The observation of GW150914 gave a new independent measurement of the luminosity distance of a gravitational wave event. In this paper, we constrain the anisotropy of the Universe by using gravitational wave events.We...The observation of GW150914 gave a new independent measurement of the luminosity distance of a gravitational wave event. In this paper, we constrain the anisotropy of the Universe by using gravitational wave events.We simulate hundreds of events of binary neutron star merger that may be observed by the Einstein Telescope. Full simulation of the production process of gravitational wave data is employed. We find that 200 binary neutron star merging events with the redshift in (0,1) observed by the Einstein Telescope may constrain the anisotropy with an accuracy comparable to that from the Union2.1 supernovae. This result shows that gravitational waves can be a powerful tool for investigating cosmological anisotropy.展开更多
In this paper, we study an application of deep learning to the advanced laser interferometer gravitational wave observatory(LIGO)and advanced Virgo coincident detection of gravitational waves(GWs) from compact binary ...In this paper, we study an application of deep learning to the advanced laser interferometer gravitational wave observatory(LIGO)and advanced Virgo coincident detection of gravitational waves(GWs) from compact binary star mergers. This deep learning method is an extension of the Deep Filtering method used by George and Huerta(2017) for multi-inputs of network detectors.Simulated coincident time series data sets in advanced LIGO and advanced Virgo detectors are analyzed for estimating source luminosity distance and sky location. As a classifier, our deep neural network(DNN) can effectively recognize the presence of GW signals when the optimal signal-to-noise ratio(SNR) of network detectors ≥ 9. As a predictor, it can also effectively estimate the corresponding source space parameters, including the luminosity distance D, right ascension α, and declination δ of the compact binary star mergers. When the SNR of the network detectors is greater than 8, their relative errors are all less than 23%.Our results demonstrate that Deep Filtering can process coincident GW time series inputs and perform effective classification and multiple space parameter estimation. Furthermore, we compare the results obtained from one, two, and three network detectors;these results reveal that a larger number of network detectors results in a better source location.展开更多
Aerosol particle deposition in a narrow horizontal channel with gravitational effects is studied in the laminar flow regime. A general explic让 solution for predicting the aerosol transportation in the channel is obta...Aerosol particle deposition in a narrow horizontal channel with gravitational effects is studied in the laminar flow regime. A general explic让 solution for predicting the aerosol transportation in the channel is obtained theoretically. The characteristics of the asymmetric concentratio n profiles and their dependence on gravitational settling are analyzed for different settings of the diffusion and sedimentation parameters. Aerosol deposition on the channel walls, which is influenced by a combination of mechanisms, is also analyzed. The results are compared with those from simplified models obtained in previous studies in which only diffusion or gravity was considered. The analysis reveals that the literature results regarding this aspect may be simplified with the present solution under specific conditions.展开更多
Pulsar timing array(PTA) provides an excellent opportunity to detect the gravitational waves(GWs) in nanoHertz frequency band.In particular, due to the larger number of 'arms' in PTA, it can be used to test gr...Pulsar timing array(PTA) provides an excellent opportunity to detect the gravitational waves(GWs) in nanoHertz frequency band.In particular, due to the larger number of 'arms' in PTA, it can be used to test gravity by probing the non-Einsteinian polarization modes of GWs, including two spin-1 shear modes labeled by 'sn' and 'se', the spin-0 transverse mode labeled by 'b' and the longitudinal mode labeled by 'l'. In this paper, we investigate the capabilities of the current and potential future PTAs, which are quantified by the constraints on the amplitudes parameters(cb, csn, cse, cl), by observing an individual supermassive black hole binary in Virgo cluster. We find that for binary with total mass Mc= 8.77 × 108 M⊙ and GW frequency f = 10-9 Hz, the PTA at current level can detect these GW modes if cb> 0.00106, cl> 0.00217, cse> 0.00271, csn> 0.00141, which will be improved by about two orders if considering the potential PTA in SKA era. Interesting enough, due to effects of the geometrical factors, we find that in SKA era, the constraints on the l, sn, se modes of GWs are purely dominated by several pulsars, instead of the full pulsars in PTA.展开更多
In this paper, we compute lower dimensional volumes Vol4(1,1) and Vol6(2,2) about Witten deformation for 4, 6-dimensional spin manifolds with boundary respectively, and get assosiated Kastler–Kalau–Walze type theore...In this paper, we compute lower dimensional volumes Vol4(1,1) and Vol6(2,2) about Witten deformation for 4, 6-dimensional spin manifolds with boundary respectively, and get assosiated Kastler–Kalau–Walze type theorems. We also give theoritic explaination of the gravitational action for 4, 6 dimensional manifolds with boundary by these noncommutative residues.展开更多
