arXiv subjects

Deng Wang

Publications and source records attributed to Deng Wang.

At least 37 records · Page 2Linked to original sources

arXiv2023

Pantheon+ tomography and Hubble tension

The recently released Type Ia supernovae (SNe Ia) sample, Pantheon+, is an updated version of Pantheon and has very important cosmological implications. To explore the origin of the enhanced constraining power and internal correlations of datasets in different redshifts, we perform a comprehensively tomographic analysis of the Pantheon+ sample without and with the Cepheid host distance calibration, respectively. Specifically, we take two binning methods to analyze the Pantheon+ sample, i.e., equal redshift interval and equal supernovae number for each bin. For the case of equal redshift interval, after dividing the sample to 10 bins, the first bin in the redshift range $z\in[0.00122, \, 0.227235]$ dominates the constraining power of the whole sample. For the case of equal supernovae number, the first three low redshift bins prefer a large matter fraction $Ω_m$ and only the sixth bin gives a relatively low cosmic expansion rate $H_0$. For both binning methods, we find no obvious evidence of evolution of $H_0$ and $Ω_m$ at the $2\,σ$ confidence level. The inclusion of the SH0ES calibration can significantly compress the parameter space of background dynamics of the universe in each bin. When not considering the calibration, combining the Pantheon+ sample with cosmic microwave background, baryon acoustic oscillations, cosmic chronometers, galaxy clustering and weak lensing data, we give the strongest $1\,σ$ constraint $H_0=67.88\pm0.42$ km s$^{-1}$ Mpc$^{-1}$. However, the addition of the calibration leads to a global shift of the parameter space from the combined constraint and $H_0=68.66\pm0.42$ km s$^{-1}$ Mpc$^{-1}$, which is inconsistent with the Planck-2018 result at about $2\,σ$ confidence level.

astro-ph.CO↗

arXiv2023

Model-independent traversable wormholes from baryon acoustic oscillations

In this paper, we investigate the model-independent traversable wormholes from baryon acoustic oscillations. Firstly, we place the statistical constraints on the average dark energy equation of state $ω_{av}$ by only using BAO data. Subsequently, two specific wormhole solutions are obtained, i.e, the cases of the constant redshift function and a special choice for the shape function. For the first case, we analyze the traversabilities of the wormhole configuration, and for the second case, we find that one can construct theoretically a traversable wormhole with infinitesimal amounts of average null energy condition violating phantom fluid. Furthermore, we perform the stability analysis for the first case, and find that the stable equilibrium configurations may increase for increasing values of the throat radius of the wormhole in the cases of a positive and a negative surface energy density. It is worth noting that the obtained wormhole solutions are static and spherically symmetrical metric, and that we assume $ω_{av}$ to be a constant between different redshifts when placing constraints, hence, these wormhole solutions can be interpreted as stable and static phantom wormholes configurations at some certain redshift which lies in the range [0.32, 2.34].

gr-qc↗

arXiv2023

Testing the first law of black hole mechanics with GW150914

Whether the first law of black hole mechanics is correct is an important question in black holes physics. Subjected to current limited gravitational wave events, we propose its weaker version that permits a relatively large perturbation to a black hole system and implement a simple test with the first event GW150914. Confronting the strain data with the theory, we obtain the constraint on the deviation parameter $α=0.07\pm0.11$, which indicates that this weaker version is valid at the 68\% confidence level. This result implies that the first law of black hole mechanics may be correct.

gr-qc↗

arXiv2023

Constraining Cosmological Phase Transitions with Chinese Pulsar Timing Array Data Release 1

The Chinese Pulsar Timing Array (CPTA) collaboration has recently reported the observational evidence of a stochastic gravitational wave background. In light of the latest CPTA observation, we aim at exploring the ability of CPTA in probing new physics. Specifically, we constrain the first-order cosmological phase transitions with CPTA data, and find that the constraining result is slightly tighter than that of NANOGrav's 12.5-yr data but weaker than NANOGrav's 15-yr data. Considering the possible complexity of gravitational wave sources, we give the constraint on a mixed scenario of cosmological phase transitions and astrophysical supermassive binary black holes. Our analysis suggests that CPTA has a great potential to probe fundamental physics in the near future.

