Warm dark matter versus bumpy power spectra


Little, Brett; Knebe, Alexander; Islam, Ranty R.


In this paper we explore the differences between a warm dark matter (WDM) model and a cold dark matter (CDM) model where the power on a certain scale is reduced by introducing a narrow negative feature ('dip'). This dip is placed in a way so as to mimic the loss of power in the WDM model: both models have the same integrated power out to the scale where the power of the dip model rises to the level of the unperturbed CDM spectrum again. Using N-body simulations we show that some of the large-scale clustering patterns of this new model follow more closely the usual CDM scenario while simultaneously suppressing small-scale structures (within galactic haloes) even more efficiently than WDM. The analysis in the paper shows that the new Dip model appears to be a viable alternative to WDM, but it is based on different physics. Where WDM requires the introduction of a new particle species, the Dip model is based on a non-standard inflationary period. If we are looking for an alternative to the currently challenged standard ΛCDM structure formation scenario, neither the ΛWDM nor the new Dip model can be ruled out based on the analysis presented in this paper. They both make very similar predictions and the degeneracy between them can only be broken with observations yet to come.

Publication year


Publication type

Journal article


Monthly Notices of the Royal Astronomical Society, Vol. 341, no. 2 (May 2003), pp. 617-622






Copyright © 2003 Royal Astronomical Society.