This article presents a new type of whitening filter (allowing the “passing” of some noise sources) applied to process the data recorded in LIGO’s GW150914 and GW151226 events. This new analysis shows that in the G...This article presents a new type of whitening filter (allowing the “passing” of some noise sources) applied to process the data recorded in LIGO’s GW150914 and GW151226 events. This new analysis shows that in the GW150914 event, the signals from the collision of two black holes are very similar to the 32.5 Hz noise sources observed in both of LIGO’s detectors. It also points out that these 32.5 Hz noise sources are powered by a 30 Hz sub harmonic, coming from the 60 Hz power system. In the GW1226 event, the same analysis points out that the NR template is very similar to the 120 Hz noise source. Therefore, the signals recorded in these events were probably generated by some small changes with the 60 Hz frequency in the US power grid. This can be caused, for example, by a power variation in the DC link, which can appear in both detectors in the same 10 ms time window. As this kind of power grid occurrence did not change the voltage levels, it may have gone unnoticed by LIGO’s electrical power supply’s monitoring system.展开更多
Laser Interferometer Space Antenna(LISA)is a project to detect and measure gravitational waves.The project has three spacecraft ying in a formation of near equilateral triangle in a heliocentric orbit trailing Earth.M...Laser Interferometer Space Antenna(LISA)is a project to detect and measure gravitational waves.The project has three spacecraft ying in a formation of near equilateral triangle in a heliocentric orbit trailing Earth.Many sources of perturbations cause the con guration to deviate from the nominal.This paper studies the formation design problem for a LISA-like mission by considering ephemeris-based dynamics.This type of mission is well-known for addressing several strict mission requirements under the realistic dynamics.The problem is formulated as optimizing multiple mission performance indices.It is observed that some indices are correlated with each other,whereas some indices have di erent sensitivities with respect to the semi-major axis.Therefore,the problem is transformed into a two-step cascade single-objective optimization,in which the optimal solution of the rst optimization problem is fed to the second optimization as initial value.In addition,the major perturbing celestial bodies are picked up to make a simpli ed but accurate enough dynamics to speed up the optimization.Numerical examples verify the analysis and show the e ectiveness of the optimization procedure.The in uences of mission lifetime and spatial scales on the optimal solutions are also presented.展开更多
In the coming decades,the space-based gravitational-wave(GW)detectors such as Taiji,TianQin,and LISA are expected to form a network capable of detecting millihertz GWs emitted by the mergers of massive black hole bina...In the coming decades,the space-based gravitational-wave(GW)detectors such as Taiji,TianQin,and LISA are expected to form a network capable of detecting millihertz GWs emitted by the mergers of massive black hole binaries(MBHBs).In this work,we investigate the potential of GW standard sirens from the Taiji-TianQin-LISA network in constraining cosmological parameters.For the optimistic scenario in which electromagnetic(EM)counterparts can be detected,we predict the number of detectable bright sirens based on three different MBHB population models,i.e.,popⅢ,Q3d,and Q3nod.Our results show that the TaijiTianQin-LISA network alone could achieve a constraint precision of 0.9%for the Hubble constant,meeting the standard of precision cosmology.Moreover,the Taiji-TianQin-LISA network could effectively break the cosmological parameter degeneracies generated by the CMB data,particularly in the dynamical dark energy models.When combined with the CMB data,the joint CMB+Taiji-TianQin-LISA data offerσ(w)=0.036 in the wCDM model,which is close to the latest constraint result obtained from the CMB+SN data.We also consider a conservative scenario in which EM counterparts are not available.Due to the precise sky localizations of MBHBs by the Taiji-TianQin-LISA network,the constraint precision of the Hubble constant is expected to reach 1.2%.In conclusion,the GW standard sirens from the Taiji-TianQin-LISA network will play a critical role in helping solve the Hubble tension and shedding light on the nature of dark energy.展开更多
文摘This article presents a new type of whitening filter (allowing the “passing” of some noise sources) applied to process the data recorded in LIGO’s GW150914 and GW151226 events. This new analysis shows that in the GW150914 event, the signals from the collision of two black holes are very similar to the 32.5 Hz noise sources observed in both of LIGO’s detectors. It also points out that these 32.5 Hz noise sources are powered by a 30 Hz sub harmonic, coming from the 60 Hz power system. In the GW1226 event, the same analysis points out that the NR template is very similar to the 120 Hz noise source. Therefore, the signals recorded in these events were probably generated by some small changes with the 60 Hz frequency in the US power grid. This can be caused, for example, by a power variation in the DC link, which can appear in both detectors in the same 10 ms time window. As this kind of power grid occurrence did not change the voltage levels, it may have gone unnoticed by LIGO’s electrical power supply’s monitoring system.
基金The work was supported by the Hundred Talents Program of the Chinese Academy of Sciences and Strategic Priority Program A(Grant No.XDA15014902).
文摘Laser Interferometer Space Antenna(LISA)is a project to detect and measure gravitational waves.The project has three spacecraft ying in a formation of near equilateral triangle in a heliocentric orbit trailing Earth.Many sources of perturbations cause the con guration to deviate from the nominal.This paper studies the formation design problem for a LISA-like mission by considering ephemeris-based dynamics.This type of mission is well-known for addressing several strict mission requirements under the realistic dynamics.The problem is formulated as optimizing multiple mission performance indices.It is observed that some indices are correlated with each other,whereas some indices have di erent sensitivities with respect to the semi-major axis.Therefore,the problem is transformed into a two-step cascade single-objective optimization,in which the optimal solution of the rst optimization problem is fed to the second optimization as initial value.In addition,the major perturbing celestial bodies are picked up to make a simpli ed but accurate enough dynamics to speed up the optimization.Numerical examples verify the analysis and show the e ectiveness of the optimization procedure.The in uences of mission lifetime and spatial scales on the optimal solutions are also presented.
基金supported by the National SKA Program of China(Grant Nos.2022SKA0110200,and 2022SKA0110203)the National Natural Science Foundation of China(Grant Nos.11975072,11875102,and 11835009)+1 种基金the National 111 Project(Grant No.B16009)the Fundamental Research Funds for the Central Universities(Grant No.N232410019)。
文摘In the coming decades,the space-based gravitational-wave(GW)detectors such as Taiji,TianQin,and LISA are expected to form a network capable of detecting millihertz GWs emitted by the mergers of massive black hole binaries(MBHBs).In this work,we investigate the potential of GW standard sirens from the Taiji-TianQin-LISA network in constraining cosmological parameters.For the optimistic scenario in which electromagnetic(EM)counterparts can be detected,we predict the number of detectable bright sirens based on three different MBHB population models,i.e.,popⅢ,Q3d,and Q3nod.Our results show that the TaijiTianQin-LISA network alone could achieve a constraint precision of 0.9%for the Hubble constant,meeting the standard of precision cosmology.Moreover,the Taiji-TianQin-LISA network could effectively break the cosmological parameter degeneracies generated by the CMB data,particularly in the dynamical dark energy models.When combined with the CMB data,the joint CMB+Taiji-TianQin-LISA data offerσ(w)=0.036 in the wCDM model,which is close to the latest constraint result obtained from the CMB+SN data.We also consider a conservative scenario in which EM counterparts are not available.Due to the precise sky localizations of MBHBs by the Taiji-TianQin-LISA network,the constraint precision of the Hubble constant is expected to reach 1.2%.In conclusion,the GW standard sirens from the Taiji-TianQin-LISA network will play a critical role in helping solve the Hubble tension and shedding light on the nature of dark energy.
