The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary ta...The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary target for the space-based detector laser interferometer space antenna due to their long-lived signals and high signal-to-noise ratios. This study explores the statistical properties of the GWB from EMRI, focusing on the calculation methods for the GWB, the astrophysical distribution of EMRI sources, and the influence of key parameters, including the spin of supermassive black holes(SMBHs) and the masses of compact objects(COs). By analyzing these factors, we determine the distribution range of the characteristic strain of the GWB from EMRIs. We find that the final eccentricity distributions appear to have negligible effect on the intensity of the GWB due to rapid circularization before they become detectable and the spin of the SMBH enhances the gravitational wave characteristic strain by approximately 1% compared to cases without spin effects. The masses of COs can also significantly affect the characteristic strain of the GWB from EMRIs, with black hole as CO producing a gravitational wave signal intensity that is approximately one order of magnitude higher compared to cases where neutron star or white dwarf are the COs.展开更多
The error propagation among estimated parameters reflects the correlation among the parameters.We study the capability of machine learning of"learning"the correlation of estimated parameters.We show that mac...The error propagation among estimated parameters reflects the correlation among the parameters.We study the capability of machine learning of"learning"the correlation of estimated parameters.We show that machine learning can recover the relation between the uncertainties of different parameters,especially,as predicted by the error propagation formula.Gravitational lensing can be used to probe both astrophysics and cosmology.As a practical application,we show that the machine learning is able to intelligently find the error propagation among the gravitational lens parameters(effective lens mass ML and Einstein radiusθ_(E))in accordance with the theoretical formula for the singular isothermal ellipse(SIE)lens model.The relation of errors of lens mass and Einstein radius,(e.g.,the ratio of standard deviations F=σ_(ML)/σ_(θ_(E)))predicted by the deep convolution neural network are consistent with the error propagation formula of the SIE lens model.As a proof-of-principle test,a toy model of linear relation with Gaussian noise is presented.We found that the predictions obtained by machine learning indeed indicate the information about the law of error propagation and the distribution of noise.Error propagation plays a crucial role in identifying the physical relation among parameters,rather than a coincidence relation,therefore we anticipate our case study on the error propagation of machine learning predictions could extend to other physical systems on searching the correlation among parameters.展开更多
The improvements in the sensitivity of the gravitational wave(GW) network enable the detection of several large redshift GW sources by third-generation GW detectors. These advancements provide an independent method to...The improvements in the sensitivity of the gravitational wave(GW) network enable the detection of several large redshift GW sources by third-generation GW detectors. These advancements provide an independent method to probe the large-scale structure of the universe by using the clustering of the binary black holes(BBHs). The black hole catalogs are complementary to the galaxy catalogs because of large redshifts of GW events, which may imply that BBHs are a better choice than galaxies to probe the large-scale structure of the universe and cosmic evolution over a large redshift range. To probe the large-scale structure, we used the sky position of the BBHs observed by third-generation GW detectors to calculate the angular correlation function and the bias factor of the population of BBHs. This method is also statistically significant as 5000 BBHs are simulated. Moreover, for the third-generation GW detectors, we found that the bias factor can be recovered to within 33% with an observational time of ten years. This method only depends on the GW source-location posteriors;hence, it can be an independent method to reveal the formation mechanisms and origin of the BBH mergers compared to the electromagnetic method.展开更多
