We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Durham University

Department of Physics

Staff profile

Publication details for Mr Tsang Chan

Lazar, 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.

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.