The prolate dark matter halo of the Andromeda galaxy

Abstract

We present new limits on the global shape of the dark matter halo in the Andromeda galaxy using and generalizing non-spherical mass models developed by Hayashi & Chiba and compare our results with theoretical predictions of cold dark matter (CDM) models. This is motivated by the fact that CDM models predict non-spherical virialized dark halos, which reflect the process of mass assembly in the galactic scale. Applying our models to the latest kinematic data of globular clusters and dwarf spheroidal galaxies in the Andromeda halo, we find that the most plausible cases for Andromeda yield a prolate shape for its dark halo, irrespective of assumed density profiles. We also find that this prolate dark halo in Andromeda is consistent with theoretical predictions in which the satellites are distributed anisotropically and preferentially located along major axes of their host halos. It is a reflection of the intimate connection between galactic dark matter halos and the cosmic web. Therefore, our result is profound in understanding internal dynamics of halo tracers in Andromeda, such as orbital evolutions of tidal stellar streams, which play important roles in extracting the abundance of CDM subhalos through their dynamical effects on stream structures.

Typos corrected. Replaced to match published version. 11 pages, 7 figures

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Cited by in corpus (11)

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• Updated constraints on WIMP dark matter annihilation by radio observations of M31
• Tightening weak lensing constraints on the ellipticity of galaxy-scale dark matter haloes
• On the origin of the asymmetric dwarf galaxy distribution around Andromeda
• The Orthogonally Aligned Dark Halo of an Edge-on Lensing Galaxy in the Hubble Frontier Fields: A Challenge for Modified Gravity
• Investigating the Dark Matter Halo of NGC 5128 using a Discrete Dynamical Model
• On Filaments, Prolate Halos and Rotation Curves
• Line-of-sight mass estimator and the masses of the Milky Way and Andromeda Galaxy
• Prospects for annihilating dark matter from M31 and M33 observations with the Cherenkov Telescope Array
• Timing Mass of the Local Group