arXiv subjects

Anirudh Pradhan

Publications and source records attributed to Anirudh Pradhan.

At least 19 recordsLinked to original sources

arXiv2026

Hu-Sawicki $f(R)$ Gravity in a Non-Flat Universe: Constraints from DESI-DR2, BBN, and Type Ia Supernovae

Late-time cosmic acceleration is conventionally ascribed to a cosmological constant, though $Λ$CDM continues to face several theoretical difficulties that keep alternative gravity models under active consideration. This work examines the Hu-Sawicki $f(R)$ model in a spatially non-flat background, with the modified-gravity parameter $b$ and the curvature density $Ω_k$ both treated as free parameters, constrained using DESI-DR2 BAO, BBN, and four Type Ia supernova compilations -- PantheonPlus, PantheonPlus+SH0ES, Union3, and DESY5yr. Across all four combinations, $H_0$ and $Ω_m$ stay close to their $Λ$CDM values, with a noticeable shift in $H_0$ appearing only for the SH0ES-calibrated dataset. The parameter $b$ departs from zero at better than $2σ$ in three of the four fits, most prominently for DESY5yr, whereas the SH0ES-calibrated combination alone prefers $b<0$. A strong positive correlation among $b$, $H_0$, and $Ω_k$ underlies this shift, suggesting that curvature signatures obtained under $Λ$CDM can be reabsorbed into the modified-gravity sector once this additional freedom is allowed. Statistical model comparison via AIC and BIC gives a mixed picture: AIC leans toward the Hu-Sawicki model in three of the four combinations, while BIC's heavier penalty on the extra parameter favors $Λ$CDM in most cases, and only DESY5yr is preferred under both criteria. These findings show that the Hu-Sawicki $f(R)$ scenario with unconstrained curvature is nonetheless a statistically feasible, if not obviously preferred, alternative to $Λ$CDM, and that curvature restrictions generated inside $Λ$CDM cannot be viewed as independent of the underlying gravity model.

gr-qc↗

arXiv2026

Horizon Response to Orbital Redistribution in Self Consistent Einstein--Vlasov Black Hole Environments

We study whether orbital redistribution in a self consistent spherical Einstein--Vlasov environment can change the asymptotic normalization of a black hole horizon while the horizon mass, particle rest mass and ADM mass are all held fixed. The matter variable is the occupation of regular bound orbital actions, so the stress tensor, orbital energies and gravitational field are determined by the same distribution. Linearization of the spherical mass constraint gives a kinetic variation law in which orbital energy is conjugate to occupation and the inner lapse ratio multiplies the horizon mass variation. On a locally regular equilibrium branch, mixed variations imply an integrated reciprocity relation between the central mass derivative of orbital energy and the directional response of the horizon normalization. We construct finite mass populations and trace constant mass redistribution curves. For the reference rest mass ratio $0.30$, the calculated endpoint surface gravity shifts are approximately $+15.37$ and $-15.33$ parts per million. The constrained response cancels at simultaneous dilute and Newtonian order, is nonzero for exact Schwarzschild orbits, and is further modified by self gravity. Independent balance, integral, derivative and refinement tests resolve the response well below its reported magnitude.

gr-qc↗

arXiv2026

Role of viscous fluid in FLRW model with observational constraints

In this study, we investigate the role of bulk viscosity in the evolution of a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe dominated by dust. We parameterize the bulk viscosity as p_tilde = -3[l + m(H'(t) + H^2) + nH^2]H, derive the modified Einstein field equations, and reformulate them in terms of redshift z. Using 46 Hubble parameter measurements and the Pantheon+ compilation of 1701 supernovae, we estimate the model parameters (H0, l, m, n) through chi2 minimization and refine them using Markov chain Monte Carlo (MCMC) simulations. The analysis gives a transition redshift z_t = 0.585 and a present deceleration parameter q0 = -0.705, consistent with Lambda CDM. The present age of the universe is estimated as t0 = 14.5734 Gyr. We obtain H0 = 68 km/s/Mpc from the Hubble datasets and approximately 73 km/s/Mpc from Pantheon+. These results illustrate the Hubble tension between late- and early-universe determinations of H0. We further investigate the evolution of the equation-of-state parameter omega(z), energy density rho(z), and pressure p(z). Statefinder diagnostics (r,s) demonstrate deviations from and convergence toward Lambda CDM at different epochs. The results highlight the potential role of bulk viscosity in describing the accelerated expansion of the universe and provide a useful framework for studying cosmological models.

