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« When do cosmic peaks, filaments or walls merge? A theory of critical events in a multi-scale landscape »

Corentin Cadiou
Department of Physics and Astronomy, University College London (Londres, Royaume-Uni)


The merging rate of critical points, used as a proxy for cosmic evolution, is computed as a function of smoothing scale from the initial cosmic landscape to forecast special events driving the assembly of dark matter haloes. Beyond the mergers of peaks with saddle points (a proxy for halo mergers), we consider the coalescence and nucleation of all sets of critical points, including wall-saddle to filament-saddle and wall-saddle to minima (a proxy for filaments mergers and void mergers respectively), as they impact the geometry of galactic infall, and in particular filament disconnection. Analytical predictions are validated against multiscale measurements in maps and cubes (the corresponding code being available upon request). Applications to cosmology, astrophysics and other fields of research are discussed. The rate of filament coalescence is compared to the merger rate of haloes and the two-point clustering of these events is computed, along with their cross-correlations with critical points. These correlations are qualitatively consistent with the preservation of the connectivity of dark matter haloes, and the impact of the large scale structures on assembly bias. The cosmic evolution of the destruction rate of haloes and voids as a function of mass and redshift is quantified for a ?CDM cosmology. The one-point statistics in higher dimensions is also presented, together with consistency relations between critical point and critical event counts.
mardi 24 mars 2020 - 11:15
Webinaire, Institut d'Astrophysique
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