Quintessence in a quandary: prior dependence in dark energy models

Abstract

The archetypal theory of dark energy is quintessence: a minimally coupled scalar field with a canonical kinetic energy and potential. By studying random potentials we show that quintessence imposes a restricted set of priors on the equation of state of dark energy. Focusing on the commonly-used parametrisation, $w(a)\approx w_0+w_a(1-a)$, we show that there is a natural scale and direction in the $(w_0,w_a)$ plane that distinguishes quintessence as a general framework. We calculate the expected information gain for a given survey and show that, because of the non-trivial prior information, it is a function of more than just the figure of merit. This allows us to make a quantitative case for novel survey strategies. We show that the scale of the prior sets target observational requirements for gaining significant information. This corresponds to a figure of merit FOM$\gtrsim 200$, a requirement that future galaxy redshift surveys will meet.

5 pages, 3 figures. For the busy reader, Fig. 1 is the money plot. v2: Minor changes, matches published version. Code open source at gitorious.org/random-quintessence

References in corpus (8)

• Cosmology and the Fate of Dilatation Symmetry
• Monodromy in the CMB: Gravity Waves and String Inflation
• Thawing quintessence with a nearly flat potential
• The Dynamics of Quintessence, The Quintessence of Dynamics
• Axions as Quintessence in String Theory
• Where in the String Landscape is Quintessence
• Dynamical behavior of generic quintessence potentials: constraints on key dark energy observables
• Can we ever distinguish between quintessence and a cosmological constant?

Cited by in corpus (12)

• Beyond the Cosmological Standard Model
• The status of varying constants: a review of the physics, searches and implications
• Scant evidence for thawing quintessence
• Underdetermination of dark energy
• Robustness of dark energy phenomenology across different parameterizations
• Quintessence's Last Stand?
• Parametrizing modified gravity for cosmological surveys
• Cosmic Birefringence from Monodromic Axion Dark Energy
• Theoretical priors in scalar-tensor cosmologies: Thawing quintessence
• Cosmological consequences of a scalar field with oscillating equation of state. II. Oscillating scaling and chaotic accelerating solutions
• Statistics of Thawing K-essence Dark Energy Models
• Thawing Quintessence: Priors, evidence, and likely trajectories