arXiv subjects

Luis A. Escamilla

Publications and source records attributed to Luis A. Escamilla.

At least 19 recordsLinked to original sources

arXiv2026

One-parameter dynamical dark energy: Hints for oscillations

There is mounting evidence from multiple cosmological probes that dark energy may be dynamical, with an equation of state that evolves over cosmic time. While this evidence is typically quantified using the Chevallier-Polarski-Linder (CPL) parametrization, based on a linear expansion of $w(a)$ in the scale factor, non-parametric reconstructions frequently suggest non-linear features, particularly at late times. In this work, we investigate four minimal one-parameter models of dark energy with non-linear dependence on the scale factor. These models are constrained using Cosmic Microwave Background (CMB) data from Planck, lensing reconstruction from ACT-DR6, Baryon Acoustic Oscillation (BAO) measurements from DESI-DR2, and three Type-Ia supernovae (SNe) samples (PantheonPlus, DESY5, and Union3), considered independently. Although our conclusions depend on the choice of SNe sample, we consistently find a preference, as measured by the chi-squared statistic and the Bayesian evidence, for these dynamical dark energy models over the standard $Λ$CDM model. Notably, with the PantheonPlus dataset, one model shows strong Bayesian evidence ($Δ\ln B \simeq 4.5$) against CPL, favoring an equation of state that peaks near $a \simeq 0.7$ and oscillates near the present day. These results highlight the impact of SNe selection and contribute to the growing collection of evidence for late-time deviations from $Λ$CDM.

astro-ph.CO↗

arXiv2026

Hubble tension: the shape wall

The standard "no-go theorem" against late-time solutions to the Hubble tension is essentially a normalization wall, since Baryon Acoustic Oscillation (BAO) measurements constrain the product $H_0r_d$, with $r_d$ the sound horizon at baryon drag. However, late-time solutions (which keep $r_d$ fixed) are tightly constrained not only by the BAO normalization $H_0r_d$, but also by the shape of the expansion history, i.e. the dimensionless expansion rate $E(z) \equiv H(z)/H_0$. We show that, if $r_d$ and the acoustic angular scale $θ_s$ are fixed, an increase in $H_0$ needs to be matched by an equal fractional increase in the dimensionless distance integral $I \equiv \int dz/E(z)$: $δH_0/H_0 \simeq δI/I$. We use this to quantify the "shape wall" set by relative distance constraints on $E(z)$, which we reconstruct nonparametrically, using Gaussian Processes and the latest unanchored Type Ia Supernovae (SNeIa) and BAO data. In our most conservative analysis using PantheonPlus SNeIa and DESI DR2 BAO data, we find a maximum fractional increase in $H_0$ of $\lesssim 2\%$, falling well short of the $\gtrsim 8\%$ required to solve the tension. This shape wall holds even in the presence of early-time new physics, and limits the maximum increase in $H_0$ which can be contributed by late-time modifications to $E(z)$ at fixed $θ_s$. Therefore, late-time modifications, whether invoked alone or alongside early-time new physics, face not only the well-known normalization wall, but also a stringent percent-level shape wall.

astro-ph.CO↗

arXiv2026

Testing Matter Diffusion with Late-Time Cosmological Observations

We investigate a class of late-time cosmological models derived from the phenomenological framework of variable matter diffusion. In these scenarios, energy-momentum conservation requires a continuous energy exchange between matter and an effective scalar-field dark-energy component, $ϕ$. We consider a baseline constant-diffusion scenario alongside four non-linear power-law parametrizations, in which the diffusion coefficient evolves as a function of the scale factor, matter density, scalar-field density, or Hubble expansion rate. To assess their cosmological viability, we implement these models within \texttt{SimpleMC} and constrain them using late-time observations, including cosmic chronometers, baryon acoustic oscillation measurements, Type Ia supernovae with and without the local SH0ES calibration. In the absence of the local calibration, the diffusion models yield only modest improvements in the fit ($Δχ^2 \approx -4$), performing comparably to the CPL parametrization while exhibiting negative Bayesian log-evidence differences relative to $Λ$CDM. In contrast, including SH0ES leads to a dramatic reduction in the minimum $χ^2$ ($Δχ^2 \approx -22$) and decisive Bayesian evidence in favor of the diffusion framework ($Δ\ln\mathcal{Z} \approx 9$). Remarkably, the single-parameter constant-diffusion model accounts for virtually all the statistical improvement, outperforming the CPL parametrization by more than 10 units in $χ^2$ and more than 8 units in $Δ\ln\mathcal{Z}$. The four non-linear extensions provide only negligible additional improvements ($Δχ^2 \approx -1$), indicating that current late-time background observations favor the presence of a non-vanishing matter-diffusion interaction over $Λ$CDM, while providing no statistically significant evidence for a specific time-dependent functional form of the diffusion coefficient.

