716 research outputs found
Galactic Nonlinear Dynamic Model
We develop a model for spiral galaxies based on a nonlinear realization of
the Newtonian dynamics starting from the momentum and mass conservations in the
phase space. The radial solution exhibits a rotation curve in qualitative
accordance with the observational data.Comment: 6 pages, 1 figure. Talk given in the 7th Alexander Friedmann
International Seminar, June 29 to July 5, 2008, Joao Pessoa, PB, Brazi
Dark matter from cosmic defects on galactic scales?
We discuss the possible dynamical role of extended cosmic defects on galactic
scales, specifically focusing on the possibility that they may provide the dark
matter suggested by the classical problem of galactic rotation curves. We
emphasize that the more standard defects (such as Goto-Nambu strings) are
unsuitable for this task, but show that more general models (such as transonic
wiggly strings) could in principle have a better chance. In any case, we show
that observational data severely restricts any such scenarios.Comment: Submitted to Phys. Rev. D (Brief Reports). v2: Reference added and
some typos corrected, matches published versio
Environmental impacts of electricity self-consumption from organic photovoltaic battery systems at industrial facilities in Denmark
Resolving the virial discrepancy in clusters of galaxies with modified Newtonian dynamics
A sample of 197 X-ray emitting clusters of galaxies is considered in the
context of Milgrom's modified Newtonian dynamics (MOND). It is shown that the
gas mass, extrapolated via an assumed model to a fixed radius of 3 Mpc,
is correlated with the gas temperature as predicted by MOND (). The observed temperatures are generally consistent with the inferred
mass of hot gas; no substantial quantity of additional unseen matter is
required in the context of MOND. However, modified dynamics cannot resolve the
strong lensing discrepancy in those clusters where this phenomenon occurs. The
prediction is that additional baryonic matter may be detected in the central
regions of rich clusters.Comment: Submitted to A&A, 4 pages, 3 figures, A&A macro
Singlet fermionic dark matter
We propose a renormalizable model of a fermionic dark matter by introducing a
gauge singlet Dirac fermion and a real singlet scalar. The bridges between the
singlet sector and the standard model sector are only the singlet scalar
interaction terms with the standard model Higgs field. The singlet fermion
couples to the standard model particles through the mixing between the standard
model Higgs and singlet scalar and is naturally a weakly interacting massive
particle (WIMP). The measured relic abundance can be explained by the singlet
fermionic dark matter as the WIMP within this model. Collider implication of
the singlet fermionic dark matter is also discussed. Predicted is the elastic
scattering cross section of the singlet fermion into target nuclei for a direct
detection of the dark matter. Search of the direct detection of the dark matter
provides severe constraints on the parameters of our model.Comment: 12 pages, 7 figure
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