On the importance of high-redshift intergalactic voids

We investigate the properties of 1D flux 'voids' (connected regions in the flux distribution above the mean-flux level) by comparing hydrodynamical simulations of large cosmological volumes with a set of observed high-resolution spectra at z similar to 2. After addressing the effects of box size and resolution, we study how the void distribution changes when the most significant cosmological and astrophysical parameters are varied. We find that the void distribution in the flux is in excellent agreement with predictions of the standard Lambda cold dark matter (Lambda CDM) cosmology, which also fits other flux statistics remarkably well. We then model the relation between flux voids and the corresponding 1D gas-density field along the line of sight and make a preliminary attempt to connect the 1D properties of the gas-density field to the 3D dark matter distribution at the same redshift. This provides a framework that allows statistical interpretations of the void population at high redshift using observed quasar spectra, and eventually it will enable linking the void properties of the high-redshift universe with those at lower redshifts, which are better known.