In section 3. Cosmology
Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples
In recent years we have discovered not onlythat the Universe expands, but that it also does so in an accelerating manner. The physical cause of this acceleration is rather uncertain and it has been attributed to either a peculiar fluid, called dark energy, or to a possible gravity modification to be introduced in Einstein's general relativity field equations. To make progress on this key cosmological problem, cosmologists use a specific type (the so-called Type Ia) of distant supernovae to precisely map the distance-redshift relation up to very large distances, thereby tracking the late-time expansion history of the Universe. This paper presents results from the latest version of this experiment by combining a recently acquired sample of 740 supernovae with high-quality light curves.