Quartzites are widespread within Earth's lithosphere,but their highly pure varieties occur quite infrequently.With the development of alternative energy sources,including solar,and with increasing demand for high-...Quartzites are widespread within Earth's lithosphere,but their highly pure varieties occur quite infrequently.With the development of alternative energy sources,including solar,and with increasing demand for high-purity quartz for optics,interest has risen in high-urity silicon-bearing materials.The quartzites discovered in the southeast part of the Eastern Sayan Mountains are particularly attractive for exploration in terms of their raw material quality and feasibility to be enriched.For this reason,their genesis also merits study.Available geochemical data show that chemogenic (d18O >29.2%o) siliceous-carbonate sediments of the Irkut Formation are fairly pure (impurity elements <800 ppm),and that half the impurities are easily removed carbonate components of the rock.Bedded quartzites remote from the intrusive granitoids and near-contact quartzites were recognized based on geochemical and petrographic data.Influenced by the Sumsunur granitoids,the near-contact quartzites originally contained >0.9%impurities,but later,under the action of sliding slabs of ophiolite dynamothermal treatment reduced impurities to <100 ppm,resulting in "superquartzites"(highly pure quartzites).The presence of only minor structural impurities is due to the enrichment capacity of superquartzites to 10.1 ppm (7.2 ppm under special conditions)of 10 elements:Fe,AI,Ti,Ca,Mg,Cu,Mn,Na,K,and Li.展开更多
We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-glu...We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-gluon mean-field is monotonously decaying in real time, its pressure undergoes a series of violent oscillations at the characteristic QCD time scales that generate a primordial multi-peaked gravitational waves signal in the radio frequencies’ domain. The signal is an echo of the QCD phase transition that is accessible by planned measurements at the FAST and SKA telescopes.展开更多
An approximation of the orography gravity wave, which is induced by mountainous topography, is considered in this study. By assuming that the horizontal wind is a linear function with respect to the height, the approx...An approximation of the orography gravity wave, which is induced by mountainous topography, is considered in this study. By assuming that the horizontal wind is a linear function with respect to the height, the approximating equation for the orography gravity waves is obtained. Four topography functions are considered in this study and the orography gravity wave are obtained. The dynamics of the orography gravity wave is then discussed by considering the effect of the surface topography and background horizontal wind.展开更多
In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related toObservatory Science targets. These include flaring stars, supernova remnants, accreting wh...In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related toObservatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-raybinaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellentlysuited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium ledby the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in themid 2020s.展开更多
The success of LISA Pathfinder in demonstrating the LISA drag-free requirement paved the way for using space interferometers to detect low-frequency and middle-frequency gravitational waves(GWs). The TAIJI GW mission ...The success of LISA Pathfinder in demonstrating the LISA drag-free requirement paved the way for using space interferometers to detect low-frequency and middle-frequency gravitational waves(GWs). The TAIJI GW mission and the new LISA GW mission propose using an arm length of 3 Gm(1 Gm = 10~6 km) and an arm length of 2.5 Gm respectively. For a space laser-interferometric GW antenna,due to astrodynamical orbit variation, time delay interferometry(TDI) is needed to achieve nearly equivalent equal-arms for suppressing the laser frequency noise below the level of optical path noise, acceleration noise, etc in order to attain the requisite sensitivity. In this paper, we simulate TDI numerically for the TAIJI mission and the new LISA mission. To do this, we work out a set of 2200-day(6-year) optimized science orbits for each mission starting on 2028 March 22 using the CGC 2.7.1 ephemeris framework. Then we use the numerical method to calculate the residual optical path differences of the first-generation TDI configurations and the selected second-generation TDI configurations. The resulting optical path differences of the second-generation TDI configurations calculated for TAIJI, new LISA and eLISA are well below their respective requirements for laser frequency noise cancelation. However, for the first-generation TDI configurations, the original requirements need to be relaxed by 3 to 30 fold to be satisfied. For TAIJI and the new LISA, about one order of magnitude relaxation would be good and recommended;this could be borne on the laser stability requirement in view of recent progress in laser stability, or the GW detection sensitivities of the second-generation TDIs have to be used in the diagnosis of the observed data instead of the commonly used X, Y and Z TDIs.展开更多
In this paper, we will give a general introduction to the Ali CMB Polarization Telescope(Ali CPT) project,which is a Sino–US joint project led by the Institute of High Energy Physics and involves many different insti...In this paper, we will give a general introduction to the Ali CMB Polarization Telescope(Ali CPT) project,which is a Sino–US joint project led by the Institute of High Energy Physics and involves many different institutes in China. It is the first ground-based Cosmic Microwave Background(CMB) polarization experiment in China and an integral part of China’s Gravitational-wave Program. The main scientific goal of the Ali CPT project is to probe the primordial gravitational waves(PGWs) originating from the very early Universe. The AliCPT project includes two stages. The first stage, referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet at an altitude of 5250 meters. Once completed, it will be the highest ground-based CMB observatory in the world and will open a new window for probing PGWs in the northern hemisphere. The AliCPT-1 telescope is designed to have about 7000 transition-edge sensor detectors at 95 GHz and 150 GHz. The second stage is to have a more sensitive telescope(Ali CPT-2) with more than 20 000 detectors. Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with three years’ observation. Besides the PGWs, Ali CPT will also enable a precise measurement of the CMB rotation angle and provide a precise test of the CPT symmetry. We show that three years’ observation will improve the current limit by two orders of magnitude.展开更多
