Gravitational Waves in the Presence of Viscosity

Abstract

We analyze gravitational waves propagating in an isotropic cosmic fluid endowed with a bulk viscosity $\zeta$ and a shear viscosity $\eta$, assuming these coefficients to vary with fluid density $\rho$ as ${\rho }^{\lambda }$, with $\lambda =1/2$ favored by experimental evidence. We give the general governing equation for the gravitational waves, and focus thereafter on two examples. The first concerns waves in the very late universe, close to the Big Rip, where the fate of the comic fluid is dependent highly on the values of the parameters. Our second example considers the very early universe, the lepton era; the motivation for this choice being that the microscopical bulk viscosity as calculated from statistical mechanics is then at maximum. We find that the gravitational waves on such an underlying medium are damped, having a decay constant equal to the inverse of the conformal Hubble parameter. Our results turn out to be in good agreement with other viscosity-based approaches.

arXiv commentVersion to appear in IJMPD. LaTeX 14 pages

References in corpus (27)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence
• GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2
• Dark energy cosmology: the equivalent description via different theoretical models and cosmography tests
• GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence
• Inhomogeneous Equation of State of the Universe: Phantom Era, Future Singularity and Crossing the Phantom Barrier
• Observational constraints on dark energy with generalized equations of state
• Damping of Tensor Modes in Cosmology
• Dark Energy and Viscous Cosmology
• Viscous Cosmology for Early- and Late-Time Universe
• Dark goo: Bulk viscosity as an alternative to dark energy
• Inflationary universe in terms of a van der Waals viscous fluid
• Gravitational Waves in Cold Dark Matter
• Damping of gravitational waves by matter
• Characteristic Properties of Two Different Viscous Cosmology Models for the Future Universe
• Dark Energy Coupled with Dark Matter in Viscous Fluid Cosmology
• The evolution of gravitons in accelerating cosmologies: the case of extended gravity
• General Bulk-Viscous Solutions and Estimates of Bulk Viscosity in the Cosmic Fluid
• Cosmological Bound from the Neutron Star Merger GW170817 in scalar-tensor and $F(R)$ gravity theories
• Constraints on cosmological viscosity and self interacting dark matter from gravitational wave observations
• On the propagation of gravitational waves in strong magnetic fields
• Inhomogeneous viscous dark fluid coupled with dark matter in the FRW universe
• Viscous Coupled Fluids in Inflationary Cosmology
• Inflationary Universe with a Viscous Fluid Avoiding Self-Reproduction
• A Ulysses Detection of Secondary Helium Neutrals
• Viscosity in a Lepton-Photon Universe

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• Relativistic viscous effects on the primordial gravitational waves spectrum
• Linearized propagation equations for metric fluctuations in a general (non-vacuum) background geometry
• Viscous attenuation of gravitational waves propagating through an inhomogeneous background
• Gravitational Wave emission in Binary Neutron Star early post-merger within a dark environment
• Lightening the Dark Matter from its Viscosity and Explanation of EDGES Anomaly
• The effect of redshift degeneracy and the damping effect of viscous medium on the information extracted from gravitational wave signals