On the Growth of Perturbations as a Test of Dark Energy and Gravity

By Edmund Bertschinger. 2006

156 citations recorded by the source corpus.

The strongest evidence for dark energy at present comes from geometric techniques such as the supernova distance-redshift relation. By combining the measured expansion history with the Friedmann equation, one determines the energy density and its time evolution and hence the equation of state of dark energy. Because these methods rely on the Friedmann equation, which has not been independently tested, it is desirable to find alternative methods that work for both general relativity and other theories of gravity. Assuming that sufficiently large patches of a perturbed Robertson-Walker spacetime evolve like separate Robertson-Walker universes, that shear stress is unimportant on large scales, and that energy and momentum are locally conserved, we derive several relations between long-wavelength metric and matter perturbations. These relations include generalizations of the initial-value constraints of general relativity. For a class of theories including general relativity we reduce the long-wavelength metric, density, and velocity potential perturbations to quadratures including curvature perturbations, entropy perturbations, and the effects of nonzero background curvature. When combined with the expansion history measured geometrically, the long-wavelength solution provides a test that could distinguish modified gravity from other explanations of dark energy.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/ec3dd8308a08cf04554b78418864579a65cab261

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In Astronomy and Astrophysics

Citations in the corpus

Simultaneous constraints on the growth of structure and cosmic expansion from the multipole power spectra of the SDSS DR7 LRG sample (2013, methodology): “Note that this dynamical measure from RSDs is complementary to weak lensing analyses or the measurements of the integrated Sachs-Wolfe effect in CMB anisotropies which probes the sum of two gravitational potentials (e.g. Bertschinger (2006); Kimura et al. (2012)).”
The clustering of galaxies in the SDSS-III DR9 Baryon Oscillation Spectroscopic Survey: testing deviations from Λ and general relativity using anisotropic clustering of galaxies (2012, background): “…are necessary to modify the temporal and spatial parts of perturb d Einstein’s equations and many different choices for these functions have been proposed in literature (see e.g., Bertschinger 2006; Caldwell, Cooray & Melchiorri 2007; Amendola, Kunz & Sapone 2008; Amin, Wagoner & Blandford 2008).”
Approaches to understanding cosmic acceleration (2009, background): “In models of modified gravity, as well as in more exotic models of dark energy, the relation between the two Newtonian potentials, and between the potentials and matter perturbations, can be different [203, 204, 205].”
CFHTLenS: testing the laws of gravity with tomographic weak lensing and redshift-space distortions (2012, background): “Since material cannot be transported at superluminal velocities, superhorizon perturbations are destined to evolve along a path determined by the global expansion (Bertschinger 2006).”