Cosmological Dark Energy Research Articles

Non-linear matter power spectrum modeling in interacting dark energy cosmologies

AbstractUnderstanding the behavior of the matter power spectrum on non-linear scales beyond the $$\Lambda $$ Λ CDM model is crucial for accurately predicting the large-scale structure (LSS) of the Universe in non-standard cosmologies. In this work, we present an analysis of the non-linear matter power spectrum within the framework of interacting dark energy-dark matter cosmologies (IDE). We employ N-body simulations and theoretical models to investigate the impact of IDE on these non-linear scales. Beginning with N-body simulations characterized by a fixed parameter space delineated by prior observational research, we adeptly fit the simulated spectra with a simple parametric function, achieving accuracy within 5%. Subsequently, we refine a modified halo model tailored to the IDE cosmology, exhibiting exceptional precision in fitting the simulations down to scales of approximately 1 h/Mpc. To assess the model’s robustness, we conduct a forecast analysis for the Euclid survey, employing our refined model. We find that the coupling parameter $$\xi $$ ξ will be constrained to $$\sigma (\xi ) = 0.0110$$ σ ( ξ ) = 0.0110 . This marks a significant improvement by an order of magnitude compared to any other current observational tests documented in the literature. These primary findings pave the way for a novel preliminary approach, enabling the utilization of IDE models for observational constraints concerning LSS data on non-linear scales.

Constraining the entropy corrected (m, n)-type pilgrim dark energy in fractal cosmology

This study explores the impact of introducing particle and future event horizon as infrared (IR) cutoff on (m, n)-type entropy corrected versions of pilgrim dark energy. We investigate (m, n)-type power-law entropy corrected pilgrim dark energy in a flat fractal platform by considering a non-interacting scenario with cold dark matter. Then, our focus shifts to (m, n)-type logarithmic entropy corrected pilgrim dark energy. We derive the evolution of some relevant cosmological parameters and cosmological planes. Finally, we constrain the model parameters using H(z)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H(z)+$$\\end{document}BAO combined observational data from the DA and BAO methods. For statistical analysis, we apply the χ2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi ^2$$\\end{document}-minimization technique (equivalent to the maximum likelihood method) to estimate the best-fit value of the model parameters. We incorporate public Cosmo Hammer (EMCEE) Python package code to perform the MCMC method. Finally, we display the plot of cosmological parameters and cosmological plane and analyze the triangular contour plot by using the optimal values of the model parameters.

Alleviating the Hubble tension using the Barrow holographic dark energy cosmology with Granda–Oliveros IR cut-off

ABSTRACT In this study, we investigate the Barrow holographic dark energy (BHDE) model with the Granda–Oliveros(G–O) infrared (IR) cut-off in the presence of neutrino masses, utilizing the latest observational data to address the Hubble tension. The GO cut-off is defined as $L_{\mathrm{ IR}}=(\alpha H^2 + \beta \dot{H})^{-1/2}$. We place constraints on the total neutrino mass $\sum m_{\nu }$ using data from Type Ia supernovae (SN) Pantheon, cosmic chronometers (CC), cosmic microwave background (CMB), Baryon Acoustic Oscillation (BAO) data sets, and Planck Lensing. Specifically, the comprehensive CMB + BAO + CC + Pantheon data set provides a total neutrino mass of $0.118\, \text{eV}$. The parameters for the Barrow-GO model are determined to be $\Delta = 0.0055^{+0.0086}_{-0.0086}$, $\alpha = 0.997^{+0.060}_{-0.060}$, and $\beta = 0.598^{+0.080}_{-0.080}$, showing good agreement with previous studies. One of the key findings of this study is the model’s ability to alleviate the Hubble tension, as evidenced by the comparison of $H_0$ measurements. Specifically, the tension value for the combination of data set (CMB + BAO + CC + Pantheon + Lensing) is $1.5\sigma$ with the Planck 2018 and $1.4\sigma$ with R22. These results underscore the importance of multi-data set integration in refining constraints on neutrino properties and highlight the model’s efficacy in probing fundamental aspects of neutrino physics. Our results demonstrate that the BHDE model with the GO cut-off can effectively address the Hubble tension, offering a coherent framework that reconciles local and cosmological measurements of the Hubble constant.

