arXiv subjects

Tonghua Liu

Publications and source records attributed to Tonghua Liu.

At least 37 records · Page 2Linked to original sources

arXiv2025

CSST Strong Lensing Preparation: Cosmological Constraints Forecast from CSST Galaxy-Scale Strong Lensing

Strong gravitational lensing by galaxies is a powerful tool for studying cosmology and galaxy structure. The China Space Station Telescope (CSST) will revolutionize this field by discovering up to $\sim$100,000 galaxy-scale strong lenses, a huge increase over current samples. To harness the statistical power of this vast dataset, we forecast its cosmological constraining power using the gravitational-dynamical mass combination method. We create a realistic simulated lens sample and test how uncertainties in redshift and velocity dispersion measurements affect results under ideal, optimistic, and pessimistic scenarios. We find that increasing the sample size from 100 to 10,000 systems dramatically improves precision: in the $Λ$CDM model, the uncertainty on the matter density parameter, $Ω_m$, drops from 0.2 to 0.01; in the $w$CDM model, the uncertainty on the dark energy equation of state, $w$, decreases from 0.3 to 0.04. With 10,000 lenses, our constraints on dark energy are twice as tight as those from the latest DESI BAO measurements. We also compare two parameter estimation techniques -- MultiNest sampling and Bayesian Hierarchical Modeling (BHM). While both achieve similar precision, BHM provides more robust estimates of intrinsic lens parameters, whereas MultiNest is about twice as fast. This work establishes an efficient and scalable framework for cosmological analysis with next-generation strong lensing surveys.

astro-ph.CO↗

arXiv2025

Torsion cosmology in the light of DESI, supernovae and CMB observational constraints

In this work, we investigate a torsion-based cosmological model within the Einstei-Cartan framework, constrained by the latest combined datasets including DESI DR2 BAO, PantheonPlus and DESY5 supernovae, and the full Planck 2018 CMB measurements (temperature, polarization, and joint NPIPE PR4 + ACT DR6 lensing). The torsion parameter is constrained to $α= -0.00066 \pm 0.00098$ with the full dataset combination, consistent with zero at less than $1σ$, while yielding a Hubble constant $H_0 = 68.41 \pm 0.32$ km/s/Mpc and matter clustering amplitude $S_8 = 0.812 \pm 0.006$. The model shows notable potential in alleviating cosmological tensions, reducing the $S_8$ discrepancy with KiDS-1000 from $\sim 2.3σ$ in $Λ$CDM to only $0.1σ$. Model comparisons based on the Akaike information criterion show consistent improvements across all datasets, with $Δ{\rm AIC}$ values ranging from $-5.68$ to $-6.62$, indicating a statistically preferred fit for the torsion model. These results suggest that the torsion framework provides a physically well-motivated extension to $Λ$CDM, capable of simultaneously addressing key cosmological tensions while maintaining excellent agreement with diverse observational probes.

astro-ph.CO↗

arXiv2025

Identifying Microlensing by Compact Dark Matter through Diffraction Patterns in Gravitational Waves with Machine Learning

Gravitational wave lensing, particularly microlensing by compact dark matter (DM), offers a unique avenue to probe the nature of dark matter. However, conventional detection methods are often computationally expensive, inefficient, and sensitive to waveform systematics. In this work, we introduce the Wavelet Convolution Detector (WCD), a deep learning framework specifically designed to identify wave-optics diffraction patterns imprinted in gravitationally lensed signals. The WCD integrates multi-scale wavelet analysis within residual convolutional blocks to efficiently extract time-frequency interference structures, and is trained on a realistically generated dataset incorporating compact DM mass functions and astrophysical lensing probabilities. This work is the first machine learning-based approach capable of identifying such wave-optics signatures in lensed gravitational waves. Tested on simulated binary black hole events, the model achieves 92.2\% accuracy (AUC=0.965), with performance rising to AUC$\sim$0.99 at high SNR. Crucially, it maintains high discriminative power across a wide range of lens masses without retraining, demonstrating particular strength in the low-impact-parameter and high-lens-mass regimes where wave-optics effects are most pronounced. Compared to Bayesian inference, the WCD provides orders-of-magnitude faster inference, making it a scalable and efficient tool for discovering compact DM through lensed gravitational waves in the era of third-generation detectors.

