Title: THE UNIVERSAL MASS-CONCENTRATION RELATION FOR COLD, WARM AND HOT DARK MATTER HALOS

Speaker:  Zhao Donghai

　  Time: Feb. 23, Thursday, 2pm

　  Location: 1714

previous related work:   http://arxiv.org/abs/0811.0828

One of the most precise calculator of halo concentration refers to　 http://www.shao.ac.cn/dhzhao/mandc.html

Abstract:
In a previous paper, Zhao et al. (2009), we proposed a very simple but physically motivated model for the mass accretion histories and concentrations of dark matter halos, which has been proved to be accurate for universes of initial density fluctuations of zero-varying or slow-varying power spectrum, such as scale free and cold dark matter power spectra. In this paper, we apply exactly the same model, without any modification to the function form or even to the parameters, to various warm and hot dark matter universes, in which spectrum power index varies very fast with scale. The model predicts much different concentration-mass relations, like a Mexican hat with concentrations topping out at intermediate halo masses and flatting at very light and massive ends, for the hot and some warm dark matter cases from those relations, with concentrations monotonically decreasing with masses, for the scale free spectra and cold dark matter cases. This is because t0.04, predicted by the model for these hot cases, also peaks at these intermediate halo masses and so below these masses the smaller the halos, the later they formed, unlike the bottom-up hierarchical clustering universe where smaller halos always formed earlier on average than massive ones. We compare these model predictions with concentration-mass relations from the literature and from our cosmological numerical simulations and find very good agreement while other models failed dramatically. fast varying power spectrum. We also revisit concentrations of (massive) CDM halos.