arXiv subjects

Ming-Ming Zhao

Publications and source records attributed to Ming-Ming Zhao.

6 recordsLinked to original sources

arXiv2019

Dark energy versus modified gravity: Impacts on measuring neutrino mass

In this paper, we make a comparison for the impacts of smooth dynamical dark energy, modified gravity, and interacting dark energy on the cosmological constraints on the total mass of active neutrinos. For definiteness, we consider the $Λ$CDM model, the $w$CDM model, the $f(R)$ model, and two typical interacting vacuum energy models, i.e., the I$Λ$CDM1 model with $Q=βHρ_{\rm c}$ and the I$Λ$CDM2 model with $Q=βHρ_Λ$. In the cosmological fits, we use the Planck 2015 temperature and polarization data, in combination with other low-redshift observations including the baryon acoustic oscillations, the type Ia supernovae, the Hubble constant measurement, and the large-scale structure observations, such as the weak lensing as well as the redshift-space distortion. Besides, the Planck lensing measurement is also employed in this work. We find that, the $w$CDM model favors a higher upper limit on the neutrino mass compared to the $Λ$CDM model, while the upper limit in the $f(R)$ model is similar with that of $Λ$CDM model. For the interacting vacuum energy models, the I$Λ$CDM1 model favors a higher upper limit on neutrino mass, while the I$Λ$CDM2 model favors an identical neutrino mass with the case of $Λ$CDM.

astro-ph.CO↗

arXiv2018

Measuring growth index in a universe with massive neutrinos: A revisit of the general relativity test with the latest observations

We make a consistency test for the general relativity (GR) through measuring the growth index $γ$ in a universe with massive (sterile/active) neutrinos. We employ the redshift space distortion measurements to do the analysis. To constrain other cosmological parameters, we also use other cosmological measurements, including the Planck 2015 cosmic microwave background temperature and polarization data, the baryon acoustic oscillation data, the type Ia supernova JLA data, the weak lensing galaxy shear data, and the Planck 2015 lensing data. In a universe with massive sterile neutrinos, we obtain $γ=0.624^{+0.055}_{-0.050}$, with the tension with the GR prediction $γ=0.55$ at the 1.48$σ$ level, showing that the consideration of sterile neutrinos still cannot make the true measurement of $γ$ be well consistent with the GR prediction. In a universe with massive active neutrinos, we obtain $γ=0.663\pm0.045$ for the normal hierarchy case, $γ=0.661^{+0.044}_{-0.050}$ for the degenerate hierarchy case, and $γ=0.668^{+0.045}_{-0.051}$ for the inverted hierarchy case, with the tensions with GR all at beyond the 2$σ$ level. We find that the consideration of massive active neutrinos (no matter what mass hierarchy is considered) almost does not influence the measurement of the growth index $γ$.

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arXiv2017

Search for sterile neutrinos in holographic dark energy cosmology: Reconciling Planck observation with the local measurement of the Hubble constant

We search for sterile neutrinos in the holographic dark energy cosmology by using the latest observational data. To perform the analysis, we employ the current cosmological observations, including the cosmic microwave background temperature power spectrum data from the Planck mission, the baryon acoustic oscillation measurements, the type Ia supernova data, the redshift space distortion measurements, the shear data of weak lensing observation, the Planck lensing measurement, and the latest direct measurement of $H_0$ as well. We show that, compared to the $Λ$CDM cosmology, the holographic dark energy cosmology with sterile neutrinos can relieve the tension between the Planck observation and the direct measurement of $H_0$ much better. Once we include the $H_0$ measurement in the global fit, we find that the hint of the existence of sterile neutrinos in the holographic dark energy cosmology can be given. Under the constraint of the all-data combination, we obtain $N_{\rm eff}= 3.76\pm0.26$ and $m_{ν,\rm sterile}^{\rm eff}< 0.215\,\rm eV$, indicating that the detection of $ΔN_{\rm eff}>0$ in the holographic dark energy cosmology is at the $2.75σ$ level and the massless or very light sterile neutrino is favored by the current observations.

astro-ph.CO↗

arXiv2017

Constraining neutrino mass and extra relativistic degrees of freedom in dynamical dark energy models using Planck 2015 data in combination with low-redshift cosmological probes: basic extensions to $Λ$CDM cosmology