The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will become one of the world-leading telescopes for pulsar timing array(PTA) research. The primary goals for PTAs are to detect(and subsequently study) u...The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will become one of the world-leading telescopes for pulsar timing array(PTA) research. The primary goals for PTAs are to detect(and subsequently study) ultra-low-frequency gravitational waves, to develop a pulsar-based time standard and to improve solar system planetary ephemerides. FAST will have the sensitivity to observe known pulsars with significantly improved signal-to-noise ratios and will discover a large number of currently unknown pulsars. We describe how FAST will contribute to PTA research and show that jitter-and timing-noise will be the limiting noise processes for FAST data sets. Jitter noise will limit the timing precision achievable over data spans of a few years while timing noise will limit the precision achievable over many years.展开更多
We present a study of spectrum estimation of relic gravitational waves(RGWs) as a Gaussian stochastic background from output signals of future space-borne interferometers, like LISA and ASTROD.As the target of detecti...We present a study of spectrum estimation of relic gravitational waves(RGWs) as a Gaussian stochastic background from output signals of future space-borne interferometers, like LISA and ASTROD.As the target of detection, the analytical spectrum of RGWs generated during inflation is described by three parameters: the tensor-scalar ratio, the spectral index and the running index. The Michelson interferometer is shown to have a better sensitivity than Sagnac and symmetrized Sagnac. For RGW detection, we analyze the auto-correlated signals for a single interferometer, and the cross-correlated, integrated as well as unintegrated signals for a pair of interferometers, and give the signal-to-noise ratio(SNR) for RGW, and obtain lower limits of the RGW parameters that can be detected. By suppressing noise level, a pair has a sensitivity2 orders better than a single for one year observation. SNR of LISA will be 4–5 orders higher than that of Advanced LIGO for the default RGW. To estimate the spectrum, we adopt the maximum likelihood(ML)estimation, calculate the mean and covariance of signals, obtain the Gaussian probability density function(PDF) and the likelihood function, and derive expressions for the Fisher matrix and the equation of the ML estimate for the spectrum. The Newton-Raphson method is used to solve the equation by iteration. When the noise is dominantly large, a single LISA is not effective for estimating the RGW spectrum as the actual noise in signals is not known accurately. For cross-correlating a pair, the spectrum cannot be estimated from the integrated output signals either, and only one parameter can be estimated with the other two being either fixed or marginalized. We use the ensemble averaging method to estimate the RGW spectrum from the un-integrated output signals. We also adopt a correlation of un-integrated signals to estimate the spectrum and three parameters of RGW in a Bayesian approach. For all three methods, we provide simulations to illustrate their feasibility.展开更多
We study the effect of the non-minimal coupling between matter and geometry on the gravitational constant in the context of f(R) theories of gravity on cosmic scales. For a class of f(R) models,the result shows that t...We study the effect of the non-minimal coupling between matter and geometry on the gravitational constant in the context of f(R) theories of gravity on cosmic scales. For a class of f(R) models,the result shows that the value of the gravitational constant not only changes over time but also has the dampened oscillation behavior.Compared with the result of the standard ACDM model, the consequence suggests that the coupling between matter and geometry should be weak.展开更多
The environment, such as an accretion disk, could modify the signal of the gravitational wavefrom astrophysical black hole binaries. In this article, we model the matter field around intermediate-mass binary black hol...The environment, such as an accretion disk, could modify the signal of the gravitational wavefrom astrophysical black hole binaries. In this article, we model the matter field around intermediate-mass binary black holes by means of an axion-like scalar field and investigate their joint evolution. Indetail, we consider equal mass binary black holes surrounded by a shell of axion-like scalar field bothin spherically symmetric and non-spherically symmetric cases, and with different strengths of the scalarfield. Our result shows that the environmental scalar field could essentially modify the dynamics. Firstly,in the spherically symmetric case, with increase of the scalar field strength, the number of circular orbitsfor the binary black hole is reduced. This means that the scalar field could significantly accelerate themerger process. Secondly, once the scalar field strength exceeds a certain critical value, the scalar fieldcould collapse into a third black hole with its mass being larger than that of the binary. Consequently,the new black hole that collapses from the environmental scalar field could accrete the binary promptlyand the binary collides head-on with each other. In this process, there is almost no quadrupole signalproduced, and, consequently, the gravitational wave is greatly suppressed. Thirdly, when the scalar fieldstrength is relatively smaller than the critical value, the black hole orbit could develop eccentricitythrough accretion of the scalar field. Fourthly, during the initial stage of the inspiral, the gravitationalattractive force from the axion-like scalar field could induce a sudden turn in the binary orbits, henceresulting in a transient wiggle in the gravitational waveform. Finally, in the non-spherical case, the scalarfield could gravitationally attract the binary moving toward the center of mass for the scalar field andslow down the merger process.展开更多