astro-ph.CO↗

arXiv2026

Modifying $Λ$CDM dynamics via out-of-equilibrium axions: reconciling SH0ES and DESI $H_0$ values

We investigate late-Universe dynamics in which the dark matter component is described by axion particles. The proposed framework departs from the standard $Λ$CDM paradigm due to a small fraction of axions driving the system away from thermal equilibrium. We analyze the evolution of the axion energy density using both a kinetic and a classical field approach, yielding an identical macroscopic evolution equation for the dark matter density. We emphasize that the BGK parameter is introduced phenomenologically at the kinetic level and this does not supply an independent microscopic derivation. The present work therefore explores the phenomenological consequences of late-time, out-of-equilibrium axion production rather than claiming a completed microphysical model. The resulting scenario modifies $Λ$CDM dynamics in the late Universe (specifically at $z \lesssim 1$), while asymptotically recovering the standard baseline at earlier cosmic epochs. We compare the theoretical predictions of our formulation against a comprehensive suite of late-Universe datasets. Our statistical analysis reveals that when the SH0ES local calibration is included, the collisional axion model becomes significantly favored over $Λ$CDM, yielding a best-fit Hubble constant of $H_0 \simeq 73~{\rm km\,s^{-1}\,Mpc^{-1}}$. Ultimately, this cosmological scenario successfully accommodates local distance-ladder measurements while maintaining excellent agreement with Baryon Acoustic Oscillation data from the DESI Collaboration.

astro-ph.CO↗

arXiv2026

Reconstructing dark energy with fewer assumptions

We perform minimalistic reconstructions of the dark energy density and equation of state using late-time distance measurements. Our methodology avoids assumptions that correlate the values of these functions over time and instead yields their approximate average evolution within seven redshift bins from $z=0$ to $z=4.2$. Constraints are obtained using combinations of BAO measurements from DESI and SDSS, alongside Type Ia supernovae measurements from Pantheon+ and the latest recalibrated samples, Union3.1 and DES-Dovekie. Only an acoustic scale prior is included from the CMB so that our results are insensitive to the possible matter density tension between early and late-time probes. All combinations yield consistent reconstructed histories: a dark energy density that rises to a local maximum before decreasing at late times and an equation of state with two apparent oscillations around the cosmological constant limit. Both functions tentatively suggest a phantom crossing in the equation of state around $z\sim0.6$-$0.8$. These patterns are robust to numerous parameter extensions, such as freely varying spatial curvature and neutrino mass, and they persist in the uncorrelated amplitudes obtained through localized principal component analysis. Deviations from $Λ$CDM in individual bins reach a maximum significance of $\sim2.6$-$3σ$, while the total chi-square difference between the reconstructions and this model provides up to $\sim2σ$ support for the seven additional parameters in the reconstructions. As these significances remain moderate, our main result is the level of consistency between combinations of the most widely used background-level observations. Our results suggest that the dark energy evolution signal is a persistent feature of the data and that it cannot be explained solely by fluctuations or systematics in individual measurements.

astro-ph.CO↗

arXiv2026

Revisiting the Matter Creation Process: Observational Constraints on Gravitationally Induced Dark Energy and the Hubble Tension

The Hubble tension and the unknown origin of dark energy motivate the exploration of alternative mechanisms for late-time cosmic acceleration. We investigate gravitationally induced particle creation (PC) as a non-equilibrium process that can effectively mimic dynamical dark energy. Within the thermodynamic framework of open systems, we adopt an agnostic approach to the extra created component, leaving its equation-of-state parameter $w_E$ free. We consider four phenomenological parametrisations of the PC rate, allowing deviations from the standard cosmological model ($Λ$CDM) only at late times ($0<z<3$). The PC models are constrained using a joint analysis of cosmic chronometers, Type Ia supernovae, local $H_0$ measurements, baryon acoustic oscillations, and cosmic microwave background data. The constraints on $w_E$ are consistent with dark energy, while particle creation of pressureless matter is disfavoured. All PC scenarios provide fits comparable to $Λ$CDM, with one showing effective dynamical dark-energy behaviour. When early- and late-time datasets are analysed separately, the PC models reduce the Hubble tension to $\simeq 2.4\,σ$--$3\,σ$, compared to $4.3\,σ$ in $Λ$CDM. Gravitationally induced dark energy thus offers a consistent late-time extension of $Λ$CDM and a viable theoretical framework for dynamical dark energy.

astro-ph.CO↗

arXiv2026

Do equation of state parametrizations of dark energy faithfully capture the dynamics of the late universe?

