Galaxy formation with BECDM - I. Turbulence and relaxation of idealized haloes

Philip Mocz*, Mark Vogelsberger, Victor H. Robles, Jesús Zavala, Michael Boylan-Kolchin, Anastasia Fialkov, Lars Hernquist

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

114 Citations (Scopus)


We present a theoretical analysis of some unexplored aspects of relaxed Bose-Einstein condensate dark matter (BECDM) haloes. This type of ultralight bosonic scalar field dark matter is a viable alternative to the standard cold dark matter (CDM) paradigm, as it makes the same large-scale predictions as CDM and potentially overcomes CDM's small-scale problems via a galaxy-scale de Broglie wavelength. We simulate BECDM halo formation through mergers, evolved under the Schrödinger-Poisson equations. The formed haloes consist of a soliton core supported against gravitational collapse by the quantum pressure tensor and an asymptotic r-3 NFW-like profile. We find a fundamental relation of the core-to-halo mass with the dimensionless invariant Θ ≡ |E|/M3/(Gm/h)2 or Mc/M ≃ 2.6Θ1/3, linking the soliton to global halo properties. For r ≥ 3.5 rc core radii, we find equipartition between potential, classical kinetic and quantum gradient energies. The haloes also exhibit a conspicuous turbulent behaviour driven by the continuous reconnection of vortex lines due to wave interference. We analyse the turbulence 1D velocity power spectrum and find a k-1.1 power law. This suggests that the vorticity in BECDM haloes is homogeneous, similar to thermally-driven counterflow BEC systems from condensed matter physics, in contrast to a k-5/3 Kolmogorov power law seen in mechanically-driven quantum systems. The mode where the power spectrum peaks is approximately the soliton width, implying that the soliton-sized granules carry most of the turbulent energy in BECDM haloes.

Original languageEnglish
Pages (from-to)4559-4570
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - Nov 2017

Bibliographical note

Publisher Copyright:
© 2018 The Author(s).

Other keywords

  • Dark matter
  • Galaxies: haloes
  • Methods: numerical


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