The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray varia...The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5-4 keV,at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions.EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard.In this paper,the science objectives of the EP mission are presented.EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales.Among them,fast extragalactic transients will be surveyed systematically in soft X-rays,which includeγ-ray bursts and their variants,supernova shock breakouts,and the predicted X-ray transients associated with binary neutron star mergers.EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei,possibly at an early phase of the flares for some.EP will monitor the variability and outbursts of X-rays from white dwarfs,neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments,and is expected to discover new objects.A large sample of stellar X-ray flares will also be detected and characterised.In the era of multi-messenger astronomy,EP has the potential of detecting the possible X-ray counterparts of gravitational wave events,neutrino sources,and ultra-high energyγ-ray and cosmic ray sources.EP is expected to help advance the studies of extreme objects and phenomena revealed in the dynamic X-ray universe,and their underlying physical processes.Besides EP's strength in time-domain science,its follow-up telescope,with excellent performance,will also enable advances in many areas of X-ray astronomy.展开更多
In this new era of time-domain and multi-messenger astronomy,various new transients and new phenomena are constantly being discovered thanks to the rapid advances in observations,which provide the excellent opportunit...In this new era of time-domain and multi-messenger astronomy,various new transients and new phenomena are constantly being discovered thanks to the rapid advances in observations,which provide the excellent opportunity to study the physics in the extreme environments.The enhanced X-ray Timing and Polarimetry mission(eXTP),planned to be launched in 2030,has several key advantages,including advanced polarimetry,high sensitivity&large effective area,and wide energy range coverage,which make it a groundbreaking project in high-energy astrophysics.In this article,we briefly introduce the potential time-domain and multi-messenger targets for eXTP,including gravitational-wave(GW)counterparts,gamma-ray bursts(GRBs),magnetars and fast radio bursts(FRBs),tidal disruption events(TDEs),supernovae,high energy neutrinos and TeV active galactic nucleus(AGNs),and so on.We discuss the advantages of future eXTP observations for detecting these sources,their detection capabilities,the abilities to distinguish theoretical models,and their applications in gravity and cosmology.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
In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory 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 to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.展开更多
For the first time,gravitational waves(GWs),a major prediction of Einstein’s 1915 general theory of relativity(GR),has been detected directly by the two detectors of the Laser Interferometer Gravitational-Wave Observ...For the first time,gravitational waves(GWs),a major prediction of Einstein’s 1915 general theory of relativity(GR),has been detected directly by the two detectors of the Laser Interferometer Gravitational-Wave Observatory(LIGO)[1,展开更多
In this article,we describe the results concerning the third coincident signal GW170104 from the coalescence of binary black holes（BBHs）during the second observation run（O2）.The result was obtained from the LIGO S...In this article,we describe the results concerning the third coincident signal GW170104 from the coalescence of binary black holes（BBHs）during the second observation run（O2）.The result was obtained from the LIGO Scientific Collaboration and the Virgo Collaboration.Following the first and second gravitational waves（GWs）detections in the first observation run（O1）[1],recently LIGO has observed a third coincident signal GW170104 from the coalescence of BBHs展开更多
For the observer at infinity, a Schwarzschild black hole serves as an attractive opaque disk with a radius of 3√3 M that will produce the diffraction pattern of gravitational waves(GWs). In this study, we demonstrate...For the observer at infinity, a Schwarzschild black hole serves as an attractive opaque disk with a radius of 3√3 M that will produce the diffraction pattern of gravitational waves(GWs). In this study, we demonstrate that a bright spot, which is a diffraction effect analogous to the Poisson-Arago spot in optics, will appear when an ingoing(quasi-)plane GW is diffracted by a Schwarzschild black hole. Here, we propose the diffraction effect of the GWs described by the exact diffraction solution of the GWs using the Heun function. For the first time, the Fresnel half-wave zone method is proposed to calculate the angular part of the GW scattering stripes for the observer at infinity. The prospect of observing the diffraction bright spot is discussed with an eikonal approximation. For normal incidence(quasi)-plane waves with 100 Hz(0.1 Hz) frequency diffracted by the central black hole of the Milky Way, the time delay between the Earth bathed in a bright spot and the minimum of the first dark stripe is 3.86(3860) d. We will witness the second bright fringe(40% amplitude of the central bright spot) after 6.2(6200) d. This new diffraction pattern involving the early phase of inspirals and pulsars as continuous gravitational wave sources is a potential scientific target for future space-and ground-based gravitational wave detectors, respectively.展开更多
