Chinese Physics Letters, 2023, Vol. 40, No. 1, Article code 019801 Latest Data Constraint of Some Parameterized Dark Energy Models Jing Yang, Xin-Yan Fan, Chao-Jun Feng*, and Xiang-Hua Zhai* Affiliations Division of Mathematica and Theoretical Physics, Shanghai Normal University, Shanghai 200234, China Received 30 September 2022; accepted manuscript online 23 November 2022; published online 14 December 2022 *Corresponding authors. Email: fengcj@shnu.edu.cn; zhaixh@shnu.edu.cn Citation Text: Yang J, Fan X Y, Feng C J et al. 2023 Chin. Phys. Lett. 40 019801    Abstract Using various latest cosmological datasets including type-Ia supernovae, cosmic microwave background radiation, baryon acoustic oscillations, and estimations of the Hubble parameter, we test some dark-energy models with parameterized equations of state and try to distinguish or select observation-preferred models. We obtain the best fitting results of the six models and calculate their values of the Akaike information criteria and Bayes information criterion. We can distinguish these dark energy models from each other by using these two information criterions. However, the $\varLambda $CDM model remains the best fit model. Furthermore, we perform geometric diagnostics including statefinder and $Om$ diagnostics to understand the geometric behavior of the dark energy models. We find that the six dark-energy models can be distinguished from each other and from $\varLambda $CDM, Chaplygin gas, quintessence models after the statefinder and $Om$ diagnostics are performed. Finally, we consider the growth factor of the dark-energy models with comparison to the $\varLambda $CDM model. Still, we find the models can be distinguished from each other and from the $\varLambda $CDM model through the growth factor approximation.
cpl-40-1-019801-fig1.png
cpl-40-1-019801-fig2.png
cpl-40-1-019801-fig3.png
cpl-40-1-019801-fig4.png
cpl-40-1-019801-fig5.png
cpl-40-1-019801-fig6.png
DOI:10.1088/0256-307X/40/1/019801 © 2023 Chinese Physics Society Article Text At the end of the 20th century, the observations of type-Ia supernovae (SNIa) first indicated that the universe is under accelerating expansion.[1,2] Later, various experimental observations, including the large-scale structure (LSS)[3,4] and the cosmic microwave background radiation (CMB),[5-10] also provided evidence for the accelerating expansion of the universe. In order to explain the acceleration of the universe, the efforts that continue to date include two aspects. On the one hand, the gravitational part may be modified, and extended theories of gravity may be constructed.[11-14] On the other hand, a matter component with negative pressure, i.e., dark energy (DE), which may drive the acceleration, is introduced into the matter part (see review articles on DE, Refs. [15-23]). The currently preferable and also the simplest cosmological model is the $\varLambda$ cold dark matter ($\varLambda$CDM) model, in which the cosmological constant $\varLambda$ plays the role of DE. However, due to the deficiencies of the $\varLambda$CDM model such as the cosmic coincidence issue and fine-tuning problem,[24-28] the dynamical DE models have been widely discussed.[29-38] Due to the fact that there is no preferable DE model that can completely describe the dynamical phenomena of the universe, several attempts have been made in recent years to model them from observations. Parameterization of cosmological or DE parameters is one of the most concerned attempts. One can parameterize the Hubble parameter, the deceleration parameter or the energy density of DE.[37,39-46] Parameterizing the DE density parameter, for example, using a simple power law expansion $\varOmega_{\rm DE}=\sum_{i=0}^{N}A_{i}z^{i}$, where $z$ is the red shift, is also a frequently used method.[47-53] Following this approach, one can parameterize the equation of state (EoS) of the DE as $w(z)=\sum_{i=0}^{N}w_{i}z^{i}$,[54-57] which is a simple parameterization of the EoS that can describe the dynamical evolutionary behavior for a large number of DE models. However, this parameterization diverges at high redshifts. Furthermore, since the angular diameter distance depends on the form of $w(z)$ and the angular scale features of the CMB temperature anisotropy varies with the peak, the constraint on the angular diameter distance to the last scattering surface by the CMB would be problematic. Then, a stable parameterization of the EoS $w(z)=w_{0}+w_{1}z/(1+z)$ that extends the parameterization of the DE to redshifts $z\gg 1$ was given and has been widely discussed.[58-66] Furthermore, a modified model $w(z)=w_{0}+w_{1}z/(1+z)^{2}$ was proposed by Jassal et al.[66] It can model a DE component that has the same value of EoS at the present time and at high redshifts. Both models are bounded at high redshifts $z\gg 1$, but they cannot be distinguished. In Ref. [63], Gong et al. also proposed two one-parameter models and the model $w(z)=w_{0}{\rm e}^{z/(1+z)}/(1+z)$ such that $w=0$ in the future $z \to -1$. Feng et al.[67] proposed two-parameter models $w(z)=w_{0}+\frac{w_{1}z}{1+z^{2}}$ and $w(z)=w_{0}+\frac{w_{1}z^{2}}{1+z^{2}}$, with $w(z)$ bounded in the future for both models. In Ref. [68], the authors classified the parameterized EoS models proposed in recent years by the number of parameters and gave the range of model parameters using numerical analysis. In the appendix of Ref. [69], the authors made a summary of various parameterized models in recent years. In our work, we aim to explore the cosmological feasibility of some DE models with parameterized EoS using recent observations to constrain the models. A large number of DE models may produce similar evolutionary behaviors and, correspondingly, similar histories of cosmic expansion. Therefore, effective differentiation of models is very important. Using various data to test DE models, to select good models, or to compare models, has become a standard approach in cosmological research. However, by using only one kind of observational data to constrain models, a degeneracy of certain cosmological parameter among different models usually occurs. In order to break this degeneracy, joint constraints of multiple observational data are often used. In our work, we will use the combination of supernova data, the temperature and