the constraint ability of EdGB gravity is limited because the uncertainty of the dimensionless deviating parameter increases with a decrease in the dimensionless deviating parameter.LISA and TaiJi offer more advantages in constraining the dimensionless deviating parameter to a more accurate level for massive black holes,whereas TianQin is more suited to less massive black holes.The Bayesian inference method is used to perform parameter estimation on simulated data,which verifies the reliability of the conclusion.展开更多
Precision measurement tools are compulsory to reduce measurement errors or machining errors in the processes of calibration and manufacturing.The laser interferometer is one of the most important measurement tools inv...Precision measurement tools are compulsory to reduce measurement errors or machining errors in the processes of calibration and manufacturing.The laser interferometer is one of the most important measurement tools invented in the 20th century.Today,it is commonly used in ultraprecision machining and manufacturing,ultraprecision positioning control,and many noncontact optical sensing technologies.So far,the state-of-the-art laser interferometers are the ground-based gravitational-wave detectors,e.g.the Laser Interferometer Gravitational-wave Observatory(LIGO).The LIGO has reached the measurement quantum limit,and some quantum technologies with squeezed light are currently being tested in order to further decompress the noise level.In this paper,we focus on the laser interferometry developed for space-based gravitational-wave detection.The basic working principle and the current status of the key technologies of intersatellite laser interferometry are introduced and discussed in detail.The launch and operation of these large-scale,gravitational-wave detectors based on space-based laser interferometry is proposed for the 2030s.展开更多
Taiji,a space-based gravitational-wave observatory,consists of three satellites forming an equilateral triangle with arm length of 3×10^6 km,orbiting around the Sun.Taiji is able to observe the gravitationalwave ...Taiji,a space-based gravitational-wave observatory,consists of three satellites forming an equilateral triangle with arm length of 3×10^6 km,orbiting around the Sun.Taiji is able to observe the gravitationalwave standard siren events of massive black hole binary(MBHB)merger,which is helpful in probing the expansion of the universe.In this paper,we preliminarily forecast the capability of Taiji for improving cosmological parameter estimation with the gravitational-wave standard siren data.We simulate fiveyear standard siren data based on three fiducial cosmological models and three models of MBHB’s formation and growth.It is found that the standard siren data from Taiji can effectively break the cosmological parameter degeneracies generated by the cosmic microwave background(CMB)anisotropies data,especially for dynamical dark energy models.The constraints on cosmological parameters are significantly improved by the data combination CMB+Taiji,compared to the CMB data alone.Compared to the current optical cosmological observations,Taiji can still provide help in improving the cosmological parameter estimation to some extent.In addition,we consider an ideal scenario to investigate the potential of Taiji on constraining cosmological parameters.We conclude that the standard sirens of MBHB from Taiji will become a powerful cosmological probe in the future.展开更多
LISA and Taiji are expected to form a space-based gravitational-wave(GW)detection network in the future.In this work,we make a forecast for the cosmological parameter estimation with the standard siren observation fro...LISA and Taiji are expected to form a space-based gravitational-wave(GW)detection network in the future.In this work,we make a forecast for the cosmological parameter estimation with the standard siren observation from the LISA-Taiji network.We simulate the standard siren data based on a scenario with configuration angle of 40°between LISA and Taiji.Three models for the population of massive black hole binary(MBHB),i.e.,popⅢ,Q3d,and Q3nod,are considered to predict the events of MBHB mergers.We find that,based on the LISA-Taiji network,the number of electromagnetic(EM)counterparts detected is almost doubled compared with the case of single Taiji mission.Therefore,the LISA-Taiji network’s standard siren observation could provide much tighter constraints on cosmological parameters.For example,solely using the standard sirens from the LISA-Taiji network,the constraint precision of H;could reach 1.3%.Moreover,combined with the CMB data,the GW-EM observation based on the LISA-Taiji network could also tightly constrain the equation of state of dark energy,e.g.,the constraint precision of w reaches about 4%,which is comparable with the result of CMB+BAO+SN.It is concluded that the GW standard sirens from the LISA-Taiji network will become a useful cosmological probe in understanding the nature of dark energy in the future.展开更多
