Answer to the Comment about the Letter entitled ``Scalar fields as dark matter in spiral galaxies''
In this manuscript the authors present a detailed answer to the comment in order to avoid misunderstandings in the future.
gr-qc↗
arXiv subjects
T. Matos
Publications and source records attributed to T. Matos.
Quintessence and Scalar Dark Matter in the Universe
Continuing with previous works, we present a cosmological model in which dark matter and dark energy are modeled by scalar fields $Φ$ and $Ψ$, respectively, endowed with the scalar potentials $V(Φ)=V_{o}[ \cosh {(λ\sqrt{κ_{o}}Φ)}-1] $ and $\tilde{V}(Ψ)=\tilde{V_{o}}[ \sinh {(α\sqrt{κ_{o}}Ψ)}] ^β$. This model contains 95% of scalar field. We obtain that the scalar dark matter mass is $m_Φ\sim 10^{-26}eV.$ The solution obtained allows us to recover the success of the standard CDM. The implications on the formation of structure are reviewed. We obtain that the minimal cutoff radio for this model is $r_{c}\sim 1.2 kpc.$
astro-ph↗
Scalar dark matter in spiral galaxies
An exact, axially symmetric solution to the Einstein-Klein-Gordon field equations is employed to model the dark matter in spiral galaxies. The extended rotation curves from a previous analysis are used to fit the model and a very good agreement is found. It is argued that, although our model possesses three parameters to be fitted, it is better than the non-relativistic alternatives in the sense that it is not of a phenomenological nature, since the dark matter would consist entirely of a scalar field.
astro-ph↗
Scalar Field as Dark Matter in the Universe
We investigate the hypothesis that the scalar field is the dark matter and the dark energy in the Cosmos, wich comprises about 95% of the matter of the Universe. We show that this hypothesis explains quite well the recent observations on type Ia supernovae.
astro-ph↗
A new cosmological tracker solution for Quintessence
In this paper we propose a quintessence model with the potential $V(Φ)=V_{o}[ \sinh {(α\sqrt{κ_{o}}ΔΦ})] ^β$, which asymptotic behavior corresponds to an inverse power-law potential at early times and to an exponential one at late times. We demonstrate that this is a tracker solution and that it could have driven the Universe into its current inflationary stage. The exact solutions and the description for a complete evolution of the Universe are also given. We compare such model with the current cosmological observations.
astro-ph↗
Quintessence at Galactic Level?
Recently it has been proposed that the main contributor to the dark energy of the Universe is a dynamical, slow evolving, spatially inhomogeneous scalar field called quintessence. We investigate the behavior of this scalar field at galactic level by assuming that it is the dark matter compossing the halos of galaxies. Using an exact solution of the Einstein's equations we find an excellent concordance between our results and observations.
astro-ph↗
Can magnetic fields of astrophysical objects be fundamental ?
We analyze a new class of static exact solutions of Einstein-Maxwell-Dilaton gravity with arbitrary scalar coupling constant $α$, representing a gravitational body endowed with electromagnetic dipole moment. This class possesses mass, dipole and scalar charge parameters. A discussion of the geodesic motion shows that the scalar field interaction is so weak that it cannot be measured in gravitational fields like the sun, but it could perhaps be detected in gravitational fields like pulsars. The scalar force can be attractive or repulsive. This gives rise to the hypothesis that the magnetic field of some astrophysical objects could be fundamental.
gr-qc↗
Post-post-newtonian limit of a dilatonic gravity model
We study a solution of the field equations for dilatonic gravity and obtain its post-post-newtonian limit. It turns out that terms to this and higher orders in the expansion may become important in strong gravitational fields, even though the post-newtonian limit coincides with that of General Relativity. This suggests that strong gravitational fields can only be studied by exact solutions of the field equations.
gr-qc↗
From vacuum field equations on principal bundles to Einstein equations with fluids
In the present work we show that the Einstein equations on $M$ without cosmological constant and with perfect fluid as source, can be obtained from the field equations for vacuum with cosmological constant on the principal fibre bundle $P(\frac{1}{I} M,U(1))$, $M$ being the space-time and $I$ the radius of the internal space $U(1)$.
gr-qc↗
Solutions in Self-Dual Gravity Constructed Via Chiral Equations
The chiral model for self-dual gravity given by Husain in the context of the chiral equations approach is discussed. A Lie algebra corresponding to a finite dimensional subgroup of the group of symplectic diffeomorphisms is found, and then use for expanding the Lie algebra valued connections associated with the chiral model. The self-dual metric can be explicitly given in terms of harmonic maps and in terms of a basis of this subalgebra.
hep-th↗