Guess the cheese flavour by the size of its holes: A cosmological test using the abundance of Popcorn voids

Understand

We present a new definition of cosmic void and a publicly available code with the algorithm that implements it.

• Underdense regions are defined as free-form objects, called popcorn voids, made from the union of spheres of maximum volume with a given joint integrated underdensity contrast.The method is inspired by the excursion-set theory and consequently no rescaling processing is needed, the removal of overlapping voids and objects with sizes below the shot noise threshold is inherent in the algorithm.
• The abundance of popcorn voids in the matter field can be fitted using the excursion-set theory provided the relationship between the linear density contrast of the barrier and the threshold used in void identification is modified relative to the spherical evolution model.
• We also analysed the abundance of voids in biased tracer samples in redshift space.