We search for isotropic stochastic gravitational-wave background(SGWB)in the International Pulsar Timing Array second data release.By modeling the SGWB as a power-law,we find very strong Bayesian evidence for a common...We search for isotropic stochastic gravitational-wave background(SGWB)in the International Pulsar Timing Array second data release.By modeling the SGWB as a power-law,we find very strong Bayesian evidence for a common-spectrum process,and further this process has scalar transverse(ST)correlations allowed in general metric theory of gravity as the Bayes factor in favor of the ST-correlated process versus the spatially uncorrelated common-spectrum process is 30±2.The median and the 90%equal-tail amplitudes of ST mode are A_(ST)=1.29^(+0.51)_(−0.44)×10^(−15),or equivalently the energy density parameter per logarithm frequency isΩSTGW=2.31^(+2.19)_(−1.30)×10^(−9),at frequency of 1 year−1.However,we do not find any statistically significant evidence for the tensor transverse(TT)mode and then place the 95%upper limits as A_(TT)<3.95×10^(−15),or equivalentlyΩ^(TT)_(GW)<2.16×10^(−9),at frequency of 1 year^(−1).展开更多
We are entering a new era of gravitational-wave astronomy. The ground-based interferometers have reached their initial design sensitivity in the audio band. Several upper limits have been set for anticipated astrophys...We are entering a new era of gravitational-wave astronomy. The ground-based interferometers have reached their initial design sensitivity in the audio band. Several upper limits have been set for anticipated astrophysical sources from the science data. The advanced detectors in the US and in Europe are expected to be operational around 2015. New advanced detectors are also planned in Japan and in India. The first direct detections of gravitational waves are expected within this decade. In the meanwhile, three pulsar timing array projects are forming an international collaboration to detect gravitational waves directly in the nanoHertz range using timing data from millisecond pulsars. The first direct detection of nanoHertz gravitational waves are also expected within this decade. In this paper, we review the status of current gravitational-wave detectors, possible types of sources, observational upper limits achieved, and future prospects for direct detection of gravitational waves展开更多
We propose a possible approach to achieve a 1/N sensitivity of Michelson interferometer by using a properly designed random phase modulation. Different from other approaches, the sensitivity improvement does not depen...We propose a possible approach to achieve a 1/N sensitivity of Michelson interferometer by using a properly designed random phase modulation. Different from other approaches, the sensitivity improvement does not depend on increasing optical powers or utilizing the quantum properties of light. Moreover the requirements for optical losses and the quantum efficiencies of photodetection systems may be lower than the quantum approaches and the sensitivity improvement is independent of frequency in all the detection bands.展开更多
We study the possibility of probing high scale phase transitions that are inaccessible by LIGO.Our study shows that the stochastic gravitational-wave radiation from cosmic strings that are formed after the first-order...We study the possibility of probing high scale phase transitions that are inaccessible by LIGO.Our study shows that the stochastic gravitational-wave radiation from cosmic strings that are formed after the first-order phase transition can be detected by space-based interferometers when the phase transition temperature is T_(n)~O(10^(8−11))GeV.展开更多
Primordial gravitational waves (GWs) encode the information about inflation [1], and the power spectrum of primordial GWs have attracted a lot of attentions. There are in general two crucial properties for the primord...Primordial gravitational waves (GWs) encode the information about inflation [1], and the power spectrum of primordial GWs have attracted a lot of attentions. There are in general two crucial properties for the primordial GW power spectrum, namely the amplitude and the tilt (n_t).展开更多
