2014/09/30 by Adam R. Solomon, Jonas Enander, Yashar Akrami +3 · 2 citations
Physics and Astronomy · #Cosmology #Cosmology and Gravitation Theories #Dark energy #Dark matter #Equivalence (formal languages) #Friedmann–Lemaître–Robertson–Walker metric #Galaxies: Formation, Evolution, Phenomena #Graviton #Massive gravity #Metric (unit) #Perfect fluid #Pulsars and Gravitational Waves Research #astro-ph.CO #gr-qc #hep-th
paper · pdf · doi:10.1088/1475-7516/2015/04/027
published as JCAP 04 (2015) 027 · 22 pages. Version published in JCAP
arxiv created 2015/04/20 · openalex publication_date 2015/04/20 · arxiv updated 2015/04/21 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
There is a no-go theorem forbidding flat and closed FLRW solutions in massive gravity on a flat reference metric, while open solutions are unstable. Recently it was shown that this no-go theorem can be overcome if at least some matter couples to a hybrid metric composed of both the dynamical and the fixed reference metric. We show that this is not compatible with the standard description of cosmological sources in terms of effective perfect fluids, and the predictions of the theory become sensitive either to the detailed field-theoretical modelling of the matter content or to the presence of additional dark degrees of freedom. This is a serious practical complication. Furthermore, we demonstrate that viable cosmological background evolution with a perfect fluid appears to require the presence of fields with highly contrived properties. This could be improved if the equivalence principle is broken by coupling only some of the fields to the composite metric, but viable self-accelerating solutions due only to the massive graviton are difficult to obtain.