Improved non-Gaussian Mass Functions for Halos and Voids

by Marcello Musso (ICTP (Trieste))

Thursday 17 Feb 2011, 16:00 → 17:30 Europe/Brussels

E/3rd floor-E.349 - Seminar room (E.349) (Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve))

The abundance of collapsed objects of a given mass in the Universe, or halo mass function, is an important and popular tool to study the imprints of primordial non-Gaussianities on large scale structures. A complementary but less studied probe is the abundance of cosmic voids, the large underdense regions empty of galaxies. Non-Gaussian corrections to both these quantities can be computed perturbatively in the framework of the excursion set theory, where the structure formation process is mapped into a random walk in the presence of one (for halos) or two (for voids) barriers. However, the involved parameters are scale dependent and some become of order unity for large masses or at high redshifts, spoiling the validity of the perturbative expansion. The use of techniques mutuated from quantum field theory and statistical mechanics allows anyway a non-perturbative treatment of the dangerous terms. Hence, an accurate theoretical prediction for the non-Gaussian mass functions can be obtained, which is valid over a larger range of scales and redshifts.