Scalar field dark matter

Pie chart showing the fractions of energy in the universe contributed by different sources. Ordinary matter is divided into luminous matter (the stars and luminous gases and 0.005% radiation) and nonluminous matter (intergalactic gas and about 0.1% neutrinos and 0.04% supermassive black holes). Ordinary matter is uncommon. Modeled after Ostriker and Steinhardt.[1] For more information, see NASA.

In astrophysics and cosmology scalar field dark matter is a classical, minimally coupled, scalar field postulated to account for the inferred dark matter.[2]

Background

The universe may be accelerating, fueled perhaps by a cosmological constant or some other field possessing long range ‘repulsive’ effects. A model must predict the correct form for the large scale clustering spectrum,[3] account for cosmic microwave background anisotropies on large and intermediate angular scales, and provide agreement with the luminosity distance relation obtained from observations of high redshift supernovae. The modeled evolution of the universe includes a large amount of unknown matter in order to agree with such observations. This matter has two components cold dark matter and dark energy. Each contributes to the theory of the origination of galaxies and the expansion of the universe. The universe must have a critical density, a density not explained by baryonic matter (ordinary matter) alone.

Scalar field

The dark matter can be modeled as a scalar field using two fitted parameters, mass and self-interaction.[4][5] In this picture the dark matter consists of an ultralight particle with a mass of O(10−22) eV when there is no self-interaction.[6][7] If there is a self-interaction a wider mass range is allowed.[8] The uncertainty in position of a particle is larger than its Compton wavelength, and for some reasonable estimates of particle mass and density of dark matter there is no point talking about the individual particle's position and momentum. The dark matter is more like a wave than a particle, and the galactic halos are giant systems of condensed bose liquid, possibly superfluid. The dark matter can be described as a Bose–Einstein condensate of the ultralight quanta of the field[9] and as boson stars.[8] The enormous Compton wavelength of these particles prevents structure formation on small subgalactic scales, which is a major problem in traditional cold dark matter models. The collapse of initial overdensities is studied in Refs.[10]

This dark matter model is also known as BEC dark matter or wave dark matter. Fuzzy dark matter and ultra-light axion are examples of scalar field dark matter.

See also

References

  1. ↑ Jeremiah P. Ostriker and Paul Steinhardt New Light on Dark Matter
  2. ↑ J. Val Blain, ed. (2005). Trends in Dark Matter Research. Contributors: Reginald T. Cahill, F. Siddhartha Guzman, N. Hiotelis, A.A. Kirillov, V.E. Kuzmichev, V.V. Kuzmichev, A. Miyazaki, Yu. A. Shchekinov, L. Arturo Urena-Lopez, E.I. Vorobyov. Nova Publishers. p. 40. ISBN 1-59454-248-1.
  3. ↑ Galaxies are not scattered about the universe in a random way, but rather form an intricate network of filaments, sheets, and clusters. How these large-scale structures formed is at the root of many key questions in cosmology.
  4. ↑ Baldeschi, M. R.; Gelmini, G. B.; Ruffini, R. (1983-03-10). "On massive fermions and bosons in galactic halos". Physics Letters B. 122 (3): 221–224. doi:10.1016/0370-2693(83)90688-3.
  5. ↑ Membrado, M.; Pacheco, A. F.; Sañudo, J. (1989-04-01). "Hartree solutions for the self-Yukawian boson sphere". Physical Review A. 39 (8): 4207–4211. doi:10.1103/PhysRevA.39.4207.
  6. ↑
    T. Matos and L. A. Ureña-López, Quintessence and Scalar Dark Matter in the Universe, Class. Quant. Grav. 17, L75-L81 (2000) preprint; A Further Analysis of a Cosmological Model of Quintessence and Scalar Dark Matter, Phys. Rev. D 63, 063506 (2001) preprint
  7. ↑ V. Sahni and L. Wang, A New Cosmological Model of Quintessence and Dark Matter, Phys. Rev. D 62, 103517 (2000) preprint
  8. 1 2 J. Lee and I. Koh Phys.Rev. D53,2236 (1996),Galactic Halos As Boson Stars preprint
  9. ↑ S.J. Sin, Phys. Rev., D50, 3650(1994), Late-time cosmological phase transition and galactic halo as Bose liquid preprint,
  10. ↑ M. Alcubierre, F. S. Guzmán, T. Matos, D. Núñez, L. A. Ureña-López and P. Wiederhold, Galactic Collapse of Scalar Field Dark Matter, Class. Quant. Grav. 19, 5017 (2002) preprint; F. S. Guzmán and L. A. Ureña-López, Evolution of the Schrödinger--Newton system for a self--gravitating scalar field, Phys. Rev. D 69, 124033 (2004) preprint; Gravitational cooling of self-gravitating Bose-Condensates, ApJ. 645, 814 (2006) preprint; A. Bernal and F. S. Guzmán, Scalar Field Dark Matter: non-spherical collapse and late time behavior, Phys. Rev. D 74, 063504 (2006) preprint.
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