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In the third-generation (3G) gravitational-wave (GW) detector era, multi-messenger GW observation for binary neutron star (BNS) merger events can exert great impacts on exploring cosmic expansion history. In this work, we comprehensively explore the potential of 3G GW standard siren observations in cosmological parameter estimations by considering 3G GW detectors and the future short γ -ray burst (GRB) detector THESEUS-like telescope joint observations. Based on a 10-year observation of different detection strategies, we predict that the numbers of detectable GW-GRB events are 334–674 with the redshifts z < 3.5 and the inclination angles ι < 15 ∘ . For the cosmological analysis, we consider the Λ CDM, wCDM, w 0 w a CDM, and interacting dark energy (IDE) models. We find that GW can tightly constrain the Hubble constant with precision of 0.345–0.065%, but does not perform well in constraining other cosmological parameters. Fortunately, GW detection could effectively break the cosmological parameter degeneracies generated by the mainstream EM observations, CMB + BAO + SN (CBS). When combining mock GW data with CBS data, CBS + GW can tightly constrain the equation of state of dark energy w with a precision of 1.26%, close to the standard of precision cosmology. Meanwhile, the addition of GW to CBS could improve constraints on cosmological parameters by 34.2–94.9%. In conclusion, GW standard siren observations from 3G GW detectors could play a crucial role in helping solve the Hubble tension and probe the fundamental nature of dark energy. [ABSTRACT FROM AUTHOR]

Gravitational waves (GWs) from compact binary coalescences encode the absolute luminosity distances of GW sources. Once the redshifts of GW sources are known, one can use the distance-redshift relation to constrain cosmological parameters. One way to obtain the redshifts is to localize GW sources by GW observations and then use galaxy catalogs to determine redshifts from a statistical analysis of redshift information of the potential host galaxies, commonly referred to as the dark siren method. The third-generation (3G) GW detectors are planned to work in the 2030s and will observe numerous compact binary coalescences. Using these GW events as dark sirens requires high-quality galaxy catalogs from future sky survey projects. The China Space Station Telescope (CSST) will be launched in 2024 and will observe billions of galaxies within a 17500 deg2 survey area with redshift up to z ∼ 4, providing photometric and spectroscopic galaxy catalogs. In this work, we simulate the CSST galaxy catalogs and the 5-year GW data from the 3G GW detectors and combine them to infer the Hubble constant (H0). Our results show that the measurement precision of H0 could reach the sub-percent level, meeting the standard of precision cosmology. We conclude that the synergy between CSST and the 3G GW detectors is of great significance in measuring the Hubble constant. [ABSTRACT FROM AUTHOR]

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., pop III, Q3d, and Q3nod. Our results show that the Taiji-TianQin-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 offer σ(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. [ABSTRACT FROM AUTHOR]

We present a forecast of the cosmological parameter estimation using fast radio bursts (FRBs) from the upcoming Square Kilometre Array (SKA), focusing on the issues of dark energy, the Hubble constant, and baryon density. We simulate 105 and 106 localized FRBs from a 10-year SKA observation, and find that: (1) using 106 FRB data alone can tightly constrain dark-energy equation of state parameters better than CMB+BAO+SNe, providing an independent cosmological probe to explore dark energy; (2) combining the FRB data with gravitational-wave standard siren data from 10-year observation with the Einstein Telescope, the Hubble constant can be constrained to a sub-percent level, serving as a powerful low-redshift probe; (3) using 106 FRB data can constrain the baryon density Ωbh to a precision of ∼0.1%. Our results indicate that SKA-era FRBs will provide precise cosmological measurements to shed light on both dark energy and the missing baryon problem, and help resolve the Hubble tension. [ABSTRACT FROM AUTHOR]

The 21 cm intensity mapping (IM) technique provides us with an efficient way to observe the cosmic large-scale structure (LSS). From the LSS data, one can use the baryon acoustic oscillation and redshift space distortion to trace the expansion and growth history of the universe, and thus measure the dark energy parameters. In this paper, we make a forecast for cosmological parameter estimation with the synergy of three 21 cm IM experiments. Specifically, we adopt a novel joint survey strategy, FAST (0 < z < 0.35) + SKA1-MID (0.35 < z < 0.8) + HIRAX (0.8 < z < 2.5), to measure dark energy. We simulate the 21 cm IM observations under the assumption of excellent foreground removal. We find that the synergy of three experiments could place quite tight constraints on cosmological parameters. For example, it provides σ(Ωm) = 0.0039 and σ(H0) = 0.27 km s−1 Mpc−1 in the ACDM model. Notably, the synergy could break the cosmological parameter degeneracies when constraining the dynamical dark energy models. Concretely, the joint observation offers σ(w) = 0.019 in the wCDM model, and σ(w0) = 0.085 and σ(wa) = 0.32 in the w0waCDM model. These results are better than or equal to those given by CMB+BAO+SN. In addition, when the foreground removal efficiency is relatively low, the strategy still performs well. Therefore, the 21 cm IM joint survey strategy is promising and worth pursuing. [ABSTRACT FROM AUTHOR]