Tightening the reins on nonminimal dark sector physics: Interacting dark energy with dynamical and nondynamical equation of state

We present a comprehensive reassessment of the state of interacting dark energy (DE) cosmology, namely models featuring a nongravitational interaction between dark matter and DE. To achieve high generality, we extend the dark sector physics by considering two different scenarios: a nondynamical DE equation of state w0≠−1, and a dynamical w(a)=w0+wa(1−a). In both cases, we distinguish two different physical regimes resulting from a phantom or quintessence equation of state. To circumvent early time superhorizon instabilities, the energy-momentum transfer should occur in opposing directions within the two regimes, resulting in distinct phenomenological outcomes. We study quintessence and phantom nondynamical and dynamical models in light of two independent cosmic microwave background (CMB) experiments—the Planck satellite and the Atacama Cosmology Telescope. We analyze CMB data both independently and in combination with supernovae distance moduli measurements from the catalog and baryon acoustic oscillations from the SDSS-IV eBOSS survey. Our results update and extend the state-of-the-art analyses, significantly narrowing the parameter space allowed for these models and limiting their overall ability to reconcile cosmological tensions. Although considering different combinations of data leaves some freedom to increase H0 towards the value measured by the SH0ES collaboration, our most constraining dataset (CMB+baryon acoustic oscillations+supernovae) indicates that fully reconciling the tension solely within the framework of interacting DE remains challenging. Published by the American Physical Society 2024

The Optical Corrector for the Dark Energy Spectroscopic Instrument

The Dark Energy Spectroscopic Instrument (DESI) is currently measuring the spectra of 40 million galaxies and quasars, the largest such survey ever made to probe the nature of cosmological dark energy. The 4 m Mayall telescope at Kitt Peak National Observatory has been adapted for DESI, including the construction of a 3.°2 diameter prime focus corrector that focuses astronomical light onto a 0.8 m diameter focal surface with excellent image quality over the DESI bandpass of 360–980 nm. The wide-field corrector includes six lenses, as large as 1.1 m in diameter and as heavy as 237 kilograms, including two counterrotating wedged lenses that correct for atmospheric dispersion over zenith angles from 0° to 60°. The lenses, cells, and barrel assembly all meet precise alignment tolerances on the order of tens of microns. The barrel alignment is maintained throughout a range of observing angles and temperature excursions in the Mayall dome by use of a hexapod, which is itself supported by a new cage, ring, and truss structure. In this paper we describe the design, fabrication, and performance of the new corrector and associated structure, focusing on how they meet DESI requirements. In particular, we describe the prescription and specifications of the lenses, design choices and error budgeting of the barrel assembly, stray light mitigations, and integration and test at the Mayall telescope. We conclude with some validation highlights that demonstrate the successful corrector on-sky performance, and we list some lessons learned during the multiyear fabrication phase.

Constraining neutrino-DM interactions with Milky Way dwarf spheroidals and supernova neutrinos

We constrain the neutrino-dark matter cross section using properties of the dark matter density profiles of Milky Way dwarf spheroidal galaxies. The constraint arises from core-collapse supernova neutrinos scattering on dark matter as a form of energy injection, allowing the transformation of the dark matter density profile from a cusped profile to a flatter profile. We assume a standard cosmology of dark energy and cold, collisionless, and non-self-interacting dark matter. By requiring that the dark matter cores do not lose too much mass or overshoot constraints from stellar kinematics, we place an upper limit on the cross section of σν−DM(Eν=15 MeV,mχ≲130 GeV)≈3.4×10−23 cm2 and σν−DM(Eν=15 MeV,mχ≳130 GeV)≈3.2×10−27(mχ1 GeV)2 cm2, which is stronger than previous bounds for these energies. Consideration of baryonic feedback or host galaxy effects on the dark matter profile can strengthen this constraint. Published by the American Physical Society 2024

Cosmology of Barrow holographic QCD ghost dark energy and a look into the thermodynamics

The present study endeavours to study the cosmology of QCD ghost dark energy based on Barrow holographic fluid, a particular example of Nojiri-Odintsov holographic dark energy (2006, General Relativity and Gravitation, 38, 1285–1304); (2017, The European Physical Journal C, 77, 1–8). The Hubble parameter is reconstructed and according the equation of state parameter is reconstructed for the Barrow holographic QCD ghost dark energy. It is observed that the effective equation of state parameter has a transition from quintessence to phantom and for the current universe the equation of state parameter is very close to −1. The deceleration parameter is computed based on the reconstructed Hubble parameter and it is observed that the model can have a transition from decelerated to accelerated universe. The statefinder trajectories are plotted and an interpolation between dust and ΛCDM phases is observed. Finally, the thermodynamics is studied considering apparent horizon as the enveloping horizon of the Universe.

