halo model

In cosmology, the term halo model is used for a particular type of model of the distribution of dark matter which makes the simplifying assumption that all dark matter resides in dark matter halos, separate regions of high mass density distributed in some random manner, describing the large scale structure of the universe as a distribution of such halos. For the purposes of the model, each halo has a simple structure: a mass and a density. Such a model can be calibrated using observational data, such as that from the distribution of galaxies and from intensity mapping, such as the mapping of neutral atomic hydrogen. In effect, halo modeling treats dark matter as gathered in areas of high density, e.g., spheres, with the aim of characterizing the universe on a large scale without getting bogged down with finer details.