Effective Fluid Description of the Dark Universe

Abstract

We propose an effective anisotropic fluid description for a generic infrared-modified theory of gravity. In our framework, the additional component of the acceleration, commonly attributed to dark matter, is explained as a radial pressure generated by the reaction of the dark energy fluid to the presence of baryonic matter. Using quite general assumptions, and a microscopic description of the fluid in terms of a Bose-Einstein condensate of gravitons, we find the static, spherically symmetric solution for the metric in terms of the Misner-Sharp mass function and the fluid pressure. At galactic scales, we correctly reproduce the leading MOND-like $\log (r)$ and subleading $(1/r)\log (r)$ terms in the weak-field expansion of the potential. Our description also predicts a tiny (of order $10^{-6}$ for a typical spiral galaxy) Machian modification of the Newtonian potential at galactic scales, which is controlled by the cosmological acceleration.

13 pages, no figures. Replaced version: major revisions in the introduction, microscopic derivation of Tully-Fisher relation using Bose-Einstein condensate of gravitons. Some typos corrected

References in corpus (7)

• Too big to fail? The puzzling darkness of massive Milky Way subhaloes
• MOND theory
• Matter and gravitons in the gravitational collapse
• Two-fluid dark matter models
• Comments on "Modeling Galaxy Halos Using Dark Matter with Pressure"
• Perspective on MOND emergence from Verlinde's "emergent gravity" and its recent test by weak lensing
• An Uneven Vacuum Energy Fluid as $\Lambda$, Dark Matter, MOND and Lens

Cited by in corpus (13)

• Gravitational antiscreening in stellar interiors
• Galactic dynamics and long-range quantum gravity
• Quasi-normal modes and microscopic description of 2D black holes
• Dark Matter Realism
• Effective metric outside bootstrapped Newtonian sources
• Entropy and Gravitation: From Black Hole Computers to Dark Energy and Dark Matter
• Is de Sitter space always excluded in semiclassical f(R) gravity?
• Dark Coincidences: Small-Scale Solutions with Refracted Gravity and MOND
• Long-Range Quantum Gravity
• A new perspective on galactic dynamics
• Refracted Gravity Solutions from Small to Large Scales
• Matter without mass: do we really need the concept of mass?
• Quantum maximally symmetric space-times