We investigate how strongly late-time inferences about DE dynamics depend on the functional prior used to represent the expansion history. Using identical late-time combinations of CC, DESI BAO measurements, the Pantheon+ SN1a sample, and the H0DN prior, we compare a node-based reconstruction of the reduced Hubble function $E(z)$ with a representative family of smooth low-dimensional DE EoS parametrizations, including CPL. Over the redshift range constrained by the data, both approaches yield consistent $H(z)$, and, in the absence of H0DN, compatible values of $H_0$. However, a clear method dependence emerges at intermediate redshift ($z\sim1.7$): the reconstruction favors stronger deceleration, $q_{\rm Rec}(1.7)\simeq0.56-0.61$, whereas the smooth parametrizations cluster at $q(1.7)\simeq0.32-0.40$, implying a persistent $\sim2-3σ$ discrepancy across dataset combinations and parametrizations. For the EoS-based parametrizations, whose effective DE densities remain positive by construction, the preferred $w_{\rm DE}(1.7)<-1$ values correspond to NECB-violating (phantom-like) behaviour, but this is a less robust discriminator as $w_{\rm DE}$ becomes ill-conditioned as $ρ_{\rm DE}\to0$. In the effective-fluid mapping, the reconstruction accommodates the same late-time kinematical preference through a rapid descent of $ρ_{\rm DE}(z)$ toward very small values and a sign change, whereas the EoS-based parametrizations absorb it through smoother, and in several cases NECB-violating, evolution over $z\sim1-2$. Although the reconstruction improves the best-fit likelihood, especially with H0DN, Bayesian evidence continues to favor the simpler parametric descriptions. Our results isolate $z\sim1.5-2$ as the key window in which EoS-based DE parametrizations can compress localized kinematic structure and associated features of DE that are still permitted by current late-time data.

astro-ph.CO↗

arXiv2026

Dark Energy with Constant Inertial Mass Density: Updated Constraints and Curvature-Induced Sign Transitions in $ρ_{\rm DE}$ and $ρ_{\rm DE}+p_{\rm DE}$

We present updated observational constraints on the simple-gDE model, characterized by a constant inertial mass density (IMD) $ρ_{\rm DE}+p_{\rm DE}$,which belongs to the broader graduated dark energy family, and compare its cosmological implications with those of the $w$CDM and the $Λ$CDM models. This parametrization provides a physically motivated, one-parameter extension of $Λ$CDM, perspective on DE dynamics beyond the usual equation-of-state approach. We use the newly released DESI DR2 BAO data in combination with either CMB measurements from Planck 2018 or late-time probes, CC and the Pantheon+ SNe Ia sample, considered both with and without SH0ES calibration in this analysis. The data favor a small positive IMD, and Bayesian evidence indicates that the models remain statistically indistinguishable within spatially flat scenarios. Consequently, none of these models exhibits a sign transition in the DE energy density, and no improvement in $H_0$ tension. Allowing spatial curvature qualitatively enlarges the phenomenology of the dark sector. In particular, the interplay between spatial curvature and a nonzero IMD permits sign transitions in both the effective dark-energy density and the IMD during cosmic evolution. For the BAO+CC+SN+SH0ES dataset, the $o$Simple-gDE model yields a transition redshift $z^\dagger = 1.51^{+0.68}_{-0.34}$, while the crossing of the Null Energy Condition boundary (NECB), defined by $ρ_{\rm DE}+p_{\rm DE}=0$, occurs at $z_{\rm NECB}=2.36^{+1.48}_{-1.48}$. The model is statistically favored over $oΛ$CDM and $ow$CDM. These results highlight the potential role of IMD as a fundamental parameter in DE phenomenology and demonstrate that geometric effects, such as spatial curvature, can reveal dynamical features of the dark sector that remain hidden within the spatially flat $Λ$CDM framework.

