Le 22 décembre 2017
De 10h30 à 12h00

Max Gronke UC Santa Barbara   The Lyman-alpha (Lya) of neutral hydrogen is the most prominent...

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Probing cosmology and gravity with Compensated Cosmic regions

Le 8 septembre 2017
De 10h30 à 12h00

Paul de Fromont

Observatoire de Paris

Cosmic voids are a prominent feature of the cosmic web and fill the very large majority of our Universe. These last years, these structures have been deeply studied with the aim of constraining cosmology. Indeed, contrary to virialized structures such as galaxies or galaxy clusters, their evolution is neither affected by shell crossing nor non linear relaxation processes, blurring the link between the primordial field and the final cosmic object. However, analysis of cosmic voids suffer from the lack of a physically motivated model describing their shape and their statistics. In this talk, I will introduce the CoSphere formalism, an extension of the peak model (Bardeen et al. 1986) which aim to describe both the generation and the evolution of such regions. I will show that it is possible to describe both the shape and the statistics of cosmic voids in the primordial Gaussian field but also in the non linearly structured Universe using the spherical collapse model. I will also show that these profiles, derived to describe cosmic voids, can be also used for modelling the large scale matter field around over-densities such as galaxy clusters. Using this extended peak model, I will discuss the possibilities to constrain efficiently cosmology and even the nature of gravity.

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