astro-ph.CO↗

arXiv2023

JWST high redshift galaxy observations have a strong tension with Planck CMB measurements

JWST high redshift galaxy observations predict a higher star formation efficiency than the standard cosmology does, which poses a new tension to $Λ$CDM. We find that the situation is worse than expected. The true situation is that the Planck CMB measurement has a strong tension with JWST high redshift galaxy observations. Specifically, we make a trial to alleviate this tension by considering alternative cosmological models including dark matter-baryon interaction, $f(R)$ gravity and dynamical dark energy. Within current cosmological constraints from Planck-2018 CMB data, we find that these models all fail to explain such a large tension. A possible scenario to escape from cosmological constraints is the extended Press-Schechter formalism, where we consider the local environmental effect on the early formation of massive galaxies. Interestingly, we find that an appropriate value of nonlinear environmental overdensity of a high redshift halo can well explain this tension.

astro-ph.CO↗

arXiv2022

Pantheon+ constraints on dark energy and modified gravity: An evidence of dynamical dark energy

We use the latest Type Ia supernovae sample Pantheon+ to explore new physics on cosmic scales. Specifically, in light of this new sample, we constrain the interacting dark energy and Hu-Sawicki $f(R)$ gravity models and employ the model-independent Gaussian processes to investigate whether there is an evidence of dark energy evolution. We find that Pantheon+ alone just gives weak constraints. However, a data combination of Pantheon+ with cosmic microwave background, baryon acoustic oscillations and cosmic chronometers gives a strong constraint on the modified matter expansion rate $ε=0.048\pm0.026$, which indicates that the momentum may transfer from dark energy to dark matter in the dark sector of the universe at the $1.85\,σ$ confidence level. In the meantime, we obtain a very tight constraint on the deviation from general relativity $\log_{10} f_{R0}< -6.32$ at the $2\,σ$ confidence level. Interestingly, when combining Pantheon+ with cosmic chronometers and cosmic microwave background data, we find a quintessence-like dark energy signal beyond the $2\,σ$ confidence level in the redshift range $z\in[0.70,1.05]$. This implies the nature of dark energy may actually be dynamical.

astro-ph.CO↗

arXiv2022

Dynamical dark energy can explain the anomalous matter density fluctuation at $z\sim4$

Recently, under the standard cosmological model, a new growth tension between the Planck-2018 observation and the combined observation of cosmic microwave background lensing and galaxy clustering at $z\sim4$ emerges over the $1\,σ$ confidence level. We demonstrate that dynamical dark energy can well solve this tension within the $1\,σ$ confidence level. This implies that the new measurement of large scale structure at high redshift may give the evidence of evolution of dark energy over time.

astro-ph.CO↗

arXiv2022

Testing the Hubble law with Pantheon+

The Hubble law (HL) governs the low-redshift (low-z) evolution of the distance of an object. However, there is a lack of an investigation of its validity and effective radius for a long time, since the low-z background data with a high precision is scarce. The latest Type Ia supernovae sample Pantheon+ having a significant increase of low-z data provides an excellent opportunity to test the HL. We propose a generalized HL and implement the first modern test of the HL with Pantheon+. We obtain the constraint on the deviation parameter $α=1.00118\pm0.00044$, confirm the validity of linear HL with a $0.04\%$ precision and give the transition redshift $z_t=0.03$ and luminosity distance $D_{L,t}=123.13\pm1.75$ Mpc, which means that HL holds when $z<0.03$ and breaks down at a distance of $D_L>123.13$ Mpc. Comparing the ability of Type Ia supernovae and HII galaxies in testing the HL, we stress the uniqueness and strong power of Type Ia supernovae in probing the low-z physics.

