Quintessence's Last Stand?

Understand

Current cosmological data puts increasing pressure on models of dark energy in the freezing class, e.g.

• early dark energy or those with equation of state $w$ substantially different from $-1$.
• We investigate to what extent data will distinguish the thawing class of quintessence from a cosmological constant.
• Since thawing dark energy deviates from $w=-1$ only at late times, we find that deviations $1+w\lesssim0.1$ are difficult to see even with next generation measurements; however, modest redshift drift data can improve the sensitivity by a factor of two.