Formation of caustics in k-essence and Horndeski theory
Abstract
We study propagation of waves and appearance of caustics in k-essence and galileon theories. First we show that previously known solutions for travelling waves in k-essence and galileon models correspond to very specific fine-tuned initial conditions. On the contrary, as we demonstrate by the method of characteristics, generic initial conditions leads to a wave in k-essence which ends up with formation of caustics. Finally, we find that any wave solution in pure k-essence is also a solution for a galileon theory with the same k-essence term. Thus in the Horndeski theory with a k-essence term formation of caustics is generic. We discuss physical consequences of the caustics formation and possible ways to cure the problem.
Keywords
Cite
@article{arxiv.1602.00735,
title = {Formation of caustics in k-essence and Horndeski theory},
author = {Eugeny Babichev},
journal= {arXiv preprint arXiv:1602.00735},
year = {2016}
}
Comments
17 pages, 3 figures, v3: References added, appendix added with a tentative approach to resolve the caustic problem; v4: typos corrected, matches published version