Multi-messenger gravitational wave(GW)observation for binary neutron star merger events could provide a rather useful tool to explore the evolution of the Universe.In particular,for the third-generation GW detectors,i...Multi-messenger gravitational wave(GW)observation for binary neutron star merger events could provide a rather useful tool to explore the evolution of the Universe.In particular,for the third-generation GW detectors,i.e.the Einstein Telescope(ET)and the Cosmic Explorer(CE),proposed to be built in Europe and the U.S.,respectively,lots of GW standard sirens with known redshifts could be obtained,which would exert great impacts on the cosmological parameter estimation.The total neutrino mass could be measured by cosmological observations,but such a measurement is model-dependent and currently only gives an upper limit.In this work,we wish to investigate whether the GW standard sirens observed by ET and CE could help improve the constraint on the neutrino mass,in particular in the interacting dark energy(IDE)models.We find that the GW standard siren observations from ET and CE can only slightly improve the constraint on the neutrino mass in the IDE models,compared to the current limit.The improvements in the IDE models are weaker than those in the standard cosmological model.Although the limit on neutrino mass can only be slightly updated,the constraints on other cosmological parameters can be significantly improved by using the GW observations.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.11690021,11690022,11690023,and 11690024)。
文摘It has been a half-decade since the first direct detection of gravitational waves, which signifies the coming of the era of the gravitational-wave astronomy and gravitational-wave cosmology. The increasing number of the detected gravitational-wave events has revealed the promising capability of constraining various aspects of cosmology, astronomy, and gravity. Due to the limited space in this review article, we will briefly summarize the recent progress over the past five years, but with a special focus on some of our own work for the Key Project "Physics associated with the gravitational waves" supported by the National Natural Science Foundation of China. In particular,(1) we have presented the mechanism of the gravitational-wave production during some physical processes of the early Universe, such as inflation, preheating and phase transition, and the cosmological implications of gravitational-wave measurements;(2) we have put constraints on the neutron star maximum mass according to GW170817 observations;(3) we have developed a numerical relativity algorithm based on the finite element method and a waveform model for the binary black hole coalescence along an eccentric orbit.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0503304)the National Natural Science Foundation of China(Grant No.11921003)+2 种基金the New Cornerstone Science Foundation through the XPLORER PRIZEthe Chinese Academy of Sciencesthe Entrepreneurship and Innovation Program of Jiangsu Province。
文摘Recently,pulsar timing array(PTA)experiments have provided compelling evidence for the existence of the nanohertz stochastic gravitational wave background(SGWB).In this work,we demonstrated that cosmic string loops generated from cosmic global strings offer a viable explanation for the observed nanohertz SGWB data,requiring a cosmic string tension parameter of log(Gμ)~-12 and a loop number density of log N~4.Additionally,we revisited the impact of cosmic string loops on the abundance of massive galaxies at high redshifts.However,our analysis revealed challenges in identifying a consistent parameter space that can concurrently explain both the SGWB data and observations from the James Webb Space Telescope.This indicates the necessity for either extending the existing model employed in this research or acknowledging distinct physical origins for these two phenomena.
基金supported by the National Natural Science Foundation of China(Grant Nos.12250010,11975019,11991052,and 12047503)the Key Research Program of Frontier Sciences,CAS(Grant No.ZDBSLY-7009)+3 种基金the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-006)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB15)supported by the National Natural Science Foundation of China(Grant Nos.12247176,and 12247112)the China Postdoctoral Science Foundation Fellowship(Grant No.2022M710429)。
文摘The pulsar timing array(PTA)collaborations have recently reported compelling evidence for a stochastic signal consistent with a gravitational-wave background.In this paper,we combine the latest data sets from NANOGrav,PPTA,and EPTA to explore cosmological interpretations for the PTA signal from first-order phase transitions,domain walls,and cosmic strings,respectively.We find that the domain wall model is strongly disfavored with the Bayes factors compared with the first-order phase transitions and cosmic strings being 1/90 and 1/189,respectively,breaking the degeneracy among these models in individual data set.We also find that:(1)a strong phase transition at temperatures below the electroweak scale is favored,and the bubble collisions make the dominant contribution to the energy density spectrum;(2)a small reconnection probability p<1.55×10^(-1)allowed by strings in(super)string theory is favored at the 95%confidence level,and ground-based detectors can further constrain the parameter space.
