Late time cosmic acceleration from natural infrared cutoff

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• 作者：Mohammad Ali Gorji ^{m.gorji@stu.umz.ac.ir" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Phenomenology of quantum gravity ; Dark energy
• 刊名：Physics Letters B
• 出版年：2016
• 出版时间：10 September 2016
• 年：2016
• 卷：760
• 期：Complete
• 页码：769-774
• 全文大小：355 K

文摘

In this paper, inspired by the ultraviolet deformation of the Friedmann–Lemaître–Robertson–Walker geometry in loop quantum cosmology, we formulate an infrared-modified cosmological model. We obtain the associated deformed Friedmann and Raychaudhuri equations and we show that the late time cosmic acceleration can be addressed by the infrared corrections. As a particular example, we applied the setup to the case of matter dominated universe. This model has the same number of parameters as ΛCDM, but a dynamical dark energy generates in the matter dominated era at the late time. According to our model, as the universe expands, the energy density of the cold dark matter dilutes and when the Hubble parameter approaches to its minimum, the infrared effects dominate such that the effective equation of state parameter smoothly changes from w_eff=0$w_{\mathrm{eff}}=0$ to w_eff=−2$w_{\mathrm{eff}}=-2$. Interestingly and nontrivially, the unstable de Sitter phase with w_eff=−1$w_{\mathrm{eff}}=-1$ is corresponding to 90cd9e8c03d52a4" title="Click to view the MathML source">Ω_m=Ω_d=0.5${\mathrm{\Omega }}_m={\mathrm{\Omega }}_d=0.5$ and the universe crosses the phantom divide from the quintessence phase with w_eff>−1$w_{\mathrm{eff}}>-1$ and Ω_m>Ω_d${\mathrm{\Omega }}_m>{\mathrm{\Omega }}_d$ to the phantom phase with w_eff<−1$w_{\mathrm{eff}}<-1$ and c1137da0e7e16623ffcc359e" title="Click to view the MathML source">Ω_m<Ω_d${\mathrm{\Omega }}_m<{\mathrm{\Omega }}_d$ which shows that the model is observationally viable. The results show that the universe finally ends up in a big rip singularity for a finite time proportional to the inverse of the minimum of the Hubble parameter. Moreover, we consider the dynamical stability of the model and we show that the universe starts from the matter dominated era at the past attractor with w_eff=0$w_{\mathrm{eff}}=0$ and ends up in a future attractor at the big rip with w_eff=−2$w_{\mathrm{eff}}=-2$.