TY - JOUR

T1 - Structure formation in an anisotropic universe

T2 - Eulerian perturbation theory

AU - Almeida, Juan P.Beltrán

AU - Motoa-Manzano, Josué

AU - Noreña, Jorge

AU - Pereira, Thiago S.

AU - Valenzuela-Toledo, César A.

N1 - Publisher Copyright:
© 2022 IOP Publishing Ltd and Sissa Medialab.

PY - 2022/2

Y1 - 2022/2

N2 - We present an effective Eulerian description, in the non-relativistic regime, of the growth of cosmological perturbations around a homogeneous but anisotropic Bianchi I spacetime background. We assume a small deviation from isotropy, sourced at late times for example by dark energy anisotropic stress. We thus derive an analytic solution for the linear dark matter density contrast, and use it in a formal perturbative approach which allows us to derive a second order (non-linear) solution. As an application of the procedure followed here we derive analytic expressions for the power spectrum and the bispectrum of the dark matter density contrast. The power spectrum receives a quadrupolar correction as expected, and the bispectrum receives several angle-dependent corrections. Quite generally, we find that the contribution of a late-time phase of anisotropic expansion to the growth of structure peaks at a finite redshift between CMB decoupling and today, tough the exact redshift value is model-dependent.

AB - We present an effective Eulerian description, in the non-relativistic regime, of the growth of cosmological perturbations around a homogeneous but anisotropic Bianchi I spacetime background. We assume a small deviation from isotropy, sourced at late times for example by dark energy anisotropic stress. We thus derive an analytic solution for the linear dark matter density contrast, and use it in a formal perturbative approach which allows us to derive a second order (non-linear) solution. As an application of the procedure followed here we derive analytic expressions for the power spectrum and the bispectrum of the dark matter density contrast. The power spectrum receives a quadrupolar correction as expected, and the bispectrum receives several angle-dependent corrections. Quite generally, we find that the contribution of a late-time phase of anisotropic expansion to the growth of structure peaks at a finite redshift between CMB decoupling and today, tough the exact redshift value is model-dependent.

KW - Cosmological perturbation theory in GR and beyond

KW - dark energy theory

KW - power spectrum

UR - http://www.scopus.com/inward/record.url?scp=85126151501&partnerID=8YFLogxK

U2 - 10.1088/1475-7516/2022/02/018

DO - 10.1088/1475-7516/2022/02/018

M3 - Article

AN - SCOPUS:85126151501

SN - 1475-7516

VL - 2022

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

IS - 2

M1 - 018

ER -