基金Supported by the NSFC(12250010,11991052)Key Research Program of Frontier Sciences,CAS,(ZDBS-LY-7009)。
文摘In the frequency band of the Laser Interferometer Space Antenna(LISA),extensive research has been conducted on the impact of foreground confusion noise generated by galactic binaries within the Milky Way Galaxy.Additionally,recent evidence of a stochastic signal,announced by the NANOGrav,EPTA,PPTA,CPTA,and InPTA,indicates that the stochastic gravitational-wave background(SGWB)generated by supermassive black hole binaries(SMBHBs)can contribute strong background noise within the LISA band.Given the presence of such strong noise,it is expected to have significant impacts on LISA's scientific missions.In this study,we investigate the impacts of the SGWB generated by SMBHBs on the detection of individual massive black hole binaries,verified galactic binaries,and extreme mass ratio inspirals in the context of LISA.We find it essential to resolve and eliminate the excess noise from the SGWB to guarantee the success of LISA's missions.
基金supported by the National Natural Science Foundation of China(Grant No.11973025)。
文摘The effective one-body method provides a framework to apply the black hole perturbation theory to the binary system where two masses can be comparable.We study the gravitational-wave equation in the background of the effective one-body system for the spinless binary,which is in general available with the spherically symmetric background as well.We obtain the gauge conditions for the decoupled wave equation,and also give the solutions to the gauge conditions in terms of the metric perturbation for a special case,which extends the result by Jing et al.(Sci.China-Phys.Mech.Astron.65,260411(2022)).Finally we obtain the gravitational-wave equation which is the generalization of the Teukolsky equation.
基金the National Key R&D Program of China(2022YFC2204602)the Natural Science Foundation of China(11925503)。
文摘Future space-based gravitational-wave detectors will detect gravitational waves with high sensitivity in the millihertz frequency band,providing more opportunities to test theories of gravity than ground-based detectors.The study of quasinormal modes(QNMs)and their application in gravity theory testing have been an important aspect in the field of gravitational physics.In this study,we investigate the capability of future space-based gravitational wave detectors,such as LISA,TaiJi,and TianQin,to constrain the dimensionless deviating parameter for Einsteindilaton-Gauss-Bonnet(EdGB)gravity with ringdown signals from the merger of binary black holes.The ringdown signal is modeled by the two strongest QNMs in EdGB gravity.Considering time-delay interferometry,we calculate the signal-to-noise ratio of different space-based detectors for ringdown signals to analyze their capabilities.The Fisher information matrix is employed to analyze the accuracy of parameter estimation,with particular focus on the dimensionless deviating parameter for EdGB gravity.The impact of the parameters of gravitational wave sources on the estimation accuracy of the dimensionless deviating parameter is also studied.We find that the constraint ability of EdGB gravity is limited because the uncertainty of the dimensionless deviating parameter increases with a decrease in the dimensionless deviating parameter.LISA and TaiJi offer more advantages in constraining the dimensionless deviating parameter to a more accurate level for massive black holes,whereas TianQin is more suited to less massive black holes.The Bayesian inference method is used to perform parameter estimation on simulated data,which verifies the reliability of the conclusion.
基金the National Natural Science Foundation of China(Grant Nos.11655001,11654004,91836104).
文摘Precision measurement tools are compulsory to reduce measurement errors or machining errors in the processes of calibration and manufacturing.The laser interferometer is one of the most important measurement tools invented in the 20th century.Today,it is commonly used in ultraprecision machining and manufacturing,ultraprecision positioning control,and many noncontact optical sensing technologies.So far,the state-of-the-art laser interferometers are the ground-based gravitational-wave detectors,e.g.the Laser Interferometer Gravitational-wave Observatory(LIGO).The LIGO has reached the measurement quantum limit,and some quantum technologies with squeezed light are currently being tested in order to further decompress the noise level.In this paper,we focus on the laser interferometry developed for space-based gravitational-wave detection.The basic working principle and the current status of the key technologies of intersatellite laser interferometry are introduced and discussed in detail.The launch and operation of these large-scale,gravitational-wave detectors based on space-based laser interferometry is proposed for the 2030s.
