Bracketing the soliton-halo relation of ultralight dark matter

Journal article

In theories of ultralight dark matter, solitons form in the inner regions of galactic halos. The observational implications of these depend on the soliton mass. Various relations between the mass of the soliton and properties of the halo have been proposed. We analyze the implications of these relations, and test them with a suite of numerical simulations. The relation of Schive et al. 2014 is equivalent to (E/M)sol = (E/M)halo where E sol(halo) and M sol(halo) are the energy and mass of the soliton (halo). If the halo is approximately virialized, this relation is parametrically similar to the evaporation/growth threshold of Chan et al. 2022, and it thus gives a rough lower bound on the soliton mass. A different relation has been proposed by Mocz et al. 2017, which is equivalent to E sol = E halo, so is an upper bound on the soliton mass provided the halo energy can be estimated reliably. Our simulations provide evidence for this picture, and are in broad consistency with the literature, in particular after accounting for ambiguities in the definition of E halo at finite volume.

Authors: Blum, K; Gorghetto, M; Hardy, E; Teodori, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: Journal of Cosmology and Astroparticle Physics
• Volume: 2025
• Issue: 06
• Article number: 050
• Publication date: 2025-06-24
• Acceptance date: 2025-05-20
• DOI: 10.1088/1475-7516/2025/06/050
• EISSN: 1475-7516
• Language: English
• Keywords: dark matter theory; dark matter simulations