astro-ph.IM↗

arXiv2025

Identification of Strongly Lensed Gravitational Wave Events Using Squeeze-and-Excitation Multilayer Perceptron Data-efficient Image Transformer

With the advancement of third-generation gravitational wave detectors, the identification of strongly lensed gravitational wave (GW) events is expected to play an increasingly vital role in cosmology and fundamental physics. However, traditional Bayesian inference methods suffer from combinatorial computational overhead as the number of events grows, making real-time analysis infeasible. To address this, we propose a deep learning model named Squeeze-and-Excitation Multilayer Perceptron Data-efficient Image Transformer (SEMD), based on Vision Transformers, which classifies strongly lensed GW events by modeling morphological similarity between time-frequency spectrogram pairs. By integrating Squeeze-and-Excitation attention mechanisms and multilayer perceptrons , SEMD achieves strong feature extraction and discrimination. Trained and evaluated on simulated datasets using Advanced LIGO and Einstein Telescope noise, the model demonstrates robustness and generalization across different detector sensitivities and physical conditions, highlighting the promise of deep learning for rapid identification of strongly lensed GW signals.

astro-ph.IM↗

arXiv2025

New tests of cosmic distance duality relation with DESI 2024 BAO observations

In this paper, we test the cosmic distance duality relation (CDDR), as required by the Etherington reciprocity theorem, which connects the angular diameter distance and the luminosity distance via the relation $ D_{\rm L}(z) = D_{\rm A}(z)(1+z)^2 $. Our analysis is based on the latest baryon acoustic oscillation (BAO) measurements provided by the Dark Energy Survey (DES), the Baryon Oscillation Spectroscopic Survey (BOSS)/Extended BOSS (eBOSS), and the Dark Energy Spectroscopic Instrument (DESI) surveys. Specifically, an unbiased test of the CDDR is performed through a novel, model-independent method inspired by the two-point diagnostic approach, with DES-SN5YR and Pantheon type Ia supernova (SN Ia) sample reconstructed using the Artificial Neural Network (ANN) technique. This methodology effectively eliminates all nuisance parameters, including the sound horizon scale $ r_{\rm d} $ from BAO and the absolute magnitude $ M_{\rm B} $ from SN Ia. A set of $ N-1 $ independent CDDR ratios $ η_{ij} $ are constructed for statistical analysis. At the current observational level, no significant deviation from the CDDR is observed at low redshifts, whereas we find positive evidence ($>2σ$ C.L.) of deviation from the CDDR at two high redshifts ($z=2.33$ and $z=2.334$). Therefore, our results confirm that the BAO measurement provides a powerful tool to test such fundamental relation in modern cosmology.

astro-ph.CO↗

arXiv2025

Dynamical Dark Energy in the Crosshairs: A Joint Analysis with DESI, Pantheon plus, and TDCOSMO Constraints

In this work, we perform a comprehensive joint analysis of three representative dark energy models - ${\rmΛCDM}$, the Chevallier-Polarski-Linder (CPL) parametrization, and the Generalised Emergent Dark Energy (GEDE) model - using the latest observational datasets: baryon acoustic oscillation (BAO) measurements from DESI Data Releases 1 and 2 (DR1/DR2), the Pantheon Plus sample of Type Ia supernovae (SNe Ia), and time-delay cosmography from TDCOSMO lensing. The CPL model yields a statistically significant improvement over ${\rmΛCDM}$, with $Δχ^2 = -3.6$ for DESI DR2+Pantheon Plus+TDCOSMO, favoring a quintessence-like behavior ($w_0=-0.87^{+0.05 }_{-0.05} $, $w_a=-0.41^{+ 0.28}_{-0.28}$ at 1$σ$ confidence level). The GEDE model also exhibits slightly favoring than ${\rmΛCDM}$ with observations, yielding $Δχ^2 =-2.83$ (DR1) and $Δχ^2 = -3.82$ (DR2). The captured potential dark energy evolution transition parameter $Δ$ in GEDE model is constrained to $-0.52^{+0.22}_{-0.20}$ (DR1) and $-0.50^{+0.18}_{-0.17}$ (DR2), showing a $2.4σ$ and $2.9σ$ deviation from zero respectively. This statistically significant ($>2σ$) non-zero value of $Δ$ provides evidence against a pure cosmological constant scenario. The negative sign indicates quintessence-like behavior ($w > -1$) in the late universe. Notably, the GEDE constraints show a $>3σ$ tension with the $Δ=1$ (Phenomenological Emergent Dark Energy model) predictions. This significant discrepancy implies that while both models belong to the emergent dark energy family, their fundamentally different transition mechanisms lead to distinct cosmological implications. Our results collectively suggest that GEDE provides a phenomenologically viable alternative to $Λ$CDM.