polarization anisotropy data from the CMB, the baryon acoustic oscillations (BAO), and Hubble parameter observational $H(z)$ data. For supernova data, we will compare the constraints from two samples: joint light-curve analysis (JLA) and Pantheon, where the redshift range is extended in the latter. In this Letter, we use the above-mentioned observational data to investigate the cosmological feasibility of six DE models with parameterized EoS,[59,63,66,67] and analyze the DE nature with geometric diagnostics. Firstly, six parametric DE models are reviewed. Secondly, we give the constraints of the models with observational data. Thirdly, we perform two diagnostic analyses that can distinguish the models, and analyze the impact of DE on the matter density perturbation by the growth factors of the models. Finally, we conclude our study. Considered Six Parameterized Dark Energy Models. According to Einstein's gravitational field equation and the flat Fridmann–Robertson–Walker (FRW) metric, the Friedmann equations can be written as \begin{align} &3H^{2}=\rho_{\rm m}+\rho_{\rm r}+\rho_{\rm de},\notag\\ &3H^{2}+2\dot{H}=-(p_{\rm m}+p_{\rm r}+p_{\rm de}),\tag {1} \end{align} where $H=\dot{a}/a$ is the Hubble parameter, $a$ is the scale factor, and the dot is the derivative with respect to cosmic time; $\rho_i$ and $p_i$ are the energy density and pressure with subscript $i=\,$m, r, and de denoting matter, radiation and DE, respectively. Here, we use units $8\pi G=1$. Assuming that there is no interaction between dark matter and DE in the universe, we have the equations of energy conservation as follows: \begin{align} \dot{\rho_{\rm de}} +3H (1+w)\rho_{\rm de}=0,\notag\\ \dot{\rho_{\rm m}} +3H \rho_{\rm m}=0,\tag {2} \end{align} and it is assumed that the matter in the universe is dusty matter with $p_{\rm m}=0$. Firstly, we give a review of the six parameterized DE models that we will consider in the following. Model 1: It was proposed by Gong and Zhang[63] with the EoS that \begin{align} w\left(z\right)=\frac{w_{0}}{1+z}, \tag {3} \end{align} where the only parameter $w_{0}$ is constant. For this model, $w(z\to 0)= w_{0}$ is the current value of the EoS. The model is bounded by $w\sim 0$ at high redshift $z\gg 1 $, which means that, at that time, DE is represented as dust matter. However, in the future $w(z\to-1)\sim \infty$, this model will have singularity. Combining Eqs. (1), (2), and (3), one obtains \begin{align} E^{2}(z)=\,&(1-\varOmega_{\rm m0}-\varOmega_{\rm r0})(1+z)^{3} {\rm e}^{\frac{3w_{0}z}{1+z}}\notag\\ &+\varOmega_{\rm m0}(1+z)^{3}+\varOmega_{\rm r0}(1+z)^{4}, \tag {4} \end{align} where $E=H/H_{0}$ is the dimensionless Hubble parameter, $H_{0}$ is the current value of the Hubble constant. $\varOmega_{i0}=\frac{\rho_{i0}}{3H_0^2} $ are the current values of density parameters. Model 2: It is also a one-parameter model proposed by Gong and Zhang,[63] and its EoS is \begin{align} w\left(z\right)=\frac{w_{0}}{1+z}{\rm e}^{\frac{z}{1+z}}. \tag {5} \end{align} Compared with Model 1, the EoS in the future $z\to-1$ for Model 2 is $w\to 0$, where DE represents dust matter. Similarly, one can obtain \begin{align} E^{2}(z)=\,&(1-\varOmega_{\rm m0}-\varOmega_{\rm r0})(1+z)^{3}{\rm e}^{3w_{0}({\rm e}^{\frac{z}{1+z}}-1)}\notag\\ &+\varOmega_{\rm m0}(1+z)^{3}+\varOmega_{\rm r0}(1+z)^{4}. \tag {6} \end{align} Model 3: For two-parameter models, the parameterized EoS can be expressed as \begin{align} w\left(z\right)=\frac{p}{\rho}=w_{0}+w_{1}f(z), \tag {7} \end{align} where $w_{0}$, $w_{1}$ are constants, and $f(z)$ is a function of the redshift $z$. Different forms of $f(z)$ correspond to different DE models. Also, the model will return to the $\varLambda $CDM model when $w_{0}=-1$ and $w_{1}=0$. The model with $f(z)=\frac{z}{1+z}$ is known as the Chevallier–Polarski–Linear (CPL) model,[59] \begin{align} w(z)=w_{0}+\frac{w_{1}z}{1+z}. \tag {8} \end{align} This model is divergent when describing future evolution. Similarly, one has \begin{align} E^{2}(z)=\,&(1-\varOmega_{\rm m0}-\varOmega_{\rm r0})(1+z)^{3(1+w_{0}+w_{1})}{\rm e}^{\frac{-3w_{1}z}{1+z}}\notag\\ &+\varOmega_{\rm m0}(1+z)^{3}+\varOmega_{\rm r0}(1+z)^{4}. \tag {9} \end{align} This is the Model 3 we will consider. Model 4: This model[66] is a modification of Model 3 and its EoS is as follows: \begin{align} w\left(z\right)=w_{0}+\frac{w_{1}z}{(1+z)^{2}}, \tag {10} \end{align} which diverges in the future as Model 3. We can obtain \begin{align} E^{2}(z)=\,&(1-\varOmega_{\rm m0}-\varOmega_{\rm r0})(1+z)^{3(1+w_{0})}{\rm e}^{\frac{3w_{1}z^{2}}{2(1+z)^{2}}}\notag\\ &+\varOmega_{\rm m0}(1+z)^{3}+\varOmega_{\rm r0}(1+z)^{4}. \tag {11} \end{align} Model 5: In Ref. [67], Feng et al. proposed two-parameter models that are different from the CPL model and can describe the evolutionary behavior of the universe from the past to the future. Model 4 is one of the models with \begin{align} w(z)=w_{0}+\frac{w_{1}z}{1+z^{2}}. \tag {12} \end{align} Then, \begin{align} \!E^{2}(z)=\,&(1-\varOmega_{\rm m0}-\varOmega_{\rm r0})(1+z)^{3(1+w_{0}-\frac{1}{2}w_{1})}{\rm e}^{\frac{3}{2}w_{1}{\rm\arctan}z}\notag\\ &\cdot(1+z^{2})^{\frac{3}{4}w_{1}}+\varOmega_{\rm m0}(1+z)^{3}+\varOmega_{\rm r0}(1+z)^{4}. \tag {13} \end{align} Model 6: It is another two-parameter model in Ref. [67] with the EoS \begin{align} w\left(z\right)=w_{0}+\frac{w_{1}z^{2}}{1+z^{2}}. \tag {14} \end{align} Similarly, one has \begin{align} \!E^{2}(z)=\,&(1-\varOmega_{\rm m0}-\varOmega_{\rm r0})(1+z)^{3(1+w_{0}+\frac{1}{2}w_{1})}{\rm e}^{-\frac{3}{2}w_{1}{\rm\arctan}z}\notag\\ &\cdot(1+z^{2})^{\frac{3}{4}w_{1}}+\varOmega_{\rm m0}(1+z)^{3}+\varOmega_{\rm r0}(1+z)^{4}.\tag {15} \end{align} The behaviors of the EoSs of the above six models are listed in Table 1. Among these models, the EoSs of Models 1, 3 and 4 will be divergent at $z\to -1$. However, the divergence can be avoided in Models 2, 5 and 6. Moreover, for Models 1 and 2 when $w_{0}=-1$, the EoSs are the same as that of $\varLambda$CDM at the present time. For Model 3, the EoS is the same as $\varLambda$CDM in the past and at present time when $w_0=-1$ and $w_1=0$. The EoS of Model 4 is the same as $\varLambda$CDM in the past and at present time when $w_0=-1$. Models 5 and 6 return to $\varLambda$CDM when $w_0=-1$ and $w_1=0$.
Table 1. Behaviors of EoS parameters for different DE models.