A preliminary estimation of gravitational waves (GWs) from the extreme-mass-ratio-inspirals (EMRIs) system in the Galactic Centre (GC) is given for the 37 observed S-stars revolving around the supermassive black hole ...A preliminary estimation of gravitational waves (GWs) from the extreme-mass-ratio-inspirals (EMRIs) system in the Galactic Centre (GC) is given for the 37 observed S-stars revolving around the supermassive black hole (SMBH) at Sagittarius (Sgr) A^*.Within this century,the total strain of the gravitational waveform calculated from the post-Newtonian (PN) method with eccentricity is well below the current planned sensitivity of pulsar-timing-array (PTA).New technology might be required in order to extract GW signal from this EMRIs system for future PTA detections.展开更多
The gamma-ray burst GR170817A associated with GW170817 is subluminous and suben-ergetic compared with other typical short gamma-ray bursts. It may be due to a relativistic jet viewedoff-axis, or a structured jet or co...The gamma-ray burst GR170817A associated with GW170817 is subluminous and suben-ergetic compared with other typical short gamma-ray bursts. It may be due to a relativistic jet viewedoff-axis, or a structured jet or cocoon emission. Giant flares from magnetars may possibly be ruled out.However, the luminosity and energetics of GRB 170817A are coincident with those of magnetar giantflares. After the coalescence of a binary neutron star, a hypermassive neutron star may be formed. Thehypermassive neutron star may have a magnetar-strength magnetic field. During the collapse of thishypermassive neutron star, magnetic field energy will also be released. This giant-flare-like event mayexplain the luminosity and energetics of GRB 170817A. Bursts with similar luminosity and energeticsare expected in future neutron star-neutron star or neutron star-black hole mergers.展开更多
Classical Solar System tests of photons coupled to Weyl tensor with two polarizations were studied in a recent work.A coupling strength parameter in this model was firstly obtained as |α| ■4×10^11m^2 by using a...Classical Solar System tests of photons coupled to Weyl tensor with two polarizations were studied in a recent work.A coupling strength parameter in this model was firstly obtained as |α| ■4×10^11m^2 by using available datasets in the Solar System.In this paper,a new test called by gravitational time advancement is proposed and investigated to test such the coupling.This new test,which is quite different from Shapiro time delay,depends strongly on round-trip proper time span (not coordinate time one) of flight of radio pulses between an observer on the Earth and a distant spacecraft.For ranging a spacecraft getting far away from the Sun,two special cases (the superior/inferior conjunctions) are used to analyse the observability in the advancement contributed by the Weyl coupling.We found that the situation of the inferior conjunction is more suitable for detecting the advancement caused by such the Weyl coupling.In either case,two kinds of polarizations make the advancement in the model smaller or larger than the one of general relativity.Although the observability in the advancement could be out of the reach of already existing technology,the implement of planetary laser ranging and optical clocks might provide us more insights on such the Weyl coupling in the near future.展开更多
Several neutrino observatories have searched for coincident neutrino signals associated with gravitational waves induced by the merging of two black holes.No statistically significant neutrino signal in excess of the ...Several neutrino observatories have searched for coincident neutrino signals associated with gravitational waves induced by the merging of two black holes.No statistically significant neutrino signal in excess of the background level was observed.These experiments use different neutrino detection technologies and are sensitive to various neutrino types.A combined analysis was performed on the KamLAND,Super-Kamiokande and Borexino experimental data with a frequentist statistical approach to achieve a global picture of the associated neutrino fluence.Both monochromatic and Fermi-Dirac neutrino spectra were assumed in the calculation.The final results are consistent with null neutrino signals associated with the process of a binary black hole merger.The derived 90%confidence level upper limits on the fluence and luminosity of various neutrino types are presented for neutrino energy less than 110MeV.展开更多
The MS7.0 Jiuzhaigou earthquake occurred on August 8,2017.The earthquake occurred in the vicinity of the Tazang fault,the Minjiang fault and the Huya fault,where the focal mechanism is of the strike slip type.The stat...The MS7.0 Jiuzhaigou earthquake occurred on August 8,2017.The earthquake occurred in the vicinity of the Tazang fault,the Minjiang fault and the Huya fault,where the focal mechanism is of the strike slip type.The static and dynamic anomalies of the gravity field can provide important physical field information for studying the structural properties of deep crust.Multi-scale decomposition techniques are used to separate Bouguer gravity at different depths and give some explanation to gravity variations at different time space scales.The results indicate that the wavelet multi-scale results of the EGM2008 model and the measured gravity data are consistent.Through comparative analysis,it is found that the Jiuzhaigou earthquake occurred in the stress enhanced region.The variation of gravity field at different time scales has a certain scientific significance for further understanding potential earthquake risk trend.展开更多
基金grants from NSFC(11675182,11690022,11603005,1177503.
文摘The observation of GW150914 gave a new independent measurement of the luminosity distance of a gravitational wave event. In this paper, we constrain the anisotropy of the Universe by using gravitational wave events.We simulate hundreds of events of binary neutron star merger that may be observed by the Einstein Telescope. Full simulation of the production process of gravitational wave data is employed. We find that 200 binary neutron star merging events with the redshift in (0,1) observed by the Einstein Telescope may constrain the anisotropy with an accuracy comparable to that from the Union2.1 supernovae. This result shows that gravitational waves can be a powerful tool for investigating cosmological anisotropy.
