Halo growth and the NFW profile

TL;DR

This paper investigates halo growth, showing inside-out accretion and the universality of NFW profiles across merger histories, while also examining the limitations of NFW fits at large masses and redshifts.

Contribution

It demonstrates that halo density profiles are similar regardless of merger history and analyzes the limitations of NFW fits at high masses and redshifts.

Findings

Halos grow inside-out during accretion.

NFW profiles fit halos across merger histories.

NFW fit accuracy decreases at large masses and redshifts.

Abstract

We perform a simple test showing that accreting halos grow inside-out and have density profiles that are statistically indistinguishable from those of halos having undergone major mergers. The test also reveals that the ability for the NFW analytical expression to fit the density profile of halos spoils towards large masses at any redshift. On view of these results, we analyze the M-c relations on extreme mass and redshift domains predicted by usual toy models based on numerical data and one physical model based on the two assumptions above confirmed by the test.