Ghost dark energy in Tsallis and Barrow cosmology

According to the thermodynamics-gravity conjecture, any modification to the entropy expression leads to the modified cosmological field equations. Based on this, we investigate the cosmological consequences of the modified Friedmann equations when the entropy associated with the horizon is in the form of Tsallis/Barrow entropy and the dark energy (DE) component is in the form of ghost dark energy (GDE). We perform a dynamical system analysis and see that the Tsallis GDE(TGDE) and Barrow GDE(BGDE) can exhibit a correct phase space evolution for suitable range of the free parameters(0<Δ<1 for BGDE and β<3/2 for TGDE). We find that in BGDE and TGDE (with Q=3b2H(ρD+ρm)), there exist an early radiation dominated phase of expansion which is absent for GDE model in standard cosmology. It is worth mentioning that seeking an unstable phase of matter dominated in TGDE leads to a new constraint on β (<3/2). Using the resulting range of free parameters from latter step we find that both models are capable to explain the cosmic evolution from deceleration to an accelerated phase. We observe that increasing Δ (β) parameters leads to a delay in the cosmic phase transition. We conclude that BGDE and TGDE are viable cosmological models which predict a consistent phase transition of the cosmic expansion for suitable ranges of the parameters. We also calculate the squared sound speed for both models and find out that they are unstable against perturbations. Next, we proceed the statefinder analysis and see that both models are significantly distinct from ΛCDM as well as with respect to each other at past epochs, while both of them catch the standard cosmology at far future. We also explore the impacts of the non-extensive parameters on the density perturbations and find out that the pattern of density contrast (δ) evolution in TGDE/BGDE is distinct from GDE in standard cosmology.

Constraining dark energy cosmologies with spatial curvature using Supernovae JWST forecasting

Recent cosmological tensions, in particular, to infer the local value of the Hubble constant H 0, have developed new independent techniques to constrain cosmological parameters in several cosmologies. Moreover, even when the concordance Cosmological Constant Cold Dark Matter (ΛCDM) model has been well constrained with local observables, its physics has shown deviations from a flat background. Therefore, to explore a possible deviation from a flat ΛCDM model that could explain the H 0 value in tension with other techniques, in this paper we study new cosmological constraints in spatial curvature dark energy models. Additionally, to standard current Supernovae Type Ia (SNIa) catalogs, we extend the empirical distance ladder method through an SNIa sample using the capabilities of the James Webb Space Telescope (JWST) to forecast SNIa up to z ∼ 6, with information on the star formation rates at high redshift. Furthermore, we found that our constraints provide an improvement in the statistics associated with Ω m when combining SNIa Pantheon and SNIa Pantheon+ catalogs with JW forecasting data.

Quark Clusters, QCD Vacuum and the Cosmological 7Li, Dark Matter and Dark Energy Problems

We propose a non-exotic electromagnetic solution (within the standard model of particle physics) to the cosmological 7Li problem based upon a narrow 2 MeV photo-emission line from the decay of light glueballs (LGBs). These LGBs form within color superconducting quark clusters (SQCs), which are tens of Fermi in size, in the radiation-dominated post-BBN epoch. The mono-chromatic line from the LGB→γ+γ decay reduces Big Bang nucleosynthesis (BBN) 7Be by 2/3 without affecting other abundances or the cosmic microwave background (CMB) physics, provided the combined mass of the SQCs is greater than the total baryonic mass in the universe. Following the LGB emission, the in-SQC Quantum ChromoDynamics (QCD) vacuum becomes unstable and “leaks” (via quantum tunneling) into the external space-time (trivial) vacuum, inducing a decoupling of SQCs from hadrons. In seeking a solution to the 7Li problem, we uncovered a solution that also addresses the Dark Energy (DE) and dark matter (DM) problem, making these critical problems intertwined in our model. Being colorless, charge-neutral, optically thin, and transparent to hadrons, SQCs interact only gravitationally, making them a viable cold DM (CDM) candidate. The leakage (i.e., quantum tunneling) of the in-SQC QCD vacuum to the trivial vacuum offers an explanation of DE in our model and allows for a cosmology that evolves into a ΛCDM universe at a low redshift with a possible resolution of the Hubble tension. Our model distinguishes itself by proposing that the QCD vacuum within SQCs possesses the ability to tunnel into the exterior trivial vacuum, resulting in the generation of DE. This implies the possibility that DM and hadrons might represent distinct phases of quark matter within the framework of QCD, characterized by different vacuum properties. We discuss SQC formation in heavy-ion collision experiments at moderate temperatures and the possibility of detection of MeV photons from the LGB→γ+γ decay.

