Derives conditions for viable screened radial solutions in multi-field de Sitter Galileons, showing curvature can mitigate superluminality at the cost of a finite validity range set by the strong-coupling point.
Galileon Cosmology
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abstract
We study the cosmology of a galileon scalar-tensor theory, obtained by covariantizing the decoupling lagrangian of the Dvali-Gabadadze-Poratti (DGP) model. Despite being local in 3+1 dimensions, the resulting cosmological evolution is remarkably similar to that of the full 4+1-dimensional DGP framework, both for the expansion history and the evolution of density perturbations. As in the DGP model, the covariant galileon theory yields two branches of solutions, depending on the sign of the galileon velocity. Perturbations are stable on one branch and ghost-like on the other. An interesting effect uncovered in our analysis is a cosmological version of the Vainshtein screening mechanism: at early times, the galileon dynamics are dominated by self-interaction terms, resulting in its energy density being suppressed compared to matter or radiation; once the matter density has redshifted sufficiently, the galileon becomes an important component of the energy density and contributes to dark energy. We estimate conservatively that the resulting expansion history is consistent with the observed late-time cosmology, provided that the scale of modification satisfies r_c > 15 Gpc.
verdicts
UNVERDICTED 3representative citing papers
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citing papers explorer
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Radial Solutions of Multi-Field de Sitter Galileons
Derives conditions for viable screened radial solutions in multi-field de Sitter Galileons, showing curvature can mitigate superluminality at the cost of a finite validity range set by the strong-coupling point.
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Radio sirens: inferring $H_0$ with binary black holes and neutral hydrogen in the era of the Einstein Telescope and the SKA Observatory
Using simulated binary black hole mergers and neutral hydrogen maps, the radio sirens method constrains H0 to 8% precision with 3000 high-SNR events, offering a 90% improvement over standard dark siren analyses.
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Modified Gravity and Cosmology
A comprehensive review of modified gravity theories and their cosmological consequences, including a parameterized post-Friedmannian formalism for constraining deviations from General Relativity.