Gravitational waves in bigravity cosmology

Journal Article · Fri May 01 04:00:00 EDT 2015 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2015/05/030· OSTI ID:22525829

Cusin, Giulia; Durrer, Ruth; Guarato, Pietro; Motta, Mariele ^[1]

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1. Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, 24 quai Ansermet, Genève 4, CH–1211 Switzerland (Switzerland)

In this paper we study gravitational wave perturbations in a cosmological setting of bigravity which can reproduce the ΛCDM background and large scale structure. We show that in general gravitational wave perturbations are unstable and only for very fine tuned initial conditions such a cosmology is viable. We quantify this fine tuning. We argue that similar fine tuning is also required in the scalar sector in order to prevent the tensor instability to be induced by second order scalar perturbations. Finally, we show that due to this power law instability, models of bigravity can lead to a large tensor to scalar ratio even for low scale inflation.

• OSTI ID: 22525829
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 05 Vol. 2015; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGICAL CONSTANT
COSMOLOGICAL INFLATION
COSMOLOGY
DISTURBANCES
GRAVITATIONAL WAVES
NONLUMINOUS MATTER
SCALARS
TENSORS