astro-ph.CO↗

arXiv2022

Testing the black hole area law with Event Horizon Telescope

Hawking's black hole area theorem can be tested by monitoring the evolution of a single black hole over time. Using current imaging observations of two supermassive black holes M87* and Sgr A* from the Event Horizon Telescope (EHT), we find their horizon area variation fractions are consistent with the prediction of the black hole area law at the $1\,σ$ confidence level. We point out that whether the black hole area law is valid or not could be determined by future high precision EHT observations of Sgr A*.

gr-qc↗

arXiv2022

Black Hole Olympics: Metric Selection from the Event Horizon Telescope and LIGO-VIRGO Observations

We propose a new paradigm in the field of black hole physics, i.e., with more and more high precision observations, one must make a metric selection to determine which black hole is observationally preferred. In light of the shadow imaging data from the Event Horizon Telescope and gravitational wave measurements from the LIGO-VIRGO collaboration, we attempt to address this issue. Although not finding any obvious preference for a specific black hole metric based on current data, as a presentation of this new research paradigm, we rank these black hole metrics using the Bayesian information criterion. We find that Kerr and Reissner-Nordström tie the first place in the black hole Olympics Games. Interestingly, we give the $2\,σ$ upper bound of the average electronic charge $Q<2.82\times10^{18}$ C for the Reissner-Nordström spacetime, and the $2\,σ$ constraint on the average spin parameter $a=-0.02^{+4.07}_{-4.04}$ m for the Kerr spacetime, which is consistent with the prediction of zero rotation for a distant observer. Future multi-messenger and multi-wavelength observations will enhance the application of this new paradigm into tests of gravitational theories and black holes.

gr-qc↗

arXiv2022

Shaving the Hair of Black Hole with Sagittarius A$^*$ from Event Horizon Telescope

Recently, the Event Horizon Telescope collaboration has reported the first image of the supermassive black hole Sagittarius in the Galactic Center. We attempt to test the validity of the no-hair theorem of black holes using this new shadow observation. Considering the Einstein-Maxwell-klein-Gordon theory with a minimally-coupled scalar field, we find that our numerical result is consistent with the prediction of the no-hair theorem. However, we can not rule out the possibility that black holes with scalar hair may exist in some special cases.

gr-qc↗

arXiv2022

Novel Physics with International Pulsar Timing Array: Axionlike Particles, Domain Walls and Cosmic Strings

After NANOGrav, the IPTA collaboration also reports a strong evidence of a stochastic gravitation wave background. This hint has very important implications for fundamental physics. With the recent IPTA data release two, we attempt to search signals of light new physics. and give new constraints on the audible axion, domain walls and cosmic strings models. We find that the best fit point corresponding to a decay constant $F\approx5\times10^{17}$ GeV and an axion mass $m_a\approx2\times10^{-13}$ eV from NANOGrav data is ruled out by IPTA at beyond $2σ$ confidence level. Fixing the coupling strength $λ=1$, we obtain a $2σ$ lower bound on the breaking scale of $Z_2$ symmetry $η>135$ TeV. Interestingly, we give a very strong restriction on the cosmic-string tension $\mathrm{log}_{10}\,Gμ=-8.93_{-0.06}^{+0.12}$ at $1σ$ confidence level. Employing the rule of Bayes factor, we find that IPTA data has a moderate, strong and inconclusive preference of an uncorrelated common power-law (CPL) model over audible axion, domain walls and cosmic strings, respectively. This means that it is hard to distinguish CPL from cosmic strings with current observations and more pulsar timing data with high precision are required to give new clues of underlying physics.