In this study,we investigate the Hawking radiation in higher dimensional Reissner-Nordstrom black holes as received by an observer located at infinity.The frequency-dependent transmission rates,which deform the therma...In this study,we investigate the Hawking radiation in higher dimensional Reissner-Nordstrom black holes as received by an observer located at infinity.The frequency-dependent transmission rates,which deform the thermal radiation emitted in the vicinity of the black hole horizon,are evaluated numerically.In addition to those in four-dimensional spacetime,the calculations are extended to higher dimensional Reissner-Nordstrom metrics,and the results are observed to be sensitive to the spacetime dimension to an extent.Generally,we observe that the transmission coefficient practically vanishes when the frequency of the emitted particle approaches zero.It increases with frequency and eventually saturates to a certain value.For four-dimensional spacetime,the above result is demonstrated to be mostly independent of the metric's parameter and the orbital quantum number of the particle,when the location of the event horizon,rh,and the product of the charges of the black hole and the particle qQ are known.However,for higher-dimensional scenarios,the convergence becomes more gradual.Moreover,the difference between states with different orbital quantum numbers is observed to be more significant.As the magnitude of the product of charges qQ becomes more significant,the transmission coefficient exceeds 1.In other words,the resultant spectral flux is amplified,which results in an accelerated process of black hole evaporation.The relationship of the calculated outgoing transmission coefficient with existing results on the greybody factor is discussed.展开更多
We present a model for tail wavelets,a phenomenon known as"echo"in the literature.The tail wavelet may appear in signal reconnaissances in the merger of binary compact objects,including black holes and neutr...We present a model for tail wavelets,a phenomenon known as"echo"in the literature.The tail wavelet may appear in signal reconnaissances in the merger of binary compact objects,including black holes and neutron stars.We show that the dark matter surrounding the compact objects lead to a speculated tail wavelet following the main gravitational wave(GW).We demonstrate that the radiation pressure of the main wave is fully capable of pushing away the surrounding matter to some altitude,and splashing down of the matter excites the tail wavelet after ringing down of the main wave.We illustrate this concept in a simplified model,where numerical estimations are conducted on the specific distribution of dark matter outside the black hole horizon and the threshold values in accordance with observations.We study the full back reaction of the surrounding dark matter to the metric and find that the effect on to the tail wavelets is insignificant.We reveal the fine difference between the tail wavelets of a dressed and a bare black hole.We demonstrate that the tail wavelet can appear as a natural phenomenon in the frame of general relativity,without invoking modified gravities or quantum effects.展开更多
基金supported by the National Key R&D Program of China (Grant No. 2020YFC2201400)。
文摘The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary target for the space-based detector laser interferometer space antenna due to their long-lived signals and high signal-to-noise ratios. This study explores the statistical properties of the GWB from EMRI, focusing on the calculation methods for the GWB, the astrophysical distribution of EMRI sources, and the influence of key parameters, including the spin of supermassive black holes(SMBHs) and the masses of compact objects(COs). By analyzing these factors, we determine the distribution range of the characteristic strain of the GWB from EMRIs. We find that the final eccentricity distributions appear to have negligible effect on the intensity of the GWB due to rapid circularization before they become detectable and the spin of the SMBH enhances the gravitational wave characteristic strain by approximately 1% compared to cases without spin effects. The masses of COs can also significantly affect the characteristic strain of the GWB from EMRIs, with black hole as CO producing a gravitational wave signal intensity that is approximately one order of magnitude higher compared to cases where neutron star or white dwarf are the COs.
