Dark Matter, Dark Energy and Cosmological Anisotropy

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