DUCA: Dynamic Universe Cosmological Analysis. II. The impact of clustering dark energy on the halo mass function

Abstract

Galaxy clusters are powerful probes of cosmology, and the halo mass function (HMF) serves as a fundamental tool for extracting cosmological information. Previous calibrations of the HMF in dynamical dark energy (DE) models either assumed a homogeneous DE component or a fixed sound speed of unity, which strongly suppresses DE perturbations. We extend the HMF calibration to clustering dark energy (CDE) models by allowing for a sound speed $(c_{\mathrm{s}})$ value different than unity. This generalization enables a broader description of the impact of DE perturbations on structure formation. Our approach builds upon the DUCA simulation suite that accounts for DE at the background and perturbative levels. We present an HMF calibration based on introducing an effective peak height while maintaining the multiplicity function as previously calibrated. The effective peak height is written as a function of the peak height computed using the matter power spectrum of the homogeneous DE case, but it is modulated by the amplitude of DE and matter perturbations on the non-homogeneous case at the turnaround. The model depends on one single parameter, which we calibrate using $N$-body simulations, following a Bayesian approach. The resulting HMF model achieves sub-percent accuracy over a wide range of $c_{\mathrm{s}}$ values. Our analysis reveals that, although the overall impact of CDE on halo abundances remains modest (typically a few percent), the effects are more pronounced in non-phantom DE scenarios. Our model qualitatively agrees with predictions based on the spherical collapse model, but predicts a significantly lower impact for low $c_{\mathrm{s}}$. Our results underscore the need for more precise modeling of CDE's nonlinear regime. Numerical simulations and theoretical approaches must be advanced to capture the complex interplay between DE perturbations and matter fully.

11 pages, 7 figures, comments welcome. v2: matches version accepted for publication

References in corpus (21)

• Dynamics of dark energy
• Massive neutrinos and cosmology
• Euclid. I. Overview of the Euclid mission
• SPT-3G: A Next-Generation Cosmic Microwave Background Polarization Experiment on the South Pole Telescope
• The FLAMINGO project: cosmological hydrodynamical simulations for large-scale structure and galaxy cluster surveys
• The Effective Theory of Quintessence: the w<-1 Side Unveiled
• Crossing the Phantom Divide with Parameterized Post-Friedmann Dark Energy
• The Parameterized Post-Friedmann Framework for Theories of Modified Gravity: Concepts, Formalism and Examples
• Tension between the power spectrum of density perturbations measured on large and small scales
• Parametrized Post-Friedmann Signatures of Acceleration in the CMB
• Dark energy with non-adiabatic sound speed: initial conditions and detectability
• Non-universality of the mass function: dependence on the growth rate and power spectrum shape
• Clustering dark energy and halo abundances
• A short review on clustering dark energy
• The cosmological simulation code $\mathrm{CO}N\mathrm{CEPT}1.0$
• Tackling non-linearities with the effective field theory of dark energy and modified gravity
• Spherical collapse of non-top-hat profiles in the presence of dark energy with arbitrary sound speed
• A new nonlinear instability for scalar fields
• Instabilities Appearing in Cosmological Effective Field theories: When and How?
• A new instability in clustering dark energy?
• DUCA: Dynamic Universe Cosmological Analysis. I. The halo mass function in dynamical dark energy cosmologies