基金supported by the National Natural Science Foundation of China(Grant Nos.11873001,11633001,11673008,and 61501069)the Natural Science Foundation of Chongqing(Grant No.cstc2018jcyjAX0767)+4 种基金the Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB23040100)Newton International Fellowship Alumni Followon Fundingthe Fundamental Research Funds for the Central Universities Project(Grant Nos.106112017CDJXFLX0014,and 106112016CDJXY300002)Chinese State Scholarship FundNewton International Fellowship Alumni Follow on Funding.
文摘In this paper, we study an application of deep learning to the advanced laser interferometer gravitational wave observatory(LIGO)and advanced Virgo coincident detection of gravitational waves(GWs) from compact binary star mergers. This deep learning method is an extension of the Deep Filtering method used by George and Huerta(2017) for multi-inputs of network detectors.Simulated coincident time series data sets in advanced LIGO and advanced Virgo detectors are analyzed for estimating source luminosity distance and sky location. As a classifier, our deep neural network(DNN) can effectively recognize the presence of GW signals when the optimal signal-to-noise ratio(SNR) of network detectors ≥ 9. As a predictor, it can also effectively estimate the corresponding source space parameters, including the luminosity distance D, right ascension α, and declination δ of the compact binary star mergers. When the SNR of the network detectors is greater than 8, their relative errors are all less than 23%.Our results demonstrate that Deep Filtering can process coincident GW time series inputs and perform effective classification and multiple space parameter estimation. Furthermore, we compare the results obtained from one, two, and three network detectors;these results reveal that a larger number of network detectors results in a better source location.
基金This study was supported by the National Natural Science Foundation of China (Grant Nos. 51578121, 11662017 and 11762019). The authors would like to thank Dr. D. Gottfried for providing valuable comments on the manuscript.
文摘Aerosol particle deposition in a narrow horizontal channel with gravitational effects is studied in the laminar flow regime. A general explic让 solution for predicting the aerosol transportation in the channel is obtained theoretically. The characteristics of the asymmetric concentratio n profiles and their dependence on gravitational settling are analyzed for different settings of the diffusion and sedimentation parameters. Aerosol deposition on the channel walls, which is influenced by a combination of mechanisms, is also analyzed. The results are compared with those from simplified models obtained in previous studies in which only diffusion or gravity was considered. The analysis reveals that the literature results regarding this aspect may be simplified with the present solution under specific conditions.
基金the National Natural Science Foundation of China(Grant Nos.11603020,11633001,11173021,11322324,11653002,and 11421303)the Project of Knowledge Innovation Program of Chinese Academy of Sciences+1 种基金the Fundamental Research Funds for the Central Universitiesthe Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB23010200).
文摘Pulsar timing array(PTA) provides an excellent opportunity to detect the gravitational waves(GWs) in nanoHertz frequency band.In particular, due to the larger number of 'arms' in PTA, it can be used to test gravity by probing the non-Einsteinian polarization modes of GWs, including two spin-1 shear modes labeled by 'sn' and 'se', the spin-0 transverse mode labeled by 'b' and the longitudinal mode labeled by 'l'. In this paper, we investigate the capabilities of the current and potential future PTAs, which are quantified by the constraints on the amplitudes parameters(cb, csn, cse, cl), by observing an individual supermassive black hole binary in Virgo cluster. We find that for binary with total mass Mc= 8.77 × 108 M⊙ and GW frequency f = 10-9 Hz, the PTA at current level can detect these GW modes if cb> 0.00106, cl> 0.00217, cse> 0.00271, csn> 0.00141, which will be improved by about two orders if considering the potential PTA in SKA era. Interesting enough, due to effects of the geometrical factors, we find that in SKA era, the constraints on the l, sn, se modes of GWs are purely dominated by several pulsars, instead of the full pulsars in PTA.
基金Science Foundation for(Grant No.BS423)Inner Mongolia Natural Science Foundation for(Grant No.2018LHO1004).
文摘In this paper, we compute lower dimensional volumes Vol4(1,1) and Vol6(2,2) about Witten deformation for 4, 6-dimensional spin manifolds with boundary respectively, and get assosiated Kastler–Kalau–Walze type theorems. We also give theoritic explaination of the gravitational action for 4, 6 dimensional manifolds with boundary by these noncommutative residues.
基金financial support of Integration Program No.0341-2016-001Russian Foundation for Basic Research Projects 15-05-02772a and 18-05-00439a with research equipment isotope-geochemical studies at IGC SB RAS.