Models $w(z)$ $z=0$ $z\to\infty$ $z\to-1$
Model 1[63] $w(z)=\frac{w_{0}}{1+z}$ $w_{0}$ $0$ $\infty$
Model 2[63] $w(z)=\frac{w_{0}}{1+z}{\rm e}^{\frac{z}{1+z}}$ $w_{0}$ $0$ $0$
Model 3[59] $w(z)=w_{0}+\frac{w_{1}z}{1+z}$ $w_{0}$ $w_{0}+w_{1}$ $\infty$
Model 4[66] $w(z)w_{0}+\frac{w_{1}z}{(1+z)^{2}}$ $w_{0}$ $w_{0}$ $\infty$
Model 5[67] $w(z)=w_{0}+\frac{w_{1}z}{1+z^{2}}$ $w_{0}$ $w_{0}$ $w_{0}-\frac{w_{1}}{2}$
Model 6[67] $w(z)=w_{0}+\frac{w_{1}z^{2}}{1+z^{2}}$ $w_{0}$ $w_{0}+w_{1}$ $w_{0}+\frac{w_{1}}{2}$
Data Constraints. The fast development of observational techniques has led to increasingly refined observational data and gradually increased constraints on DE models. Moreover, in order to break down the degeneracy in cosmological parameters among different models, the combination of multiple observational data is frequently used to give subtle constraints. Here, we constrain the DE models mentioned above with the Pantheon + CMB + BAO + $H(z)$ and the JLA + CMB + BAO + $H(z)$ data sets. The constraint results are used to distinguish or compare the models. A brief introduction to these datasets are given in the following. Pantheon and JLA Sample. We use the Pantheon SNIa sample at redshifts of $0.01 < z < 2.3$,[70] which is a combination of Pan-STARRS1 (PS1), Sloan Digital Sky Survey (SDSS), Supernova Legacy Survey (SNLS), some low redshift data, and the Hubble Space Telescope (HST) sample of a total of 1048 supernovae. The JLA dataset contains a total of 740 SNIa at redshifts of $0.01 < z < 1$,[71] including several samples at low redshifts ($z < 0.1$), all three seasons of SDSS-II ($0.05 < z < 0.4$) and three years of SNLS ($0.2 < z < 1$). Due to the linear relationship between the extreme luminosity of SNIa bursts with the color of the light and the rate of decrease of the light-change curve, they are treated as standard candles for the detection of cosmological distances in astronomical observations. The luminosity distance is expressed in astronomical observations by introducing a distance modulus $m_{\rm cor}-M$,[72,73] i.e., \begin{align} \mu=m_{\rm cor}-M=5{\log}_{10}(d_{\scriptscriptstyle{\rm L}}/{\rm Mpc})+25, \tag {16} \end{align} where $m_{\rm cor}$ is the corrected magnitude in the Pantheon observable, $d_{\scriptscriptstyle{\rm L}}=(1+z)\int_{0}^{z}\frac{dz'}{H(z') }=(1+z)r(z)$ is the photometric distance and $r(z)$ is the co-movement distance. Therefore, the actual observed distance of SNIa modulus is \begin{align} \mu_{\rm obs}=m_{\scriptscriptstyle{\rm B}}-M+\alpha x_{1}-\beta c+\varDelta_{\scriptscriptstyle{\rm M}}+\varDelta_{\scriptscriptstyle{\rm B}}, \tag {17} \end{align} where $m_{\scriptscriptstyle{\rm B}}$ is the apparent magnitude in the $B$-band, $M$ is the absolute magnitude of the SN in the $B$-band when the stretching parameter $x_{1}=0$ and the color parameter $c=0$, $\alpha$ is the luminosity versus stretching coefficient, $\beta$ is the luminosity versus color number, $\varDelta_{\scriptscriptstyle{\rm M}}$ is a distance correction based on the host galaxy mass of the SN, and $\varDelta_{\scriptscriptstyle{\rm B}}$ is a distance correction based on the deviation predicted from the simulation (for details, see Ref. [70]). The $\chi^{2}$ for the SNIa dataset is \begin{align} \chi^{2}_{\scriptscriptstyle{\rm SNIa}}=[\mu_{i}^{\rm obs}-\mu_{i}^{\rm th}(p)] ({\rm Cov}_{\scriptscriptstyle{\rm SN}}^{-1})_{ij}[\mu_{j}^{\rm obs}-\mu_{j}^{\rm th}(p)], \tag {18} \end{align} where $p=(p_{1},\dots ,p_{n})$ is a vector of $n$ fit parameters, ${\rm Cov}_{\scriptscriptstyle{\rm SN}}$ is the covariance matrix describing the systematic error of the supernova observations, $\mu_{i}^{\rm obs}$ and $\mu_{i}^{\rm th} $ are the observed and theoretical distance moduli, respectively. Cosmic Microwave Background. Generally, three observables from cosmic microwave background (CMB) observations are used to constrain the cosmological model parameters: the redshift $z_{*}=1048[1+0.00124(\varOmega _{\rm b}h^{2})^{-0.738}][1+g_{1}(\varOmega _{\rm m}h^{2})^{g_{2}}]$ during the photon decoupling period, the position of the first peak in the temperature rise power spectrum $l_{\scriptscriptstyle{\rm A}}=(1+z_{*})\frac{\pi D_{\scriptscriptstyle{\rm A}}z_{*}}{r_{\rm s}(z_{*})}$, and the translation parameter $\Re \equiv \sqrt{\varOmega _{\rm m}H_{0}^{2}}(1+z_{*})D_{\scriptscriptstyle{\rm A}}(z_{*})$. The $\chi^{2}$ of the CMB is \begin{align} \chi^{2}_{\scriptscriptstyle{\rm CMB}}=\Delta p_{i}[{\rm Cov}_{\scriptscriptstyle{\rm CMB}}^{-1}(p_{i},p_{j})]\Delta p_{j}, \tag {19} \end{align} where $\Delta p_{i}=p_{i}-p_{i}^{\rm data}$, $p_{i}=\{l_{\scriptscriptstyle{\rm A}},\Re,w_{\rm b}\} $, and $w_{\rm b}=\varOmega_{\rm b}h^{2}$. Using the Planck 2018[74] data including temperature (TT), the polarization (EE), the cross correlation of temperature, and polarization (TE) power spectra, where the low multipoles (low-$\ell$) temperature Commander likelihood in TT, the low-$\ell $ SimAll likelihood in EE and the high multipoles (high-$\ell$) part of Planck TT, TE, EE are contributed in the range $\ell \in [2,2500]$, one can obtain the central value of $p_{i}^{\rm data}$ and the error in the $1 \sigma$ confidence interval (the relevant results are given in Ref. [74]). Baryon Acoustic Oscillations. Baryon acoustic oscillations (BAOs) are used in astronomical observations as a standard ruler for cosmological measurements of cosmic distances, and their data are analyzed from BAO eigenpower spectra or correlation functions in large scale surveys of galaxy clusters to extract the physical quantities: redshift and distance. In the direction of sight there is \begin{align} H(z)=\frac{c \cdot \delta z_{\rm s}(z)}{r_{\rm s}(z_{d})}. \tag {20} \end{align} Here, $r_{\rm s}(z_{d})$ is the co-moving acoustic horizon during the baryon towing period, and $\delta z_{\rm s}$ denotes the BAO characteristic redshift distance along the direction of sight with redshift $z$. In the direction perpendicular to the line of sight there is \begin{align} d_{\scriptscriptstyle{\rm A}}(z)=\frac{r_{\rm s}(z_{d})}{\theta_{\rm s}(z)(1+z)}, \tag {21} \end{align} where $\theta_{\rm s}(z)$ denotes the angle at which the BAO feature is opened perpendicular to the line of the sight direction. The data of BAO features can now be directly measured out of the value of the effective distance $D_{\scriptscriptstyle{\rm V}}(z)$ corresponding to the redshift, \begin{align} D_{\scriptscriptstyle{\rm V}}(z)&=\frac{r_{\rm s}(z_{d})}{[\theta_{\rm s}(z)^{2}\delta z_{\rm s}(z)]^{\frac{1}{3}}}\notag\\ &=\Big[\frac{(1+z)^{2} d_{\scriptscriptstyle{\rm A}}^{2}(z)cz}{H(z)}\Big]^{\frac{1}{3}}. \tag {22} \end{align} The $\chi^{2}$ of BAO is \begin{align} \chi^{2}_{\scriptscriptstyle{\rm BAO}}=\Delta p_{i}[{\rm Cov}_{\scriptscriptstyle{\rm BAO}}^{-1}(p_{i},p_{j})]\Delta p_{j}. \tag {23} \end{align} In our work, we utilize BAO measurements from 6dFGS,[75] SDSS-MGS[76] and BOSS DR12[77] as published by Planck 2018 results.