arXiv subjects

Dorian Araya

Publications and source records attributed to Dorian Araya.

4 recordsLinked to original sources

arXiv2026

Cosmological evolution of interacting dark energy with a CPL equation of state

This paper examines interacting dark energy models within the Chevallier-Polarski-Linder (CPL) parametrization, emphasizing both theoretical structure and observational viability. Two commonly adopted interaction terms are considered: $Q = \beta H \rho_{de}$ and $Q = \beta H \rho_c$. We derive exact analytic solutions that describe how the dark sector evolves. These solutions involve incomplete gamma functions and reveal a non-trivial mathematical structure that is often missed in numerical analyses. We perform a Bayesian analysis using current cosmological observations, including the Hubble parameter (OHD), Type Ia supernovae (SNIa), baryon acoustic oscillations (BAO), and cosmic microwave background (CMB) data. Relative to the non-interacting CPL scenario, the interacting model with $Q = \beta H \rho_{de}$ yields a modestly improved fit, as indicated by the Akaike Information Criterion (AIC). However, the Bayesian Information Criterion (BIC) penalizes increased model complexity, leading to a continued preference for $\Lambda$CDM. In contrast, the interaction model that depends on dark matter density does not provide observational support. The preferred interacting scenario indicates that the dark energy equation of state evolves dynamically, transitioning from an effective phantom regime at high redshift to quintessence-like behavior at late times. Further analysis indicates the potential for a transient phase of cosmic acceleration in the future. These findings suggest that interacting dark energy models within the CPL framework enrich the standard cosmological model by introducing more diverse phenomenology while maintaining consistency with current observations.

astro-ph.CO↗

arXiv2025

Cosmological dynamics and observational constraints of an interacting early scalar field coupled to radiation

We study the cosmic evolution of an interacting scalar field radiation model, in which a minimally coupled scalar field exchanges energy with the radiation sector through an exponential coupling. Extending previous formulations, a non-relativistic matter component is included explicitly, which allows a self consistent description of cosmological dynamics from the radiation-dominated era to late-time acceleration. Analytical expressions for the background expansion are derived and characterized using kinematic diagnostics. We constrain the model using observational Hubble data, Type Ia Supernovae, baryon acoustic oscillations (including DESI DR2), and compressed cosmic microwave background distance information, performing a Bayesian MCMC analysis. The interaction parameter is found to be consistent with zero, though small deviations from standard radiation scaling are allowed. These deviations can partially alleviate the Hubble tension by modifying the sound horizon, but this is accompanied by correlated shifts in the matter density. The reconstructed expansion history remains close to LCDM at late times. Model comparison suggest that the interacting scenario is statistically competitive but not decisively preferred by current background data.

astro-ph.CO↗

arXiv2025

Extended datasamples under the lens of Brane World Theory

This work revises the Brane World Theory known as Randall-Sundrum with the modification of an exponential, redshift-dependent brane tension. This model is studied in a scenario assuming no dark energy, with the aim of determining whether it can reproduce the universe's acceleration on its own, without the addition of a dark energy fluid. Bayesian statistical analysis is performed in order to constrain the free parameters of each scenario using SLS, SNIa, OHD, and BAO data samples, the last two considering newly added data points. Both Planck and Riess priors for h are used and compared. In both cases, we are able to reproduce the late-time accelerated expansion in agreement with observational data. Interesting consistencies at the transition redshift zt with LCDM are found, suggesting that this might be a suitable model for studying the evolution of the universe up to the present date. However, some pathologies are detected in this model, namely a "Big Rip" divergence of H(z) at z = 1, as well as a strong dependence between the functional form of the brane tension and the future evolution of the universe.

astro-ph.CO↗

arXiv2025

$w_{dm}$-$w_{de}$ cosmological model with new data samples of cosmological observations

We revisit a cosmological model where dark matter (DM) and dark energy (DE) follow barotropic equations of state, allowing deviations from the standard $\Lambda$CDM framework (i.e. $w_{dm} \neq 0$, $w_{de} \neq -1$), considering both flat and non-flat curvature. Using a dynamical system approach, we identify equilibrium states that govern stability, expansion, and contraction. Expansion occurs when $H>0$, while contraction is linked to $H < 0$. Accelerated expansion arises from DE dominance, whereas radiation- and matter-dominated phases lead to deceleration. Some solutions are unphysical due to density constraints, but viable cases offer insights into cosmic transitions, including the Einstein static universe, which allows for shifts between accelerating and decelerating phases. We perform a Bayesian analysis with updated datasets, including observational Hubble data, Pantheon+ Type Ia supernovae, strong lensing systems, baryon acoustic oscillations and cosmic microwave background, to constrain the parameters $w_{dm}$ and $w_{de}$. Our results from the data joint analysis show consistency with $\Lambda$CDM within $3\sigma$, but none of the cases reproduce $w_{dm} = 0$ and $w_{de} = -1$. Nevertheless, the comparison with the standard model using the Akaike and Bayesian information criteria indicates that only the non-flat scenario has the potential to be competitive. This suggests that a non-dust-like DM may impact structure formation, while DE could shift toward quintessence fluid. While $\Lambda$CDM remains a strong model, our findings indicate that alternative dark sector models with non-standard EoS could be viable and offer new insights into cosmic evolution.

astro-ph.CO↗