astro-ph.CO↗

arXiv2022

Squeezing Cosmological Phase Transitions with International Pulsar Timing Array

A first-order MeV-scale cosmological phase transition (PT) can generate a peak in the power spectrum of stochastic gravitational wave background around nanohertz frequencies. With the recent International Pulsar Timing Array data release two covering nanohertz frequencies, we search for such a phase transition signal. For the standard 4-parameter PT model, we obtain the PT temperature $T_\star\in$ [66 MeV, 30 GeV], which indicates that dark or QCD phase transitions occurring below 66 MeV have been ruled out at $2\,σ$ confidence level. This constraint is much tighter than $T_\star\sim$ [1 MeV, 100 GeV] from NANOGrav. We also give much tighter $2\,σ$ bounds on the PT duration $H_\star/β>0.1$, strength $α_\star>0.39$ and friction $η<2.74$ than NANOGrav. For the first time, we find a positive correlation between $\mathrm{log}_{10}T_\star$ and $\mathrm{log}_{10}H_\star/β$ implying that PT temperature increases with increasing bubble nucleation rate. To avoid large theoretical uncertainties in calculating PT spectrum, we make bubble spectral shape parameters $a$, $b$, $c$ and four PT parameters free together, and confront this model with data. We find that pulsar timing is very sensitive to the parameter $a$, and give the first clear constraint $a=1.27_{-0.54}^{+0.71}$ at $1\,σ$ confidence level.

astro-ph.CO↗

arXiv2022

Wormholes in a viscous universe

We study the static and spherically symmetric wormhole spacetime configurations at present time in a viscous universe. Considering three classes of viscous models, i.e., bulk viscosity as a function of Hubble constant $H_0$, present cosmic temperature $T_0$ and dark energy density $ρ_0$, respectively, we obtain several wormhole solutions. Through the analysis for the anisotropic solutions, we conclude that, to some extent, these three classes of viscous models have very high degeneracy with each other, and deviate slightly from the ideal fluid consequence. Subsequently, without the loss of generality, to investigate the traversabilities, energy conditions and stability for the wormhole solution, we study the wormhole solution of the constant redshift function of the viscous $ω$CDM model with a constant bulk viscosity coefficient. We obtain the following conclusions: the value of traversal velocity decreases for decreasing bulk viscosity, and the traversal velocity for a traveler depends on not only the wormhole geometry but also the effects of cosmological background evolution; the null energy condition will be violated more clearly when the bulk viscosity or the cosmic expansion velocity decreases; for the case of a positive surface energy density, the range of the junction radius decreases and the values of the parameter $λ$ are further restricted when the throat radius of the wormhole $r_0/M$ increases, bulk viscosity coefficient $ζ_0$ decreases and present-day Hubble parameter $H_0$ decreases, respectively; for the case of a negative surface energy density, by increasing $r_0/M$, decreasing $ζ_0$ and increasing $H_0$, the values of the parameter $λ$ are less restricted, one may conclude that the total stability region increases, and the range of the junction radius increases, increases and decreases, respectively. \end{abstract}

gr-qc↗

arXiv2021

Testing modified gravity with 21 cm intensity mapping, HI galaxy, cosmic microwave background, optical galaxy, weak lensing, galaxy clustering, type Ia supernovae and gravitational wave surveys

In modern cosmology, an important task is investigating whether there exists a signal of modified gravity in the universe. Due to the limited resolutions and sensitivities of facilities, current observations can not detect any signal of modified gravity. As a consequence, it is urgent to predict the constraining power of future cosmological surveys on modified gravity. We constrain the Hu-Sawicki $f(R)$ gravity with eight future mainstream probes encompassing 21 cm intensity mapping, HI galaxy, cosmic microwave background, optical galaxy, weak lensing, galaxy clustering, type Ia supernovae and gravitational wave. We find that the HI galaxy survey SKA2 gives the strongest constraint $σ_{f_{R0}}=1.36\times10^{-8}$ among eight probes. The promising 21 cm intensity mapping survey SKA1-MID-B1 and optical galaxy survey Euclid also reach the order $\mathcal{O}$(-8). The fourth-generation CMB experiments SO and CORE produces the order $\mathcal{O}$(-6), while large scale structure surveys Euclid weak lensing, Euclid galaxy clustering and CSST weak lensing obtain the order $\mathcal{O}$(-5). Interestingly, CSST galaxy clustering gives the same order $\mathcal{O}$(-6) as SO and CORE, and the gravitational wave survey ET also obtain the order $\mathcal{O}$(-5). The combination of eight probes gives the tightest constraint $1.14\times10^{-8}$, which is just a little stronger than $1.34\times10^{-8}$ from the combination of SKA2 and SK1-MID-B1. This indicates that, to a large extent, future 21 cm intensity mapping and HI galaxy surveys can improve our understanding of modified gravity and energy budget in the cosmic pie.

