arXiv subjects

Minghui Du

Publications and source records attributed to Minghui Du.

45 records · Page 3Linked to original sources

arXiv2023

Probing Supermassive Black Hole Binaries with Orbital Resonances of Laser-Ranged Satellite

Coalescing supermassive black hole binaries (SMBHBs) are the primary source candidates for low frequency gravitational wave (GW) detections, which could bring us deep insights into galaxy evolutions over cosmic time and violent processes of spacetime dynamics. Promising candidates had been found based on optical and X-ray observations, which claims for new and ready-to-use GW detection approaches before the operations of space-borne antennas. We show that, satellite laser ranging (SLR) missions could serve as probes of coalescing SMBHBs through the GW-induced resonant effects. Lasting and characteristic imprints caused by such resonances in the residual distances or accelerations from SLR measurements are studied, and the detection SNR is analyzed with both the current and future improved ranging precisions. Within redshift $z \sim 1$, the threshold SNR=5 requires 1-2 years of accumulated data for the current precision and months of data for improved precision, which are workable for the data processing of SLR missions. Meanwhile, joint detections with multiple SLR missions could further improve the total SNR and the confidence level. Such a detection scheme could fulfill the requirement of a tentative SMBHB probe during the preparing stage of LISA and Taiji, and it requires no further investment to any new and advanced facilities. It is also worthwhile to look back and re-process the archived data from the past decades, in where resonant signals from SMBHBs might be hidden.

gr-qc↗

arXiv2021

Attention based Broadly Self-guided Network for Low light Image Enhancement

During the past years,deep convolutional neural networks have achieved impressive success in low-light Image Enhancement.Existing deep learning methods mostly enhance the ability of feature extraction by stacking network structures and deepening the depth of the network.which causes more runtime cost on single image.In order to reduce inference time while fully extracting local features and global features.Inspired by SGN,we propose a Attention based Broadly self-guided network (ABSGN) for real world low-light image Enhancement.such a broadly strategy is able to handle the noise at different exposures.The proposed network is validated by many mainstream benchmark.Additional experimental results show that the proposed network outperforms most of state-of-the-art low-light image Enhancement solutions.

eess.IV↗

arXiv2021

How will our knowledge of short gamma-ray bursts affect the distance measurement of binary neutron stars?

GWs from BNS associated with SGRBs have drawn considerable attention due to their prospect in cosmology. For such events, the sky locations of sources can be pinpointed with techniques such as identifying the host galaxies. However, the cosmological applications of these events still suffer from the problem of degeneracy between luminosity distance and inclination angle. To address this issue, a technique was proposed in previous study, i.e., using the property of SGRBs. Based on the observations, we assume that the cosine of inclination follows a Gaussian distribution, which may act as a prior in the Bayes analysis to break the degeneracy. This paper investigates the effects of different Gaussian priors and detector configurations on distance measurement and cosmological research. We first derive a simplified Fisher information matrix for demonstration, and then conduct quantitative analyses via simulation. By varying the number of third-generation detectors and the scale of prior, we generate four catalogs of 1000 events. It is shown that, in the same detecting period, a network of detectors can recognize more and farther events than a single detector. Besides, adopting tighter prior and employing multiple detectors both decrease the error of luminosity distance. Also considered is the performance of a widely adopted formula in the error budget, which turns out to be a conservative choice in each case. As for cosmological applications, for LCDM model, 500, 200, 600, and 300 events are required for the four configurations to achieve 1% H_0 accuracy. With all 1000 events in each catalog, H_0 and Omega_m can be constrained to 0.66%, 0.37%, 0.76%, 0.49%, and 0.010, 0.006, 0.013, 0.010, respectively. The results of the Gaussian process also show that the GW standard siren can serve as a probe of high-redshift universe.

astro-ph.CO↗

arXiv2021

Testing the effect of $H_0$ on $fσ_8$ tension using a Gaussian Process method

Using the $fσ_8(z)$ redshift space distortion (RSD) data, the $σ_8^0-Ω_m^0$ tension is studied utilizing a parameterization of growth rate $f(z) = Ω_m(z)^γ$. Here, $f(z)$ is derived from the expansion history $H(z)$ which is reconstructed from the observational Hubble data applying the Gaussian Process method. It is found that different priors of $H_0$ have great influences on the evolution curve of $H(z)$ and the constraint of $σ_8^0-Ω_m^0$. When using a larger $H_0$ prior, the low redshifts $H(z)$ deviate significantly from that of the $Λ$CDM model, which indicates that a dark energy model different from the cosmological constant can help to relax the $H_0$ tension problem. The tension between our best-fit values of $σ_8^0-Ω_m^0$ and that of the \textit{Planck} 2018 $Λ$CDM (PLA) will disappear (less than $1σ$) when taking a prior for $H_0$ obtained from PLA. Moreover, the tension exceeds $2σ$ level when applying the prior $H_0 = 73.52 \pm 1.62$ km/s/Mpc resulted from the Hubble Space Telescope photometry. By comparing the $S_8 -Ω_m^0$ planes of our method with the results from KV450+DES-Y1, we find that using our method and applying the RSD data may be helpful to break the parameter degeneracies.

astro-ph.CO↗

arXiv2020

Forecast constraints on Anisotropic Stress in Dark Energy using gravitational-waves

