Dark Matter, Dark Energy and Cosmological Anisotropy

Topic Information

Dear Colleagues,

Investigating the origin of dark matter and dark energy is crucial to modern astroparticle physics and cosmology. After the first direct detection of the gravitational wave event from binary black holes by LIGO in 2015, we have entered the era of gravitational wave cosmology.

For the origin of dark matter, two main possibilities exist: One is new weakly interacting massive particles in particle theory models beyond the standard model. The other is astrophysical objects. On the other hand, the origin of dark energy, there are two representative approaches explaining the properties of dark energy components, realizing the late-time cosmic acceleration. The first is the introduction of unknown matter, called dark energy, with its negative pressure, in general relativity. The other is to extend a gravity theory on cosmological scales. The latter approach is known as geometrical dark energy. Moreover, another remarkable approach with anisotropies emerging during the cosmic expansion could have contributed to the generation of particle creation, through mechanisms activated under conditions of rapid spacetime variation, causing an anisotropic dark energy. Additionally, observations of the cosmic microwave background (CMB) reveal that the universe is not perfectly isotropic. On local scales, structures such as galaxies, clusters, voids, and cosmic filaments introduce local anisotropies, challenging the assumption of large-scale homogeneity and symmetry. In addition, the directional asymmetry of mass particles has recently been investigated. Moreover, cosmic expansion may exhibit directional dependence, influenced by factors such as primordial magnetic fields or asymmetric galaxy rotation. The anisotropies observed in the universe may be directly related to its matter content.

The main subject of this Topic project is an understanding of the true nature of dark matter and dark energy. We can consider both phenomenological approaches and the procedures based on fundamental physics, including higher-dimensional gravity theories, which extend GR by introducing additional degrees of freedom, offering alternative explanations for cosmic evolution,  and high-energy phenomena, quantum gravity, quantum field theories, and gauge field theories in curved spacetime, string theories, brane world models, and holographic principles.

It is our pleasure to invite submissions to this Topic on dark matter and dark energy, as well as relevant foundations of physics. 

Prof. Dr. Kazuharu Bamba
Prof. Dr. Panayiotis Stavrinos
Prof. Dr. Ivan De Martino
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Astronomy astronomy	-	2.3	2022	30.2 Days	CHF 1200	Submit
Galaxies galaxies	3.8	6.3	2013	25.8 Days	CHF 1500	Submit
Particles particles	2.3	3.0	2018	22 Days	CHF 1600	Submit
Symmetry symmetry	2.2	5.3	2009	15.8 Days	CHF 2400	Submit
Universe universe	2.6	5.2	2015	21.8 Days	CHF 1600	Submit

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Published Papers (5 papers)

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All Symmetry Galaxies Universe Particles Astronomy

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11 pages, 709 KB  

Open AccessCommunication

Long-Lived Merger Signatures in the Perseus Cluster and a Candidate Remnant Interpretation

by Shawn Hackett

Galaxies 2026, 14(3), 52; https://doi.org/10.3390/galaxies14030052 - 18 May 2026

Viewed by 117

Abstract

Weak-lensing observations of the Perseus Cluster now indicate a massive sub-halo associated with NGC 1264 and a connecting mass bridge in a system long treated as a benchmark relaxed cool-core cluster. Perseus is also known from X-ray observations to host large-scale gas sloshing [...] Read more.

