Cosmological perturbations for two cold fluids in $\Lambda$CDM

Abstract

The cosmic large-scale structure of our Universe is comprised of baryons and cold dark matter (CDM). Yet it is customary to treat these two components as a combined single-matter fluid with vanishing pressure, which is justified only for sufficiently large scales and late times. Here we go beyond the single-fluid approximation and develop the perturbation theory for two gravitationally coupled fluids while still assuming vanishing pressure. We mostly focus on perturbative expansions in powers of $D$ (or $D_{+}$), the linear structure growth of matter in a $\Lambda$CDM Universe with cosmological constant $\Lambda$. We derive in particular (1) explicit recursion relations for the two fluid densities, (2) complementary all-order results in the Lagrangian-coordinates approach, as well as (3) the associated component wavefunctions in a semi-classical approach to cosmic large-scale structure. In our companion paper (Hahn et al. 2020) we apply these new theoretical results to generate novel higher-order initial conditions for cosmological hydrodynamical simulations.

15 pages + appendices, one figure, MNRAS in press

References in corpus (33)

• Ultralight scalars as cosmological dark matter
• Transients from Initial Conditions in Cosmological Simulations
• Resumming Cosmological Perturbations via the Lagrangian Picture: One-loop Results in Real Space and in Redshift Space
• Generation of Vorticity and Velocity Dispersion by Orbit Crossing
• Flowing with Time: a New Approach to Nonlinear Cosmological Perturbations
• Nonlinear Perturbation Theory Integrated with Nonlocal Bias, Redshift-space Distortions, and Primordial Non-Gaussianity
• Analytic Prediction of Baryonic Effects from the EFT of Large Scale Structures
• Accurate initial conditions for cosmological N-body simulations: Minimizing truncation and discreteness errors
• Lagrangian perturbations and the matter bispectrum I: fourth-order model for non-linear clustering
• Lagrangian perturbation theory at one loop order: successes, failures, and improvements
• Structure formation with massive neutrinos: going beyond linear theory
• Higher-order initial conditions for mixed baryon-CDM simulations
• On the signature of the baryon-dark matter relative velocity in the two and three-point galaxy correlation functions
• Third-order Perturbation Theory With Non-linear Pressure
• Solving the Vlasov equation in two spatial dimensions with the Schrödinger method
• The Effective Field Theory of Large-Scale Structure in the presence of Massive Neutrinos
• A Lagrangian Perturbation Theory in the presence of massive neutrinos
• Chasing the non-linear evolution of matter power spectrum with numerical resummation method: solution of closure equations
• General relativistic weak-field limit and Newtonian N-body simulations
• How smooth are particle trajectories in a $\Lambda$CDM Universe?
• Lagrangian perturbations and the matter bispectrum II: the resummed one-loop correction to the matter bispectrum
• Biased Tracers of Two Fluids in the Lagrangian Picture
• Observational constraints on cosmic neutrinos and dark energy revisited
• Large-scale structure perturbation theory without losing stream crossing
• Vlasov-Poisson in 1D for initially cold systems: post-collapse Lagrangian perturbation theory
• A coarse grained perturbation theory for the Large Scale Structure, with cosmology and time independence in the UV
• Cosmological $N$-body simulations including radiation perturbations
• Trajectories of point particles in cosmology and the Zel'dovich approximation
• Renormalization-group flow of the effective action of cosmological large-scale structures
• Accurate initial conditions in mixed Dark Matter--Baryon simulations
• Gravitational instability via the Schrodinger equation
• Lagrangian theory for cosmic structure formation with vorticity: Newtonian and post-Friedmann approximations
• Wave-mechanics and the adhesion approximation

Cited by in corpus (19)

• The FLAMINGO project: cosmological hydrodynamical simulations for large-scale structure and galaxy cluster surveys
• A new analysis of galaxy 2-point functions in the BOSS survey, including full-shape information and post-reconstruction BAO
• Large-scale dark matter simulations
• Redshift-Space Distortions in Lagrangian Perturbation Theory
• Accurate initial conditions for cosmological N-body simulations: Minimizing truncation and discreteness errors
• Higher-order initial conditions for mixed baryon-CDM simulations
• Higher-order initial conditions with massive neutrinos
• SPICE: the connection between cosmic reionisation and stellar feedback in the first galaxies
• Shell-crossing in a $\Lambda$CDM Universe
• The FLAMINGO project: Baryon effects on the matter power spectrum
• Cosmological Vlasov-Poisson equations for dark matter: Recent developments and connections to selected plasma problems
• An Analytic Hybrid Halo + Perturbation Theory Model for Small-scale Correlators: Baryons, Halos, and Galaxies
• Analytical growth functions for cosmic structures in a $\Lambda$CDM Universe
• Perturbation-theory informed integrators for cosmological simulations
• Starting Cosmological Simulations from the Big Bang
• Effect of Separate Initial Conditions on the Lyman-$\alpha$ Forest in Simulations
• Baryonic effects in the Effective Field Theory of Large-Scale Structure and an analytic recipe for lensing in CMB-S4
• Cosmological constraints on the big bang quantum cosmology model
• Cosmic voids and BAO with relative baryon-CDM perturbations