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Lookup NU author(s): Professor Nikolaos ProukakisORCiD, Dr Gerasimos Rigopoulos, Dr Alex SotoORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2024 authors. Published by the American Physical Society. We analyze perturbations of self-interacting, scalar field dark matter that contains modes in both a coherent condensate state and an incoherent particlelike state. Starting from the coupled equations for the condensate, the particles' phase-space distribution, and their mutual gravitational potential, first derived from first principles in earlier work by the authors, we derive a hydrodynamic limit of two coupled fluids and study their linearized density perturbations in an expanding universe, also including particle pressure under an assumption for an equation of state consistent with the dynamical equations. We find that away from the condensate-only or particle-only limits, and for certain ranges of the parameters, such self-interacting mixtures can significantly enhance the density power spectrum above the standard linear ΛCDM value at localized wave numbers, even pushing structure formation into the nonlinear regime earlier than expected in ΛCDM for these scales. We also note that such mixtures can lead to degeneracies between models with different boson masses and self-coupling strengths, in particular, between self-coupled models and noncoupled fuzzy dark matter made up of heavier bosons. These findings open up the possibility of a richer phenomenology in scalar field dark matter models and could further inform efforts to place observational limits on their parameters.
Author(s): Proukakis NP, Rigopoulos G, Soto A
Publication type: Article
Publication status: Published
Journal: Physical Review D
Year: 2024
Volume: 110
Issue: 2
Print publication date: 15/07/2024
Online publication date: 02/07/2024
Acceptance date: 04/06/2024
Date deposited: 15/07/2024
ISSN (print): 2470-0010
ISSN (electronic): 2470-0029
Publisher: American Physical Society
URL: https://doi.org/10.1103/PhysRevD.110.023504
DOI: 10.1103/PhysRevD.110.023504
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