[74] $H(z)$ Observational Data. The Hubble parameter can characterize the evolution rate of the universe, and to some extent, the size and age of the universe. With the progress of the observational techniques, the accuracy of the current value of the Hubble constant has greatly improved. We use in our analysis a total of 57 data points[78] from direct observations of $H(z)$, i.e., $H(z)$ observational data (OHD), by both the age differential measurement method and the BAO effect. The $\chi^{2}$ of the observed data for $H(z)$ is \begin{align} \chi^{2}_{\scriptscriptstyle{\rm OHD}}=\sum_{i=1}^{57}\frac{[H_{\rm th}-H_{\rm obs}]^{2}}{\sigma_{_{\scriptstyle H({z_{i}})}}^{2}}. \tag {24} \end{align} The total $\chi^{2}$ combining the above four datasets is \begin{align} \chi^{2}_{\rm tot}= \chi^{2}_{\scriptscriptstyle{\rm SNIa}}+\chi^{2}_{\scriptscriptstyle{\rm CMB}}+\chi^{2}_{\scriptscriptstyle{\rm BAO}}+\chi^{2}_{\scriptscriptstyle{\rm OHD}}. \tag {25} \end{align} The minimum values of $\chi^{2}$, i.e., the $\chi^{2}_{{\min}}$ values, reflect the goodness of fit for models. That is, the smaller $\chi^{2}_{{\min}}$ values indicate that the model can be better supported by the current observation data. Since the $\chi^{2}_{{\min}}$ values decrease as the number of the model parameters increases, it is unlikely to make a fair judgement on the merit of the model by the $\chi^{2}_{{\min}}$ values alone. Considering the influence of the number of parameters, we will compare the models by using two information criterions, Akaike information criteria (AIC)[79] and Bayes information criterion (BIC),[80] \begin{align} &{\rm AIC}=\chi^{2}_{{\min}}+2\,K, \tag {26}\\ &{\rm BIC}=\chi^{2}_{{\min}}+K{\ln}N, \tag {27} \end{align} where $K$ is the number of free parameters, and $N$ is the total data points. We use the Markov Chain Monte Carlo (MCMC) method to explore the parameter space of these six parametrized DE models mentioned above and fit the data using the Pydm package (https://github.com/shfengcj/pydm) written by our own group. Here, we use two sets of combined data, i.e., JLA + CMB + BAO + $H(z)$ (JCBH) and Pantheon + CMB + BAO + $H(z)$ (PCBH) data sets, to obtain the best-fit values of the parameters of different DE models and their 1$\sigma$ to 2$\sigma$ confidence levels. The results are given in Tables 2 and 3. One can see that the EoS parameter crosses $-1$ at a certain redshift in Models 3 and 6. Taking the best fit results from the JCBH data for instance, in Model 3, the value of the EoS parameter at $z=0$ is $w_0=-0.9$, and it becomes $w_0+w_1=-1.41$ at $z=\infty$. In Model 6, the value of the EoS parameter at $z=0$ is $w_0=-0.95$, and it becomes $w_0+w_1=-1.58$ at $z=\infty$. This crossing behavior of the EoS parameter cannot be realized in single field models such as quintessence models, but can be realized in two-field models (see Refs. [81,82] for more details).
Table 2. The best fit values of the model parameters and 1$\sigma$ confidence level of Models 1,2 and $\varLambda$CDM model under two sets of combined data.
Parameter $\varLambda$CDM Model 1 Model 2
JCBH PCBH JCBH PCBH JCBH PCBH
$H_{0}$ $68.26^{+0.45}_{ -0.51}$ $68.31^{+0.47}_{-0.50}$ $70.97^{+1.16}_{-1.16}$ $69.86^{+0.99}_{-0.99}$ $69.20^{+1.18}_{-1.09}$ $68.90^{+0.97}_{-0.98}$
$w_{0}$ $-1.31^{+0.05}_{ -0.05}$ $-1.26^{+0.04}_{-0.05}$ $-1.06^{+0.05}_{-0.05}$ $-1.04^{+0.04}_{-0.04}$
$\chi^{2}_{{\min}}$ $720.06$ $1062.87$ $745.31$ $1090.19$ $725.20$ $1067.81$
Table 3. The best fit values of the model parameters and 1$\sigma$ confidence level of Models 3–6 under two sets of combined data.
Parameter Model 3 Model 4 Model 5 Model 6
JCBH PCBH JCBH PCBH JCBH PCBH JCBH PCBH
$H_{0}$ $67.94^{+1.30}_{-1.23}$ $68.24^{+1.01}_{-1.00}$ $68.31^{+1.21}_{-1.32}$ $68.33^{+1.04}_{-1.02}$ $68.17^{+1.32}_{-1.23}$ $68.37^{+1.08}_{-1.03}$ $67.84^{+1.27}_{-1.36}$ $68.21^{+1.03}_{-1.03}$
$w_{0}$ $-0.90^{+0.09}_{-0.09}$ $-0.95^{+0.09}_{-0.08}$ $-0.93^{+0.11}_{-0.11}$ $-0.97^{+0.12}_{-0.11}$ $-0.94^{+0.10}_{-0.10}$ $-0.98^{+0.09}_{-0.08}$ $-0.95^{+0.07}_{-0.07}$ $-0.97^{+0.05}_{-0.05}$
$w_{1}$ $-0.51^{+0.33}_{-0.45}$ $-0.34^{+0.39}_{-0.45}$ $-0.49^{+0.65}_{-0.76}$ $-0.26^{+0.75}_{-0.85}$ $-0.29^{+0.33}_{-0.38}$ $-0.14^{+0.33}_{-0.39}$ $-0.63^{+0.33}_{-0.44}$ $-0.50^{+0.33}_{-0.49}$
$\chi^{2}_{{\min}}$ $719.07$ $1062.05$ 719.85 1062.60 $719.49$ $1062.56$ $718.18$ $1061.53$
For better analysis and comparison, the $\varLambda$CDM model is chosen as a reference. The $\chi^{2}_{{\min}}$ values reflect the goodness of fit, and we note that Model 6 has the smallest $\chi^{2}_{{\min}}$ value in Tables 2 and 3, which is supported by current observational data. The best-fit values of model parameters for Model 6 and 1$\sigma$ to 2$\sigma$ confidence level are given in Fig. 1 by using the PCBH data. However, as mentioned above, the $\chi^{2}_{{\min}}$ values are not suitable for comparing models because of the $\chi^{2}_{{\min}}$ values are affected by the number of parameters. Here, we use the difference of AIC between a certain DE model and the $\varLambda$CDM model, $\Delta {\rm AIC}=\Delta \chi ^{2}_{{\min}}+2\Delta K $, and the difference of BIC, $\Delta {\rm BIC}=\Delta \chi ^{2}_{{\min}}+2\Delta K{\ln}N $, to quantitatively compare the models. We show in Table 4 the comparison of the models using the two information criterions. It is noted that for Models 1–6, $\Delta {\rm AIC}>2$ and $\Delta {\rm BIC}>2$, then, according to Refs. [83-85], the best model is still the $\varLambda$CDM model. The main difference between the two sets of combined data is that the covariance matrices of the two supernova samples, Pantheon and JLA, are analyzed differently. The covariance matrix in the JLA sample depends explicitly on the parameters $\alpha$ and $\beta$, so these two parameters must be added as additional parameters in the MCMC search. In contrast, for the Pantheon sample, they do not need to be changed during the MCMC search because the effects of $\alpha$ and $\beta$ have been considered in the covariance calculation. As described in Ref. [86], the constraints of PCBH and JCBH are known to be in good agreement. We note that, although the PCBH datasets cover a larger range of redshifts, they still have poor constraints for $w_{1}$ of Models 3–5. Meanwhile, the PCBH constraint results show that for Models 3–6 compared to JCBH, the values of $w_{0}$ are more negative and the values of $w_{1}$ are less negative, which is consistent with the result of Ref. [87]. For Models 1 and 2, the fit results prefer to choose less negative values of $w_{0}$.
cpl-40-1-019801-fig1.png
Fig. 1. Best-fit values of model parameters and their 1$\sigma$-to-2$\sigma$ confidence levels for Model 6 by using the PCBH data.
