A study at the University of Provence in Marseille (France), which has used the measurement of the geometry of distant pairs of galaxies, confirms that the Universe is flat and indicates that dark energy is probably Einstein's cosmological constant . The results of the work are published in the journal 'Nature'.
The accelerated expansion of the Universe seems to require the existence of a dark energy that opposes gravity. In principle, it is possible to study cosmic expansion by analyzing the distortions imposed on distant structures through the geometry of space time. In practice, however, local non-cosmological motions of astronomical objects have made this test difficult to implement.
The researchers, led by Christian Marinoni and Adelina Buzzi, have overcome this problem by applying the geometric test to pairs of distant galaxies in orbit. After calibrating their method using pairs of nearby galaxies, the authors have discovered that the apparent geometry of distant pairs requires the Universe to be flat. Additionally, when the data was combined with observations of large-scale galaxy clusters, the data identifies Einstein's cosmological constant, equivalent to a proposed vacuum energy, as the likely explanation for dark energy.