astro-ph.CO↗

arXiv2025

Revisiting the Hubble constant, sound horizon and cosmography from late-time Universe observations

The Hubble tension has become one of the central problems in cosmology. In this work, we determine the Hubble constant $H_0$ and sound horizon $r_d$ by using the combination of Baryon Acoustic Oscillations (BAOs) from DESI surveys, time-delay lensed quasars from H0LiCOW collaborations and the Pantheon supernovae observations. We consider two cosmological approaches, i.e., Taylor series and Padé polynomials, to avoid cosmological dependence. The reason for using this combination of data is that the absolute distance provided by strong gravitational lensing helps anchor the relative distance of BAO, and supernovae provide a robust history of universe evolution. {{Combining the 6 time-delay distance (6$D_{Δt}$) plus 4 angular diameter distance to the deflector (4$D_d$) measurements of time-delay lensed quasars,}} the BAO and the type Ia of supernovae (SNe Ia) datasets, we obtain a model-independent result of $r_d = 138.2_{-3.9}^{+3.3}$ Mpc and $H_0 = 72.9^{+1.8}_{-1.8}$ ${\mathrm{~km~s^{-1}~Mpc^{-1}}}$ for the Taylor series cosmography and $r_d = 137.0_{-3.7}^{+3.2}$ Mpc and $H_0 = 73.1_{-1.7}^{+1.8}$ ${\mathrm{~km~s^{-1}~Mpc^{-1}}}$ for the Padé polynomials cosmography. The determination of $r_d$ and $H_0$ prefers larger $H_0$ and smaller $r_d$ than Planck data under the assumption of flat-$Λ$CDM model. However, the values of $H_0$ are consistent with the $H_0$ determination from SH0ES collaboration.

astro-ph.CO↗

arXiv2025

Advancing Cosmological Parameter Estimation and Hubble Parameter Reconstruction with Long Short-Term Memory and Efficient-Kolmogorov-Arnold Networks

In this work, we propose a novel approach for cosmological parameter estimation and Hubble parameter reconstruction using Long Short-Term Memory (LSTM) networks and Efficient-Kolmogorov-Arnold Networks (Ef-KAN). LSTM networks are employed to extract features from observational data, enabling accurate parameter inference and posterior distribution estimation without relying on solvable likelihood functions. This method achieves performance comparable to traditional Markov Chain Monte Carlo (MCMC) techniques, offering a computationally efficient alternative for high-dimensional parameter spaces. By sampling from the reconstructed data and comparing it with mock data, our designed LSTM constraint procedure demonstrates the superior performance of this method in terms of constraint accuracy, and effectively captures the degeneracies and correlations between the cosmological parameters. Additionally, the Ef-KAN model is introduced to reconstruct the Hubble parameter H(z) from both observational and mock data. Ef-KAN is entirely data-driven approach, free from prior assumptions, and demonstrates superior capability in modeling complex, non-linear data distributions. We validate the Ef-KAN method by reconstructing the Hubble parameter, demonstrating that H(z) can be reconstructed with high accuracy. By combining LSTM and Ef-KAN, we provide a robust framework for cosmological parameter inference and Hubble parameter reconstruction, paving the way for future research in cosmology, especially when dealing with complex datasets and high-dimensional parameter spaces.

