Quantum mechanics

Theoretical physics

Neutrino oscillation

Vacuum energy

Cosmology

Particle physics

Lambda

Planck

Astrophysics

Energy (signal processing)

Neutrino

Metric expansion of space

Dark energy

Imaging phantom

Physics

Optics

Sterile neutrino

Dark matter

Universe

Physics of the Dark Universe

Since physics of the dark sector components of the Universe is not yet well-understood, the phenomenological studies of non-minimal interaction in the dark sector could possibly pave the way to theoretical and experimental progress in this direction. Therefore, in this work, we intend to explore some features and consequences of a phenomenological interaction in the dark sector. We use the Planck 2018, BAO, JLA, KiDS and HST data to investigate two extensions of the base ΛCDM model, viz., (i) we allow the interaction among vacuum energy and dark matter, namely the IΛCDM model, wherein the interaction strength is proportional to the vacuum energy density and expansion rate of the Universe, and (ii) the IΛCDM scenario with free effective neutrino mass and number, namely the νIΛCDM model. We also present comparative analyses of the interaction models with the companion models, namely, ΛCDM, νΛCDM, wCDM and νwCDM. In both the interaction models, we find non-zero coupling in the dark sector up to 99% CL with energy transfer from dark matter to vacuum energy, and observe a phantom-like behavior of the effective dark energy without actual "phantom crossing". The well-known tensions on the cosmological parameters H0 and σ8, prevailing within the ΛCDM cosmology, are relaxed significantly in these models wherein the νIΛCDM model shows consistency with the standard effective neutrino mass and number. Both the interaction models find a better fit to the combined data compared to the companion models under consideration.

Remedy of some cosmological tensions via effective phantom-like behavior of interacting vacuum energy