LISA and Taiji are expected to form a space-based gravitational-wave (GW) detection network in the future. In this work, we make a forecast for the cosmological parameter estimation with the standard siren observation from the LISA-Taiji network. We simulate the standard siren data based on a scenario with configuration angle of 40° between LISA and Taiji. Three models for the population of massive black hole binary (MBHB), i.e., pop III, Q3d, and Q3nod, are considered to predict the events of MBHB mergers. We find that, based on the LISA-Taiji network, the number of electromagnetic (EM) counterparts detected is almost doubled compared with the case of single Taiji mission. Therefore, the LISA-Taiji network's standard siren observation could provide much tighter constraints on cosmological parameters. For example, solely using the standard sirens from the LISA-Taiji network, the constraint precision of H0 could reach 1.3%. Moreover, combined with the CMB data, the GW-EM observation based on the LISA-Taiji network could also tightly constrain the equation of state of dark energy, e.g., the constraint precision of w reaches about 4%, which is comparable with the result of CMB+BAO+SN. It is concluded that the GW standard sirens from the LISA-Taiji network will become a useful cosmological probe in understanding the nature of dark energy in the future. [ABSTRACT FROM AUTHOR]

We investigate the impacts of dark energy on constraining massive (active/sterile) neutrinos in interacting dark energy (IDE) models by using the current observations. We employ two typical IDE models, the interacting w cold dark matter (IwCDM) model and the interacting holographic dark energy (IHDE) model, to make an analysis. To avoid large-scale instability, we use the parameterized post-Friedmann approach to calculate the cosmological perturbations in the IDE models. The cosmological observational data used in this work include the Planck cosmic microwave background (CMB) anisotropies data, the baryon acoustic oscillation data, the type Ia supernovae data, the direct measurement of the Hubble constant, the weak lensing data, the redshift-space distortion data, and the CMB lensing data. We find that the dark energy properties could influence the constraint limits of active neutrino mass and sterile neutrino parameters in the IDE models. We also find that the dark energy properties could influence the constraints on the coupling strength parameter γ and a positive coupling constant, γ > 0, can be detected at the 2.5σ statistical significance for the IHDE+vs model by using the all-data combination. In addition, we also discuss the “Hubble tension” issue in these scenarios. We find that the H0 tension can be effectively relieved by considering massive sterile neutrinos, and in particular in the IHDE+vs model the H0 tension can be reduced to be at the 1.28σ level. [ABSTRACT FROM AUTHOR]

We investigate what role the SKA neutral hydrogen (HI) intensity mapping (IM) and galaxy sky surveys will play in weighing neutrinos in cosmology. We use the simulated data of the baryon acoustic oscillation (BAO) measurements from the HI surveys based on SKA1 (IM) and SKA2 (galaxy) to do the analysis. For the current observations, we use the Planck 2015 cosmic microwave background (CMB) anisotropies observation, the optical BAO measurements, the type Ia supernovae (SN) observation (Pantheon compilation), and the latest H0 measurement. We consider three mass ordering cases for massive neutrinos, i.e., the normal hierarchy (NH), inverted hierarchy (IH), and degenerate hierarchy (DH) cases. It is found that the SKA observation can significantly improve the constraints on Ωm and H0. Compared to the current observation, the SKA1 data can improve the constraints on Ωm by about 33%, and on H0 by about 36%; the SKA2 data can improve the constraints on Ωm by about 58%, and on H0 by about 66%. It is also found that the SKA observation can only slightly improve the constraints on ∑mv. Compared to the current observation, the SKA1 data can improve the constraints on ∑mv by about 4%, 3%, and 10%, for the NH, IH, and DH cases, respectively; the SKA2 data can improve the constraints on ∑mv by about 7%, 7%, and 16%, for the NH, IH, and DH cases, respectively. [ABSTRACT FROM AUTHOR]

