Resolving the Jeans Mass in Hydrodynamic Simulations of Hierarchical Clustering

We examine the necessity of resolving the Jeans mass in hydrodynamical simulations of the hierarchical formation of cosmological structures. We consider a standard two-component fluid and use smoothed particle hydrodynamics to model the baryonic component. It is found that resolution of the Jeans mass is not necessary to extract bulk properties of bound objects that are independent of resolution, provided that the objects have undergone a number of merger events. The degree of merging must be sufficient to populate the objects with substructure of similar total mass. After this criterion is met, neither the density profiles of structures nor their density-temperature distributions depend appreciably on the resolution of the simulation. Resolution of the Jeans mass by the imposition of a minimum temperature is not found to affect adversely the state of the matter in the final clusters. The baryon concentration profiles still indicate a deficit of gas with respect to the dark matter in the interiors of the dense halo structures. This is offset by a baryon enrichment in the filamentary and sheetlike structures as well as the voids.