Abstract
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.
| Original language | English |
|---|---|
| Article number | 050 |
| Number of pages | 33 |
| Journal | Journal of Cosmology and Astroparticle Physics |
| Volume | 2025 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 1 Jun 2025 |
Funding
We thank S. Sibiryakov for discussions and providing valuable insights. We also thank J. M. Camalich, P. Mocz, S. Sibiryakov and W. Xue for feedback on a draft of this work. KB and LT acknowledge the support by the European Research Area (ERA) via the UNDARK project (project number 101159929). The work of MG is supported by the Alexander von Humboldt foundation and has been partially funded by the Deutsche Forschungsgemeinschaft under Germany’s Excellence Strategy — EXC 2121 Quantum Universe — 390833306. EH acknowledges the U.K. Science and Technology Facilities Council for support through the Quantum Sensors for the Hidden Sector collaboration under the grant ST/T006145/1 and U.K. Research and Innovation Future Leader Fellowship MR/V024566/1. For the purpose of open access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript (AAM) version arising from this submission.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics