LARGE-SCALE STRUCTURE FORMATION FOR POWER SPECTRA WITH BROKEN SCALE-INVARIANCE

We have simulated the formation of large-scale structure arising from COBE-normalized spectra computed by convolving a primordial double-inf lation perturbation spectrum with the cold dark matter (CDM) transfer function. As a result of the broken scale invariance (BSI) characteriz ing the primordial perturbation spectrum, this model has less small-sc ale power than the (COBE-normalized) standard CDM model. The particle- mesh code (with 512(3) cells and 256(3) particles) includes a model fo r thermodynamic evolution of baryons in addition to the usual gravitat ional dynamics of dark matter. It provides an estimate of the local ga s temperature. In particular, our galaxy-finding procedure seeks peaks in the distribution of gas that has cooled. It exploits the fact that 'cold' particles trace visible matter better than average and thus pr ovides a natural biasing mechanism. The basic picture of large-scale s tructure formation in the BSI model is the familiar hierarchical clust ering scenario. We obtain particles-in-cell statistics, the galaxy cor relation function, the cluster abundance and the cluster-cluster corre lation function, and statistics for large- and small-scale velocity fi elds. We also report here on a semiquantitative study of the distribut ion of gas in different temperature ranges. Based on confrontation wit h observations and comparison with standard CDM, we conclude that the BSI scenario could represent a promising modification of the CDM pictu re capable of describing many details of large-scale structure formati on.