Splashback in accreting dark matter halos

TL;DR

This paper presents a simple, parameter-free model based on spherical collapse that accurately predicts the splashback radius in dark matter halos, depending on accretion rate and redshift.

Contribution

It introduces a first-principles model for the splashback feature in dark matter halos, improving understanding of their outer density profiles.

Findings

Model accurately predicts splashback radius

Dependence on accretion rate and redshift clarified

No free parameters needed for the prediction

Abstract

Recent work has shown that density profiles in the outskirts of dark matter halos can become extremely steep over a narrow range of radius. This behavior is produced by splashback material on its first apocentric passage after accretion. We show that the location of this splashback feature may be understood quite simply, from first principles. We present a simple model, based on spherical collapse, that accurately predicts the location of splashback without any free parameters. The important quantities that determine the splashback radius are accretion rate and redshift.