We investigate how the properties of dark energy affect the cosmological measurements of neutrino mass and extra relativistic degrees of freedom. We limit ourselves to the most basic extensions of $Λ$ cold dark matter (CDM) model, i.e. the $w$CDM model with one additional parameter $w$, and the $w_{0}w_{a}$CDM model with two additional parameters, $w_{0}$ and $w_{a}$. In the cosmological fits, we employ the 2015 cosmic microwave background temperature and polarization data from the Planck mission, in combination with low-redshift measurements such as the baryon acoustic oscillations, Type Ia supernovae and the Hubble constant ($H_{0}$). Given effects of massive neutrinos on large-scale structure, we further include weak lensing, redshift space distortion, Sunyaev--Zeldovich cluster counts and Planck lensing data. We show that, though the cosmological constant $Λ$ is still consistent with the current data, a phantom dark energy ($w<-1$) or an early phantom dark energy (i.e. quintom evolving from $w<-1$ to $w>-1$) is slightly more favoured by current observations, which leads to the fact that in both $w$CDM and $w_0w_a$CDM models we obtain a larger upper limit of $\sum m_ν$. We also show that in the three dark energy models, the constraints on $N_{\rm eff}$ are in good accordance with each other, all in favour of the standard value 3.046, which indicates that the dark energy parameters almost have no impact on constraining $N_{\rm eff}$. Therefore, we conclude that the dark energy parameters can exert a significant influence on the cosmological weighing of neutrinos, but almost cannot affect the constraint on dark radiation.

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arXiv2015

Neutrinos in the holographic dark energy model: constraints from latest measurements of expansion history and growth of structure

The model of holographic dark energy (HDE) with massive neutrinos and/or dark radiation is investigated in detail. The background and perturbation evolutions in the HDE model are calculated. We employ the PPF approach to overcome the gravity instability difficulty (perturbation divergence of dark energy) led by the equation-of-state parameter $w$ evolving across the phantom divide $w=-1$ in the HDE model with $c<1$. We thus derive the evolutions of density perturbations of various components and metric fluctuations in the HDE model. The impacts of massive neutrino and dark radiation on the CMB anisotropy power spectrum and the matter power spectrum in the HDE scenario are discussed. Furthermore, we constrain the models of HDE with massive neutrinos and/or dark radiation by using the latest measurements of expansion history and growth of structure, including the Planck CMB temperature data, the baryon acoustic oscillation data, the JLA supernova data, the Hubble constant direct measurement, the cosmic shear data of weak lensing, the Planck CMB lensing data, and the redshift space distortions data. We find that $\sum m_ν<0.186$ eV (95\% CL) and $N_{\rm eff}=3.75^{+0.28}_{-0.32}$ in the HDE model from the constraints of these data.

astro-ph.CO↗

arXiv2014

Revisiting the holographic dark energy in a non-flat universe: alternative model and cosmological parameter constraints

We propose an alternative model for the holographic dark energy in a non-flat universe. This new model differs from the previous one in that the IR length cutoff $L$ is taken to be exactly the event horizon size in a non-flat universe, which is more natural and theoretically/conceptually concordant with the model of holographic dark energy in a flat universe. We constrain the model using the recent observational data including the type Ia supernova data from SNLS3, the baryon acoustic oscillation data from 6dF, SDSS-DR7, BOSS-DR11, and WiggleZ, the cosmic microwave background data from Planck, and the Hubble constant measurement from HST. In particular, since some previous studies have shown that the color-luminosity parameter $β$ of supernovae is likely to vary during the cosmic evolution, we also consider such a case that $β$ in SNLS3 is time-varying in our data fitting. Compared to the constant $β$ case, the time-varying $β$ case reduces the value of $χ^2$ by about 35 and results in that $β$ deviates from a constant at about 5$σ$ level, well consistent with the previous studies. For the parameter $c$ of the holographic dark energy, the constant $β$ fit gives $c=0.65\pm 0.05$ and the time-varying $β$ fit yields $c=0.72\pm 0.06$. In addition, an open universe is favored (at about 2$σ$) for the model by the current data.

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