Cosmology of Tsallis and Kaniadakis holographic dark energy in Saez–Ballester theory and consideration of viscous van der Waals fluid

In the framework of Saez–Ballester (SB) theory, the current study proposes a reconstruction scheme for Tsallis and Kaniadakis holographic dark energy, particular cases of a more generalised Nojiri–Odintsov holographic dark energy (Nojiri and Odintsov, 2006; The European Physical Journal C, 2017, 77, pp.1-8.), with Hubble horizon and future event horizons serving as the universe’s respective trapping horizons. The Hubble parameter was rebuilt by placing a constraint on the metric potential inside the conservation equation. As a result, the holographic dark energy of Tsallis and Kaniadakis are recreated, and the cosmology and thermodynamics are examined. Lastly, an interacting van der Waals (VDW) coupled fluid model was examined in the context of bulk viscosity, and the behaviour of the equation of state (EoS) parameter was examined.

Barrow holographic dark energy in Brane world cosmology

Cosmological features of barrow holographic dark energy (BHDE), a recent generalization of original Holographic dark energy (DE) with a richer structure, are studied in the context of Dvali–Gabadadze–Porrati (DGP) brane, Randall and Sundrum (RS II) brane-world, and the cyclic Universe. It is found that a flat FRW scenario with pressure less dust and a DE component described as BHDE can accommodate late time acceleration with Hubble horizon considered as infrared cut off even in the absence of interaction between the dark sectors. Statefinder diagnostic reveals that these model resemble ΛCDM cosmology in future. It is found that BHDE parameter Δ, despite its theoretically constrained range of values, is significant in describing the evolution of the Universe, however, a classically stable cosmological model cannot be obtained in the RS-II and DGP brane. Viability of the models is also probed with observed Hubble data.

Sharma–Mittal holographic dark energy and scalar field in Bianchi type-I cosmology

Sharma–Mittal holographic dark energy and scalar field in Bianchi type-I cosmology

Electromagnetic plasma waves in dark energy cosmology

We explore the electromagnetic wave modes that can exist in a cosmological plasma dominated by dark energy due to a cosmological constant. It is found that, in the cold and hot plasma cases, electromagnetic plasma wave modes can be found exactly. The effect of this cosmology appears as a time-dependent potential in the wave equation for the electromagnetic modes, which effectively modifies the frequency response of the plasma. This potential depends on the metric of the spacetime and on the thermodynamical properties of the plasma. For both cases, cold and hot, the solutions are found in terms of Airy and Bessel functions, respectively. When those solutions are required to have vanishing initial conditions, a discretization on the wavelengths of the electromagnetic plasma waves is imposed. Thus, only some specific wave modes can exist in this dark energy cosmology. Relaxing those conditions, we obtain other solutions that approximate to plane waves only in the very hot plasma limit.

Studies of Density Contrast of Cold Dark Matter in Cosmological Radiation and Dark Energy Background: A Symmetry-Based Approach

Studies of Density Contrast of Cold Dark Matter in Cosmological Radiation and Dark Energy Background: A Symmetry-Based Approach

Canonical Hubble-Tension-Resolving Early Dark Energy Cosmologies Are Inconsistent with the Lyman-α Forest.

