The shape dependence of Vainshtein screening in the cosmic matter bispectrum

Clare Burrage, Johannes Dombrowski*, Daniela Saadeh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 α a3/2. The magnitude of the effect today is up to 2% for a model whose linear growth rate deviates up to 5% from ΛCDM.

Original languageEnglish
Article number023
Number of pages28
JournalJournal of Cosmology and Astroparticle Physics
Issue number10
Publication statusPublished - 8 Oct 2019


  • cosmic web
  • dark energy theory
  • modified gravity


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