基金supported by the National Natural Science Foundation of China(grant No.11922303)the Natural Science Foundation of Chongqing(grant No.CSTB2023NSCQ-MSX0103)+1 种基金the Key Research Program of Xingtai 2020ZC005the Fundamental Research Funds for the Central Universities(grant No.2042022kf1182)。
文摘The error propagation among estimated parameters reflects the correlation among the parameters.We study the capability of machine learning of"learning"the correlation of estimated parameters.We show that machine learning can recover the relation between the uncertainties of different parameters,especially,as predicted by the error propagation formula.Gravitational lensing can be used to probe both astrophysics and cosmology.As a practical application,we show that the machine learning is able to intelligently find the error propagation among the gravitational lens parameters(effective lens mass ML and Einstein radiusθ_(E))in accordance with the theoretical formula for the singular isothermal ellipse(SIE)lens model.The relation of errors of lens mass and Einstein radius,(e.g.,the ratio of standard deviations F=σ_(ML)/σ_(θ_(E)))predicted by the deep convolution neural network are consistent with the error propagation formula of the SIE lens model.As a proof-of-principle test,a toy model of linear relation with Gaussian noise is presented.We found that the predictions obtained by machine learning indeed indicate the information about the law of error propagation and the distribution of noise.Error propagation plays a crucial role in identifying the physical relation among parameters,rather than a coincidence relation,therefore we anticipate our case study on the error propagation of machine learning predictions could extend to other physical systems on searching the correlation among parameters.
基金supported by the National Natural Science Foundation of China (grant Nos. 11922303, 119201003 and 12021003)supported by Hubei province Natural Science Fund for the Distinguished Young Scholars (No.2019CFA052)supported by CAS Project for Young Scientists in Basic Research YSBR-006。
文摘The improvements in the sensitivity of the gravitational wave(GW) network enable the detection of several large redshift GW sources by third-generation GW detectors. These advancements provide an independent method to probe the large-scale structure of the universe by using the clustering of the binary black holes(BBHs). The black hole catalogs are complementary to the galaxy catalogs because of large redshifts of GW events, which may imply that BBHs are a better choice than galaxies to probe the large-scale structure of the universe and cosmic evolution over a large redshift range. To probe the large-scale structure, we used the sky position of the BBHs observed by third-generation GW detectors to calculate the angular correlation function and the bias factor of the population of BBHs. This method is also statistically significant as 5000 BBHs are simulated. Moreover, for the third-generation GW detectors, we found that the bias factor can be recovered to within 33% with an observational time of ten years. This method only depends on the GW source-location posteriors;hence, it can be an independent method to reveal the formation mechanisms and origin of the BBH mergers compared to the electromagnetic method.
基金supported by Strategic Priority Program on Space Science of Chinese Academy of Sciences,in collaboration with ESA,MPE and CNES(Grant Nos.XDA15310000,and XDA15052100)supported by the National Natural Science Foundation of China(Grant Nos.61234003,61434004,and 61504141)CAS Interdisciplinary Project(Grant No.KJZD-EW-L11-04)。
文摘The Einstein Probe(EP)is an interdisciplinary mission of time-domain and X-ray astronomy.Equipped with a wide-field lobstereye X-ray focusing imager,EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5-4 keV,at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions.EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard.In this paper,the science objectives of the EP mission are presented.EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales.Among them,fast extragalactic transients will be surveyed systematically in soft X-rays,which includeγ-ray bursts and their variants,supernova shock breakouts,and the predicted X-ray transients associated with binary neutron star mergers.EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei,possibly at an early phase of the flares for some.EP will monitor the variability and outbursts of X-rays from white dwarfs,neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments,and is expected to discover new objects.A large sample of stellar X-ray flares will also be detected and characterised.In the era of multi-messenger astronomy,EP has the potential of detecting the possible X-ray counterparts of gravitational wave events,neutrino sources,and ultra-high energyγ-ray and cosmic ray sources.EP is expected to help advance the studies of extreme objects and phenomena revealed in the dynamic X-ray universe,and their underlying physical processes.Besides EP's strength in time-domain science,its follow-up telescope,with excellent performance,will also enable advances in many areas of X-ray astronomy.