physics.gen-ph↗

arXiv2026

Quark stars in regularized 4D Einstein-Gauss-Bonnet gravity: A perturbative QCD equation of state

We investigate the equilibrium structure and stability of selfbound quark stars in the framework of regularized four-dimensional Einstein--Gauss--Bonnet (4DEGB) gravity, employing the perturbative QCD equation of state of Fraga, Kurkela and Vuorinen [1]. The equation of state, parameterised by a single renormalization-scale parameter $X$, contains no effective bag constant and defines the stellar surface entirely through the vanishing of the quark-matter pressure. We solve the modified Tolman-Oppenheimer--Volkoff equations derived from the scalar--tensor formulation of 4DEGB gravity for $X \in \{3, 4\}$ and Gauss--Bonnet coupling $α\in \{0, 1, 10\}\,\mathrm{km}^2$. For the soft EOS ($X = 3$), the maximum mass increases from $2.0431\,M_\odot$ (GR) to $2.5013\,M_\odot$ at $α= 10\,\mathrm{km}^2$, with only the latter entering the PSR~J0952$-$0607 mass band. For the stiff EOS($X = 4$), the GR baseline already yields $3.0415\,M_\odot$, and all configurations exceed both the GW190814 secondary mass and the PSR~J0952$-$0607 constraint. The compactness $C = M/R$ at maximum mass ranges from $0.2531$ to $0.3123$ across all configurations, remaining well below the Buchdahl bound throughout. Radial profiles of the squared speed of sound confirm that $c_s^2 < 1/3$ holds pointwise throughout the stellar interior for all parameter choices, establishing that the quark matter remains sub-conformal and causal inside the maximum-mass star. These results demonstrate that higher-curvature corrections in 4DEGB gravity systematically enhance the maximum supported mass of perturbative QCD quark stars, with the stiff ($X = 4$) branch already exceeding the most massive compact objects currently observed even at the GR level, while the soft ($X = 3$) branch requires $\alphaGB \sim 10\,\mathrm{km}^2$ to approach those thresholds.

gr-qc↗

arXiv2026

Testing a Sign-Switch Cosmological Model with Curvature through Latest Planck 2018, DESI DR2 and PantheonPlus\&SH0ES Observational Data

We investigate the spatial geometry of the Universe within the framework of a sign-switch dark energy scenario by extending the recently proposed $Λ_{\rm s}$CDM model to include a free curvature parameter $Ω_k$.In this framework, the effective cosmological constant undergoes a transition from a negative to a positive value at a characteristic redshift $z_{\dagger}$. Using the latest Planck 2018 cosmic microwave background (CMB) data, DESI DR2 baryon acoustic oscillation (BAO) measurements, and the PantheonPlus\&SH0ES Type Ia supernova sample, we derive joint constraints on the spatial curvature parameter $Ω_k$ and other cosmological parameters. We find that Planck data itself slightly favors a closed universe within both the $Λ_{\rm s}$CDM$+Ω_k$ and $Λ$CDM$+Ω_k$ frameworks, although spatial flatness remains well within the allowed uncertainties. When low-redshift probes were included, the curvature constraints were significantly tightened. In particular, the full Pk18+DR2+PP\&SH0ES dataset yields $Ω_k = 0.0001 \pm 0.0014$ for the $Λ_{\rm s}$CDM model, indicating a universe that is remarkably consistent with spatial flatness. We further analyzed the correlations between $Ω_k$, $H_0$, and $S_8$, finding that the inclusion of curvature and a sign-switch dark energy component helps stabilize cosmological parameter estimates while remaining compatible with current observational constraints. Model comparison using AIC and Bayesian evidence shows that the $Λ_{\rm s}$CDM model receives inconclusive/weak observational support relative to $Λ$CDM.

