Dark matter annihilation radiation in hydrodynamic simulations of Milky Way haloes

Schaller, Matthieu; Frenk, Carlos S.; Theuns, Tom; Calore, Francesca; Bertone, Gianfranco; Bozorgnia, Nassim; Crain, Robert A.; Fattahi, Azadeh; Navarro, Julio F.; Sawala, Till; Schaye, Joop

Abstract

We obtain predictions for the properties of cold dark matter annihilation radiation using high-resolution hydrodynamic zoom-in cosmological simulations of Milky Way-like galaxies (APOSTLE project) carried out as part of the ‘Evolution and Assembly of GaLaxies and their Environments’ (EAGLE) programme. Galactic haloes in the simulation have significantly different properties from those assumed in the ‘standard halo model’ often used in dark matter detection studies. The formation of the galaxy causes a contraction of the dark matter halo, whose density profile develops a steeper slope than the Navarro–Frenk–White (NFW) profile between r ≈ 1.5 kpc and r ≈ 10 kpc. At smaller radii, r ≲ 1.5 kpc, the haloes develop a flatter than NFW slope. This unexpected feature may be specific to our particular choice of subgrid physics model but nevertheless the dark matter density profiles agree within 30 per cent as the mass resolution is increased by a factor 150. The inner regions of the haloes are almost perfectly spherical (axis ratios b/a > 0.97 within r = 1 kpc) and there is no offset larger than 45 pc between the centre of the stellar distribution and the centre of the dark halo. The morphology of the predicted dark matter annihilation radiation signal is in broad agreement with γ-ray observations at large Galactic latitudes (b ≳ 3°). At smaller angles, the inferred signal in one of our four galaxies is similar to that which is observed but it is significantly weaker in the other three.

Citation

Schaller, M., Frenk, C. S., Theuns, T., Calore, F., Bertone, G., Bozorgnia, N., …Schaye, J. (2016). Dark matter annihilation radiation in hydrodynamic simulations of Milky Way haloes. Monthly Notices of the Royal Astronomical Society, 455(4), 4442-4451. https://doi.org/10.1093/mnras/stv2667

• Journal Article Type: Article
• Acceptance Date: Nov 10, 2015
• Online Publication Date: Dec 9, 2015
• Publication Date: Feb 1, 2016
• Deposit Date: Feb 22, 2016
• Publicly Available Date: Feb 23, 2016
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 455
• Issue: 4
• Pages: 4442-4451
• DOI: https://doi.org/10.1093/mnras/stv2667
• Keywords: Methods: numerical, Galaxy: centre, Cosmology: theory, Dark matter, Gamma-rays: galaxies.
• Public URL: https://durham-repository.worktribe.com/output/1419076
• Related Public URLs: http://arxiv.org/abs/1509.02166