The universal multiplicity function: counting haloes and voids

• Published in: Journal of cosmology and astroparticle physics 2024-10, Vol.2024 (10), p.79
• Main Authors: Verza, Giovanni, Carbone, Carmelita, Pisani, Alice, Porciani, Cristiano, Matarrese, Sabino
• Format: Article
• Language: English
• Subjects: cluster counts; cosmic web; galaxy clustering
• ISSN: 1475-7516; 1475-7516
• DOI: 10.1088/1475-7516/2024/10/079

We present a novel combination of the excursion-set approach with the peak theory formalism in Lagrangian space and provide accurate predictions for halo and void statistics over a wide range of scales. The set-up is based on an effective moving barrier. Besides deriving the corresponding numerical multiplicity function, we introduce a new analytical formula reaching the percent level agreement with the exact numerical solution obtained via Monte Carlo realisations down to small scales, ∼ 10 12 h -1 M ⊙ . In the void case, we derive the dependence of the effective moving barrier on the void formation threshold, δ v , by comparison against the Lagrangian void size function measured in the DEMNUni simulations. We discuss the mapping from Lagrangian to Eulerian space for both haloes and voids; adopting the spherical symmetry approximation, we obtain a strong agreement at intermediate and large scales. Finally, using the effective moving barrier, we derive Lagrangian void density profiles accurately matching measurements from cosmological simulations, a major achievement towards using void profiles for precision cosmology with the next generation of galaxy surveys.