astro-ph.CO↗

arXiv2026

Neutron Stars in Energy--Momentum Squared Gravity: Structure, Stability, and Multimessenger Constraints

We study nonrotating neutron stars in energy--momentum squared gravity (EMSG). The stellar models are obtained from the modified Tolman--Oppenheimer--Volkoff equations and four original tabulated hadronic equations of state: WFF1, SLy4, APR4, and MPA1. We use the common coupling set $α\in\{-20,-10,0,+5,+7.5\}\,\mathrm{km}^{2}$ and construct mass--radius and mass--central-density sequences. We compare these sequences with the $2\,M_\odot$ mass requirement, the NICER measurements of PSR J0030+0451 and PSR J0740+6620, and the region inferred from GW170817. Within the sampled coupling range, the computed pre-turning-point branches remain compatible with these four benchmarks. Negative values of $α$ generally shift the high-density branches toward larger masses. Positive values produce smaller shifts in the opposite direction. The microscopic sound speed becomes superluminal at high density in the WFF1 and SLy4 tables, whereas APR4 and MPA1 remain causal over their tabulated ranges. For WFF1, the causal boundary falls within a coarse table segment. Its compatibility with the $2\,M_\odot$ requirement therefore cannot be decided at the available density resolution. At $α=-20\,\mathrm{km}^{2}$, the effective-fluid sound-speed diagnostic becomes singular for WFF1, SLy4, and APR4. This singularity is absent from the explicit modified TOV system. All computed sequences remain below the standard Buchdahl reference values for compactness and surface redshift.

physics.gen-ph↗

arXiv2026

Charged Penrose Extraction in RN--AdS Black Holes with Dark Energy: Ergosphere Geometry and Rigorous Efficiency Bounds

We develop a quantitative framework for charge assisted Penrose extraction in Reissner--Nordström Anti-de Sitter black holes surrounded by a Kiselev type anisotropic dark energy sector. The generalized electrostatic ergosphere is defined by the balance between redshift and electrostatic work. Under explicitly stated monotonicity assumptions on the lapse and electrostatic potential, we prove uniqueness of the exterior ergosphere boundary and of the turning point of negative energy trajectories. We derive a local upper bound on the escaping energy, formulate a finite radius reception criterion appropriate to AdS asymptotics, and map the allowed extraction domains in terms of the mass, charge, cosmological constant, Kiselev normalization, and state parameter. We also introduce first order adiabatic discharge and accretion laws for slowly varying mass and charge, clarifying the regime in which the evolving horizon and ergosphere can be tracked consistently. The results provide controlled analytic and numerical diagnostics for charged Penrose extraction in RN--AdS backgrounds with a dark energy environment, while clearly separating local kinematic bounds from backreaction, radiative losses, and near extremal stability effects.

gr-qc↗

arXiv2026

Kinematic Bounds on Charged Energy Extraction in the Purely Electric Branch of Euler--Heisenberg Type f(R,T) Black Holes

