Beyond Λ CDM: Problems, solutions, and the road ahead
Abstract
Despite its continued observational successes, there is a persistent (and growing) interest in extending cosmology beyond the standard model, Λ CDM. This is motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the CMB and on small scales, and the predictivity and testability of the inflationary paradigm. In this paper, we summarize the current status of Λ CDM as a physical theory, and review investigations into possible alternatives along a number of different lines, with a particular focus on highlighting the most promising directions. While the fundamental problems are proving reluctant to yield, the study of alternative cosmologies has led to considerable progress, with much more to come if hopes about forthcoming high-precision observations and new theoretical ideas are fulfilled.
- Publication:
-
Physics of the Dark Universe
- Pub Date:
- June 2016
- DOI:
- 10.1016/j.dark.2016.02.001
- arXiv:
- arXiv:1512.05356
- Bibcode:
- 2016PDU....12...56B
- Keywords:
-
- Cosmology;
- Dark energy;
- Cosmological constant problem;
- Modified gravity;
- Dark matter;
- Early universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies;
- General Relativity and Quantum Cosmology;
- High Energy Physics - Phenomenology;
- High Energy Physics - Theory
- E-Print:
- 99 pages, 8 figures. Version published in Physics of the Dark Universe