In this work, we investigate what role the redshift-drift data of the Square Kilometre Array (SKA) will play in the cosmological parameter estimation in the future. To test the constraint capability of the redshift-drift data of SKA-only, the Λ CDM model is chosen as a reference model. We find that using the SKA1 mock data, the Λ CDM model can be loosely constrained, while the model can be well constrained when the SKA2 mock data are used. When the mock data of SKA are combined with the data of the European Extremely Large Telescope (E-ELT), the constraints can be significantly improved, becoming almost as good as the data combination of the type Ia supernovae observation (SN), the cosmic microwave background observation (CMB), and the baryon acoustic oscillations observation (BAO). Furthermore, we explore the impact of the redshift-drift data of SKA on the basis of SN+CMB+BAO+E-ELT in the Λ CDM model, the wCDM model, the CPL model, and the HDE model. We find that the redshift-drift measurement of SKA could help to significantly improve the constraints on dark energy and could break the degeneracy between the cosmological parameters. Therefore, we conclude that redshift-drift observation of SKA would provide a good improvement in the cosmological parameter estimation in the future and has the enormous potential to be one of the most competitive cosmological probes in constraining dark energy. [ABSTRACT FROM AUTHOR]

We study the holographic dark energy (HDE) model by using the future gravitational wave (GW) standard siren data observed from the Einstein Telescope (ET) in this work. We simulate 1000 GW standard siren data based on a 10-year observation of the ET to make this analysis. We find that all the cosmological parameters in the HDE model can be tremendously improved by including the GW standard siren data in the cosmological fit. The GW data combined with the current cosmic microwave background anisotropies, baryon acoustic oscillations, and type Ia supernovae data will measure the cosmological parameters Ω m , H 0 , and c in the HDE model to be at the accuracies of 1.28%, 0.59%, and 3.69%, respectively. A comparison with the cosmological constant model and the constant-w dark energy model shows that, compared to the standard model, the parameter degeneracies will be broken more thoroughly in a dynamical dark energy model. We find that the GW data alone can provide a fairly good measurement for H 0 , but for other cosmological parameters the GW data alone can only provide rather weak measurements. However, due to the fact that the parameter degeneracies can be broken by the GW data, the standard sirens can play an essential role in improving the parameter estimation. [ABSTRACT FROM AUTHOR]

In this paper, we make a deep analysis for the five typical interacting holographic dark energy models with the interaction terms $$Q=3\beta H_{0}\rho _\mathrm{{de}}$$ , $$Q=3\beta H_{0}\rho _\mathrm{{c}}$$ , $$Q=3\beta H_{0}(\rho _\mathrm{{de}}+\rho _\mathrm{c})$$ , $$Q=3\beta H_{0}\sqrt{\rho _\mathrm{{de}}\rho _\mathrm{c}}$$ , and $$Q=3\beta H_{0}\frac{\rho _\mathrm{{de}}\rho _{c}}{\rho _\mathrm{{de}}+\rho _\mathrm{c}}$$ , respectively. We obtain observational constraints on these models by using the type Ia supernova data (the Joint Light-Curve Analysis sample), the cosmic microwave background data (Planck 2015 distance priors), the baryon acoustic oscillations data, and the direct measurement of the Hubble constant. We find that the values of $$\chi _\mathrm{min}^2$$ for all the five models are almost equal (around 699), indicating that the current observational data equally favor these IHDE models. In addition, a comparison with the cases of an interaction term involving the Hubble parameter H is also made. [ABSTRACT FROM AUTHOR]

We report the result of a search for sterile neutrinos with the latest cosmological observations. Both cases of massless and massive sterile neutrinos are considered in the $$\Lambda $$ CDM cosmology. The cosmological observations used in this work include the Planck 2015 temperature and polarization data, the baryon acoustic oscillation data, the Hubble constant direct measurement data, the Planck Sunyaev-Zeldovich cluster counts data, the Planck lensing data, and the cosmic shear data. We find that the current observational data give a hint of the existence of massless sterile neutrino (as dark radiation) at the 1.44 $$\sigma $$ level, and the consideration of an extra massless sterile neutrino can indeed relieve the tension between observations and improve the cosmological fit. For the case of massive sterile neutrino, the observations give a rather tight upper limit on the mass, which implies that actually a massless sterile neutrino is more favored. Our result is consistent with the recent result of neutrino oscillation experiment done by the Daya Bay and MINOS collaborations, as well as the recent result of cosmic ray experiment done by the IceCube collaboration. [ABSTRACT FROM AUTHOR]

