Speaker: Seshadri Nadathur

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 galaxy surveys in which they are found, and identify some universal properties – in particular the relationship between voids and the gravitational potential – which are independent of these details, thus providing useful tools for cosmology. I will also briefly discuss rare “supervoids”, the ISW effect, and void lensing.