astro-ph.CO↗

arXiv2026

Hints of sign-changing scalar field energy density and a transient acceleration phase at $z\sim 2$ from model-agnostic reconstructions

We present a data-driven reconstruction of the late-time expansion history and its implications for dark-energy dynamics. Modeling the reduced Hubble rate with a node-based Gaussian-process-kernel interpolant, we constrain the reconstruction using CC, Pantheon+ SNIa, BAO data from SDSS and DESI, transversal BAO data, and external $H_0$ priors (SH0ES and H0DN). Assuming GR at the background level, we map the reconstructed kinematics onto a dark-energy fluid and a scalar-field description, yielding the total potential and kinetic contributions that reproduce the inferred $H(z)$. To interpret the reconstruction, we consider both a minimal single-field model (canonical or phantom) and a two-field (quintom) system consisting of one canonical and one phantom scalar field (or families). Within the GR-based effective-fluid mapping, the inferred dark-energy density changes sign for all dataset combinations explored, transitioning from $ρ_{\rm DE}<0$ at higher redshift to $ρ_{\rm DE}>0$ toward the present, and defining a transition redshift $z_\dagger$ by $ρ_{\rm DE}(z_\dagger)=0$. A single canonical scalar cannot realize such a smooth evolution during expansion, whereas a phantom field or a two-field quintom framework can accommodate the required behavior; in particular, the two-field system permits smooth phantom-divide crossings at finite $ρ_{\rm DE}>0$ and distinguishes them from the separate notion of a density zero crossing. The reconstructed kinematics admit intermediate-redshift structure in some combinations, including hints of an additional accelerated-expansion interval around $z\sim 1.7$--$2.3$. The present-day equation of state remains close to a cosmological constant: combinations including supernovae give $w_0\simeq -1$, while combinations without supernovae but with an external $H_0$ prior show only a mild preference for $w_0<-1$ at the $\sim1.5$--$1.7σ$ level.

astro-ph.CO↗

arXiv2026

BAO miscalibration cannot rescue late-time solutions to the Hubble tension

Baryon Acoustic Oscillation (BAO) measurements play a key role in ruling out post-recombination solutions to the Hubble tension. However, because the data compression leading to these measurements assumes a fiducial $Λ$CDM cosmology, their reliability in testing late-time modifications to $Λ$CDM has at times been called into question. We play devil's advocate and posit that fiducial cosmology assumptions do indeed affect BAO measurements in such a way that low-redshift acoustic angular scales (proportional to the Hubble constant $H_0$) are biased low, and test whether such a rescaling can rescue post-recombination solutions. The answer is no. Firstly, strong constraints on the shape of the $z \lesssim 2$ expansion history from unanchored Type Ia Supernovae (SNeIa) prevent large deviations from $Λ$CDM. In addition, unless $Ω_m$ is significantly lower than $0.3$, the rescaled BAO measurements would be in strong tension with geometrical information from the Cosmic Microwave Background. We demonstrate this explicitly on several dark energy (DE) models ($w$CDM, CPL DE, phenomenologically emergent DE, holographic DE, $Λ_s$CDM, and the negative cosmological constant model), finding that none can address the Hubble tension once unanchored SNeIa are included. We argue that the $Λ_s$CDM sign-switching cosmological constant model possesses interesting features which make it the least unpromising one among those tested. Our results demonstrate that possible fiducial cosmology-induced BAO biases cannot be invoked as loopholes to the Hubble tension "no-go theorem", and highlight the extremely important but so far underappreciated role of unanchored SNeIa in ruling out post-recombination solutions.

astro-ph.CO↗

arXiv2025

When Dark Matter Heats Up: A Model-Independent Search for Non-Cold Behavior

This article questions the common assumption of cold dark matter (DM) by exploring the possibility of a non-zero equation of state (EoS) without relying on any parametric approach. In standard cosmological analyses, DM is typically modeled as pressureless dust with $w_{\rm DM} = 0$, an assumption that aligns with large-scale structure formation, supports the empirical success of the $Λ$CDM model, and simplifies cosmological modeling. However, there is no fundamental reason to exclude a non-zero $w_{\rm DM}$ from the cosmological framework. In this work, we explore this possibility through non-parametric and parametric reconstructions based on Gaussian Process Regression. The reconstructions use Hubble parameter measurements from Cosmic Chronometers (CC), the Pantheon+ sample of Type Ia supernovae, and Baryon Acoustic Oscillation (BAO) data from DESI DR1 and DR2. Our findings suggest that a dynamical EoS for DM, although only mildly supported statistically, cannot be conclusively ruled out. Notably, we observe a mild tendency ($\sim 1σ$) toward a negative $w_{\rm DM}$ at the present epoch, which is most likely due to inconsistencies between the BAO data from DESI and other datasets.

astro-ph.CO↗

arXiv2025

Decay of $f(R)$ quintessence into dark matter: mitigating the Hubble tension?