astro-ph.CO↗

arXiv2024

Newest measurements of Hubble constant from DESI 2024 BAO observations

In this Letter, we use the latest results from the Dark Energy Spectroscopic Instrument (DESI) survey to measure the Hubble constant. Baryon acoustic oscillation (BAO) observations released by the DESI survey, allow us to determine $H_0$ from the first principles. Our method is purely data-driven and relies on unanchored luminosity distances reconstructed from SN Ia data and $H(z)$ reconstruction from cosmic chronometers. Thus it circumvents calibrations related to the value of the sound horizon size at the baryon drag epoch or intrinsic luminosity of SN Ia. We find $H_0=68.4^{+1.0}_{-0.8}~{\rm km~s^{-1}~Mpc^{-1}}$ at 68% C.L., which provides the Hubble constant at an accuracy of 1.3% with minimal assumptions. Our assessments of this fundamental cosmological quantity using the BAO data spanning the redshift range $z=0.51-2.33$ agree very well with Planck's results and TRGB results within $1σ$. This result is still in a $4.3σ$ tension with the results of the Supernova H0 for the Equation of State (SH0ES).

astro-ph.CO↗

arXiv2024

Determination of cosmic curvature independent of the sound horizon and $H_0$ using BOSS/eBOSS and DESI DR1 BAO observations

We present an improved model-independent method for determining the cosmic curvature using the observations of Baryon Acoustic Oscillations (BAOs) and the Hubble parameter. The purpose of this work is to provide insights into late-universe curvature measurements using available observational data and techniques. Thus, we use two sources of BAO data sets, BOSS/eBOSS and latest DESI DR1, and two reconstruction methods, Gaussian process (GP) and artificial neural network (ANN). It is important to highlight that our method circumvents influence induced by the sound horizon in BAO observations and the Hubble constant. Combining BAO data from BOSS/eBOSS plus DESI DR1, we find that the constraint on the cosmic curvature results in $Ω_K=-0.040^{+0.142}_{-0.145}$ with an observational uncertainty of $1σ$ in the framework of GP method. This result changes to $Ω_K=-0.010^{+0.405}_{-0.424}$ when the ANN method is applied. Further comparative analysis of samples from two BAO data sources, we find that there is almost no difference between the two samples. Although the curvature values obtained from the data samples using DESI DR1 are on the slightly positive and the samples using BOSS/eBOSS are on the slightly negative, these results both report that our universe has a flat spatial curvature within uncertainties, and the precision of constraining the curvature with two BAO samples is almost equal.

astro-ph.CO↗

arXiv2024

A model-independent determination of the sound horizon using recent BAO measurements and strong lensing systems

We propose an improved method to determine the sound horizon in a cosmological model-independent way by using the latest observations of BAO measurements from DES, BOSS/eBOSS, and DESI surveys and gravitationally time-delay lensed quasars from H0LiCOW collaboration. Combining the 6$D_{Δt}$ plus 4$D_{d}$ measurements and the reconstructed BAO datasets, we obtain a model-independent result of $r_d=139.7^{+5.2}_{-4.5}$ Mpc, with the precision at the $\sim3.7\%$ level, which is in agreement with the result of Planck 2018 within $\sim1.7σ$ uncertainty. Our method is independent of cosmological parameters such as the Hubble constant, dark energy, (and, more importantly, does not involve the cosmic curvature when using the $D_d$ measurements of the lenses, and also avoids the obstacle of mass-sheet degeneracy in gravitational lensing). Meanwhile, it does not need to consider the Eddington relation with concerning the transformation of distance. Since only two types of data are considered, the contribution of each can be clearly understood. Our results also highlight the Hubble tension and may give us a better understanding of the discordance between the datasets or reveal new physics beyond the standard model.

astro-ph.CO↗

arXiv2024

Model independent calibration for sound horizon combining observations of supernovae and transversal BAO measurements

The sound horizon is a key theoretical prediction of the cosmological model that depends on the speed of sound and the rate of expansion in the early universe, before matter and radiation decoupled. The standard ruler for low redshift calibration of baryon acoustic oscillations (BAOs) is a direct measurement that would exist even if the standard cosmological model and the standard assumptions of early physics did not. We propose a new model-independent method to calibrate sound horizon $r^h_s$ (relative standard ruler) by using the latest observations of SNe Ia and transversal BAO measurements. The final result reports $r_s^{h}=107.10^{+1.36}_{-1.32}$ $Mpc/h$ in the framework of the Pantheon dataset. This result changes to $r_s^{h}=105.63^{+1.33}_{-1.31}$ $Mpc/h$ when uses Pantheon+ dataset. Note that even without an estimate of dimensionless Hubble constant $h$, the combination of BAO and SNe Ia datasets already constrain the low-redshift standard ruler scale $r_s^{h}$ at the $\sim1.26\%$ level. More importantly, it is interesting to find that most of the $r_s^{h}$ obtained at high redshifts have a larger value (9 out of 15 results are larger than the result obtained by combining all BAOs). This finding may give us a better understanding of the discordance between the data sets or Hubble tension or reveal new physics beyond the standard model.