Table 4. The results of AIC and BIC of PCBH data for the models.
Criterion $\varLambda$CDM Model 1 Model 2 Model 3 Model 4 Model 5 Model 6
AIC 1066.87 1096.16 1073.81 1070.05 1070.60 1070.56 1069.53
BIC 1076.89 1111.22 1088.84 1090.08 1090.63 1090.59 1089.56
Diagnostics of DE Models. So far, we are able to distinguish DE models from each other with observational constraints. With the purpose of investigating the cosmological behavior of various DE models and distinguishing one model from others, we will further use statefinder diagnostic, $Om$ diagnostics, and growth factor to distinguish Models 1–6 from each other as well as from the $\varLambda$CDM, quintessence, and Chaplygin gas models.
cpl-40-1-019801-fig2.png
Fig. 2. Evolution trajectories of the six DE models in the $r$–$s$ plane, where the arrows indicate the temporal evolution of these models. The solid dots on these lines indicate the current states of the models and the point (0,1) represents the $\varLambda $CDM model.
Statefinder Diagnostics. Sahni et al.[88,89] proposed a statefinder diagnostics $\{r, s\}$, which is a geometric-parametric method to distinguish different DE models. The parameters are defined as follows: \begin{align} &r=\frac{\dddot{a}}{aH^{3}}, \tag {28}\\ &s=\frac{r-1}{3(q-\frac{1}{2})},~~~q\ne\frac{1}{2}, \tag {29} \end{align} where $q=-\frac{\ddot{a}}{aH^{2}}$ is the deceleration parameter. Different $(r,s)$ pairs correspond to different DE models.[88,89] For example,
  • $(r=1,s=0)\to \varLambda $CDM model,
  • $(r\langle 1,s \rangle 0)\to $ quintessence model,
  • $(r>1,s < 0)\to $ Chaplygin gas (CG) model.
According to the best-fit values given in Tables 2 and 3, we plot the evolution of the statefinder diagnostic parameter pair $\{r, s\}$ for the six DE models in Fig. 2, and also give the local enlargement in Fig. 3 for clarity. The arrows indicate the directions of evolution of the models. Moreover, we compare the six DE models with the CG and quintessence models and the $\varLambda $CDM model. It is found that Model 1 behaves like the quintessence model at early time, then makes transition from quintessence to $\varLambda $CDM fixed point, and finally gets into the CG region. Model 2 behaves like quintessence at early time, and passes through the $\varLambda$CDM point as it evolves. After performing a swirl, it lies at quintessence region in the future. Model 5 is exactly the opposite. Its early evolution resembles the CG model, then crosses the $\varLambda$CDM point and swivels round, finally enters the CG region in the future. The evolutionary trajectories of Models 3, 4, and 5 are like the CG model at early time, then they cross the $\varLambda$CDM fixed point into quintessence region. However, the evolutionary trajectories of the two models do not overlap. Thus, the six DE models can be distinguished from each other and from the $\varLambda$CDM, CG, quintessence models by using the statefinder diagnostics method.
cpl-40-1-019801-fig3.png
Fig. 3. The local enlargement of Fig. 2.
Om Diagnostics. Another diagnostic tool is often used to distinguish the DE models and to deeply understand the constructed cosmological models, called $Om(z)$ diagnostics.[90,91] $Om(z)$ is defined as \begin{align} Om(z)=\frac{E^{2}(z)-1}{(1+z)^{3}-1}. \tag {30} \end{align}
cpl-40-1-019801-fig4.png
Fig. 4. Evolutions of the six DE models in $Om$–$z $ plots.
The slope of $Om(z)$ can distinguish different DE models. The positive, negative and null slopes of $Om(z)$ correspond to phantom $(w < -1)$, quintessence $(w>-1)$ and $\varLambda$CDM $(w=-1)$ models, respectively. In Fig. 4, we plot the evolution curves of $Om(z)$ to these six DE models by using the best-fit values given in Tables 2 and 3. None of these models have an evolution curve with a null slope. From the evolution trends of these six models in Fig. 4, we find that Models 2–6 are not significantly distinguishable in the early stage, but can be clearly distinguished at $z < 1$. It is obvious that the results of the $Om(z)$ diagnostic are consistent with the statefinder results. Growth Factor. During the evolution of the universe, gravity can increase the amplitude of matter perturbations, especially at the period of matter dominance. DE not only accelerates the expansion of the universe, but also changes the growth rate of matter perturbations. On the other hand, different models possibly give the similar accelerated expansion at late time, but they may produce different growths of matter perturbations.[92-101] Therefore, in addition to using observational data to distinguish DE models, exploring the effect of the DE models on the growth rate of matter perturbations on large scales in the universe is another available way. Here we analyze the types of the six DE models by considering the growth rate of matter density perturbations. Assume that the fluid in the universe satisfies the continuity equation, Euler's equation, and Poisson's equation as follows: \begin{align} &\dot{\rho }+\nabla\cdot (\rho v) =0, \tag {31}\\ &\dot{v}+(v\cdot \nabla) v+\frac{1}{\rho}\nabla p +\nabla \phi =0, \tag {32}\\ &\nabla ^{2}\phi =4\pi G \rho, \tag {33} \end{align} where $\phi$ is the gravitational potential, $\rho$ is the fluid density, $p$ is the pressure, and $v$ is the velocity of fluid motion. Assume that Eqs. (31)-(33) have perturbative solutions $\rho =\rho _{0}+\delta \rho $, $v=v_{0}+\delta v$, $p=p_{0}+\delta p$, $\phi =\phi _{0}+\delta \phi $. Introducing a new quantity $\delta(t,r)=\frac{\delta\rho}{\rho_{\rm m}}=\delta(t){\exp}(ik\cdot x)$ and further assuming that the system is an adiabatic state, one can reach the linear perturbation equation \begin{align} \ddot{\delta }(t)+2H\dot{\delta}(t)-4\pi G \rho _{\rm m}\delta (t) =0. \tag {34} \end{align} From Eqs. (1) and (2), one has the evolutionary equation of the material density parameter $\varOmega_{\rm m}=\frac{\rho_{\rm m}}{3H^{2}}$, \begin{align} \frac{{d}\varOmega_{\rm m}}{d{\ln}a}=3w(1-\varOmega_{\rm m})\varOmega_{\rm m}. \tag {35} \end{align} In general, the growth of perturbation is described by introducing a growth factor \begin{align} f=\frac{d{\ln}\delta_{+}}{d{\ln}a}, \tag {36} \end{align} where $\delta_{+}$ denotes the growth solution of the perturbation equation. Then, using Eqs. (35) and (36), the perturbation equation (34) can be rewritten as \begin{align} \frac{{d}f}{d{\ln}a}+f^{2}+\Big[\frac{1}{2}-\frac{3}{2}(1-\varOmega_{\rm m})w\Big]f=\frac{3}{2}\varOmega_{\rm m}. \tag {37} \end{align} We assume that the perturbation equation has a good approximate solution $f=\varOmega_{\rm m}^{\gamma}$,[93-98] where $\gamma$ is the growth index. Substituting $f=\varOmega_{\rm m}^{\gamma}$ into Eq. (37) yields \begin{align} &3w (1-\varOmega_{\rm m})\varOmega_{\rm m}{\ln}\varOmega_{\rm m}\frac{{d}\gamma }{{d}\varOmega_{\rm m}}-3w \Big(\gamma -\frac{1}{2}\Big)\varOmega_{\rm m}\notag\\ &+\varOmega_{\rm m}^{\gamma}-\frac{3}{2}\varOmega_{\rm m}^{1-\gamma}+3w \gamma-\frac{3}{2}w +\frac{1}{2}=0. \tag {38} \end{align} Ignoring radiation, we have $\varOmega_{\rm m}+\varOmega_{\rm de}=1$. Setting a new variable $x=1-\varOmega_{\rm m}$, taking the Taylor expansion of Eq. (38) near $x=0$ and letting $\gamma=\gamma_{0}+\gamma_{1}x+\gamma_{2}x^{2}+\cdot \cdot\cdot $, we can obtain the growth index as follows:[93,94] \begin{align} \gamma=\,&\frac{3(1-w)}{5-6w }-\frac{3(w -1)(3w -2)}{2(5-6w)^{2}(12w -5)}x\notag\\ &-\frac{(w -1)(-194+1131w -1908w ^{2}+972w ^{3})}{4(5-6w ^{4})(12w -5)} x^{2}\notag\\ &+ o (x^{3}). \tag {39} \end{align} From Eq. (39), it is clear that the value of $\gamma$ is model-dependent. The EoS of the $\varLambda $CDM model is a constant $w=-1$, then $\gamma\approx0.554698$. Based on the best-fit values in Tables 2 and 3, we give the growth index of each model as a function of redshift, as shown in Fig. 5. Furthermore, we plot in Fig. 6 the relative error $\sigma=\frac{f_{{\rm \varLambda CDM}}-f_{\rm Model}}{f_{\rm Model}}$[94] of the growth factor approximation between the $\varLambda $CDM model and all the other DE models. We note that although approximations of $f_{{\rm \varLambda CDM}}$ and $f_{\rm Model}$ are very close to relative errors in the thousands of parts, we can still distinguish the six DE models from the $\varLambda$CDM model.