We propose a revised cosmological scenario that extends the $Λ$ Cold Dark Matter ($Λ$CDM) framework by incorporating metric $f(R)$ gravity in the Jordan frame. In this model, the dark energy component arises from a non-minimally coupled scalar field, decomposed into a smooth background (set to unity to recover General Relativity) and a rapidly varying, massive fluctuation that decays into the dark matter sector. In the near-GR limit, this setup provides a phenomenological extension of $Λ$CDM characterized by two additional parameters: the present-day value of the scalar fluctuation and a normalized decay rate. Using a Markov Chain Monte Carlo analysis of low-redshift cosmological data, comprising Type Ia Supernovae, Baryon Acoustic Oscillation (BAO), and Cosmic Chronometer measurements, we find that the proposed model achieves a better overall fit than $Λ$CDM, while the Bayesian evidence remains statistically inconclusive given the inclusion of two extra parameters. The model predicts a moderate increase in the inferred value of $H_0$ and an improved consistency with DESI BAO data when adopting the SH0ES prior. Furthermore, describing dark matter particle creation as a transition phase in the late Universe offers an intriguing physical interpretation, potentially capturing features already present in current data and providing a promising avenue to explore extensions of the standard cosmological model within modified gravity frameworks.

astro-ph.CO↗

arXiv2025

Pressure Parametrization of Dark Energy: First and Second-Order Constraints with Latest Cosmological Data

We explore an extension of the $Λ$CDM model in which the pressure $p$ of the dark energy (DE) fluid evolves with the expansion of the Universe, expressed as a function of the scale factor $a$. The corresponding energy density $ρ$ is derived from the continuity equation, resulting in a dynamical equation-of-state parameter $w \equiv p/ρ$ during the late-time expansion of the Universe. The pressure is modeled using a Taylor expansion around the present epoch ($a = 1$), introducing deviations from a cosmological constant within the dynamical dark energy (DDE) framework. At first order, a single new parameter $Ω_1$ captures linear deviations, while a second-order parameter, $Ω_2$, accounts for quadratic evolution in the pressure. We constrain the first- and second-order DDE models using multiple observational datasets and compare their performance against $Λ$CDM and the CPL parameterization. A joint analysis of Planck CMB, DESI, and DESY5 data yields the strongest evidence for DDE, with a $2.7σ$ deviation in the first-order model and over $4σ$ in the second-order model, providing strong statistical support for a departure from a cosmological constant. The reconstructed DE evolution in the second-order case reveals a distinctive non-monotonic behavior in both energy density and $w_{\rm DE}(a)$, including clear phantom-crossing phenomena. Notably, the late-time evolution of $w_{\rm DE}(a)$ remains consistent across datasets and shows strong agreement with the CPL parameterization, underscoring the robustness of the pressure-based approach.

astro-ph.CO↗

arXiv2025

The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics

The standard model of cosmology has provided a good phenomenological description of a wide range of observations both at astrophysical and cosmological scales for several decades. This concordance model is constructed by a universal cosmological constant and supported by a matter sector described by the standard model of particle physics and a cold dark matter contribution, as well as very early-time inflationary physics, and underpinned by gravitation through general relativity. There have always been open questions about the soundness of the foundations of the standard model. However, recent years have shown that there may also be questions from the observational sector with the emergence of differences between certain cosmological probes. In this White Paper, we identify the key objectives that need to be addressed over the coming decade together with the core science projects that aim to meet these challenges. These discordances primarily rest on the divergence in the measurement of core cosmological parameters with varying levels of statistical confidence. These possible statistical tensions may be partially accounted for by systematics in various measurements or cosmological probes but there is also a growing indication of potential new physics beyond the standard model. After reviewing the principal probes used in the measurement of cosmological parameters, as well as potential systematics, we discuss the most promising array of potential new physics that may be observable in upcoming surveys. We also discuss the growing set of novel data analysis approaches that go beyond traditional methods to test physical models. [Abridged]