astro-ph.CO↗

arXiv2021

Assessing the potential of cluster edges as a standard ruler

We assess comprehensively the potential of galaxy cluster edges as a standard ruler in measuring cosmological distances and probing exotic physics. Confronting five alternative cosmological models with cluster edges from the near future Dark Energy Spectroscopic Instrument survey, we conclude that cluster edges can serve as a promising probe to constrain models beyond $Λ$CDM. Especially, the constraining precision of equation of state of dark energy from cluster edges is just about two times larger than that from the Pantheon Type Ia supernovae sample. We find that the constraining power of cluster edges can be exhibited better by combining it with other probes. Combining cluster edges with cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers and simulated gravitational-wave events from the space-based Einstein Telescope, respectively, we constrain $Λ$CDM and find that the data combination of cosmic microwave background and cluster edges gives the best constraint on the Hubble constant $H_0$ with a $0.5\%$ precision and the matter density ratio $Ω_m$ with a $1.6\%$ precision among these five pair datasets, and that the data combination of gravitational waves and cluster edges almost shares the same constraining power as that of Type Ia supernovae and cluster edges. We also give the most stringent constraint on $Λ$CDM by combining cluster edges with available cosmological data. With the help of other probes, galaxy cluster edges can give new insights on exotic physics better at cosmological scales.

astro-ph.CO↗

arXiv2021

Can $f(R)$ gravity relieve $H_0$ and $σ_8$ tensions?

To investigate whether $f(R)$ gravity can relieve current $H_0$ and $σ_8$ tensions, we constrain the Hu-Sawicki $f(R)$ gravity with Planck-2018 cosmic microwave background and redshift space distortions observations. We find that this model fails to relieve both $H_0$ and $σ_8$ tensions, and that its two typical parameters $\log_{10}f_{R0}$ and $n$ are insensitive to other cosmological parameters. Combining the cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers with redshift space distortions observations, we give our best constraint $\log_{10}f_{R0}<-6.75$ at the $2σ$ confidence level.

astro-ph.CO↗

arXiv2021

4D Gauss-Bonnet gravity: cosmological constraints, $H_0$ tension and large scale structure

We perform correct and reasonable cosmological constraints on the newly proposed 4D Gauss-Bonnet gravity. Using the joint constraint from cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers and redshift space distortions, we obtain, so far, the strongest constraint $\tildeα=(1.2\pm5.2)\times 10^{-17}$, namely $α=(2.69\pm11.67)\times10^{48}$ eV$^{-2}$, among various observational limitations from different information channels, which is tighter than previous bound from the speed of gravitational wave by at least one order of magnitude. We find that our bound is well supported by the observations of temperature and lensing potential power spectra of cosmic microwave background from the Planck-2018 final release. Very interestingly, the large $H_0$ tension between the local measurement from the Hubble Space Telescope and global derivation from the Planck-2018 final data under the assumption of $Λ$CDM can be greatly resolved from $4.4σ$ to $1.94σ$ level in the 4D Gauss-Bonnet gravity. In theory, we find that this model can partly relieve the coincidence problem and the rescaling Gauss-Bonnet term, which needs the help of the cosmological constant to explain current cosmic acceleration, is unable to serve as dark energy alone.

astro-ph.CO↗