424 research outputs found
Is dark matter a BEC or scalar field?
This is a brief review on the history of the Bose-Einstein condensate (BEC)
or boson star model of galactic dark matter halos, where ultra-light scalar
dark matter particles condense in a single BEC quantum state. The halos can be
described as a self-gravitating, possibly self-interacting, coherent scalar
field.
On a scale larger than galaxies, dark matter behaves like cold dark matter
while below that scale the quantum mechanical nature suppresses the dark matter
structure formation due to the minimum length scale determined by the mass
m\st{>}{\sim}10^{-24} eV and the self-interaction of the particles. This
property could alleviate the cusp problem and missing satellite problems of the
CDM model. Furthermore, this model well reproduces the observed
rotation curves of spiral and dwarf galaxies, which makes the model promising.Comment: published versio
Brief History of Ultra-light Scalar Dark Matter Models
This is a review on the brief history of the scalar field dark matter model
also known as fuzzy dark matter, BEC dark matter, wave dark matter, or
ultra-light axion.
In this model ultra-light scalar dark matter particles with mass condense in a single Bose-Einstein condensate state and behave
collectively like a classical wave. Galactic dark matter halos can be described
as a self-gravitating coherent scalar field configuration called boson stars.
At the scale larger than galaxies the dark matter acts like cold dark matter,
while below the scale quantum pressure from the uncertainty principle
suppresses the smaller structure formation so that it can resolve the small
scale crisis of the conventional cold dark matter model.Comment: 5 page
Fermion Scattering at a Phase Wave
We study fermion reflection at a phase wave which is formed during a bubble
collision in a first order phase transition. We calculate the reflection and
the transmission coefficients by solving the Dirac equation with the phase wave
background. Using the results we analyze the damping and the velocity of the
wave.Comment: 19 pages. Standard Latex file with 2 tex figure
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