基金supported by China’s Space Origins Exploration Programsupport from the Chinese Academy of Sciences (Grant No.E32983U810)+13 种基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDB0550300)the National Natural Science Foundation of China (Grant No.12325301)supported by the National Natural Science Foundation of China (Grant Nos.12233002,and 12041306)the National SKA Program of China (Grant No.2020SKA0120300)the National Key R&D Program of China (Grant No.2021YFA0718500)the support from the Xinjiang Tianchi Programsupported by the National Natural Science Foundation of China (Grant No.12333007)the International Partnership Program of the Chinese Academy of Sciences (Grant No.113111KYSB20190020)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA15020100)supported by the Beijing Municipal Natural Science Foundation (Grant No.1242032)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No.2022056)supported by the National Key Research and Development Program of China (Grant Nos.2022YFC2205201,and 2020YFC2201400)funding by the European Union-Next Generation EU RFF M4C2 1.1 PRIN 2022 project “2022RJLWHN URKA”INAF 2023 Theory Grant Ob Fu 1.05.23.06.06 “Understanding R-process & Kilonovae Aspects (URKA)”.
文摘In this new era of time-domain and multi-messenger astronomy,various new transients and new phenomena are constantly being discovered thanks to the rapid advances in observations,which provide the excellent opportunity to study the physics in the extreme environments.The enhanced X-ray Timing and Polarimetry mission(eXTP),planned to be launched in 2030,has several key advantages,including advanced polarimetry,high sensitivity&large effective area,and wide energy range coverage,which make it a groundbreaking project in high-energy astrophysics.In this article,we briefly introduce the potential time-domain and multi-messenger targets for eXTP,including gravitational-wave(GW)counterparts,gamma-ray bursts(GRBs),magnetars and fast radio bursts(FRBs),tidal disruption events(TDEs),supernovae,high energy neutrinos and TeV active galactic nucleus(AGNs),and so on.We discuss the advantages of future eXTP observations for detecting these sources,their detection capabilities,the abilities to distinguish theoretical models,and their applications in gravity and cosmology.
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supported by the Royal Society,ERC Starting(Grant No.639217)he European Union Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Global Fellowship(Grant No.703916)+10 种基金the National Natural Science Foundation of China(Grant Nos.11233001,11773014,11633007,11403074,11333005,11503008,and 11590781)the National Basic Research Program of China(Grant No.2015CB857100)NASA(Grant No.NNX13AD28A)an ARC Future Fellowship(Grant No.FT120100363)the National Science Foundation(Grant No.PHY-1430152)the Spanish MINECO(Grant No.AYA2016-76012-C3-1-P)the ICCUB(Unidad de Excelencia’Maria de Maeztu’)(Grant No.MDM-2014-0369)EU’s Horizon Programme through a Marie Sklodowska-Curie Fellowship(Grant No.702638)the 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)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the 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 to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.
基金supported by the National Natural Science Foundation of China(Grant No.11303009)
文摘For the first time,gravitational waves(GWs),a major prediction of Einstein’s 1915 general theory of relativity(GR),has been detected directly by the two detectors of the Laser Interferometer Gravitational-Wave Observatory(LIGO)[1,
基金supported by the National Natural Science Foundation of China(Grant Nos.11673008,and 11205254)the Newton International Fellowship Alumni Follow on Funding,the Fundamental Research Funds for the Central Universities(Grant No.106112016CDJXY300002)Chinese State Scholarship Fund
文摘In this article,we describe the results concerning the third coincident signal GW170104 from the coalescence of binary black holes（BBHs）during the second observation run（O2）.The result was obtained from the LIGO Scientific Collaboration and the Virgo Collaboration.Following the first and second gravitational waves（GWs）detections in the first observation run（O1）[1],recently LIGO has observed a third coincident signal GW170104 from the coalescence of BBHs
基金supported by the National Natural Science Foundation of China(Grant Nos.11922303,11673008,11075106,11575083,and 11275128)supported by the Hubei Province Natural Science Fund for the Distinguished Young Scholars(Grant No.2019CFA052)+1 种基金Newton International Fellowship Alumni Follow on Fundingsupported Shandong Province Natural Science Foundation(Grant No.ZR201709220395)。
文摘For the observer at infinity, a Schwarzschild black hole serves as an attractive opaque disk with a radius of 3√3 M that will produce the diffraction pattern of gravitational waves(GWs). In this study, we demonstrate that a bright spot, which is a diffraction effect analogous to the Poisson-Arago spot in optics, will appear when an ingoing(quasi-)plane GW is diffracted by a Schwarzschild black hole. Here, we propose the diffraction effect of the GWs described by the exact diffraction solution of the GWs using the Heun function. For the first time, the Fresnel half-wave zone method is proposed to calculate the angular part of the GW scattering stripes for the observer at infinity. The prospect of observing the diffraction bright spot is discussed with an eikonal approximation. For normal incidence(quasi)-plane waves with 100 Hz(0.1 Hz) frequency diffracted by the central black hole of the Milky Way, the time delay between the Earth bathed in a bright spot and the minimum of the first dark stripe is 3.86(3860) d. We will witness the second bright fringe(40% amplitude of the central bright spot) after 6.2(6200) d. This new diffraction pattern involving the early phase of inspirals and pulsars as continuous gravitational wave sources is a potential scientific target for future space-and ground-based gravitational wave detectors, respectively.