We derive and test kinematic upper bounds on charged energy extraction in the purely electric branch of a static $f(R,T)$ black hole family sourced by an Euler--Heisenberg type nonlinear electromagnetic sector. The analysis is restricted to external, minimally coupled probe particles on the fixed background. In this electric solution the field remains Coulombic up to an additive gauge constant; the nonlinear electromagnetic and matter-coupling coefficients therefore affect extraction indirectly through the metric, the event-horizon position, and the global causal structure. We obtain a general local bound retaining nonzero angular momentum and radial velocity of the negative energy fragment, and identify the commonly used zero angular momentum turning-point choice as an upper envelope rather than a generic decay configuration. A co-moving split supplies a locally four momentum-conserving benchmark. We classify horizons with the double root conditions $\mathcal F=\mathcal F'=0$, distinguish asymptotically flat, de Sitter, and anti-de Sitter branches, and impose the corresponding global outward-accessibility criterion. In the de Sitter static patch the electrostatic energy is referenced to the cosmological horizon, so the relevant scale is $Q(1/r_+-1/r_c)$ rather than $Q/r_+$. Reproducible scans compare Reissner--Nordström, Einstein--Euler--Heisenberg type, $f(R,T)$--Maxwell, and full $f(R,T)$--Euler--Heisenberg type backgrounds. The results show that the branch-referenced horizon potential controls the local upper envelope, whereas the asymptotic structure determines whether an outward trajectory can reach infinity, a cosmological horizon, or only a finite outer turning point.

gr-qc↗

arXiv2026

Coupled Gravitoelectromagnetic Response of a Magnetically Supported Generalized Hayward Black Hole in Nonlinear Electrodynamics

We construct the exterior coupled gravitational and electromagnetic response of a magnetically supported generalized Hayward black hole within a specified nonlinear electrodynamic completion. Both parity sectors reduce to canonical two channel wave systems with explicit potentials and the correct Schwarzschild and effective Reissner--Nordström limits. We compute the quasinormal spectrum, metric and optical characteristics, extremal throat weights, quadrupolar wave conversion, finite bandwidth transfer, and coherent absorption eigenchannels while verifying exterior hyperbolicity and flux conservation. An effective charged operator captures the leading weak core geometry and mode mixing; after its subtraction, the residual hierarchy is consistent with cubic spectral corrections in the primarily electromagnetic branch and quartic corrections in the primarily gravitational branch and principal scattering observables. The fundamental quadrupolar branches become intrinsically linewidth separated near $χ\simeq0.70$, whereas parity splitting remains subleading. Metric and optical characteristic families separate monotonically toward extremality. At $χ=0.9$, positive parity reflected conversion reaches $45.8\%$ and remains $40.8\%$ after moderate bandwidth averaging, while coherent incident combinations yield $98.4\%$ bright and $1.3\%$ dark absorption. These independently evaluated observables provide mutually consistent diagnostics of the same nonlinear electrodynamic operator.

gr-qc↗

arXiv2026

Finite mass two throat wormholes: global light rings, branch resolved strong lensing, and scalar transmission

We introduce a static, horizonless, asymptotically flat two throat wormhole family in which one global metric determines the geometry, effective source, null dynamics, lensing, and test field propagation. A finite mass deformation of a quartic embedding profile produces two symmetric throats and an intermediate equator, while the associated Misner--Sharp mass tends to the same finite value at both asymptotic ends. The temporal sector yields the same mass parameter, and the Einstein tensor defines a single conserved anisotropic source. In addition to the local flare out identity, the complete radial averaged null functional is obtained exactly and is strictly negative. The global null potential admits a complete phase classification for all positive masses and nonnegative redshift deformation. Depending on the parameters, the global unstable set consists of throat rings, four off throat rings, or exterior rings accompanied by a subcritical equatorial ring. In the four ring phase, all unstable rings have the same impact scale but the inner and outer branches have different Lyapunov exponents. We derive the logarithmic strong deflection coefficients analytically and show that the cross throat coefficient is the sum of the contributions from every global maximum traversed by the ray. Direct numerical integration verifies these coefficients. The scalar scattering problem exhibits phase dependent barriers and resonant transmission. The resulting model provides a finite mass setting in which topology, averaged energy conditions, branch resolved strong lensing, and wave transmission are derived from one spacetime.