It is always interesting to investigate how well can a future experiment perform with respect to others (present or future ones). Cosmology is really an exciting field where a lot of puzzles are still unknown. In this article we consider a generalized dark energy (DE) scenario where anisotropic stress is present. We constrain this generalized cosmic scenario with an aim to investigate how gravitational waves standard sirens (GWSS) may constrain the anisotropic stress, which according to the standard cosmological probes, remains unconstrained. In order to do this, we generate the luminosity distance measurements from $\mathcal{O} (10^3)$ mock GW events which match the expected sensitivity of the Einstein Telescope. Our analyses report that, first of all, GWSS can give better constraints on various cosmological parameters compared to the usual cosmological probes, but the viscous sound speed appearing due to the dark energy anisotropic stress, is totally unconstrained even after the inclusion of GWSS.

astro-ph.CO↗

arXiv2019

General Cosmography Model with Spatial Curvature

The cosmographic approach is adopted to determine the spatial curvature (i.e., $Ω_K$) combining the latest released cosmic chronometers data (CC), the Pantheon sample of type Ia supernovae observations, and the baryon acoustic oscillation measurements. We use the expanded transverse comoving distance $D_M(z)$ as a basic function for deriving $H(z)$ and the other cosmic distances. In this scenario, $Ω_K$ can be constrained only by CC data. To overcome the convergence issues at high-redshift domains, two methods are applied: the Padé approximants and the Taylor series in terms of the new redshift $y=z/(1+z)$. Adopting the Bayesian evidence, we find that there is positive evidence for the Padé approximant up to order ($2,2$) and weak evidence for the Taylor series up to 3-rd order against $Λ\text{CDM}+Ω_K$ model. The constraint results show that a closed universe is preferred by the present observations under all the approximants used in this study. And the tension level of the Hubble constant $H_0$ is less than $2σ$ significance between different approximants and the local distance ladder determination. For each assumed approximant, $H_0$ is anti-correlated with $Ω_K$ and the sound horizon at the end of the radiation drag epoch, which indicates that the $H_0$ tension problem can be slightly relaxed by introducing $Ω_K$ or any new physics which can reduce the sound horizon in the early universe.

astro-ph.CO↗

arXiv2019

Future Constraints on Dynamical Dark-Energy using Gravitational-Wave Standard Sirens

The detection of gravitational waves (GW) by the LIGO and Virgo collaborations offers a whole new range of possible tests and opens up a new window which may shed light on the nature of dark energy and dark matter. In the present work we investigate how future gravitational waves data could help to constrain different dynamical dark energy models. In particular, we perform cosmological forecastings of a class of well known and most used dynamical dark energy models using the third-generation gravitational wave detector, the Einstein Telescope. We have considered 1000 simulated GW events in order to constrain the parameter space of the dynamical dark energy models. Our analyses show that the inclusion of the GW data from the Einstein Telescope, significantly improves the parameter space of the dynamical dark energy models compared to their constraints extracted from the standard cosmological probes, namely, the cosmic microwave observations, baryon acoustic oscillations distance measurements, Supernove type Ia, and the Hubble parameter measurements.

astro-ph.CO↗

arXiv2019

Detecting the neutrino mass and mass hierarchy from global data

In this paper, we have constrained the neutrino mass and mass hierarchy in the $Λ$CDM cosmology with the neutrino mass hierarchy parameter $Δ$, which represents different mass orderings, by using the {\it Planck} 2015 + BAO + SN + $H_{0}$ data set, together with the neutrino oscillation and neutrinoless double beta decay data. We find that the mass of the lightest neutrinos and the total neutrino mass are no more than $0.035$eV and $0.133$ eV at $95\%$ confidence level, respectively. Comparing the result of our joint analysis with that obtained using cosmological data alone, we find that, by adding the neutrino oscillation and neutrinoless double beta decay data, the tendency for normal hierarchy has increased a lot. By means of importance sampling, three other priors are taken into account, i.e., the flat logarithmic prior on the absolute value of the neutrino hierarchy parameter $Δ$, the flat linear prior on the total neutrino mass $Σm_ν$, and the flat logarithmic prior on $Σm_ν$. We find that the preference for the normal hierarchy is in agreement whatever what kinds of priors we choose. Finally, we make a Bayesian model analysis about four priors and we find that flat-linear and the flat logarithmic priors on $Σm_ν$ are the most favored priors.

astro-ph.CO↗

arXiv2018

Probing the Neutrino Mass Hierarchy beyond $Λ$CDM Model

Taking the neutrino oscillation data into consideration, a dimensionless parameter $Δ= (m_3-m_1)/(m_3+m_1)$ is adopted to parameterize the three neutrino mass eigenstates and the normal (positive $Δ$) or inverted (negative $Δ$) mass hierarchies in three typical cosmological models. Using the currently available cosmic observational data, several Markov Chain Monte Carlo chains are obtained with uniform priors on the free parameters at first. Applying importance sampling the results are compared with three new priors, i.e., logarithmic prior on $|Δ|$, linear and logarithmic priors on $Σm_ν$. It turns out that the three new priors increase the upper limits of neutrino mass, but do not change the tendency towards different model's preference for different hierarchies, i.e., the normal hierarchy tends to be favored by $Λ$CDM and $w$CDM, which, however, disappears in the $w_0 w_a$CDM model. In addition, the almost symmetrical contours in the $w-Δ$, $w_0-Δ$, $w_a-Δ$ planes indicate that the normal and inverted hierarchy have strong degeneracy. Finally, we perform a Bayesian model comparison analysis, finding that flat linear prior on $Δ$ and $w_0 w_a$CDM are the most preferred prior and model, respectively.

astro-ph.CO↗