Browsing by Author "Leon, Genly"

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    Barrow Entropy Cosmology: an observational approach with a hint of stability analysis
    (2021) Leon, Genly; Magana, Juan; Hernandez-Almada, A.; Garcia-Aspeitia, Miguel A.; Verdugo, Tomas; Motta, V
    In this work, we use an observational approach and dynamical system analysis to study the cosmological model recently proposed by Saridakis (2020), which is based on the modification of the entropy-area black hole relation proposed by Barrow (2020). The Friedmann equations governing the dynamics of the Universe under this entropy modifica-tion can be calculated through the gravity-thermo dynamics conjecture. We investigate two models, one considering only a matter component and the other including matter and ra-diation, which have new terms compared to the standard model sourcing the late cosmic acceleration. A Bayesian analysis is performed in which using five cosmological observations (observational Hubble data, type Ia supernovae, HII galaxies, strong lensing systems, and baryon acoustic oscillations) to constrain the free parameters of both models. From a joint analysis, we obtain constraints that are consistent with the standard cosmological paradigm within 2a-confidence level. In addition, a complementary dynamical system analysis using local and global variables is developed which allows obtaining a qualitative description of the cosmology. As expected, we found that the dynamical equations have a de Sitter solution at late times.
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    Generalized emergent dark energy: observational Hubble data constraints and stability analysis
    (2020) Hernandez-Almada, A.; Leon, Genly; Magana, Juan; Garcia-Aspeitia, Miguel A.; Motta, V
    Recently, a phenomenologically emergent dark energy (PEDE) model was presented with a dark energy density evolving as (Omega) over tilde (DE)(z) = Omega(DE,0)[1 - tanh(log(10)(1 + z))], i.e. with no degree of freedom. Later on, a generalized model was proposed by adding one degree of freedom to the PEDE model, encoded in the parameter Delta. Motivated by these proposals, we constrain the parameter space (h, Omega((0))(m)) and (h, Omega((0))(m), Delta) for PEDE and generalized emergent dark energy (GEDE), respectively, by employing the most recent observational (non-)homogeneous and differential age Hubble data. Additionally, we reconstruct the deceleration and jerk parameters and estimate yield values at z = 0 of q(0) = -0.784(-0.027)(+0.028) and j(0) = 1.241(-0.149)(+0.164) for PEDE and q(0) = -0.730(-0.067)(+0.059) and j(0) = 1.293(-0.187)(+0.194) for GEDE using the homogeneous sample. We report values on the deceleration-acceleration transition redshift with those reported in the literature within 2 sigma CL. Furthermore, we perform a stability analysis of the PEDE and GEDE models to study the global evolution of the Universe around their critical points. Although the PEDE and GEDE dynamics are similar to the standard model, our stability analysis indicates that in both models there is an accelerated phase at early epochs of the Universe evolution.
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    Kaniadakis-holographic dark energy: observational constraints and global dynamics
    (2022) Hernandez-Almada, A.; Leon, Genly; Magana, Juan; Garcia-Aspeitia, Miguel A.; Motta, V; Saridakis, Emmanuel N.; Yesmakhanova, Kuralay
    We investigate Kaniadakis-holographic dark energy by confronting it with observations. We perform a Markov Chain Monte Carlo analysis using cosmic chronometers, supernovae type Ia, and Baryon Acoustic Oscillations data. Concerning the Kaniadakis parameter, we find that it is constrained around zero, namely around the value in which Kaniadakis entropy recovers standard Bekenstein-Hawking one. Additionally, for the present matter density parameter Omega((0))(m), we obtain a value slightly smaller compared to Lambda CDM scenario. Furthermore, we reconstruct the evolution of the Hubble, deceleration, and jerk parameters extracting the deceleration-acceleration transition redshift as z(T) = 0.86(-0.14)(+0.21). Finally, performing a detailed local and global dynamical system analysis, we find that the past attractor of the Universe is the matter-dominated solution, while the late-time stable solution is the dark-energy-dominated one.