Galaxy formation with BECDM – I. Turbulence and relaxation of idealized haloes
Name
1705.05845.pdf
Description
Accepted version
Size
3.45 MB
Format
Adobe PDF
Checksum (MD5)
68382618e8033dc2bb54844847c8170f
Author(s)
Mocz, Philip
Vogelsberger, Mark
Robles, Victor H
Zavala, Jesús
Boylan-Kolchin, Michael
Fialkov, Anastasia
Hernquist, Lars
Date Issued
2017
Journal
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press (OUP)
Version
Author's final manuscript
Abstract
© 2018 The Author(s). 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.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1093/MNRAS/STX1887