Weak-lensing observations of the Perseus Cluster now indicate a massive sub-halo associated with NGC 1264 and a connecting mass bridge in a system long treated as a benchmark relaxed cool-core cluster. Perseus is also known from X-ray observations to host large-scale gas sloshing and an ancient cold front extending to several hundred kiloparsecs. This paper uses Perseus as a motivation for a narrower population question: do nominally relaxed clusters retain merger history information in residual mass–gas offsets after the obvious signatures of an active merger have faded? A candidate remnant stress–energy interpretation is introduced as one possible covariant language for such a long-lived structure, but the empirical test does not require acceptance of that interpretation. The work then carries out a literature-based pilot test using the cold front outer radius as an independent merger history proxy, published mass–gas or gas tracer offsets for relaxed/cool-core systems, and a separate control cohort of actively dissociative mergers. The resulting three-regime comparison separates young active mergers, relaxed low-offset systems, and relaxed systems with sourced offsets above 5 kpc. For all seven Regime 3 (relaxed, offset $>5$ kpc) systems with vetted cold front/history proxies and sourced mass–gas offset measurements, the directional rank-order association has the predicted sign, ${\rho }_s=0.68$, with $p_{\mathrm{one-sided}}\approx 0.047$ ($p_{\mathrm{two-sided}}\approx 0.094$, $N=7$). The one-sided statistic crosses the conventional $5\%$ threshold. The sample mixes lensing–X-ray centroid offsets, BCG/X-ray peak offsets, and weak-lensing sub-halo separations, and the result is not a decisive population detection: it is a suggestive directional signal in a small heterogeneous archival pilot. Its significance is that a framework-derived directional diagnostic, specified before the sample was assembled, is non-zero in the predicted sense and can now be tested with a homogeneous weak-lensing/X-ray/SZ survey. Full article

(This article belongs to the Topic Dark Matter, Dark Energy and Cosmological Anisotropy)

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17 pages, 1183 KB  

Open AccessArticle

Observational Constraints and Cosmological Dynamics of Interacting Fractional Holographic Dark Energy in Light of DESI DR2

by Qihong Huang, Hao Chen and Qingdong Wu

Universe 2026, 12(5), 134; https://doi.org/10.3390/universe12050134 - 4 May 2026

Viewed by 258

Abstract

Based on the fractional entropy originating from fractional quantum mechanics, the fractional holographic dark energy (FHDE) model has been proposed. In this paper, we consider an interaction between the pressureless matter and FHDE and analyze three different interacting FHDE models. Combining the latest [...] Read more.

Based on the fractional entropy originating from fractional quantum mechanics, the fractional holographic dark energy (FHDE) model has been proposed. In this paper, we consider an interaction between the pressureless matter and FHDE and analyze three different interacting FHDE models. Combining the latest observational data including SNIa, OHD, BAO, and CMB, we estimate the model parameters and find that the interaction forms $Q=\gamma H{\rho }_{de}$ and $Q=\beta H{\rho }_m+\gamma H{\rho }_{de}$ show some preference from the observational data. Using phase space analysis, we further find that only interacting FHDE model with $Q=\beta H{\rho }_m+\gamma H{\rho }_{de}$ can describe the full evolutionary history of the universe. The statefinder diagnostic pair reveals that this model deviates from the $\mathsf{\Lambda }$CDM model but converges to the $\mathsf{\Lambda }$CDM fixed point and the de Sitter expansion fixed point in the future. Finally, we analyze the evolution of cosmological parameters and demonstrate that this model can drive the late time acceleration of the universe. Full article

(This article belongs to the Topic Dark Matter, Dark Energy and Cosmological Anisotropy)

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22 pages, 1411 KB  

Open AccessArticle

Late-Time Cosmic Acceleration from QCD Confinement Dynamics

by Jonathan Rincón Saucedo, Humberto Martínez-Huerta, Adolfo Huet, Alberto Hernández-Almada and Miguel A. García-Aspeitia

Universe 2026, 12(5), 127; https://doi.org/10.3390/universe12050127 - 28 Apr 2026

Viewed by 236

Abstract

We explore a phenomenological extension of the Polyakov–Nambu–Jona-Lasinio (PNJL) model by introducing a curvature-sensitive effective contribution to the Polyakov-loop potential, motivated by the hypothesis that the non-perturbative QCD vacuum in the confined phase may retain a residual sensitivity to cosmic expansion. In a [...] Read more.

