A void perspective of the cosmic web

Voids are nearly empty regions in the Universe that can extend to millions of lightyears in size. They are a characteristic part of a complex bubble-like foam called the Large Scale Structure. It consists of dense nodes that are interconnected by a network of filaments and sheets, hence the origin of the alternative name, the Cosmic Web. We have developed an accurate method to find such voids. The method can even provide a classification of the overdense structures that surround the voids. This allows us to describe in one consistent way the building blocks of the Cosmic Web: voids, filaments and walls. Using our methods we are able to make accurate cosmographical maps of the Large Scale Structures in the nearby Universe. We show that the voids are an integral part of these mapped structures. For example their shape is deformed by strong tidal forces extorted by massive clusters that surround the voids. Such clusters are usually clustered into larger agglomerates called superclusters. Also the voids cluster, forming even more extended objects called supervoids. Such superclusters and supervoids align themselves to form larger entities called Great Walls, they appear to be common elements in the nearby Universe. On smaller scales we can also locate the lonely galaxies that reside in the midst of large and almost empty voids. Free from all the complexities in denser regions, the properties of such isolated galaxies tells us a lot about the general formation scenario of galaxies. For example one of our studied voidgalaxies is embedded within a voidwall and has an oddly configured gas-disk. The disk is not regularly oriented with its stars, but is aligned perpendicular to it, suggesting that cold gas has been accreted from out of the voids. The voids thus provides us with an unique and distinct perspective on the the Universe. Zie: Summary.