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Abstract: Voids are a dominant feature of the low-redshift galaxy distribution. Severalrecent surveys have found evidence for the existence of large-scale structureat high redshifts as well. We present analytic estimates of galaxy void sizesat redshifts z ~ 5 - 10 using the excursion set formalism. We find that recentnarrow-band surveys at z ~ 5 - 6.5 should find voids with characteristic scalesof roughly 20 comoving Mpc and maximum diameters approaching 40 Mpc. This isconsistent with existing surveys, but a precise comparison is difficult becauseof the relatively small volumes probed so far. At z ~ 7 - 10, we expectcharacteristic void scales of ~ 14 - 20 comoving Mpc assuming that all galaxieswithin dark matter haloes more massive than 10^10 M sun are observable. We findthat these characteristic scales are similar to the sizes of empty regionsresulting from purely random fluctuations in the galaxy counts. As a result,true large-scale structure will be difficult to observe at z ~ 7 - 10, unlessgalaxies in haloes with masses less than ~ 10^9 M sun are visible. Galaxysurveys must be deep and only the largest voids will provide meaningfulinformation. Our model provides a convenient picture for estimating the-worst-case- effects of cosmic variance on high-redshift galaxy surveys withlimited volumes.



Author: Anson D'Aloisio, Steven R. Furlanetto

Source: https://arxiv.org/







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