Universality of the halo mass function in modified gravity cosmologies

Abstract

We study the halo mass function (HMF) in modified gravity (MG) models using a set of large $N$-body simulations -- the ELEPHANT suite. We consider two popular beyond-general relativity scenarios: the Hu-Sawicki chameleon $f(R)$ model and the normal branch of the Dvali-Gabadadze-Porrati braneworld (nDGP). We show that in MG, analytic formulation based on the Press-Schechter framework offers a grossly inaccurate description of the HMF. We find, however, that once the HMF is expressed in terms of the dimensionless multiplicity function, it approximately assumes a redshift-independent universal character for all the models. Exploiting this property, we propose universal fits for the MG HMF in terms of their fractional departures from the $\mathrm{\Lambda }\text{CDM}$ case. We find two enclosed formulas, one for $f(R)$ and another for nDGP, that provide a reliable description of the HMF over the mass range covered by the simulations. These are accurate to a few percent with respect to the $N$-body data. We test the extrapolation potential of our fits against separate simulations with a different cosmological background and mass resolution, and find very good accuracy, within $\sim 10\%$. A particularly interesting finding from our analysis is a Gaussian-like shape of the HMF deviation that seems to appear universally across the whole $f(R)$ family, peaking at a mass variance scale characteristic for each $f(R)$ variant. We attribute this behavior to the specific physics of the environmentally-dependent chameleon screening models.

16 pages and 8 figures

References in corpus (21)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• The Confrontation between General Relativity and Experiment
• Models of f(R) Cosmic Acceleration that Evade Solar-System Tests
• Beyond the Cosmological Standard Model
• Transients from Initial Conditions in Cosmological Simulations
• Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
• Non-linear Evolution of f(R) Cosmologies III: Halo Statistics
• The Halo Mass Function: High-Redshift Evolution and Universality
• Cluster Constraints on f(R) Gravity
• Testing gravity with CAMB and CosmoMC
• Non-linear evolution of f(R) cosmologies II: power spectrum
• Linking Tests of Gravity On All Scales: from the Strong-Field Regime to Cosmology
• Vainshtein mechanism after GW170817
• Dynamical Masses in Modified Gravity
• Non-linear interactions in a cosmological background in the DGP braneworld
• Nonlinear structure formation in Nonlocal Gravity
• Speeding up $N$-body simulations of modified gravity: Chameleon screening models
• Dark Matter Gravitational Clustering With a Long-Range Scalar Interaction
• A general framework to test gravity using galaxy clusters IV: Cluster and halo properties in DGP gravity
• Constraining f(R) Gravity with Planck Sunyaev-Zel'dovich Clusters
• Non-linear matter power spectrum without screening dynamics modelling in $f(R)$ gravity