Abstract
We present a comparative confrontation of both the Bose-Einstein Condensate (BEC) and the Navarro-Frenk-White (NFW) dark halo models with galactic rotation curves. We employ 6 High Surface Brightness (HSB), 6 Low Surface Brightness (LSB), and 7 dwarf galaxies with rotation curves falling into two classes. In the first class rotational velocities increase with radius over the observed range. The BEC and NFW models give comparable fits for HSB and LSB galaxies of this type, while for dwarf galaxies the fit is significantly better with the BEC model. In the second class the rotational velocity of HSB and LSB galaxies exhibits long flat plateaus, resulting in better fit with the NFW model for HSB galaxies and comparable fits for LSB galaxies. We conclude that due to its central density cusp avoidance the BEC model fits better dwarf galaxy dark matter distribution. Nevertheless it suffers from sharp cutoff in larger galaxies, where the NFW model performs better. The investigated galaxy sample obeys the Tully-Fisher relation, including the particular characteristics exhibited by dwarf galaxies. In both models the fitting enforces a relation between dark matter parameters: the characteristic density and the corresponding characteristic distance scale with an inverse power.
Highlights
The visible part of most galaxies is embedded in a dark matter (DM) halo of yet unknown composition, observable only through its gravitational interaction with the baryonic matter
The Bose-Einstein Condensate (BEC) and NFW models give comparable fits for High Surface Brightness (HSB) and Low Surface Brightness (LSB) galaxies of this type, while for dwarf galaxies the fit is significantly better with the BEC model
The validity of our model was tested by confronting the rotation curve data of a sample of 6 HSB, 6 LSB, and 7 dwarf galaxies, with both the NFW DM and the BEC density profiles
Summary
The visible part of most galaxies is embedded in a dark matter (DM) halo of yet unknown composition, observable only through its gravitational interaction with the baryonic matter. In model [55] where a normal dark matter phase with an equation of state P = ρc2σt2r condensed into a BEC with selfinteraction (σtr = 0.0017 being the one-dimensional velocity dispersion and c the speed of light), the stability of the BEC halo depends on the particle mass and scattering length. The model has been tested on kpc scales confronting it with galactic rotation curve observations [10] It was pointed out by [58] that the effects of BEC DM should be seen in the matter power spectrum if the boson mass is in the range 15 meV < m < 35 meV and 300 meV < m < 700 meV for the scattering lengths a = 106 fm and a = 1010 fm, respectively.
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