Publication details for Mr Tsang ChanLazar, Alexandres, Bullock, James S., Boylan-Kolchin, Michael, Chan, T.K., Hopkins, Philip F., Graus, Andrew S., Wetzel, Andrew, El-Badry, Kareem, Wheeler, Coral, Straight, Maria C., Kereš, Dušan, Faucher-Giguère, Claude-André, Fitts, Alex & Garrison-Kimmel, Shea (2020). A dark matter profile to model diverse feedback-induced core sizes of ΛCDM haloes. Monthly Notices of the Royal Astronomical Society 497(2): 2393-2417.
- Publication type: Journal Article
- ISSN/ISBN: 0035-8711 (print), 1365-2966 (electronic)
- DOI: 10.1093/mnras/staa2101
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
We analyse the cold dark matter density profiles of 54 galaxy haloes simulated with Feedback In Realistic Environments (FIRE)-2 galaxy formation physics, each resolved within 0.5 per cent of the halo virial radius. These haloes contain galaxies with masses that range from ultrafaint dwarfs (M⋆≃104.5M⊙) to the largest spirals (M⋆≃1011M⊙) and have density profiles that are both cored and cuspy. We characterize our results using a new, analytic density profile that extends the standard two-parameter Einasto form to allow for a pronounced constant density core in the resolved innermost radius. With one additional core-radius parameter, rc, this three-parameter core-Einasto profile is able to characterize our feedback-impacted dark matter haloes more accurately than other three-parameter profiles proposed in the literature. To enable comparisons with observations, we provide fitting functions for rc and other profile parameters as a function of both M⋆ and M⋆/Mhalo. In agreement with past studies, we find that dark matter core formation is most efficient at the characteristic stellar-to-halo mass ratio M⋆/Mhalo ≃ 5 × 10−3, or M⋆∼109M⊙, with cores that are roughly the size of the galaxy half-light radius, rc ≃ 1−5 kpc. Furthermore, we find no evidence for core formation at radii ≳100 pc in galaxies with M⋆/Mhalo < 5 × 10−4 or M⋆≲106M⊙. For Milky Way-size galaxies, baryonic contraction often makes haloes significantly more concentrated and dense at the stellar half-light radius than DMO runs. However, even at the Milky Way scale, FIRE-2 galaxy formation still produces small dark matter cores of ≃ 0.5−2 kpc in size. Recent evidence for a ∼2 kpc core in the Milky Way’s dark matter halo is consistent with this expectation.