The Sandage-Loeb (SL) test is a promising method for probing dark energy because it measures the redshift drift in the spectra of Lyman- α forest of distant quasars, covering the 'redshift desert' of 2 ≲ z ≲ 5, which is not covered by existing cosmological observations. Therefore, it could provide an important supplement to current cosmological observations. In this paper, we explore the impact of SL test on the precision of cosmological constraints for two typical holographic dark energy models, i.e., the original holographic dark energy (HDE) model and the Ricci holographic dark energy (RDE) model. To avoid data inconsistency, we use the best-fit models based on current combined observational data as the fiducial models to simulate 30 mock SL test data. The results show that SL test can effectively break the existing strong degeneracy between the present-day matter density Ω and the Hubble constant H in other cosmological observations. For the considered two typical dark energy models, not only can a 30-year observation of SL test improve the constraint precision of Ω and h dramatically, but can also enhance the constraint precision of the model parameters c and α significantly. [ABSTRACT FROM AUTHOR]

We explore the impact of the Sandage-Loeb (SL) test on the precision of cosmological constraints for f( T) gravity theories. The SL test is an important supplement to current cosmological observations because it measures the redshift drift in the Lyman-α forest in the spectra of distant quasars, covering the 'redshift desert' of 2 ≤ z ≤ 5. To avoid data inconsistency, we use the best-fit models based on current combined observational data as fiducial models to simulate 30 mock SL test data. We quantify the impact of these SL test data on parameter estimation for f( T) gravity theories. Two typical f( T) models are considered, the power-law model f( T) and the exponential-form model f( T). The results show that the SL test can effectively break the existing strong degeneracy between the present-day matter density Ω and the Hubble constant H in other cosmological observations. For the considered f( T) models, a 30-year observation of the SL test can improve the constraint precision of Ω and H enormously but cannot effectively improve the constraint precision of the model parameters. [ABSTRACT FROM AUTHOR]

Since the B-mode polarization of the cosmic microwave background (CMB) was detected by the BICEP2 experiment and an unexpectedly large tensor-to-scalar ratio, $$r=0.20^{+0.07}_{-0.05}$$ , was found, the base standard cosmology should at least be extended to the 7-parameter $$\Lambda $$ CDM+ $$r$$ model. In this paper, we consider the extensions to this base $$\Lambda $$ CDM+ $$r$$ model by including additional base parameters relevant to neutrinos and/or other neutrino-like relativistic components. Four neutrino cosmological models are considered, i.e., the $$\Lambda $$ CDM+ $$r$$ + $$\sum m_\nu $$ , $$\Lambda $$ CDM+ $$r$$ + $$N_\mathrm{eff}$$ , $$\Lambda $$ CDM+ $$r$$ + $$\sum m_\nu $$ + $$N_\mathrm{eff}$$ , and $$\Lambda $$ CDM+ $$r$$ + $$N_\mathrm{eff}$$ + $$m_{\nu ,\mathrm{sterile}}^\mathrm{eff}$$ models. We combine the current data, including the Planck temperature data, the WMAP 9-year polarization data, the baryon acoustic oscillation data, the Hubble constant direct measurement data, the Planck Sunyaev-Zeldovich cluster counts data, the Planck CMB lensing data, the cosmic shear data, and the BICEP2 polarization data, to constrain these neutrino cosmological models. We focus on the constraints on the parameters $$\sum m_\nu $$ , $$N_\mathrm{eff}$$ , and $$m_{\nu ,\mathrm{sterile}}^\mathrm{eff}$$ . We also discuss whether the tension on $$r$$ between Planck and BICEP2 can be relieved in these neutrino cosmological models. [ABSTRACT FROM AUTHOR]

We apply the statefinder diagnostic to the holographic dark energy models, including the original holographic dark energy (HDE) model, the new holographic dark energy model, the new agegraphic dark energy (NADE) model, and the Ricci dark energy model. In the low-redshift region the holographic dark energy models are degenerate with each other and with the $$\Lambda $$ CDM model in the $$H(z)$$ and $$q(z)$$ evolutions. In particular, the HDE model is highly degenerate with the $$\Lambda $$ CDM model, and in the HDE model the cases with different parameter values are also in strong degeneracy. Since the observational data are mainly within the low-redshift region, it is very important to break this low-redshift degeneracy in the $$H(z)$$ and $$q(z)$$ diagnostics by using some quantities with higher order derivatives of the scale factor. It is shown that the statefinder diagnostic $$r(z)$$ is very useful in breaking the low-redshift degeneracies. By employing the statefinder diagnostic the holographic dark energy models can be differentiated efficiently in the low-redshift region. The degeneracy between the holographic dark energy models and the $$\Lambda $$ CDM model can also be broken by this method. Especially for the HDE model, all the previous strong degeneracies appearing in the $$H(z)$$ and $$q(z)$$ diagnostics are broken effectively. But for the NADE model, the degeneracy between the cases with different parameter values cannot be broken, even though the statefinder diagnostic is used. A direct comparison of the holographic dark energy models in the $$r$$ - $$s$$ plane is also made, in which the separations between the models (including the $$\Lambda $$ CDM model) can be directly measured in the light of the current values $$\{r_0, s_0\}$$ of the models. [ABSTRACT FROM AUTHOR]