文摘Quartzites are widespread within Earth's lithosphere,but their highly pure varieties occur quite infrequently.With the development of alternative energy sources,including solar,and with increasing demand for high-purity quartz for optics,interest has risen in high-urity silicon-bearing materials.The quartzites discovered in the southeast part of the Eastern Sayan Mountains are particularly attractive for exploration in terms of their raw material quality and feasibility to be enriched.For this reason,their genesis also merits study.Available geochemical data show that chemogenic (d18O >29.2%o) siliceous-carbonate sediments of the Irkut Formation are fairly pure (impurity elements <800 ppm),and that half the impurities are easily removed carbonate components of the rock.Bedded quartzites remote from the intrusive granitoids and near-contact quartzites were recognized based on geochemical and petrographic data.Influenced by the Sumsunur granitoids,the near-contact quartzites originally contained >0.9%impurities,but later,under the action of sliding slabs of ophiolite dynamothermal treatment reduced impurities to <100 ppm,resulting in "superquartzites"(highly pure quartzites).The presence of only minor structural impurities is due to the enrichment capacity of superquartzites to 10.1 ppm (7.2 ppm under special conditions)of 10 elements:Fe,AI,Ti,Ca,Mg,Cu,Mn,Na,K,and Li.
基金A.A and A.M. acknowledge support by the NSFC(11875113)the Shanghai Municipality(KBH 1512299)+5 种基金by Fudan University(JJH 1512105)R.P. was partially supported by the Swedish Research Council, contract numbers 621-2013-428 and 2016-05996by CONICYT grant MEC80170112 (Chile)the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme(668679 )supported in part by the Ministry of Education, Youth and Sports of the Czech Republic, project LT1701been performed in the framework of COST Action CAI 5213 “Theory of hot matter and relativistic heavy-ion collisions”(THOR).
文摘We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-gluon mean-field is monotonously decaying in real time, its pressure undergoes a series of violent oscillations at the characteristic QCD time scales that generate a primordial multi-peaked gravitational waves signal in the radio frequencies’ domain. The signal is an echo of the QCD phase transition that is accessible by planned measurements at the FAST and SKA telescopes.
基金Supported by the Natural Science Foundation of China under Grant Nos.91437215,41575047The Third Scientific Experiment of Tibetan Plateau under Grant No.GYHY201406001.
文摘An approximation of the orography gravity wave, which is induced by mountainous topography, is considered in this study. By assuming that the horizontal wind is a linear function with respect to the height, the approximating equation for the orography gravity waves is obtained. Four topography functions are considered in this study and the orography gravity wave are obtained. The dynamics of the orography gravity wave is then discussed by considering the effect of the surface topography and background horizontal wind.
基金National Natural Science Foundation of China (Grant Nos. 11233001, 11773014, 11633007, 11403074, 11333005, 11503008, and 11590781)National Basic Research Program of China (Grant No. 2015CB857100)+8 种基金NASA (Grant No. NNX13AD28A)ARC Future Fellowship (Grant No. FT120100363)National Science Foundation (Grant No. PHY-1430152)Spanish MINECO (Grant No. AYA2016-76012-C3-1-P)ICCUB (Unidad de Excelencia 'María de Maeztu') (Grant No. MDM-2014-0369)EU's Horizon Programme through a Marie Sklodowska-Curie Fellowship (Grant No. 702638)Polish National Science Center (Grant Nos. 2015/17/B/ST9/03422, 2015/18/M/ST9/00541, 2013/10/M/ST9/00729, and 2015/18/A/ST9/00746)Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA15020100)NWO Veni Fellowship (Grant No. 639.041.647).
文摘In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related toObservatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-raybinaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellentlysuited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium ledby the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in themid 2020s.
基金GW receives funding in support of his work leading to these results from the People Programme(Marie Curie Actions)of the European Union's Seventh Framework Programme FP7/2007-2013/(PEOPLE-2013-ITN)under REA grant agreement n[606176].
文摘The success of LISA Pathfinder in demonstrating the LISA drag-free requirement paved the way for using space interferometers to detect low-frequency and middle-frequency gravitational waves(GWs). The TAIJI GW mission and the new LISA GW mission propose using an arm length of 3 Gm(1 Gm = 10~6 km) and an arm length of 2.5 Gm respectively. For a space laser-interferometric GW antenna,due to astrodynamical orbit variation, time delay interferometry(TDI) is needed to achieve nearly equivalent equal-arms for suppressing the laser frequency noise below the level of optical path noise, acceleration noise, etc in order to attain the requisite sensitivity. In this paper, we simulate TDI numerically for the TAIJI mission and the new LISA mission. To do this, we work out a set of 2200-day(6-year) optimized science orbits for each mission starting on 2028 March 22 using the CGC 2.7.1 ephemeris framework. Then we use the numerical method to calculate the residual optical path differences of the first-generation TDI configurations and the selected second-generation TDI configurations. The resulting optical path differences of the second-generation TDI configurations calculated for TAIJI, new LISA and eLISA are well below their respective requirements for laser frequency noise cancelation. However, for the first-generation TDI configurations, the original requirements need to be relaxed by 3 to 30 fold to be satisfied. For TAIJI and the new LISA, about one order of magnitude relaxation would be good and recommended;this could be borne on the laser stability requirement in view of recent progress in laser stability, or the GW detection sensitivities of the second-generation TDIs have to be used in the diagnosis of the observed data instead of the commonly used X, Y and Z TDIs.
基金supported in part by the National Natural Science Foundation of China(11653001,11653002,11653005,11653004)the CAS pilot B project(XDB23020000)the Sino–US cooperation project(2016YFE0104700).
