Resolving the outer density profile of dark matter halo in Andromeda galaxy

TL;DR

This study uses N-body simulations to analyze the outer dark matter halo of Andromeda, revealing a steeper density profile than standard CDM predictions, based on observed stellar structures.

Contribution

It provides the first detailed simulation-based analysis of M31's outer dark matter density profile, challenging existing CDM model predictions.

Findings

Outer dark matter halo density profile is steeper than CDM predictions.

Simulation reproduces observed stellar streams and shells around M31.

Supports revising dark matter halo models for M31.

Abstract

Large-scale faint structure detected by the recent observations in the halo of the Andromeda galaxy (M31) provides an attractive window to explore the structure of outer cold dark matter (CDM) halo in M31. Using an N-body simulation of the interaction between an accreting satellite galaxy and M31, we investigate the mass density profile of the CDM halo. We find the sufficient condition of the outer density profile of CDM halo in M31 to reproduce the Andromeda giant stream and the shells at the east and west sides of M31. The result indicates that the density profile of the outer dark matter halo of M31 is a steeper than the prediction of the theory of the structure formation based on the CDM model.