The Shape Dependence of Vainshtein Screening in the Cosmic Matter Bispectrum

Abstract

One of the most pressing questions in modified gravity is how deviations from general relativity can manifest in upcoming galaxy surveys. This is especially relevant for theories exhibiting Vainshtein screening, where such deviations are efficiently suppressed within a (typically large) Vainshtein radius. However, Vainshtein screening is known to be shape dependent: it is most effective around spherical sources, weaker around cylindrical objects and completely absent for planar sources. The Cosmic Web therefore offers a testing ground, as it displays many shapes in the form of clusters, filaments and walls. In this work, we explicitly derive the signature of the shape dependence of Vainshtein screening on the matter bispectrum, by considering a cubic Galileon model with a conformal coupling to matter and a cosmological constant. We perform a second order perturbative analysis, deriving analytic, integral expressions for the bispectrum, which we integrate using hi_class. We find that the shape dependence of Vainshtein screening enters the bispectrum with a unique scale-factor dependence of $\propto a^{3/2}$. The magnitude of the effect today is up to 2 % for a model whose linear growth rate deviates up to 5 % from $\Lambda$CDM.

27 pages, 7 figures. Matches version accepted for publication in JCAP

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Cited by in corpus (9)

• Gravity in the Era of Equality: Towards solutions to the Hubble problem without fine-tuned initial conditions
• hi_class: Background Evolution, Initial Conditions and Approximation Schemes
• Consistency relations for large-scale structure in modified gravity and the matter bispectrum
• New constraints on cosmological modified gravity theories from anisotropic three-point correlation functions of BOSS DR12 galaxies
• Probing Vainsthein-screening gravity with galaxy clusters using internal kinematics and strong and weak lensing
• Scalar-tensor cosmologies without screening
• First test of the consistency relation for the large-scale structure using the anisotropic three-point correlation function of BOSS DR12 galaxies (An explanatory video is available at https://youtu.be/Zi36ooLPhss.)
• Testing Screening Mechanisms with Mass Profiles of Galaxy Clusters
• Probing gravity beyond general relativity with bispectrum multipoles of cosmological tracers: I. Theoretical Foundations