astro-ph.CO↗

arXiv2024

Optimal quantum strategy for locating Unruh channels

From the perspective of quantum information theory, the effect of Unruh radiation on a two-level accelerated detector can be modeled as a quantum channel. In this work, we employ the tools of channel-position finding to locate Unruh channels. The signal-idler and idler-free protocols are explored to determine the position of the target Unruh channel within a sequence of background channels. We derive the fidelity-based bounds for the ultimate error probability of each strategy and obtain the conditions where the signal-idler protocol is superior to the protocol involving idler-free states. It is found that the lower bound of the error probability for the signal-idler scheme exhibits clear advantages in all cases, while the idler-free scheme can only be implemented when the temperature of the two channels is very close and the number of initial states is insufficient. Interestingly, it is shown that the optimal detection protocol relies on the residual correlations shared between the emitted probe state and the retained idler modes.

gr-qc↗

arXiv2024

Does anti-Unruh effect assist quantum entanglement and coherence?

In this paper, we use the concepts of quantum entanglement and coherence to analyze the Unruh and anti-Unruh effects based on the model of Unruh-DeWitt detector. For the first time, we find that (i) the Unruh effect reduces quantum entanglement but enhances quantum coherence; (ii) the anti-Unruh effect enhances quantum entanglement but reduces quantum coherence. This surprising result refutes the notion that the Unruh effect can only destroy quantum entanglement and coherence simultaneously, and that the anti-Unruh can only protect quantum resources. Consequently, it opens up a new source for discovering experimental evidence supporting the existence of the Unruh and anti-Unruh effects.

gr-qc↗

arXiv2024

Constraining on the non-standard cosmological models combining the observations of high-redshift quasars and BAO

In this work, we studied four types of cosmological models with different mechanisms driving the accelerated expansion of the universe, include Braneworld models, Chaplygin Gas models, Emergent Dark Energy models, and cosmological torsion models. Considering that the dynamics of these models at low redshifts are very similar and difficult to distinguish, we used the latest and largest UV and X-ray measurements of quasars (QSOs) observations covering the range of redshift $0.009<z<7.5$. However, the high intrinsic dispersion of this sample and the degeneracy between cosmological model parameters, we added 2D-BAO and 3D-BAO datasets to help us constrain the parameters of these cosmological models. Our results suggest that standard cold dark matter scenario may not be the best cosmological model preferred by the high-redshift observations. The Generalized Chaplygin Gas (GCG) and cosmological constant plus torsion (named Case II) models perform best by Akaike Information Criterion (AIC), but the $Λ$CDM is the best cosmological model preferred by Bayesian Information Criterion (BIC). Our work also supports that the Phenomenologically Emergent Dark Energy and cosmological torsion models may alleviate the Hubble tension, the reported value of the Hubble constant obtained from QSO+BAO datasets combination lies between Planck 2018 observations and local measurements from the SH0ES collaboration, while other cosmological models all support that the Hubble constant tends to be closer to recent Planck 2018 results, but these model are penalized by information criterion.

astro-ph.CO↗

arXiv2024

Model-independent way to determine the Hubble constant and the curvature from phase shift of gravitational waves with DECIGO