astro-ph.CO↗

arXiv2025

Exploring the Growth-Index ($γ$) Tension with $Λ_{\rm s}$CDM

Recent observational analyses have revealed a significant tension in the growth index $γ$, which characterizes the growth rate of cosmic structures. Specifically, when treating $γ$ as a free parameter within $Λ$CDM framework, a combination of Planck and $ fσ_8 $ data yields $γ\approx 0.64$, in $\sim4σ$ tension with the theoretically expected value $γ\approx 0.55$ (assuming general relativity). This discrepancy, closely related to the $ S_8 $ tension, poses a new challenge to the standard cosmological model by suggesting that it predicts an excessive growth of structure. In this work, we demonstrate that the $Λ_{\rm s}$CDM framework (featuring a rapid sign-switching cosmological constant (mirror AdS-to-dS transition) in the late universe at redshift $ z_\dagger \sim 2 $) can simultaneously alleviate the $ γ$, $ H_0 $, and $ S_8 $ tensions. We also examined a scenario with fixed $ z_\dagger = 1.7 $, previously identified as a sweet spot for alleviating multiple major cosmological tensions (including those in $ H_0 $, $ M_B $, and $ S_8 $) finding that it completely eliminates both the $ γ$ and $ H_0 $ tensions, although it is statistically disfavored by our dataset combinations. Our findings suggest that $Λ_{\rm s}$CDM is a promising model, providing a potential unified resolution to multiple major cosmological tensions.

astro-ph.CO↗

arXiv2025

Kinetic Model for Dark Energy - Dark Matter Interaction: Scenario for the Hubble Tension

We analyze a model for Dark Energy - Dark Matter interaction, based on a decaying process of the former into the latter. The dynamical equations are constructed following a kinetic formulation, which separates the interacting fluctuations from an equilibrium distribution of both species. The emerging dynamical picture consists of coupled equations, which are specialized in the case of a Dark Energy equation of state parameter; we deal with a modified Lambda Cold Dark Matter ($Λ$CDM) model, which is investigated versus a possible interpretation of the Hubble tension. Using an optimized set of the model's free parameters, it can be shown that the obtained Hubble parameter can, in principle, address the tension. We then use the most recent datasets from late Universe sources and compressed information from the Cosmic Microwave Background data to constrain the free parameters and compare the addressed scenario to the standard $Λ$CDM model. The study outlines how our proposal is preferred by the data in all cases, based on fit quality, while also alleviating the tension.

gr-qc↗

arXiv2025

Testing an oscillatory behavior of dark energy

The main aim of this work is to use a model-independent approach, along with late-time observational probes, to reconstruct the dark energy (DE) equation of state $w_{\rm DE}(z)$. Our analysis showed that, for a late time universe, $w_{\rm DE}$ deviates from being a constant but in contrast exhibits an oscillatory behavior, hence both quintessence ($w_{\rm DE}> -1$) and phantom ($w_{\rm DE} < -1$) regimes are equally allowed. In order to portray this oscillatory behavior, we explored various parametrizations for the equation of state and identified the closest approximation based on the goodness of fit with the data and the Bayesian evidence analysis. Our findings indicated that while all considered oscillating DE parametrizations provided a better fit to the data, compared to the cosmological constant, they are penalized in the Bayesian evidence analysis due to the additional free parameters. Overall, the present article demonstrates that in the low redshift regime, the equation of state of the DE prefers to be dynamical and oscillating. We anticipate that future cosmological probes will take a stand in this direction.

astro-ph.CO↗

arXiv2024

Non-parametric reconstruction of cosmological observables using Gaussian Processes Regression

The current accelerated expansion of the Universe remains ones of the most intriguing topics in modern cosmology, driving the search for innovative statistical techniques. Recent advancements in machine learning have significantly enhanced its application across various scientific fields, including physics, and particularly cosmology, where data analysis plays a crucial role in problem-solving. In this work, a non-parametric regression method with Gaussian processes is presented along with several applications to reconstruct some cosmological observables, such as the deceleration parameter and the dark energy equation of state, in order to contribute with some information that helps to clarify the behavior of the Universe. It was found that the results are consistent with $Λ$CDM and the predicted value of the Hubble parameter at redshift zero is $H_{0}=68.798\pm 6.340(1σ) \text{ km}\text{ s}^{-1}\text{ Mpc}^{-1}$.

astro-ph.CO↗