Abstract
Title: "Dark energy in the Universe"
Abstract:
Recent numerous observational data obtained from such independent
sources as angular anisotropies of the cosmic microwave background
radiation, large-scale gravitational clustering of galaxies and their
clusters and observations of supernovae explosions at high redshifts
prove convincingly that about 70% of the total energy density of matter
in the present Universe is due to a new kind of matter in the Universe
("dark energy") which is non-baryonic, has negative pressure which
modulus is very close to dark energy density (if the Einsteinian form of
gravity field equations is assumed) and remains unclustered at all scales
where clustering of baryons and dust-like cold dark matter is seen. I
discuss different forms of phenomenological description of dark energy
properties, consider a possibility of decaying dark energy and present
limits on this process from supernovae data, and make a brief review of
different theoretical models of dark energy including those in which it
has a purely geometrical origin. However, the simplest possibility of dark
energy being a cosmological constant and nothing more still remains the
best fit to all existing observational data.