In this Letter, we propose a model-independent method to determine the Hubble constant and curvature simultaneously taking advantage of the possibilities of future space-borne gravitational wave (GW) detector DECIGO in combination with the radio quasars as standard rulers. Similarly to the redshift drift in the electromagnetic domain, accelerating expansion of the Universe causes a characteristic phase correction to the gravitational waveform detectable by DECIGO. Hence, one would be able to extract the Hubble parameter $H(z)$. This could be used to recover distance-redshift relation supported by the data not relying on any specific cosmological model. Assuming the FLRW metric, and using intermediate luminosity radio quasars as standard rulers one achieves an interesting opportunity to directly assess $H_0$ and $Ω_k$ parameters. To test this method we simulated a set of acceleration parameters achievable by future DECIGO. Based on the existing sample of 120 intermediate-luminosity radio-quasars calibrated as standard rulers, we simulated much bigger samples of such standard rulers possible to obtain with VLBI. In the case of $(N=100)$ of radio quasars, which is the size of currently available sample, the precision of cosmological parameters determined would be $σ_{H_0}=2.74$ ${\mathrm{~km~s^{-1}~Mpc^{-1}}}$ and $σ_{Ω_k}=0.175$. In the optimistic scenario $(N = 1000)$ achievable by VLBI, the precision of $H_{0}$ would be improved to $1\%$, which is comparable to the result of $σ_{H_0} =0.54$ ${\mathrm{~km~s^{-1}~Mpc^{-1}}}$ from \emph{Planck} 2018 TT, TE, EE+lowE+lensing data, and the precision of $Ω_k$ would be 0.050. Our results demonstrate that such combined analysis, possible in the future, could be helpful to solve the current cosmological issues concerning the Hubble tension and cosmic curvature tension.

astro-ph.CO↗

arXiv2024

A robust test of general relativity at the galactic scales by combining strong lensing systems and gravitational wave standard sirens

The measurement of the parametrized post-Newtonian parameter $γ_{\rm{PPN}}$ is a robust test of general relativity (GR). In some modified theories of gravity, $γ_{\rm{PPN}}$ may evolve with the redshift and deviate from one at high redshifts. This means that precise constraints on $γ_{\rm{PPN}}$ acquired in the solar system experiments could not be sufficient to test such theories and it is necessary to constrain $γ_{\rm{PPN}}$with high precision at high redshifts. However, in many approaches aimed at extragalactic tests of GR, the results might be biased due to entanglement of various factors, such as cosmic curvature, cosmic opacity, and the Hubble constant. Strong lensing systems naturally provide a laboratory to test $γ_{\rm{PPN}}$ at galactic scales and high redshifts, but there is degeneracy between measured strength of gravity and cosmic distances in the lensing system. Gravitational waves (GWs) from binary neutron star mergers (standard sirens) provide a direct way to break this degeneracy by providing self-calibrated measurements of the luminosity distance. {We investigate the possibility of estimating $γ_{\rm{PPN}}$ by combining well measured strongly lensed systems with GW signals from coalescing neutron stars. Such combination provides a cosmological-model independent, relatively pure and unbiased method for the inference of $γ_{\rm{PPN}}$ parameter, avoiding the influence of the above factors and the mass-sheet degeneracy in the lens.} Based on the simulated future 55 lensed quasar systems we demonstrated that the precision of $γ_{\rm{PPN}}$ parameter obtained by our method could be of order of $\sim 10^{-2}$. One may reasonably expect that our approach will play an increasingly important role in precise testing the validity of general relativity at galactic scales and high redshifts.

gr-qc↗

arXiv2024

Sharing Energy in Wide Area: A Two-Layer Energy Sharing Scheme for Massive Prosumers

The popularization of distributed energy resources transforms end-users from consumers into prosumers. Inspired by the sharing economy principle, energy sharing markets for prosumers are proposed to facilitate the utilization of renewable energy. This paper proposes a novel two-layer energy sharing market for massive prosumers, which can promote social efficiency by wider-area sharing. In this market, there is an upper-level wide-area market (WAM) in the distribution system and numerous lower-level local-area markets (LAMs) in communities. Prosumers in the same community share energy with each other in the LAM, which can be uncleared. The energy surplus and shortage of LAMs are cleared in the WAM. Thanks to the wide-area two-layer structure, the market outcome is near-social-optimal in large-scale systems. However, the proposed market forms a complex mathematical program with equilibrium constraints (MPEC). To solve the problem, we propose an efficient and hierarchically distributed bidding algorithm. The proposed two-layer market and bidding algorithm are verified on the IEEE 123-bus system with 11250 prosumers, which demonstrates the practicality and efficiency for large-scale markets.

cs.GT↗