An Accurate Comprehensive Approach to Substructure: II. Stripped Subhaloes

TL;DR

This paper models the evolution of subhaloes and diffuse dark matter within host haloes, focusing on tidal effects and the role of halo concentration, providing insights into substructure features observed in simulations.

Contribution

It introduces a comprehensive, parameter-free model for subhalo evolution, including tidal stripping and heating, and clarifies the influence of halo concentration and dynamical friction.

Findings

Accurately predicts subhalo and dDM abundance and distribution.

Reveals the impact of halo concentration on substructure.

Unravels the effects of dynamical friction on subhalo evolution.

Abstract

In Paper I we used the CUSP formalism to derive from first principles and no single free parameter the accurate abundance and radial distribution of both diffuse DM (dDM) and subhaloes accreted onto haloes and their progenitors at all previous times. Here we use those results as initial conditions for the monitoring of the evolution of subhaloes and dDM within the host haloes. Specifically, neglecting dynamical friction, we accurately calculate the effects of repetitive tidal stripping and heating on subhaloes as they orbit inside the host halo and infer the amount of dDM and subsubhaloes they release into the intra-halo medium. We then calculate the expected abundance and radial distribution of stripped subhaloes and dDM. This derivation clarifies the role of halo concentration in substructure and unravels the origin of some key features found in simulations including the dependence of substructure on halo mass. In addition, it unveils the specific effects of dynamical friction on substructure. The results derived here are for purely accreting haloes. In Paper III we complete the study by addressing the case of low-mass subhaloes, unaffected by dynamical friction, in ordinary haloes having suffered major mergers.