Mass function, velocity dispersion and temperature function of clusters in the Cold + Hot dark matter model
Session 62 -- Large Scale Structures
Display presentation, Thursday, 2, 1994, 10:00-11:30

## [62.09] Mass function, velocity dispersion and temperature function of clusters in the Cold + Hot dark matter model

Yi-Peng Jing, Li-Zhi Fang (Univ. of Arizona)

Using a set of $P^{3}M$ simulation which accurately treats the density evolution of two components of dark matter, we study the evolution of clusters in the Cold + Hot dark matter (CHDM) model. The mass function, the velocity dispersion function and the temperature function of clusters are calculated for four different epochs of $z\leq 0.5$. We also use the simulation data to test the Press-Schechter expression of the halo abundance as a function of the velocity dispersion $\sigma_v$. The model predictions are in good agreement with the observational data of local cluster abundances ($z=0$). We also tentatively compare the model with the Gunn and his collaborators' observation of rich clusters at $z\approx 0.8$ and with the x-ray luminous clusters at $z\approx 0.5$ of the Einstein Extended Medium Sensitivity Survey. The important feature of the model is the rapid formation of clusters in the near past: the abundances of clusters of $\sigma_v\geq 700$kms$^{-1}$ and of $\sigma_v\geq 1200$kms$^{-1}$ at $z=0.5$ are only 1/4 and 1/10 respectively of the present values ($z=0$). Ongoing ROSAT and AXAF surveys of distant clusters will provide sensitive tests to the model. The abundance of clusters at $z\approx 0.5$ would also be a good discriminator between the CHDM model and a low-density flat CDM model both of which show very similar clustering properties at $z=0$.