Скачать или смотреть Myth and truth about halo formation in cold-dark-matter models

IAP weekly specialised seminars / Friday 26 April 2019

Cristiano Porciani, Argelander-Inst. Astronomie, Univ. Bonn, (Bonn, Allemagne)

Invited by Sandrine Codis & Yohan Dubois

The conventional wisdom in cosmology is that that cold-dark-matter haloes form out of initial density peaks and continuously accrete matter from the surroundings becoming more and more massive with time. These concepts form the basis of several semi-analytical tools that are regularly used to interpret data from galaxy and cluster surveys and develop galaxy-formation models (e.g. for the halo mass function, merger trees, and galaxy biasing). Using a suite of numerical simulations, we present thorough tests of the established scenario and show that it is mandatory to introduce new elements in the theory of the gravitational collapse of cold matter. In particular, we demonstrate that filamentary structures in the cosmic web inhibit accretion of new matter onto collapsed haloes. We also illustrate how this phenomenon explains the origin of the so-called `assembly bias' for galaxy-sized haloes and also influences the dynamics of satellite galaxies.

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