Journal
PHYSICAL REVIEW D
Volume 105, Issue 12, Pages -Publisher
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevD.105.123529
Keywords
-
Funding
- U.S. Department of Energy [DE-FG02-13ER41958]
- Simons Foundation
- Kavli Institute for Cosmological Physics at the University of Chicago [NSF PHY-1125897]
Ask authors/readers for more resources
This article introduces a new method for efficiently and accurately evolving ultralight axions, addressing the challenge of tracking the oscillations of axions on cosmological timescales. The method achieves subpercent accuracy for the linear theory suppression of axion density fluctuations relative to cold dark matter without the need to track complete oscillations.
Ultralight axions are theoretically interesting and phenomenologically rich dark sector candidates, but they are difficult to track across cosmological timescales because of their fast oscillations. We resolve this problem by developing a novel method to evolve them efficiently and accurately. We first construct an exact effective fluid which at late times matches the axion but which evolves in a simple way. We then approximate this evolution with a carefully chosen equation of state and sound speed. With our scheme we find that we can obtain subpercent accuracy for the linear theory suppression of axion density fluctuations relative to that of cold dark matter without tracking even a single complete oscillation of the axion field. We use our technique to test other approximation schemes and to provide a fitting formula for the transfer function for the matter power spectrum in linear theory in axion models. Implementing our approach in existing cosmological axion codes is straightforward and will help unleash the potential of high-precision next-generation experiments.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available