Cold plus hot dark matter and the cosmic microwave background

We examine the cosmic microwave background power spectrum for adiabatic models with a massive neutrino component. We present the results of a detailed numerical evolution of cold + hot dark matter (CHDM) models and compare these results with the standard cold dark matter (CDM) spectrum. The difference is of order 5%-10% for 400 < l < 1000 for currently popular CHDM models. Using semianalytic approximations, we also discuss the relevant physics involved. Finally, we remark on the ability of future experiments to differentiate between these models. An all-sky experiment with a beam size smaller than 30' can distinguish between CHDM and CDM if other cosmological parameters are known. Even allowing other parameters to vary, it may be possible to distinguish CDM from CHDM.