The nature of voids: theory, simulation and cosmology

The London Relativity and Cosmology Seminar
Seshadri Nadathur (Portsmouth)
October 14th, 2015 at 16:30
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Cosmic voids are an exciting tool which can potentially be used to test a number of different cosmological scenarios, including dark energy and modified gravity. Yet voids are not well understood. I will discuss the general properties of voids in simulations show that they do not match the predictions of the standard theoretical model of voids based on the excursion set formalism. I will discuss the reasons for this discrepancy and argue that it points to the need for simulation-based calibration of void properties for comparison with observation. I discuss the dependence of void properties on those of the galaxies in which they are found, and identify some universal properties which are independent of these details, thus providing useful tools for cosmology. In particular I will focus on the gravitational potential within voids, rare supervoids, and void lensing.