文摘In this paper, we will give a general introduction to the Ali CMB Polarization Telescope(Ali CPT) project,which is a Sino–US joint project led by the Institute of High Energy Physics and involves many different institutes in China. It is the first ground-based Cosmic Microwave Background(CMB) polarization experiment in China and an integral part of China’s Gravitational-wave Program. The main scientific goal of the Ali CPT project is to probe the primordial gravitational waves(PGWs) originating from the very early Universe. The AliCPT project includes two stages. The first stage, referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet at an altitude of 5250 meters. Once completed, it will be the highest ground-based CMB observatory in the world and will open a new window for probing PGWs in the northern hemisphere. The AliCPT-1 telescope is designed to have about 7000 transition-edge sensor detectors at 95 GHz and 150 GHz. The second stage is to have a more sensitive telescope(Ali CPT-2) with more than 20 000 detectors. Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with three years’ observation. Besides the PGWs, Ali CPT will also enable a precise measurement of the CMB rotation angle and provide a precise test of the CPT symmetry. We show that three years’ observation will improve the current limit by two orders of magnitude.
基金the Australian Research Council(ARC)Future Fellowship programmethe National Natural Science Foundation of China(11225314).
文摘The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will become one of the world-leading telescopes for pulsar timing array(PTA) research. The primary goals for PTAs are to detect(and subsequently study) ultra-low-frequency gravitational waves, to develop a pulsar-based time standard and to improve solar system planetary ephemerides. FAST will have the sensitivity to observe known pulsars with significantly improved signal-to-noise ratios and will discover a large number of currently unknown pulsars. We describe how FAST will contribute to PTA research and show that jitter-and timing-noise will be the limiting noise processes for FAST data sets. Jitter noise will limit the timing precision achievable over data spans of a few years while timing noise will limit the precision achievable over many years.
基金the National Natural Science Foundation of China(Grant Nos.11421303,11675165 and 11633001)SRFDP+1 种基金CASthe Strategic Priority Research Program“The Emergence of Cosmological Structures”of the Chinese Academy of Sciences(Grant No.XDB09000000).
文摘We present a study of spectrum estimation of relic gravitational waves(RGWs) as a Gaussian stochastic background from output signals of future space-borne interferometers, like LISA and ASTROD.As the target of detection, the analytical spectrum of RGWs generated during inflation is described by three parameters: the tensor-scalar ratio, the spectral index and the running index. The Michelson interferometer is shown to have a better sensitivity than Sagnac and symmetrized Sagnac. For RGW detection, we analyze the auto-correlated signals for a single interferometer, and the cross-correlated, integrated as well as unintegrated signals for a pair of interferometers, and give the signal-to-noise ratio(SNR) for RGW, and obtain lower limits of the RGW parameters that can be detected. By suppressing noise level, a pair has a sensitivity2 orders better than a single for one year observation. SNR of LISA will be 4–5 orders higher than that of Advanced LIGO for the default RGW. To estimate the spectrum, we adopt the maximum likelihood(ML)estimation, calculate the mean and covariance of signals, obtain the Gaussian probability density function(PDF) and the likelihood function, and derive expressions for the Fisher matrix and the equation of the ML estimate for the spectrum. The Newton-Raphson method is used to solve the equation by iteration. When the noise is dominantly large, a single LISA is not effective for estimating the RGW spectrum as the actual noise in signals is not known accurately. For cross-correlating a pair, the spectrum cannot be estimated from the integrated output signals either, and only one parameter can be estimated with the other two being either fixed or marginalized. We use the ensemble averaging method to estimate the RGW spectrum from the un-integrated output signals. We also adopt a correlation of un-integrated signals to estimate the spectrum and three parameters of RGW in a Bayesian approach. For all three methods, we provide simulations to illustrate their feasibility.
基金Supported by the National Natural Science Foundation of China under Grant No 11647079the Scientific Research Foundation of Education Department of Yunnan Province under Grant No 2016ZZX011+1 种基金the Key Laboratory of Astroparticle Physics of Yunnan Provincethe Donglu Youth Teacher Plan of Yunnan University
文摘We study the effect of the non-minimal coupling between matter and geometry on the gravitational constant in the context of f(R) theories of gravity on cosmic scales. For a class of f(R) models,the result shows that the value of the gravitational constant not only changes over time but also has the dampened oscillation behavior.Compared with the result of the standard ACDM model, the consequence suggests that the coupling between matter and geometry should be weak.
