Substructure effects on the collapse of density perturbations

Abstract

We solve numerically the equations of motion for the collapse of a shell of baryonic matter, made of galaxies and substructure of $10^6{M}_{\odot }-10^9{M}_{\odot }$, falling into the central regions of a cluster of galaxies taking account of dynamical friction. We calculate the evolution of the expansion parameter, a(t), of the perturbation using a coefficient of dynamical friction, ${\eta }_0$, calculated for a perturbation in which clustering is absent and a coefficient ${\eta }_{cl}$ obtained from a clustered one. The effect of the dynamical friction is to slow down the collapse (V. Antonuccio-Delogu \& S. Colafrancesco 1994, hereafter AC) producing an observable variation of the parameter of expansion of the shell. The effect increases with increasing $\eta$ and with the increasing of clustering. Finally, we show how the collapse time depends on ${\eta }_0$ and ${\eta }_{cl}$. keywords: {cosmology: theory- galaxies: formation}

5 pages + 3 PostScript figures, Latex (use laa.sty), accepted for the pubblication in Astr. and Astrop

Cited by in corpus (9)

• Small scale problems of the $\Lambda$CDM model: a short review
• The Cusp/Core problem: supernovae feedback versus the baryonic clumps and dynamical friction model
• A high precision semi-analytic mass function
• A unified solution to the small scale problems of the $\Lambda$CDM model II: introducing parent-satellite interaction
• Energy transfer from baryons to dark matter as a unified solution to small-scale structure issues of the $\Lambda$CDM model
• On the dark matter haloes inner structure and galaxy morphology
• Chandrasekhar's Dynamical Friction and non-extensive statistics
• On the dwarf galaxies rotation curves diversity problem
• A Mass Dependent Density Profile from Dwarfs to Clusters