Current cosmological data exhibit discordance between indirect and some direct inferences of the present-day expansion rate H_{0}. Early dark energy (EDE), which briefly increases the cosmic expansion rate prior to recombination, is a leading scenario for resolving this "Hubble tension" while preserving a good fit to cosmic microwave background (CMB) data. However, this comes at the cost of changes in parameters that affect structure formation in the late-time universe, including the spectral index of scalar perturbations n_{s}. Here, we present the first constraints on axionlike EDE using data from the Lyman-α forest, i.e., absorption lines imprinted in background quasar spectra by neutral hydrogen gas along the line of sight. We consider two independent measurements of the one-dimensional Lyα forest flux power spectrum from the Sloan Digital Sky Survey (SDSS eBOSS) and from the MIKE/HIRES and X-Shooter spectrographs. We combine these with a baseline dataset comprised of Planck CMB data and baryon acoustic oscillation (BAO) measurements. Combining the eBOSS Lyα data with the CMB and BAO dataset reduces the 95% confidence level (C.L.) upper bound on the maximum fractional contribution of EDE to the cosmic energy budget f_{EDE} from 0.07 to 0.03 and constrains H_{0}=67.9_{-0.4}^{+0.4} km/s/Mpc (68% C.L.), with maximum aposteriori value H_{0}=67.9 km/s/Mpc. Similar results are obtained for the MIKE/HIRES and X-Shooter Lyα data. Our Lyα-based EDE constraints yield H_{0} values that are in >4σ tension with the SH0ES distance-ladder measurement and are driven by the preference of the Lyα forest data for n_{s} values lower than those required by EDE cosmologies that fit Planck CMB data. Taken at face value, the Lyα forest severely constrains canonical EDE models that could resolve the Hubble tension.

Shape of CMB lensing in the early dark energy cosmology

Shape of CMB lensing in the early dark energy cosmology

Quintessence reconstruction through new Tsallis holographic dark energy model

In statistical theory, the Tsallis entropy is an extended form of the Boltzmann–Gibbs entropy. The dimensionless parameter [Formula: see text] is employed to state the quantitative difference from the standard scenario. The concepts of Tsallis entropy and the future event horizon are employed in formulating the present new Tsallis holographic dark energy (NTHDE) model. The model attempts to explain the properties of dark energy using the foundation of quantum gravity. The differential equation characterizing the evolution of the NTHDE density parameter is obtained. Expressions stating the dynamic behavior such as equation of state (EoS), deceleration and jerk parameters are obtained in terms of the NTHDE density parameter. For [Formula: see text], the quintessence nature of scalar field could completely characterize the NTHDE. A reconstruction of the scalar field’s dynamics and quintessence potential is attempted. We demonstrate that the diagnosis made by statefinder is adaptive enough to distinguish between quintessence and cosmological constant-based dark energy models. Additionally, observational data obtained from CC[Formula: see text] SNIa [Formula: see text] union 2.1 sources are used to evaluate the model’s effectiveness.

IDECAMB: an implementation of interacting dark energy cosmology in CAMB

Interacting dark energy (IDE) scenario is a natural and important extension to the standard ΛCDM cosmology. We develop a full numerical routine, called IDECAMB, as a patch to the public Einstein-Boltzmann solver CAMB, to solve the background and perturbation equations of the IDE models. The IDECAMB solver provides a unified interface for the widely studied IDE models by employing a parametrization model with five free functions. By configuring these five functions, one can easily map the coupled quintessence (CQ) and coupled fluid (CF) models into the parametrization. We handle the perturbation evolutions of the CF models with the parametrized post-Friedmann (PPF) approach to avoid the possible large-scale instability. Compared with the previous established PPF approach whose form depends on a specific IDE model, the PPF approach in this work are model-independent, making it easy to use. We constrain a specific CQ model with the IDECAMB package. The fitting results are consistent with those obtained by Planck Collaboration, which confirms the validity of the package.

Anisotropic Segre [(11)(1,1)] dark energy following a particular equation of state

A generally anisotropic equation of state originally derived in the context of Newman-Janis rotating systems allows for vacuum energy at a specific density. In this paper we examine the possibility of using that equation of state for cosmological dark energy. We treat the case of large scale ordering of the directions of the energy-momentum tensor eigenvectors with a Bianchi cosmological model, and treat the case where the ordering is random on small scales with an effectively isotropic FLRW system. We find particular spacetimes which evolve towards a vacuum energy/ de Sitter like configuration in either case. In the anisotropic Bianchi case, the system can have behavior reminiscent of big bounce cosmologies, in which the matter content approaches vacuum energy at large scale factor and can behave in a variety of ways at small scale factor. For particular conditions in the effectively isotropic case, we can evolve between true and false vacuum configurations, or between radiation like and vacuum energy configurations. We also show how some simpler equations of state behave under the same assumptions to elucidate the methods for analysis.