gr-qc↗

arXiv2026

Testing Exponential $f(R)$ Gravity with CMB, DESI-DR2, and Supernova Data

One of the most popular competitors to the CDM paradigm as an explanation for the late-time acceleration of the universe is the modification of general relativity (GR), with models such as $f(R)$ gravity among the main motivations. In this study, we consider an exponential $f(R)$ gravity model as a possible extensions of the GR. The extra scalar degrees of freedom and their effects on the cosmic expansion and structure formation are continuously considered in this scenario. By combining the PPS, BBN, CC, DESI-DR2, and CMB datasets, we imposed limitations on this model. We performed a detailed statistical analysis of the free model parameter $b$ together with the standard cosmological parameters. Our analysis yields values of $H_0$ that are slightly lower than those obtained in $Λ$CDM, indicating no significant relaxation of the $H_0$ tension. In contrast, the model predicts systematically higher values of $S_8$, leading to a moderate alleviation of the $S_8$ tension by up to $\sim 1.2σ$ when late-time datasets are included. Overall, these results demonstrate that although the considered $f(R)$ gravity model does not resolve all cosmological tensions simultaneously, it provides a consistent improvement in the description of large-scale structure formation.

gr-qc↗

arXiv2026

Particle Creation and Variable Generalized Chaplygin Gas in $\mathcal{F}(\mathcal{R},Σ,\mathcal{T})$ Gravity

In this work, we investigate the cosmological dynamics of a spatially flat Friedmann--Lemaître--Robertson--Walker Universe in the framework of generalized $ \mathcal{F}(\mathcal{R},Σ,\mathcal{T}) $ gravity by incorporating gravitationally induced particle creation together with the variable generalized Chaplygin gas scenario. The modified gravitational action depends explicitly on the Ricci scalar $ \mathcal{R} $, the matter-coupling scalar $ Σ$, and the trace of the energy--momentum tensor $ \mathcal{T} $, which collectively generate significant corrections to the standard cosmological evolution. The particle creation mechanism is introduced through an open thermodynamic description of the Universe. In addition, the dark sector is modeled using the variable generalized Chaplygin gas formalism. To examine the observational consistency of the model, the free parameters are constrained using the Pantheon$^+$ Type Ia Supernova compilation together with the combined observational Hubble and Pantheon$^+$ datasets through a statistical $χ^2$-analysis. The cosmological behavior of the model is further explored through the evolution of the cosmological parameters. Furthermore, the thermodynamic properties of the model are investigated using the apparent horizon formalism. The obtained results demonstrate that the entropy evolution remains physically consistent throughout the cosmic evolution. Hence, the present $ \mathcal{F}(\mathcal{R},Σ,\mathcal{T}) $ gravity framework with particle creation provides a viable geometrical description of the late-time accelerated Universe and remains compatible with recent cosmological observations.

gr-qc↗

arXiv2026

Dark Energy Phenomenology in a $f(R,Σ,T)$ Gravity Framework: $O_m(z)$ Parameterization Approach

This study investigates the cosmological implications of $f(R,Σ,T)$ gravity by reconstructing the Hubble parameter from a logarithmic parameterization of the $O_m(z)$ diagnostic. Our approach offers a model-independent way to probe the nature of dark energy and differentiate it from a cosmological constant. We derive the field equations for $f(R,Σ,T) = R + Σ+ 2πηT$ within the homogeneous, isotropic, and spatially flat Friedmann-Robertson-Walker (FRW) metric. A comprehensive analysis of key physical parameters, including the equation of state (EoS) parameter $ω(z)$, the $(ω-ω')$-plane, the squared sound speed $\vartheta^2$, and various energy conditions (Null, Dominant, Strong), is presented. Our findings reveal a dynamic EoS parameter that consistently remains within the quintessence regime ($-1 < ω< -1/3$), approaching $ω= -1$ in the far future, thereby avoiding phantom behavior and maintaining the weak energy condition. The model successfully reproduces the cosmic transition from deceleration to acceleration, as indicated by the deceleration parameter $q(z)$ crossing zero. While the model aligns well with observational data for cosmic expansion, the analysis of $\vartheta^2$ indicates classical instability, a point requiring further theoretical refinement. Overall, this work demonstrates the viability of $f(R,Σ,T)$ gravity as a framework capable of describing the universe's accelerated expansion, consistent with current cosmological observations, while offering a dynamic alternative to the $Λ$CDM model.

