Gemini's Nod-&-Shuffle Provides Critical Deep Spectroscopic Data for Supernova Legacy Survey

Contours at 68.3%, 95.5% and 99.7% confidence level for the fit to an (Ω_M, Ω_Λ) cosmology from the SNLS Hubble diagram (solid contours, the SDSS baryon acoustic oscillations (Eisenstein et al. 2005, dotted lines), and the joint confidence contours (dashed lines). From the first year of SNLS, the strength of the dark energy appears to remain constant as the universe expands. This is at odds with a number of theretical ideas aobut the nature of dark energy.