基金the National Natural Science Foundation of China(11975072,11690021,11875102,and 11835009)the National Program for Support of Top-Notch Young Professionals+1 种基金the Liaoning Revitalization Talents Program(XLYC1905011)the Fundamental Research Funds for the Central Universities(N2005030)。
文摘Taiji,a space-based gravitational-wave observatory,consists of three satellites forming an equilateral triangle with arm length of 3×10^6 km,orbiting around the Sun.Taiji is able to observe the gravitationalwave standard siren events of massive black hole binary(MBHB)merger,which is helpful in probing the expansion of the universe.In this paper,we preliminarily forecast the capability of Taiji for improving cosmological parameter estimation with the gravitational-wave standard siren data.We simulate fiveyear standard siren data based on three fiducial cosmological models and three models of MBHB’s formation and growth.It is found that the standard siren data from Taiji can effectively break the cosmological parameter degeneracies generated by the cosmic microwave background(CMB)anisotropies data,especially for dynamical dark energy models.The constraints on cosmological parameters are significantly improved by the data combination CMB+Taiji,compared to the CMB data alone.Compared to the current optical cosmological observations,Taiji can still provide help in improving the cosmological parameter estimation to some extent.In addition,we consider an ideal scenario to investigate the potential of Taiji on constraining cosmological parameters.We conclude that the standard sirens of MBHB from Taiji will become a powerful cosmological probe in the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.11975072,11835009,11875102,and 11690021)the Liaoning Revitalization Talents Program(Grant No.XLYC1905011)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.N2005030)the National Program for Support of Top-Notch Young Professionals(Grant No.W02070050)。
文摘LISA and Taiji are expected to form a space-based gravitational-wave(GW)detection network in the future.In this work,we make a forecast for the cosmological parameter estimation with the standard siren observation from the LISA-Taiji network.We simulate the standard siren data based on a scenario with configuration angle of 40°between LISA and Taiji.Three models for the population of massive black hole binary(MBHB),i.e.,popⅢ,Q3d,and Q3nod,are considered to predict the events of MBHB mergers.We find that,based on the LISA-Taiji network,the number of electromagnetic(EM)counterparts detected is almost doubled compared with the case of single Taiji mission.Therefore,the LISA-Taiji network’s standard siren observation could provide much tighter constraints on cosmological parameters.For example,solely using the standard sirens from the LISA-Taiji network,the constraint precision of H;could reach 1.3%.Moreover,combined with the CMB data,the GW-EM observation based on the LISA-Taiji network could also tightly constrain the equation of state of dark energy,e.g.,the constraint precision of w reaches about 4%,which is comparable with the result of CMB+BAO+SN.It is concluded that the GW standard sirens from the LISA-Taiji network will become a useful cosmological probe in understanding the nature of dark energy in the future.
基金This work is supported by the National Key Research and Development Program of China Grant No.2020YFC2201502, grants from NSFC (Grant No.11 975 019,11 991 052,12 047 503)Key Research Program of Frontier Sciences, CAS, Grant NO. ZDBS-LY-7009+1 种基金CAS Project for Young Scientists in Basic Research YSBR-006the Key Research Program of the Chinese Academy of Sciences (Grant NO. XDPB15)。
文摘We search for isotropic stochastic gravitational-wave background(SGWB)in the International Pulsar Timing Array second data release.By modeling the SGWB as a power-law,we find very strong Bayesian evidence for a common-spectrum process,and further this process has scalar transverse(ST)correlations allowed in general metric theory of gravity as the Bayes factor in favor of the ST-correlated process versus the spatially uncorrelated common-spectrum process is 30±2.The median and the 90%equal-tail amplitudes of ST mode are A_(ST)=1.29^(+0.51)_(−0.44)×10^(−15),or equivalently the energy density parameter per logarithm frequency isΩSTGW=2.31^(+2.19)_(−1.30)×10^(−9),at frequency of 1 year−1.However,we do not find any statistically significant evidence for the tensor transverse(TT)mode and then place the 95%upper limits as A_(TT)<3.95×10^(−15),or equivalentlyΩ^(TT)_(GW)<2.16×10^(−9),at frequency of 1 year^(−1).
