UNDERSTANDING THE ‘FEEBLE GIANT’ CRATER II WITH TIDALLY STRETCHED WAVE DARK MATTER
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Date
2022
Authors
Pozo, Alvaro
Broadhurst, Tom
Emami, Razieh
Smoot, George
Journal Title
Journal ISSN
Volume Title
Publisher
Monthly Notices of the Royal Astronomical Society
Abstract
The unusually large ‘dwarf’ galaxy Crater II, with its small velocity dispersion, ≃3 km s−1, defies expectations that low-mass galaxies should be small and dense. We combine the latest stellar and velocity dispersion profiles finding Crater II has a prominent dark core of radius ≃0.71+0.09−0.08
kpc, surrounded by a low density halo, with a transition visible between the core and the halo. We show that this profile matches the distinctive core-halo profile predicted by ‘Wave Dark Matter’ as a Bose-Einstein condensate, ψDM, where the ground state soliton core is surrounded by a tenuous halo of interfering waves, with a marked density transition predicted between the core and halo. Similar core-halo structure is seen in most dwarf spheroidal galaxies (dSphs), but with smaller cores, ≃0.25 kpc and higher velocity dispersions, ≃9 km s−1, and we argue here that Crater II may have been a typical dSph that has lost most of its halo mass to tidal stripping, so its velocity dispersion is lower by a factor of 3 and the soliton is wider by a factor of 3, following the inverse scaling required by the Uncertainty Principle. This tidal solution for Crater II in the context of ψDM is supported by its small pericenter of ≃20 kpc established by Gaia, implying significant tidal stripping of Crater II by the Milky Way is expected.
Description
Keywords
Type of access: Open Access, Dark Matter, Galaxy: kinematics and dynamics
Citation
Pozo, A., Broadhurst, T., Emami, R., & Smoot, G. F. (2022). Understanding the ‘feeble giant’ Crater II with tidally stretched wave dark matter. Monthly Notices of the Royal Astronomical Society, 515(2), 2624–2632. https://doi.org/10.1093/mnras/stac1862