Anisotropic fluid cosmology: An alternative to dark matter?

We use anisotropic fluid cosmology to describe the present, dark energy-dominated Universe without assuming the presence of dark matter. The resulting anisotropic fluid spacetime naturally generates inhomogeneities at small scales, triggered by an anisotropic stress, that could therefore be responsi...

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Bibliographic Details
Published in:Physical review. D 2020-07, Vol.102 (2), p.1, Article 023514
Main Authors: Cadoni, M., Sanna, A. P., Tuveri, M.
Format: Article
Language:English
Subjects:
Anisotropic fluids
Anisotropy
Astronomical models
Chaplygin gas
Cosmology
Dark energy
Dark matter
Density distribution
Equations of state
Inhomogeneity
Perturbation theory
Supernovae
Universe
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Summary:We use anisotropic fluid cosmology to describe the present, dark energy-dominated Universe without assuming the presence of dark matter. The resulting anisotropic fluid spacetime naturally generates inhomogeneities at small scales, triggered by an anisotropic stress, that could therefore be responsible for structure formation at these scales. We show that the dynamics of the scale factor a is described by the usual Friedmann-Lemaître-Robertson-Walker cosmology and decouples completely from that describing inhomogeneities. Assuming that the fluid inherits the equation of state from galactic dynamics, we show that, in the large scale regime, it can be described as a generalized Chaplygin gas. We find that our model fits well the distance modulus experimental data of type Ia supernovae, thus correctly modeling the observed accelerated expansion of the Universe. Conversely, in the small scale regime, we use cosmological perturbation theory to derive the power spectrum P(k) for mass density distribution. At short wavelengths, we find a 1/k4 behavior, in good accordance with the observed correlation function for matter distribution at small scales.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.102.023514