文摘The environment, such as an accretion disk, could modify the signal of the gravitational wavefrom astrophysical black hole binaries. In this article, we model the matter field around intermediate-mass binary black holes by means of an axion-like scalar field and investigate their joint evolution. Indetail, we consider equal mass binary black holes surrounded by a shell of axion-like scalar field bothin spherically symmetric and non-spherically symmetric cases, and with different strengths of the scalarfield. Our result shows that the environmental scalar field could essentially modify the dynamics. Firstly,in the spherically symmetric case, with increase of the scalar field strength, the number of circular orbitsfor the binary black hole is reduced. This means that the scalar field could significantly accelerate themerger process. Secondly, once the scalar field strength exceeds a certain critical value, the scalar fieldcould collapse into a third black hole with its mass being larger than that of the binary. Consequently,the new black hole that collapses from the environmental scalar field could accrete the binary promptlyand the binary collides head-on with each other. In this process, there is almost no quadrupole signalproduced, and, consequently, the gravitational wave is greatly suppressed. Thirdly, when the scalar fieldstrength is relatively smaller than the critical value, the black hole orbit could develop eccentricitythrough accretion of the scalar field. Fourthly, during the initial stage of the inspiral, the gravitationalattractive force from the axion-like scalar field could induce a sudden turn in the binary orbits, henceresulting in a transient wiggle in the gravitational waveform. Finally, in the non-spherical case, the scalarfield could gravitationally attract the binary moving toward the center of mass for the scalar field andslow down the merger process.
基金Supported by the Natural Science Foundation of China under Grant Nos.11690022,11375247,11435006,and 11647601the Strategic Priority Research Program of CAS under Grant No.XDB23030100the Key Research Program of Frontier Sciences of CAS.
文摘A preliminary estimation of gravitational waves (GWs) from the extreme-mass-ratio-inspirals (EMRIs) system in the Galactic Centre (GC) is given for the 37 observed S-stars revolving around the supermassive black hole (SMBH) at Sagittarius (Sgr) A^*.Within this century,the total strain of the gravitational waveform calculated from the post-Newtonian (PN) method with eccentricity is well below the current planned sensitivity of pulsar-timing-array (PTA).New technology might be required in order to extract GW signal from this EMRIs system for future PTA detections.
文摘The gamma-ray burst GR170817A associated with GW170817 is subluminous and suben-ergetic compared with other typical short gamma-ray bursts. It may be due to a relativistic jet viewedoff-axis, or a structured jet or cocoon emission. Giant flares from magnetars may possibly be ruled out.However, the luminosity and energetics of GRB 170817A are coincident with those of magnetar giantflares. After the coalescence of a binary neutron star, a hypermassive neutron star may be formed. Thehypermassive neutron star may have a magnetar-strength magnetic field. During the collapse of thishypermassive neutron star, magnetic field energy will also be released. This giant-flare-like event mayexplain the luminosity and energetics of GRB 170817A. Bursts with similar luminosity and energeticsare expected in future neutron star-neutron star or neutron star-black hole mergers.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11773080,11473072,and 11533004.
文摘Classical Solar System tests of photons coupled to Weyl tensor with two polarizations were studied in a recent work.A coupling strength parameter in this model was firstly obtained as |α| ■4×10^11m^2 by using available datasets in the Solar System.In this paper,a new test called by gravitational time advancement is proposed and investigated to test such the coupling.This new test,which is quite different from Shapiro time delay,depends strongly on round-trip proper time span (not coordinate time one) of flight of radio pulses between an observer on the Earth and a distant spacecraft.For ranging a spacecraft getting far away from the Sun,two special cases (the superior/inferior conjunctions) are used to analyse the observability in the advancement contributed by the Weyl coupling.We found that the situation of the inferior conjunction is more suitable for detecting the advancement caused by such the Weyl coupling.In either case,two kinds of polarizations make the advancement in the model smaller or larger than the one of general relativity.Although the observability in the advancement could be out of the reach of already existing technology,the implement of planetary laser ranging and optical clocks might provide us more insights on such the Weyl coupling in the near future.
基金funded by the National Natural Science Foundation of China (Grant No. 11080922)
文摘Several neutrino observatories have searched for coincident neutrino signals associated with gravitational waves induced by the merging of two black holes.No statistically significant neutrino signal in excess of the background level was observed.These experiments use different neutrino detection technologies and are sensitive to various neutrino types.A combined analysis was performed on the KamLAND,Super-Kamiokande and Borexino experimental data with a frequentist statistical approach to achieve a global picture of the associated neutrino fluence.Both monochromatic and Fermi-Dirac neutrino spectra were assumed in the calculation.The final results are consistent with null neutrino signals associated with the process of a binary black hole merger.The derived 90%confidence level upper limits on the fluence and luminosity of various neutrino types are presented for neutrino energy less than 110MeV.
基金the National Key Research and Development Program of China(2018YFC1503305)the National Nature Science Foundation of China(41874092).
文摘The MS7.0 Jiuzhaigou earthquake occurred on August 8,2017.The earthquake occurred in the vicinity of the Tazang fault,the Minjiang fault and the Huya fault,where the focal mechanism is of the strike slip type.The static and dynamic anomalies of the gravity field can provide important physical field information for studying the structural properties of deep crust.Multi-scale decomposition techniques are used to separate Bouguer gravity at different depths and give some explanation to gravity variations at different time space scales.The results indicate that the wavelet multi-scale results of the EGM2008 model and the measured gravity data are consistent.Through comparative analysis,it is found that the Jiuzhaigou earthquake occurred in the stress enhanced region.The variation of gravity field at different time scales has a certain scientific significance for further understanding potential earthquake risk trend.