cpl-40-1-019801-fig5.png
Fig. 5. The evolution of growth index with redshift in different DE models.
cpl-40-1-019801-fig6.png
Fig. 6. Evolution of relative errors of the growth factor approximation between the $\varLambda $CDM model and the different DE models with redshift.
Conclusion and Discussion. In the face of many kinds of DE models, the observation data play an extremely important role to constrain the parameter space of the DE models. In this work, we mainly use two sets of combined data: JLA + CMB + BAO + OHD (JCBH) and Pantheon + CMB + BAO + OHD (PCBH) to constrain the six parameterized DE models. The fitting results of the two combined datasets indicate that Models 3–6 are supported by recent observations, whereas the AIC and BIC results show that $\varLambda$CDM is still the best model. Hence, it is feasible to use the observational data to effectively distinguish and compare the DE models. Comparing the PCBH with the JCBH, we find that, though covering a larger redshift range, the PCBH still has poor constraints and broadens the uncertainty of the model parameters, and is also unable to relieve the $H_{0}$ tension. The reason may be in the precision and the numbers of the observed data. As is known, large redshift data points have larger relative errors than small redshift data points. Therefore, although the PCBH data cover a larger redshift range, they give poor constraints on model parameters (see Ref. [87] for detailed discussion). Then we expect more measurement results to help solve this problem, as mentioned in Ref. [102]. We also use some geometrical methods to distinguish the DE models. By using statefinder and $Om$ diagnostics, we can distinguish the six parameterized models from each other and from the $\varLambda$CDM, CG, and quintessence models. The two diagnostic results are consistent. In addition, we analyze the growth factors of the matter density perturbations of the six DE models and compare them with the $\varLambda$CDM model. The results show that these DE models can be clearly distinguished. Actually, direct parameterization of growth factor or growth index can also be used to understand the properties of DE,[94,103-108] and observational constraints may further distinguish different models. This issue is worth further study in the future by considering new forms of parameterization and using more new observational data. The problems of $H_0$ tension and $\sigma_8$ tension are very important in modern cosmology. In this study, we mainly focus on testing and performing constraints on some parameterized dark energy models with latest data. The $H_0$ tension does not seem to be relieved in these models. The best fitting value for $H_0$ is around 67.84–70.97 with 1$\sigma$ confidence about $\pm 1.0$. It means that one needs some mechanism to alleviate the $H_0$ tension for these models. The root-mean-square amplitude of matter perturbations[109] $\sigma_8$ also has tension between the result from the low-redshift probes such as the weak gravitational lensing and galaxy clustering and the value from CMB observations.[109,110] A way to solve this problem is to introduce a friction between dark matter and dark energy[111] (see Ref. [112] for other possible solutions). The models discussed here are lack of corresponding methods to alleviate this problem. The problems of $H_0$ tension and $\sigma_8$ tension are worthy of deep study for the parameterized dark energy models and we leave them to our next work. Acknowledgment. This work was supported by the National Natural Science Foundation of China (Grant No. 11105091).
References Measurements of Ω and Λ from 42 High‐Redshift SupernovaeObservational Evidence from Supernovae for an Accelerating Universe and a Cosmological ConstantCosmological parameters from SDSS and WMAPCosmological parameter analysis including SDSS Ly α forest and galaxy bias: Constraints on the primordial spectrum of fluctuations, neutrino mass, and dark energyFirst‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Preliminary Maps and Basic ResultsThree‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Implications for CosmologyFirst‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Determination of Cosmological ParametersPlanck early results. XIV. ERCSC validation and extreme radio sourcesPlanck early results. I. The Planck missionPlanck early results. II. The thermal performance of Planck INTRODUCTION TO MODIFIED GRAVITY AND GRAVITATIONAL ALTERNATIVE FOR DARK ENERGYf(R) TheoriesExtended Theories of Gravityf ( T ) teleparallel gravity and cosmologyThe Cosmological ConstantThe cosmological constant and dark energyThe dark UniverseDYNAMICS OF DARK ENERGYDark EnergyDark energy: A brief reviewDark Energy and the Accelerating UniverseDARK ENERGY: RECENT DEVELOPMENTSArticle identifier not recognizedInteracting phantom energyCosmological evolution of interacting phantom energy with dark matterProbing the coupling between dark components of the universeReconstructing the interaction between dark energy and dark matter using Gaussian processesCosmological consequences of a rolling homogeneous scalar fieldQuintessence, Cosmic Coincidence, and the Cosmological ConstantRobustness of quintessenceQuintessence arising from exponential potentialsPerturbations in k-inflationA phantom menace? Cosmological consequences of a dark energy component with super-negative equation of statePhantom Energy: Dark Energy with w < 1 Causes a Cosmic DoomsdayEffective equation of state for dark energy: Mimicking quintessence and phantom energy through a variable ΛQuintessence or phantom: Study of scalar field dark energy models through a general parametrization of the Hubble parameterObservational constraints on one-parameter dynamical dark-energy parametrizations and the H 0 tensionA model of the universe free of cosmological problemsA critical density cosmological model with varying gravitational and cosmological ?constants?LRS Bianchi type-I models with a time-dependent cosmological “constant”Study of the Magnitude-Redshift Relation for Type Ia Supernovae in a Model Resulting from a Ricci-SymmetryFriedman—Robertson—Walker Models with Late-Time