Viable cosmology in bimetric theory

Journal Article · Sun Jun 01 00:00:00 EDT 2014 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2014/06/037· OSTI ID:22373507

Felice, Antonio De ^[1]; Gümrükçüoğlu, A. Emir ^[2]; Mukohyama, Shinji; Tanahashi, Norihiro ^[3]; Tanaka, Takahiro ^[4]

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1. Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)
2. School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom)
3. Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo (WPI), 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)
4. Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

We study cosmological perturbations in bimetric theory with two fluids each of which is coupled to one of the two metrics. Focusing on a healthy branch of background solutions, we clarify the stability of the cosmological perturbations. For this purpose, we extend the condition for the absence of the so-called Higuchi ghost, and show that the condition is guaranteed to be satisfied on the healthy branch. We also calculate the squared propagation speeds of perturbations and derive the conditions for the absence of the gradient instability. To avoid the gradient instability, we find that the model parameters are weakly constrained.

• OSTI ID: 22373507
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 06 Vol. 2014; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGY
FOCUSING
INSTABILITY
MATHEMATICAL SOLUTIONS
METRICS
PERTURBATION THEORY
STABILITY
VELOCITY