gr-qc↗

arXiv2026

Anisotropic Cosmology with interacting Dark Energy in f(R,T) Gravity: A Data-Constrained & independent Approach

In this work, we investigate the cosmological dynamics of an anisotropic Universe within the framework of $f(R,T)$ gravity by incorporating pressureless dark matter and the dark energy models. The analysis is carried out in a Bianchi type-I space-time, allowing us to capture possible deviations from isotropy and their evolution during cosmic expansion. A phenomenological reconstruction scheme based on a variable deceleration parameter is adopted to derive a redshift-dependent Hubble function. To establish observational viability, we constrain the free parameters of the model using a comprehensive statistical analysis that combines observational Hubble data and the Pantheon+ Type Ia supernova compilation. The resulting parameter space is tightly bounded, and the reconstructed expansion history exhibits strong consistency with current observational expectations. The model successfully reproduces the transition from an early decelerating phase to the present accelerated epoch, while asymptotically approaching a de Sitter-like regime. Further we analyzed the geometrical diagnostics, including the statefinder and $O_m$ diagnostics, which indicate a close correspondence with the standard $Λ$CDM scenario at late times. The behavior of the effective equation of state suggests a dynamically evolving dark energy component consistent with a quintessence-like regime. Additionally, the analysis of energy conditions confirms the physical admissibility of the model, whereas the stability investigation reveals the presence of classical instabilities at the perturbative level.

gr-qc↗

arXiv2026

Comparative Study of $f(T)$ Gravity Models with Observational Constraints from \textit{OHD} and \textit{Pantheon+ datasets}

The late-time acceleration of the universe remains one of the most significant open problems in modern cosmology. Modified gravity frameworks such as $f(T)$ gravity provide a geometric alternative to dark energy by attributing cosmic acceleration to torsional effects. In this study, we present a comparative analysis of three different forms of $f(T)$ models: (i) a simple power-law form $f(T) = η(-T)^{n}$, (ii) the exponential form $f(T) = βT_{0}\left(1-e^{-p \sqrt{T/T_{0}}}\right)$ and (iii) a logarithmic form $f(T) = γT \ln\!\left(\frac{T}{T_{0}}\right)$. Using parameterization of the deceleration parameter $q(z)$ and the corresponding $H(z)$ expression, we constrain the model parameters with the recent Hubble parameter and BAO data through a Markov Chain Monte Carlo (MCMC) approach. The physical behavior of the effective energy density, equation of state parameter, squared sound speed, cosmological $Om(z)$ diagnostics, and energy conditions (NEC, DEC, SEC) were investigated for all three models. Our comparative analysis shows that all models asymptotically approach the $Λ$CDM behavior at late times, while they differ in stability properties and energy condition behaviors. In particular, the violation of the strong energy condition (SEC) has emerged as a common feature consistent with current accelerated expansion. This study highlights how different $f(T)$ functional forms can yield distinct cosmological dynamics while maintaining consistency with observational data.

