Resolving the Jeans Mass in Hydrodynamic Simulations of Hierarchical Clustering

We examine the necessity of resolving the Jeans mass in hydrodynamicalsimulations of the hierarchical formation of cosmological structures. Weconsider a standard two-component fluid and use smoothed particle hydrodynamicsto model the baryonic component. It is found that resolution of the Jeans massis not necessary to extract bulk properties of bound objects that areindependent of resolution, provided that the objects have undergone a number ofmerger events. The degree of merging must be sufficient to populate the objectswith substructure of similar total mass. After this criterion is met, neitherthe density profiles of structures nor their density-temperature distributionsdepend appreciably on the resolution of the simulation. Resolution of the Jeansmass by the imposition of a minimum temperature is not found to adverselyaffect the state of the matter in the final clusters. The baryon concentrationprofiles still indicate a deficit of gas with respect to the dark matter in theinteriors of structures.Comment: 24 pages, 7 figures, 2 table