基金We gratefully acknowledge the financial support from Fundacao de Amparo a Pesquisa do Estado de Sao Paulo(FAPESP)Fundacao de Amparo a Pesquisa do Estado do Rio de Janeiro(FAPERJ)+2 种基金Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior(CAPES)National Natural Science Foundation of China(NSFC)(11805166,11673008,11922303)。
文摘In this study,we investigate the Hawking radiation in higher dimensional Reissner-Nordstrom black holes as received by an observer located at infinity.The frequency-dependent transmission rates,which deform the thermal radiation emitted in the vicinity of the black hole horizon,are evaluated numerically.In addition to those in four-dimensional spacetime,the calculations are extended to higher dimensional Reissner-Nordstrom metrics,and the results are observed to be sensitive to the spacetime dimension to an extent.Generally,we observe that the transmission coefficient practically vanishes when the frequency of the emitted particle approaches zero.It increases with frequency and eventually saturates to a certain value.For four-dimensional spacetime,the above result is demonstrated to be mostly independent of the metric's parameter and the orbital quantum number of the particle,when the location of the event horizon,rh,and the product of the charges of the black hole and the particle qQ are known.However,for higher-dimensional scenarios,the convergence becomes more gradual.Moreover,the difference between states with different orbital quantum numbers is observed to be more significant.As the magnitude of the product of charges qQ becomes more significant,the transmission coefficient exceeds 1.In other words,the resultant spectral flux is amplified,which results in an accelerated process of black hole evaporation.The relationship of the calculated outgoing transmission coefficient with existing results on the greybody factor is discussed.
基金Supported in part by the National Natural Science Foundation of China(NSFC)(11805166,11575083)Supported by the National Natural Science Foundation of China(11673008,11633001)+5 种基金Shandong Province Natural Science Foundation(ZR201709220395)financial support from Brazilian funding agencies Fundacao de AmparoàPesquisa do Estado de Sao Paulo(FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nível Superior(CAPES)the Strategic Priority Program of the Chinese Academy of Sciences(XDB 23040100)Newton International Fellowship Alumni Follow-on Funding。
文摘We present a model for tail wavelets,a phenomenon known as"echo"in the literature.The tail wavelet may appear in signal reconnaissances in the merger of binary compact objects,including black holes and neutron stars.We show that the dark matter surrounding the compact objects lead to a speculated tail wavelet following the main gravitational wave(GW).We demonstrate that the radiation pressure of the main wave is fully capable of pushing away the surrounding matter to some altitude,and splashing down of the matter excites the tail wavelet after ringing down of the main wave.We illustrate this concept in a simplified model,where numerical estimations are conducted on the specific distribution of dark matter outside the black hole horizon and the threshold values in accordance with observations.We study the full back reaction of the surrounding dark matter to the metric and find that the effect on to the tail wavelets is insignificant.We reveal the fine difference between the tail wavelets of a dressed and a bare black hole.We demonstrate that the tail wavelet can appear as a natural phenomenon in the frame of general relativity,without invoking modified gravities or quantum effects.
