A unified solution to the small scale problems of the $\Lambda$CDM model II: introducing parent-satellite interaction

TL;DR

This paper presents a semi-analytical model incorporating parent-satellite interactions via dynamical friction to address small-scale issues in the $ ext{Lambda}$CDM model, successfully reconciling several longstanding problems with observations.

Contribution

It introduces a novel approach by including parent-satellite interactions through dynamical friction to solve multiple small-scale $ ext{Lambda}$CDM problems.

Findings

Flattened inner density cusps due to dynamical friction.

Number of luminous satellites matches observations.

Angular momentum distribution aligns with dwarf galaxy data.

Abstract

We continue the study of the impact of baryon physics on the small scale problems of the $\Lambda$CDM model, based on a semi-analytical model (Del Popolo, 2009). Withsuch model, we show how the cusp/core, missing satellite (MSP), Too Big to Fail (TBTF) problems and the angular momentum catastrophe can be reconciled with observations, adding parent-satellite interaction. Such interaction between darkmatter (DM) and baryons through dynamical friction (DF) can sufficiently flattenthe inner cusp of the density profiles to solve the cusp/core problem. Combining, in our model, a Zolotov et al. (2012)-like correction, similarly to Brooks et al. (2013), and effects of UV heating and tidal stripping, the number of massive, luminous satellites, as seen in the Via Lactea 2 (VL2) subhaloes,is in agreement with the numbers observed in the MW, thus resolving the MSP and TBTF problems. The model also produces a distribution of the angular spin parameter and angular momentum in agreement with observations of the dwarfs studied by van den Bosch, Burkert, \\& Swaters (2001).