AccelerationOn the simultaneous variation of some cosmological parameters in the presence of interacting dark energyA new parametrization for dark energy density and future decelerationCan dark energy be expressed as a power series of the Hubble parameter?Is there supernova evidence for dark energy metamorphosis?The case for dynamical dark energy revisitedA Model‐Independent Determination of the Expansion and Acceleration Rates of the Universe as a Function of Redshift and Constraints on Dark EnergyDirect Determination of the Kinematics of the Universe and Properties of the Dark Energy as Functions of RedshiftOBSERVATIONAL CONSTRAINTS ON DARK ENERGY MODELNo evidence for dark energy metamorphosis?Rejoinder to "No Evidence of Dark Energy Metamorphosis", astro-ph/0404468Opportunities for Future Supernova Studies of Cosmic AccelerationProbing dark energy: Methods and strategiesFuture supernovae observations as a probe of dark energyCan luminosity distance measurements probe the equation of state of dark energy?ACCELERATING UNIVERSES WITH SCALING DARK MATTERExploring the Expansion History of the UniverseCosmological parameters from supernova observations: A critical comparison of three data setsDark energy constraints from the cosmic age and supernovaModel-independent analysis of dark energy: supernova fitting resultProbing the curvature and dark energyObservational Constraints on Dynamical Dark Energy with Pivoting RedshiftModel selection applied to non-parametric reconstructions of the Dark EnergyWMAP constraints on low redshift evolution of dark energyA new class of parametrization for dark energy without divergenceBarotropic fluid compatible parametrizations of dark energyDark energy models from a parametrization of H: a comprehensive analysis and observational constraintsThe Complete Light-curve Sample of Spectroscopically Confirmed SNe Ia from Pan-STARRS1 and Cosmological Constraints from the Combined Pantheon SampleImproved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samplesInvestigating the relationship between cosmic curvature and dark energy models with the latest supernova sampleComparing the scalar-field dark energy models with recent observationsPlanck 2018 resultsThe 6dF Galaxy Survey: baryon acoustic oscillations and the local Hubble constantThe clustering of the SDSS DR7 main Galaxy sample – I. A 4 per cent distance measure at z = 0.15The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from DR12 galaxy clustering – towards an accurate modelHow predictions of cosmological models depend on Hubble parameter data setsA new look at the statistical model identificationEstimating the Dimension of a ModelCosmological evolution of a quintom model of dark energyTwo-field quintom models in the w w planeBayes FactorsComparison of dark energy models after Planck 2015Observational constraints on the oscillating dark energy cosmologiesMeasuring Dark Energy Properties with Photometrically Classified Pan-STARRS Supernovae. II. Cosmological ParametersSoundness of dark energy propertiesExploring the expanding Universe and dark energy using the statefinder diagnosticStatefinder—A new geometrical diagnostic of dark energyTwo new diagnostics of dark energyConsistency Tests for the Cosmological ConstantHow to determine an effective potential for a variable cosmological termCluster Abundance Constraints for Cosmological Models with a Time‐varying, Spatially Inhomogeneous Energy Component with Negative PressureGrowth factor parametrization in curved spaceDynamical measures of density in exotic cosmologiesDecaying Λ cosmologies and power spectrumGrowth factor parametrization and modified gravityThe growth of matter perturbations in some scalar–tensor DE modelsTesting Λ CDM with the growth function δ ( a ) : Current constraintsWhen is the growth index constant?LSST: From Science Drivers to Reference Design and Anticipated Data ProductsA parametrization for the growth index of linear matter perturbationsImproved parametrization of the growth index for dark energy and DGP modelsA parametrization of the growth index of matter perturbations in various Dark Energy models and observational prospects using a Euclid-like surveyGCG parametrization for growth function and current constraintsGrowth of perturbations in dark energy parametrization scenariosThe growth factor parametrization versus numerical solutions in flat and non-flat dark energy modelsOn the Tension between Large Scale Structures and Cosmic Microwave BackgroundThe Sigma-8 Tension is a DragEarly or phantom dark energy, self-interacting, extra, or massive neutrinos, primordial magnetic fields, or a curved universe: An exploration of possible solutions to the $H_0$ and $σ_8$ problems
[1] Perlmutter S et al. [Supernova Cosmology Project] 1999 Astrophys. J. 517 565
[2] Riess A G et al. [Supernova Search Team] 1998 Astron. J. 116 1009
[3] Tegmark M et al. [SDSS] 2004 Phys. Rev. D 69 103501
[4] Seljak U et al. [SDSS] 2005 Phys. Rev. D 71 103515
[5] Bennett C L et al. [WMAP] 2003 Astrophys. J. Suppl. 148 1
[6] Spergel D N et al. [WMAP] 2007 Astrophys. J. Suppl. 170 377
[7] Spergel D N et al. [WMAP] 2003 Astrophys. J. Suppl. 148 175
[8] Ade P A R et al. [Planck] 2011 Astron. Astrophys. 536 A14
[9] Ade P A R et al. [Planck] 2011 Astron. Astrophys. 536 A1
[10] Ade P A R et al. [Planck] 2011 Astron. Astrophys. 536 A2
[11]Nojiri S and Odintsov S D 2006 Int. J. Geometr. Methods Mod. Phys. 04 115
[12] De Felice A and Tsujikawa S 2010 Living Rev. Relativ. 13 3
[13] Capozziello S and De Laurentis M 2011 Phys. Rep. 509 167
[14] Cai Y F, Capozziello S, De Laurentis M, and Saridakis E N 2016 Rept. Prog. Phys. 79 106901
[15] Carroll S M 2001 Living Rev. Relativ. 4 1
[16] Peebles P J E and Ratra B 2003 Rev. Mod. Phys. 75 559
[17] Bartelmann M 2010 Rev. Mod. Phys. 82 331
[18]Sahni V 2004 Lecture Notes in Physics (Berlin: Springer) vol 653 p 141
[19] Copeland E J, Sami M, and Tsujikawa S 2006 Int. J. Mod. Phys. D 15 1753
[20] Li M, Li X D, Wang S, and Wang Y 2011 Commun. Theor. Phys. 56 525
[21] Li M, Li X D, Wang S, and Wang Y 2013 Front. Phys. 8 828
[22] Frieman J, Turner M, and Huterer D 2008 Ann. Rev. Astron. Astrophys. 46 385