We explore a phenomenological extension of the Polyakov–Nambu–Jona-Lasinio (PNJL) model by introducing a curvature-sensitive effective contribution to the Polyakov-loop potential, motivated by the hypothesis that the non-perturbative QCD vacuum in the confined phase may retain a residual sensitivity to cosmic expansion. In a spatially flat FLRW background, this modification reduces to a term proportional to $\alpha {(H/H_0)}^{d}f(\Phi ,{\Phi }^{*})$, which naturally vanishes in the deconfined regime and behaves as an effective dynamical vacuum component at late times, without invoking a fundamental cosmological constant. The construction provides an effective thermodynamic description of the QCD sector within an adiabatic framework and introduces a minimal phenomenological extension characterized by the exponent d and the amplitude parameter $\alpha$. We analyze the cosmological implications at the background level and compare the model with low-redshift observations, including cosmic chronometers, Type Ia supernovae, HII galaxies, and quasars. Using Bayesian Monte Carlo techniques, we constrain the model parameters and compare its performance with the ΛCDM. Our results indicate that the modified PNJL cosmology provides a statistically competitive fit to current data while allowing small departures from the ΛCDM within observational uncertainties. We also investigate the impact of the coupling on the QCD phase diagram and the critical end point. The framework offers a tractable effective approach to connect confinement physics with late-time cosmology and suggests directions for further theoretical development in QCD under curved backgrounds. Full article

(This article belongs to the Topic Dark Matter, Dark Energy and Cosmological Anisotropy)

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48 pages, 5383 KB  

Open AccessArticle

A Dark Atom Scenario for Direct Dark Matter Investigation

by Pierluigi Belli, Rita Bernabei, Vitaly Beylin, Timur Bikbaev, Artem Kharakhashyan, Maxim Khlopov, Vladimir Korchagin, Andrey Mayorov and Danila Sopin

Universe 2026, 12(4), 116; https://doi.org/10.3390/universe12040116 - 15 Apr 2026

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Abstract

This paper extensively explores the concept of dark atoms, hypothetical stable lepton-like particles with a charge of $-2n$ (where n is any natural number) that form neutral bound states with n primordial helium nuclei. The discussion begins with the introduction of [...] Read more.

This paper extensively explores the concept of dark atoms, hypothetical stable lepton-like particles with a charge of $-2n$ (where n is any natural number) that form neutral bound states with n primordial helium nuclei. The discussion begins with the introduction of multiply charged stable particles. Next, the formation and evolution of dark atoms are examined, followed by a review of related constraints. The capture of dark atoms by the Earth and implications for direct dark matter search are subsequently discussed. Then, the quantum-mechanical description of bound states between dark atoms and ordinary nuclei is addressed. Moreover, procedures for systematic comparisons with this model, which have general interest, are presented considering the DAMA published results on the dark matter annual and diurnal modulation signatures as a benchmark. Full article

(This article belongs to the Topic Dark Matter, Dark Energy and Cosmological Anisotropy)

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29 pages, 767 KB  

Open AccessReview

The Impact of Dark Matter on Gravitational Wave Detection by Space-Based Interferometers

by Yuezhe Chen, Pan-Pan Wang, Bo Wang, Rui Luo and Cheng-Gang Shao

Universe 2026, 12(2), 48; https://doi.org/10.3390/universe12020048 - 11 Feb 2026

Cited by 1 | Viewed by 1362

Abstract

The existence of dark matter is supported by multiple astrophysical observations, yet its particle nature remains unknown. The development of gravitational wave astronomy, especially with future space-based detectors such as LISA, provides new opportunities to study the interactions between dark matter and compact-object [...] Read more.

The existence of dark matter is supported by multiple astrophysical observations, yet its particle nature remains unknown. The development of gravitational wave astronomy, especially with future space-based detectors such as LISA, provides new opportunities to study the interactions between dark matter and compact-object systems. This review summarizes the main dark matter candidates and their macroscopic distributions, and highlights three mechanisms through which dark matter can affect gravitational wave observations: (1) modifications to compact-object orbits and the dynamics of systems such as extreme mass-ratio inspirals, including dark matter spikes, dynamical friction, and potential perturbations; (2) gravitational lensing effects induced by the spatial distribution of dark matter, altering waveform amplitudes and phases; and (3) direct couplings between ultralight dark matter fields and detectors. As low-frequency gravitational wave detection techniques are proposed and continue to develop, these effects may offer a novel avenue for probing the properties of dark matter, and combining precise waveform modeling with multi-messenger observations could reveal insights into its microscopic structure. Full article

(This article belongs to the Topic Dark Matter, Dark Energy and Cosmological Anisotropy)

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