gr-qc↗

arXiv2026

Generalized Second Law and Thermodynamical Aspects of $f(Q,\mathcal{T})$ Gravity

Late-time cosmic acceleration has motivated the exploration of various extensions of general relativity, among which $f(Q,\mathcal{T})$ gravity, based on the non-metricity scalar $Q$ and the trace of the energy--momentum tensor $\mathcal{T}$, has gained increasing attention. In this study, we explore the thermodynamic aspects of $f(Q,\mathcal{T})$ gravity by establishing the first law and generalized second law of thermodynamics at the apparent horizon of a flat FLRW universe. By applying the Gibbs relation, we determined the rate of change of the total entropy and assessed the conditions under which the generalized second law remains valid for various choices of $f(Q,\mathcal{T})$. Our analysis focuses on linear, power-law, quadratic trace, exponential, and cross-coupling models, inspired by frameworks such as $f(R,\mathcal{T})$, $f(T)$, and modifications motivated by string theory. Our analysis showed that linear and mildly nonlinear models are generally thermodynamically consistent, whereas strongly nonlinear or interaction-type models require fine-tuned parameters for the generalized second law to hold. The present analysis underscores that thermodynamic considerations serve as effective criteria for assessing the viability of modified gravity models and their relevance to cosmological dynamics.

gr-qc↗

arXiv2026

Alleviating the Hubble Tension with Logarithmic Dark Energy: Constraints on the $w_{log}$CDM Model

Observational constraints are considered on a $w_{log}$CDM model of the dark energy equation of state, $w_{d}(z) = w_{0} + w_{a}\left( \frac{\ln(2+z)}{1+z} - \ln 2 \right)$, using the most recent cosmological datasets including DESI Baryon Acoustic Oscillation (BAO) measurements, Big Bang Nucleosynthesis (BBN) priors, Cosmic Chronometer (CC) observations, and Pantheon Plus (PPS) Type Ia supernovae. From the combined DESI BAO+BBN+CC+PPS dataset, we obtain $H_0 = 71.02 \pm 0.66~\text{kms}^{-1}\text{Mpc}^{-1}$, $Ω_m = 0.2863 \pm 0.0080,$ $w_0 = -0.875 \pm 0.066,$ $w_a = -0.69^{+0.37}_{-0.32},$ at the 68\% and 95\% confidence levels, indicating a preference for phantom dark energy with mild evidence for temporal evolution. The Hubble constant obtained from our model is closer to the local SH0ES measurement than the standard $Λ$CDM prediction, partially easing the Hubble tension. We perform extensive parameter-space exploration revealing correlations between $w_0$, $w_a$, and $H_0$, showing that dynamical dark energy models can fit higher values of the Hubble constant. The reconstructed deceleration parameter $q(z)$ shows the transition from deceleration to acceleration at $z \sim 0.6$--$0.7$, while the equation-of-state reconstruction remains consistent with a cosmological constant across the observed redshift range. A model comparison using information criteria indicates that the $w_{log}$CDM model remains statistically competitive with $Λ$CDM.

physics.gen-ph↗

arXiv2026

Observational Constraints and Geometric Diagnostics of Barboza-Alcaniz and Logarithmic Dark Energy Parametrizations

This study investigates and compares two prominent two-dimensional dark energy (DE) parameterizations: Barboza-Alcaniz (BA) and Logarithmic forms by comparing them with a comprehensive set of observational data comprising Type Ia Supernovae (SNe Ia) from the Pantheon compilation, Baryon Acoustic Oscillations (DESI BAO), and Cosmic Chronometers (CC). The primary objective was to explore the constraining power and cosmological implications of each parameterization in light of the current data. After formulating the theoretical framework and background equations governing cosmic expansion, we employ Markov Chain Monte Carlo (MCMC) techniques using the emcee Python package to constrain the free parameters of each model. The best-fit values for parameters $ω_0$, $ω_a$, and $H_0$ were extracted for each model using individual and combined datasets. The results include confidence contours at the levels $1σ$ and $2σ$. Our findings demonstrate that both parameterizations are consistent with observational data, with logarithmic parameterization showing slightly better constraints in terms of parameter evolution. Furthermore, we employed a statefinder diagnostic to analyze the geometric behavior of the models, providing an effective distinction between the two DE scenarios. This study contributes to a deeper understanding of DE evolution and its constraints in light of current cosmological data.

physics.gen-ph↗