Precision cosmology with voids: definition, methods, dynamics

We propose a new definition of cosmic voids based on methods of Lagrangian orbit reconstruction
\nas well as an algorithm to find them in actual data called DynamIcal Void Analysis. Our
\ntechnique is intended to yield results which can be modelled sufficiently accurately to create
\na new probe of precision cosmology. We then develop an analytical model of the ellipticity of
\nvoids found by our method based on the Zel’dovich approximation. We measure in N-body
\nsimulation that this model is precise at the ~0.1 per cent level for the mean ellipticity of voids
\nof size greater than ~4 h
\n^(−1) Mpc. We estimate that at this scale we are able to predict the
\nellipticity with an accuracy of σ_ε ~ 0.02. Finally, we compare the distribution of void shapes
\nin N-body simulation for two different equations of state w of the dark energy. We conclude
\nthat our method is far more accurate than Eulerian methods and is therefore promising as a
\nprecision probe of dark energy phenomenology.