基金Acknowledgements The authors thank Dick Manchester, George Hobbs, David Blair, Jonathan Gair, Thomas Bauer, Marie- Anne Bizouard and David Shoemaker for useful comments. LW acknowledges gratefully funding support from the Australian Research Council. GG acknowledges support from the National Science Foundation, NSF-PHY 0905184 and 1205882. This paper has been assigned LIGO document number LIGO-P1300010.
文摘We are entering a new era of gravitational-wave astronomy. The ground-based interferometers have reached their initial design sensitivity in the audio band. Several upper limits have been set for anticipated astrophysical sources from the science data. The advanced detectors in the US and in Europe are expected to be operational around 2015. New advanced detectors are also planned in Japan and in India. The first direct detections of gravitational waves are expected within this decade. In the meanwhile, three pulsar timing array projects are forming an international collaboration to detect gravitational waves directly in the nanoHertz range using timing data from millisecond pulsars. The first direct detection of nanoHertz gravitational waves are also expected within this decade. In this paper, we review the status of current gravitational-wave detectors, possible types of sources, observational upper limits achieved, and future prospects for direct detection of gravitational waves
基金Supported by the National Natural Science Foundation of China under Grant No 60407003.
文摘We propose a possible approach to achieve a 1/N sensitivity of Michelson interferometer by using a properly designed random phase modulation. Different from other approaches, the sensitivity improvement does not depend on increasing optical powers or utilizing the quantum properties of light. Moreover the requirements for optical losses and the quantum efficiencies of photodetection systems may be lower than the quantum approaches and the sensitivity improvement is independent of frequency in all the detection bands.
基金supported in part by the National Key Research and Development Program of China(2021YFC2203004)in part by the National Natural Science Foundation of China(12075041,12047564)+1 种基金the Fundamental Research Funds for the Central Universities of China(2021CDJQY-011,2020CDJQY-Z003)Chongqing Natural Science Foundation(cstc2020jcyj-msxmX0814)。
文摘We study the possibility of probing high scale phase transitions that are inaccessible by LIGO.Our study shows that the stochastic gravitational-wave radiation from cosmic strings that are formed after the first-order phase transition can be detected by space-based interferometers when the phase transition temperature is T_(n)~O(10^(8−11))GeV.
基金supported by the National Natural Science Foundation of China(Grant Nos.11690021,11575271,and 11747601)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB23000000,and XDA15020701)the Top-Notch Young Talents Program of China
文摘Primordial gravitational waves (GWs) encode the information about inflation [1], and the power spectrum of primordial GWs have attracted a lot of attentions. There are in general two crucial properties for the primordial GW power spectrum, namely the amplitude and the tilt (n_t).
基金This work was supported by the National Natural Science Foundation of China(Grants Nos.11975072,11835009,11875102,and 11690021)the Liaoning Revitalization Talents Program(Grant No.XLYC1905011)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.N2005030)the National 111 Project of China(Grant No.B16009)the Science Research Grants from the China Manned Space Project(Grant No.CMS-CSST-2021-B01).
文摘Multi-messenger gravitational wave(GW)observation for binary neutron star merger events could provide a rather useful tool to explore the evolution of the Universe.In particular,for the third-generation GW detectors,i.e.the Einstein Telescope(ET)and the Cosmic Explorer(CE),proposed to be built in Europe and the U.S.,respectively,lots of GW standard sirens with known redshifts could be obtained,which would exert great impacts on the cosmological parameter estimation.The total neutrino mass could be measured by cosmological observations,but such a measurement is model-dependent and currently only gives an upper limit.In this work,we wish to investigate whether the GW standard sirens observed by ET and CE could help improve the constraint on the neutrino mass,in particular in the interacting dark energy(IDE)models.We find that the GW standard siren observations from ET and CE can only slightly improve the constraint on the neutrino mass in the IDE models,compared to the current limit.The improvements in the IDE models are weaker than those in the standard cosmological model.Although the limit on neutrino mass can only be slightly updated,the constraints on other cosmological parameters can be significantly improved by using the GW observations.