By inverting fault slip data, the parameters of 12 tectonic stress tensors in the mine region can be determined. The following characteristics can be obtained for recent tectonic stress fields, which are found deep in the study region. The results show that the recent tectonic stress field mainly presents the characteristics of near NWW-SSE maximum compressional stress and near NE-SW minimum extensional stress, while the stress regimes are mainly of strike slip, part of the reverse-fault type. Recent tectonic stress field in the region is characterized by horizontal components. The maximum principal compression stress direction was from NEE to SEE, the average principal compression stress direction was near NWW-SSE maximum compressional stress and near NE-SW minimum extensional. The recent tectonic stress field of the studied area can be controlled by a large tectonic stress area. [ABSTRACT FROM AUTHOR]

We perform a global fit study on the new agegraphic dark energy (NADE) model in a non-flat universe by using the MCMC method with the full CMB power spectra data from the WMAP 7-yr observations, the SNIa data from Union2.1 sample, BAO data from SDSS DR7 and WiggleZ Dark Energy Survey, and the latest measurements of H from HST. We find that the value of Ω is greater than 0 at least at the 3 σ confidence levels (CLs), which implies that the NADE model distinctly favors an open universe. Besides, our results show that the value of the key parameter of NADE model, $n=2.673^{+0.053+0.127+0.199}_{-0.077-0.151-0.222}$, at the 1-3 σ CLs, where its best-fit value is significantly smaller than those obtained in previous works. We find that the reason leading to such a change comes from the different SNIa samples used. Our further test indicates that there is a distinct tension between the Union2 sample of SNIa and other observations, and the tension will be relieved once the Union2 sample is replaced by the Union2.1 sample. So, the new constraint result of the NADE model obtained in this work is more reasonable than before. [ABSTRACT FROM AUTHOR]

The holographic Λ( t)CDM model in a non-flat universe is studied in this paper. In this model, to keep the form of the stress-energy of the vacuum required by general covariance, the holographic vacuum is enforced to exchange energy with dark matter. It is demonstrated that for the holographic model the best choice for the IR cutoff of the effective quantum field theory is the event horizon size of the universe. We derive the evolution equations of the holographic Λ( t)CDM model in a non-flat universe. We constrain the model by using the current observational data, including the 557 Union2 type Ia supernovae data, the cosmic microwave background anisotropy data from the 7-yr WMAP, and the baryon acoustic oscillation data from the SDSS. Our fit results show that the holographic Λ( t)CDM model tends to favor a spatially closed universe (the best-fit value of Ω is −0.042), and the 95 % confidence level range for the spatial curvature is −0.101< Ω<0.040. We show that the interaction between the holographic vacuum and dark matter induces an energy flow of which the direction is first from vacuum to dark matter and then from dark matter to vacuum. Thus, the holographic Λ( t)CDM model is just a time-varying vacuum energy scenario in which the interaction between vacuum and dark matter changes sign during the expansion of the universe. [ABSTRACT FROM AUTHOR]

The model of holographic dark energy in which dark energy interacts with dark matter is investigated in this paper. In particular, we consider the interacting holographic dark energy model in the context of a perturbed universe, which was never investigated in the literature. To avoid the large-scale instability problem in the interacting dark energy cosmology, we employ the generalized version of the parameterized post-Friedmann approach to treating the dark energy perturbations in the model. We use the current observational data to constrain the model. Since the cosmological perturbations are considered in the model, we can then employ the redshift-space distortions (RSD) measurements to constrain the model, in addition to the use of the measurements of expansion history, which has never been done in the literature. We find that, for both the cases with Q=βHρc and with Q=βH0ρc, the interacting holographic dark energy model is more favored by the current data, compared to the holographic dark energy model without interaction. It is also found that, with the help of the RSD data, a positive coupling β can be detected at the 2.95σ statistical significance for the case of Q=βH0ρc. [ABSTRACT FROM AUTHOR]