No CrossRef data available.
Published online by Cambridge University Press: 19 May 2006
The formation and structure of dark matter halos is studied by constrained simulations. A series of experiments of theformation of a 1012h-1 M๏ halo is designed to study the dependenceof the density profile on its merging history.We find that the halo growth consist of several quiescent phases intermitted by violent events, with the density well approximated by the NFWprofile during the former phases. We find that (1) the NFW scale radiusRs stays constant during the quiescent phase and grows abruptly during theviolent one. In contrast, the virial radiusgrows linearly during the quiescent and abruptly during the violentphases. (2) The central density stays unchanged during the quiescentphase while dropping abruptly during the violent phase, and it does not reflectthe formation time of the halo.(3) The clear separation of the evolution of an individual halo into quiescent and violent phases implies that its entire evolution cannot be fitted by simple scaling relations.