[23] Straumann N 2006 Mod. Phys. Lett. A 21 1083
[24] Weinberg S 2000 arXiv: astro-ph/0005265
[25] Guo Z K and Zhang Y Z 2005 Phys. Rev. D 71 023501
[26]Guo Z K, Cai R G, and Zhang Y Z 2005 J. Cosmol. Astropart. Phys. 2005(05) 002
[27] Guo Z K, Ohta N, and Tsujikawa S 2007 Phys. Rev. D 76 023508
[28] Yang T, Guo Z K, and Cai R G 2015 Phys. Rev. D 91 123533
[29] Ratra B and Peebles P J E 1988 Phys. Rev. D 37 3406
[30] Zlatev I, Wang L M, and Steinhardt P J 1999 Phys. Rev. Lett. 82 896
[31] Brax P and Martin J 2000 Phys. Rev. D 61 103502
[32] Barreiro T, Copeland E J, and Nunes N J 2000 Phys. Rev. D 61 127301
[33] Garriga J and Mukhanov V F 1999 Phys. Lett. B 458 219
[34] Caldwell R R 2002 Phys. Lett. B 545 23
[35] Caldwell R R, Kamionkowski M, and Weinberg N N 2003 Phys. Rev. Lett. 91 071301
[36] Sol̀a J and Štefančić H 2005 Phys. Lett. B 624 147
[37] Roy N, Goswami S, and Das S 2022 Phys. Dark Univ. 36 101037
[38] Yang W, Pan S, Di Valentino E, Saridakis E N, and Chakraborty S 2019 Phys. Rev. D 99 043543
[39] Özer M and Taha M O 1987 Nucl. Phys. B 287 776
[40] Abdel-Rahman A M M 1990 Gen. Rel. Gravit. 22 655
[41] Vishwakarma R G, A, and Beesham A 1999 Phys. Rev. D 60 063507
[42] Vishwakarma R G 2001 Gen. Rel. Gravit. 33 1973
[43] A and Prajapati S R 2011 Chin. Phys. Lett. 28 029803
[44] Pacif S K J and A 2014 Eur. Phys. J. Plus 129 244
[45] Mamon A A 2018 Mod. Phys. Lett. A 33 1850113
[46] Rezaei M, Malekjani M, and Sola J 2019 Phys. Rev. D 100 023539
[47] Alam U, Sahni V, Saini T D, and Starobinsky A A 2004 Mon. Not. Roy. Astron. Soc. 354 275
[48] Alam U, Sahni V, and Starobinsky A A 2004 J. Cosmol. Astropart. Phys. 2004(06) 008
[49] Daly R A and Djorgovski S G 2003 Astrophys. J. 597 9
[50] Daly R A and Djorgovski S G 2004 Astrophys. J. 612 652
[51] Gong Y G 2012 Int. J. Mod. Phys. D 14 599
[52]Jonsson J, Goobar A, Amanullah R, and Bergstrom L 2004 J. Cosmol. Astropart. Phys. 2004(09) 007
[53] Alam U, Sahni V, Saini T D, and Starobinsky A A 2004 arXiv:astro-ph/0406672 [astro-ph]
[54] Weller J and Albrecht A 2001 Phys. Rev. Lett. 86 1939
[55] Huterer D and Turner M S 2001 Phys. Rev. D 64 123527
[56] Weller J and Albrecht A 2002 Phys. Rev. D 65 103512
[57] Astier P 2001 Phys. Lett. B 500 8
[58] Chevallier M and Polarski D 2001 Int. J. Mod. Phys. D 10 213
[59] Linder E V 2003 Phys. Rev. Lett. 90 091301
[60] Choudhury T R and Padmanabhan T 2005 Astron. Astrophys. 429 807
[61] Feng B, Wang X L, and Zhang X M 2005 Phys. Lett. B 607 35
[62] Gong Y G 2005 Class. Quantum Grav. 22 2121
[63] Gong Y G and Zhang Y Z 2005 Phys. Rev. D 72 043518
[64] Yang W, Pan S, Di Valentino E, and Saridakis E N 2019 Universe 5 219
[65] Escamilla L A, and Vazquez J A 2021 arXiv:2111.10457 [astro-ph.CO]
[66]Jassal H K, Bagla J S, and Padmanabhan T 2005 Mon. Not. Roy. Astron. Soc. 356 L11
[67]Feng C J, Shen X Y, Li P, and Li X Z 2012 J. Cosmol. Astropart. Phys. 2012(09) 023
[68] Perković D and Štefančić H 2020 Eur. Phys. J. C 80 629
[69] Pacif S K J 2020 Eur. Phys. J. Plus 135 792
[70] Scolnic D M et al. [Pan-STARRS1] 2018 Astrophys. J. 859 101
[71] Betoule M et al. [SDSS] 2014 Astron. Astrophys. 568 A22
[72] Gao C, Chen Y, and Zheng J 2020 Res. Astron. Astrophys. 20 151
[73] Xu T, Chen Y, Xu L, and Cao S 2022 Phys. Dark Univ. 36 101023
[74] Aghanim N et al. [Planck] 2020 Astron. Astrophys. 641 A5
[75] Beutler F, Blake C, Colless M, Jones D H, Staveley-Smith L, Campbell L, Parker Q, Saunders W, and Watson F 2011 Mon. Not. Roy. Astron. Soc. 416 3017
[76] Ross A J, Samushia L, Howlett C, Percival W J, Burden A M M 2015 Mon. Not. Roy. Astron. Soc. 449 835
[77] Chuang C H et al. [BOSS] 2017 Mon. Not. Roy. Astron. Soc. 471 2370
[78]Sharov G S and Vasiliev V O 2018 Math. Model. Geom. 6 1
[79]Akaike H 1974 IEEE Trans. Automat. Control 19 716
[80] Schwarz G 1978 Ann. Statist. 6 461
[81] Guo Z K, Piao Y S, Zhang X M, and Zhang Y Z 2005 Phys. Lett. B 608 177
[82] Guo Z K, Piao Y S, Zhang X M, and Zhang Y Z 2006 Phys. Rev. D 74 127304
[83] Kass R E and Raftery A E 1995 J. Am. Statist. Assoc. 90 773
[84] Xu Y Y and Zhang X 2016 Eur. Phys. J. C 76 588
[85] Rezaei M 2019 Mon. Not. Roy. Astron. Soc. 485 550
[86] Jones D O, Scolnic D M, Riess A G et al. 2018 Astrophys. J. 857 51
[87] Di Valentino E, Gariazzo S, Mena O, and Vagnozzi S 2020 J. Cosmol. Astropart. Phys. 2020(07) 045
[88] Alam U, Sahni V, Saini T D, and Starobinsky A A 2003 Mon. Not. Roy. Astron. Soc. 344 1057
[89] Sahni V, Saini T D, Starobinsky A A, and Alam U 2003 JETP Lett. 77 201
[90] Sahni V, Shafieloo A, and Starobinsky A A 2008 Phys. Rev. D 78 103502
[91] Zunckel C and Clarkson C 2008 Phys. Rev. Lett. 101 181301
[92] Starobinsky A A 1998 JETP Lett. 68 757
[93] Wang L M and Steinhardt P J 1998 Astrophys. J. 508 483
[94] Gong Y G, Ishak M, and Wang A Z 2009 Phys. Rev. D 80 023002
[95]Peebles P J E 1980 The Whole Truth: A Cosmologist's Reflections on the Search for Objective Reality (New Jersey: Princeton University Press)
[96] Fry J N 1985 Phys. Lett. B 158 211
[97] Silveira V and Waga I 1994 Phys. Rev. D 50 4890
[98] Gong Y G 2008 Phys. Rev. D 78 123010
[99] Gannouji R and Polarski D 2008 J. Cosmol. Astropart. Phys. 2008(05) 018
[100] Nesseris S and Perivolaropoulos L 2008 Phys. Rev. D 77 023504
[101] Polarski D, Starobinsky A A, and Giacomini H 2016 J. Cosmol. Astropart. Phys. 2016(12) 037
[102] Ivezić Ž, Kahn S M, Tyson J A et al. [LSST] 2019 Astrophys. J. 873 111
[103]Wu P, Yu H W, and Fu X 2009 J. Cosmol. Astropart. Phys. 2009(06) 019
[104] Jing J L and Chen S B 2010 Phys. Lett. B 685 185
[105]Bueno B A, Garcia-Bellido J, and Sapone D 2011 J. Cosmol. Astropart. Phys. 2011(10) 010
[106]Gupta G, Sen S, and Sen A A 2012 J. Cosmol. Astropart. Phys. 2012(04) 028
[107] Mehrabi A 2018 Phys. Rev. D 97 083522
[108] Velásquez-Toribio A M and Fabris J C 2020 Eur. Phys. J. C 80 1210
[109]Aghanim N, Akrami Y, Ashdown M et al. [Planck] 2020 Astron. Astrophys. 641 A6 [Erratum: Astron. Astrophys. 652 C4]
[110]Douspis M, Salvati L, and Aghanim N 2018 Proc. Sci. 335 037
[111] Poulin V, Bernal J L, Kovetz E, and Kamionkowski M 2022 arXiv:2209.06217 [astro-ph.CO]
[112] Escudero H G, Kuo J L, Keeley R E, and Abazajian K N 2022 arXiv:2208.14435 [astro-ph.CO]